Skip to main content

Full text of "A study of the preparation of cyclic azo compounds and the structure of naphthalene, tetralin and hydrindene"

See other formats


university or AiDerta Library 



283 8 





For Reference 

NOT TO BE TAKEN FROM THIS ROOM 

§ 

THESIS 

A STUDY OE THE PREPARATION OF 
CYCLIC AZO COMPOUNDS, 
and 

THE STRUCTURE OF NAPHTHALENE, 
TETRALIN AND HYDRINDENE• 

submitted by 

Taylor Herbert Evans, B.So. 





















































































































































































































Sx UBJtW 

otoebsiwis 

H1BERMIHSJS 


tfY Op 























































A STUDY OF THE PREPARATI OH OF CYCLIC AZO COMPOUNDS 


and 

THE STRUCTURE OF NAPHTHALENE, TETRALIN AND HYDRINDENE 


by 

Taylor Herbert Evans, B.So. 


Department of Chemistry 
University of Alberta 


A THESIS 

Submitted to the Committee on 
Graduate Studies, University of 
Alberta, in fulfilment of the 
requirements for the degree of 
Master of Science. 


Edmonton, Alberta 


May, 1938 



Digitized by the internet Archive 
in 2018 with funding from 
University of Alberta Libraries 



https://archive.org/details/studyofpreparatiOOevan 


ACKNOWLEDGMENT 


The author wishes to express his gratitude to 
Dr. R.B.Sandin, without whose assistance and guidance this 
work would not have been possible, and to Mr. W.A.Lang, 
who kindly carried out the combustion analyses. 











' 

f ; ' .■ '-■*' t ;; •• 

? . . ^ .. " 









• to ' U 




























PART I 


A STUDY OF THE PREPARATION OF CYCLIC AZO COMPOUNDS 

Introduction 

The main purpose of this work was to make a study 
of the preparation of some simple cyclic azo compounds 
which might correspond to the now known carcinogenic fused 
carbocyclic systems. The latter are known to contain 
essentially the phenanthrene skeleton. Cyclic azo compounds 
comparable to phenanthrene are known. 




Phenanthrene Cyclic o,o'-azodiphenyl 

It was therefore thought that compounds corresponding to 
cyclic o ,o' -azodiphenyl, but a little more complicated, 
might be synthesized, and their properties studied. 

Behind this synthetic work there was the faint 
hope that these compounds might in some way be connected 
with the cancer problem. A very simple azo dye, 
o-aminoazotoluene, has been shown to be cancer-producing. 

At the same time, the well-known azo dye, congo red, has 
proved to be detrimental to the growth of cancer. It would 











; - : ' . J -:J- ' v: : o.: . " 







■ r • .. ... ■. •; . „w ..••• ■ v o'Vo 

• . ' : li ’ ■ 

r 

: •'.. . . . .. ' ■■ V- x V-: • 

; - .v .>-V, o : ... ,v . . V .... . . v... 

o . ... ; , - 














r - -o', c ; 


: .. 


. _ . o ; . V:.- ; 

.;; ; . o. .: - . •. ;...-. ;o 

V: : . . . V .V. .V ... : .V.. 

. . ; ."... . : V . 

!*!•: {, 

.; V... V: : : •• . ■. i VI . 

! |V.J s . j . C - ' , - ■ ■ ■ ". . . 

• I . . . . - . - • 

i 



2 


seem, therefore, that some azo compounds promote the growth 
of cancer, whereas other azo compounds have a retarding 
effect. 

The mechanism vfoereby certain hydrocarbons 
start normal cells on a career of malignancy is entirely 
unknown, and if a chemical reaction is involved, the 
nature of the change is quite obscure* Most of the 
carcinogenic hydrocarbons are more susceptible to oxidation 
than to other reactions, but there is no evidence that an 
oxidation is involved. The high degree of specificity 
in structure among the derivatives of 1,2-benzanthracene 
is difficult to reconcile with the hypothesis that an 
agent of a certain reducing intensity is required to 
initiate malignant growth, and this same specificity 
probably rules out the explanation based upon the concep¬ 
tion of a chronic irritation. Possibly the molecular 
dimensions and the surface activity of the substances are 
as important as their chemical characteristics. 

The experimental work on this particular problem 
was found to be rather difficult, and time-consuming. 

Many steps were involved in the synthesis of the one cyclic 
azo compound which has been prepared, and the yield 
diminished with each step. This meant constant repetition, 
so that we are only now really ready to start on the 
problem. 

The accompanying flow sheet indicates the steps 
involved in the preparation of the first azo compound. 




o ... ■«- . . •: .... 







. : or. c» .. 

. . . :• 


; ■ : : ... c : : :: ‘ 

. . . : o r .: I.-.; ' : . . ' ’ 

. - • 

. ' . .. .' : ... . 

: : • .. 1 ': .. •: 

j ■ • 

BB • • <I 1 HBn B ■ • | BB 9 h' 

. . • ”, ... : ~ ... 

; . V r: •• ... . : v ' . .r ' : . . / r ‘ rJ. 

. [ 11 1 
[ x • 3 ■ oxfJ 

t 

: 

. : . ' : ■ 

. 

. ■ ' . . . •. ... / . ... 

' 

. ■ 

. 

' 

• . j . . c . 

1 

’ 

- . J ' x - 0 . 

' 


3 




oC -Naphthylamine (I) was acetylated, and nitrated. 
The resulting isomeric nitroacenaphthalides were hydrolyzed, 
and 2-nitro-l-naphthylamine (II) isolated. This was then 
diazotized, forming l-iodo-2-nitro-naphthalene (III). Two 
molecules of the latter were coupled by removing the two 
iodine atoms with copper bronze, and 2,2 -dinitro-1,1 - 
dinaphthyl (IV) was formed. The latter compound was 

4 4 . . 

reduced to give cyclic 2,2 -azo-1,1 -dinaphthyl (V). 

Experimental Part 

Preparation of 2-nitno-1-naphthylamine ♦ - 
Acylation of an amine prior to nitration is necessary to 
protect it against oxidation. oC -Naphthylamine has been 
acylated by several methods: 


























... .. . : c,.' -u, ' ' 

# 

' 

- - ; . - 

- LSI . : -- £ l C • . td ■ >i 




. . •: f ;CC ■ ■ Js.ol 

' . . Vs ' : 

: - : , ■ - . ' :q . .. .. 


; 




1 

. . . . : " - • j j ■ '• c 

, elo Mb b J® d 3xi leg s J s no; 


: . ' : •' . . • 















4 


1. Boiling the amine with acetic anhydride and 
glacial acetic acid 3 . 

2. Refluxing the amine for one hour with 5 
parts of 50 °Jo acetic acid, and one part of acetic anhydride. 

3. Treating the amine with acetic acid and 
acetic anhydride at room temperature for 15 minutes, then 
cooling in an ice-bath, and stirring. 

4. Heating the amine at 100° for 20 minutes with 
glacial acetic acid, and a slight excess of acetic anhydride. 
This latter method gave very satisfactory results, and was 
the one used. 

Whether nitration is carried out with nitric acid 
alone, or with nitric acid combined with some other reagent, 
does not seem to affect the total yield to any great extent, 
but it may affect the individual yields of the various 
possible isomers 1 . The temperature of nitration exerts 
a considerable effect both on the total yield and on the 
individual yields of the isomers 2 . An increase in the 
temperature of nitration decreases the total yield, and 
also the relative proportion of the ortho isomer, as shown 
in the following table 2 . Eight grams of aceto-C- 
naphthalide, nitrated, and then hydrolyzed with alkali, 
gave the following results*. 




Temperature 

5-10° 

30° 

50° 

70° 

Grams 

of 

2-nitro-l-naphthol 

1.5 

1.1 

1.1 

1.1 

Grams 

of 

4-nit ro-1-naphth ol 

4.4 

4.4 

3.9 

3.6 


Hodgson and Walker 1 found that the mixed nitro- 


. ;. . -. ' :I doc 









p; h 


p.p'c 



O 







- • y • •• -~r 

. 




PC 

‘. . . . c ' 

y - 

'PC ;■■■ 

P .7.7. 




*4* A A 

■. O' . . 

; or 

: . 

. .. : 

pppp 

.... ' 

4- . . -W. • > 




t ‘ 

• • 


r 




Pt 7 . 

: m 


■ r d 

1 c. 

v v.. . ... , 







V > 



- 

. p : 

' 

•: 

- ■ 


. * 



- 3 

i 



- 








C, 77' 



. .j j. > 

. 

pd-p.p •. 

* 

.. V, s. 4... 

. . 

p dp. 




■ _ . v- ; y pp " P id ... ' 7 - J J . d 7 .ddd 

1; o o.Pd 


ixo.1 :ti ' i 'J 

i. 

f- l',J .P.7 

... ... C . - , •. — * '• 












•• .p; 

V •«. ... ...... • , ... .. - V, • ^ v < • V - ' - - 


,:o 




. ; 




' ; . ■ d V ••: 7 p ; 7 t : d 

■; ; ; ;. d j ... ' 77 .... J odd. :o p 

; ' p d : c o v:.. \.p :oo j ; 

. 

. i - . 


d. p . ’ p . v -’..dpi 

• : .. ' - - : : • '• ■- - 

j ' B d 0 111 I £ eiL$ c d . 




... . 






d 




, ' d . ; .• .../. ■/.. . 

' ... dd 

... ..; PC V. ... dd Y.VP 


: ,ddi7;o : 

: . 










o‘.x d;. pc pp:. ': 

— 


• w . . X ^ . 


. . . . . : 







5 


acenaphthalides formed an equimolar compound at 171° (the 
maximum), and also formed a metastable eutectic. 

The principal difference in the methods used by 
early workers in preparing 2-nitro-oC -naphthylamine was 
in the separation of the 2- and 4-nitro-acenaphthalides. 
Lelleman and Remy 4 treated the nitro-acenaphthalides with 
alcoholic potassium hydroxide. The 4-nitroamine pre¬ 
cipitated fairly rapidly, and the unchanged 2-nitro- 
acenaphthalide crystallized from the filtrate upon standing. 
Morgan and Micklethwaite 5 carried out the hydrolysis in a 
similar manner, but dissolved the product in ethyl acetate, 
and cooled the solution rapidly. The unchanged 2-nitro- 
acenaphthalide precipitated, the 4-nitro-naphthyl amine 
remained in solution, and could be recovered by concen¬ 
tration of the solvent. Hodgson and Kilner 2 hydrolyzed 
the nitro-acenaphthalides with alcoholic alkali, made the 
solution acid, and steam distilled the volatile 2-nitro- 

1- naphthol. 4-Nitro-l-naphthol is non-volatile with steam. 

Saunders and Hamilton 8 dissolved the nitroacenaphthalides 

in methanol, and passed in dry hydrogen chloride gas. The 
hydrochloride of 4-nitro-l-naphihylamine separated, while 

2- nitro-acenaphthalide remained unchanged in solution. 

Hydrolysis of the nitro-acenaphthalides with 
alcoholic alkali has been used to produce the nit ro-amine s 7 , 
or only the 4-nitro-amine from the mixed nitro-ace- 
naphthalides*> 4 » 5 > 6 . A similar procedure is used to 
produce the corresponding nitro-naphthols 2 , and acid 
hydrolysis is recommended for the production of the nitro- 

i , 3 

amines 




c 

< 






... ' • 

J3 ■ ' • 

_ . 

,' - - , ; > : : r.; 

. - j ■ ... . ... ... .' ; 

■ A ' . ; 

. . . : ; ; .. " ' ' c c '. . 

. : : , : i '. ..: : c 

; ... .r •. . ■ • 

: ; . : ■ r ' ..., .. 1 : : ; .-i r.j . :c - 

.. .. . - . ■ - 






vV" 


„. o 


. i . 

... 

■ v./i 


i 


cc ■ ~ 

' ; ; .. v. . ■ I■ 


.. . .1 - 








- - 

j 


..li.' 


. ... . ..• 










- - . - : . o, ' 

' : ■ : 

J 


■ 

. . .. « . . 'C „ . 










- : : 


. • < . y - 

... 


". ■ . . z ■: ..' . : 

. 




... 








6 


Hodgson and Walker 1 did not separate the mixed 
nitro-acenaphthslides when preparing 2-nitro-1-naphthyl- 
amine , but hydrolyzed them to the corresponding nitro-amines 
with sulfuric acid and ethanol. The nitro-amines were 
then separated by dissolving in glacial acetic acid, and 
adding concentrated hydrochloric acid. The hydrochloride 
of 4-nitro-l-naphthylamine formed, and precipitated from 
the organic solvent quantitatively, whereas the more weakly 
basic (due to the nitro-group ortho to the amino group) 
2-nitro-1-naphthylamine remained in solution unchanged. 

The latter could be recovered by diluting with water the 
filtrate from the 4-nitro-naphthylamine hydrochloride, or 
by adding sulfuric acid to the undiluted filtrate, whereby 
the stable sulfate of the 2-nitro-amine is precipitated. 

The acetic acid-hydrochloric acid method of 
separation of the nitro-amines was not the preferred method 
of Hodgson and Walker 1 . In the latter, the mixed nitro- 
amines were dissolved in dry benzene, and dry hydrogen 
chloride gas passed into the benzene solution. The hydro¬ 
chloride of the 4-nitro-amine precipitated quantitatively, 
while 2-nit ro-naphthylamine remained in solution, and could 
be recovered as the sulfate upon addition of sulfuric acid. 

The simpler acetic acid-hydrochloric acid method gave much 
better results in our hands. 

Another possible separation of the nitro-amines 1 
depends upon the fact that 2-nitro-1-naphthylamine is volatile 
with superheated steam at 160°, 1 g. per liter condensed 
distillate. (This volatility suggests chelation between 







7 


the two substituents.) This method is too slow to be 
practicable. 

The detailed procedure used in this work is 
as follows: 

Nitration of aceto-< -naohthalide c/T -Naphthyl- 
amine (Eastman’s technical grade), 60 g.,acetic anhydride, 

55 cc. (slight excess), and glacial acetic acid, 400 cc., 
were heated to 100°, and maintained at that temperature 
for 20 minutes. The solution was allowed to cool to 
about 20°, during which time beautiful white crystals of 
aceto-^C-naphthalide separated. Twenty-nine cc. of 
concentrated nitiic acid was added dropwise, the temper¬ 
ature being maintained at 15-20° by means of cooling with 
an ice-bath, and mechanical stirring. Some crystallization 
of the nitro-acenaphthalides occurred during the nitration, 
but the solution was q.uite clear when all the nitric acid 
had been added. Stirring was continued for some time 
after this. The container was then set in the ice-box 
overnight, and crystallization was generally complete in 
less than 20 hours. The crystalline precipitate consisted 
of all the 2-nitro-acenaphthalide, and most of the 4-nitro- 
acenaphthalide, the remainder of which could be obtained 
by diluting the acetic acid filtrate from the mixed 
crystals. 

Hydrolysis of the mixed 2- and 4-nitro-ace - 
naphthalides .- Eighty g. of the mixed crystals (light 
yellow), 250 cc. of 95 jo ethanol, and 250 cc. of 50^ by weight 
sulfuric acid were refluxed for 8 hours. The solution was 
then poured into 2 liters of distilled water, and the 








: .;; . /-• - - - :::• 

* . \ ' 

; .. 

:.... ; Q,. 

- _ . _ - •• . ■ _ . . 


, . : 


■ vj' 

. 

v ... .... 

; . 


. . ."L-: 

. 



. . 

V ' - V* V.' 

j .' 


.1 

. o o.. 

. .. : ,■ ;■ 


j .. - . .. - - rnjj - 

. .. ■ ■' ; : .... i : C , 

. . :/ . - - v .. 

. . ... , /• : .' . . :: : '. r. o 

. • . ~ . ! , : .; 

: ■ .... - ■. .. , 


: ' :: 

_ . . .. ... .. . ..■.....x, .... ..x J-vJ 

-. : x.'.; . ; .J - .... ..... ..... .xx: - 

... . : . . - J ... : .. . ... . 


.' xJ . , . x ..../ x 

. - ic x: . . -. • ’ . ... . 8 ■■ . ' . X' 


.' - . .. 

. ,. . .... x . x. . ex 

- -: xx j oV ...,x.x. \;o 

- . J l; xio 

.. / . . 

x ■ ■: -■ ... .... .. 

. 8 * hrt t S.Oi - lit ^ ;f,2 Vcc v DO 

• • . . ■'. ,' .. x.. :x: . . j. [ : . 

.' > : . . : : • 




8 


precipitated nitro-amines filtered. The hydrolysis of 
4-nitro-acenaphthalide (dark brown) was carried out in a 
similar manner. The use of 50fo by volume sulfuric acid 
led to tar formation during hydrolysis. 

Separation of the nitro-nanhthylamines .- Fifty 
grams of the mixed nitro-amines was dissolved in 500 cc . 
of glacial acetic aoid, and the solution filtered while 
hot into 33 cc. of concentrated hydrochloric acid. On 
cooling, the hydrochloride of 4-nitro-naphthylamine preci¬ 
pitated quantitatively, and 2-nitro-naphthylamine remained 
in solution. The salt was filtered off, and the 2-nitro- 
naphthylamine obtained from the filtrate by dilution. 
Hydrolysis of the hydrochloride in distilled water gave 
4-nitro-naphthylamine. 

Of the first three reactions, acylation, nitration 
and hydrolysis, the second one is not quantitative. In this 
case, viz. nitration, a serious difficulty was encountered. 
This was the fact that of the two isomers produced, the 
ortho isomer which was desired, was produced in the smaller 
amount (25 fo) . This is what would be expected, however, 
since the para isomer is nearly always the one produced in 
greater amount, and the ortho in a less amount. 

From 120 g. <&£ -naphthylamine, average yields 
of 32.5 g. of 2-nitro-naphthylamine, orange-red crystals, 
m.p. 143-4°, and 58 g. of 4-nitro-naphthylamine, yellow 
crystals, m.p. 193-4°, were obtained. There was also 
obtained 40 g. of 4-nitro-acenaphthalide (producing 
approximately 31 g. of the nitro-amine), by diluting the 






9 


original nitration solution. The nitro-amines were 
sufficiently pure and did not require recrystallization 
before diazotization. The total yield of the nitro- 
amines obtained averages 121-2 g., the theoretical being 
158 g. from 120 g. -naphthylamine. 

Preparation of l-iodo-2-nitro-naphthalene .- 
Since 2-nitro-l-naphthylamine is a weak base, it might 
be expected that ordinary methods of diazotization would 
be unsuitable. However, the literature contains 
references to diazotization using dilute sulfuric acid 7 , 
concentrated sulfuric acid 3 , and concentrated hydrochloric 

• j O 

acid 

The method adopted was that of Sandin and 
Liskear 9 . Forty-six grams of the finely-ground nitre- 
amine was dissolved in 290 cc. of concentrated sulfuric 
acid at room temperature, and the solution cooled to 0°. 

To this solution was then added, with Stirling, a cold 
solution of sodium nitrite (19 g.) in 190 cc. concentrated 
sulfuric acid. The diazotization was completed by the 
slow addition of sirupy phosphoric acid (290 cc.) with 
vigorous stirring, the temperature being maintained at 
5-10°. The stirring was continued for several hours 
after all the phosphoric acid had been added, to ensure 
as complete diazotization as possible. The diazonium salt 
solution was then poured into 3 kg. of a mixture of ice 
and water, filtered, and treated with urea to remove any 
excess of nitrous acid, and then with a saturated solution 
of 50.7 g. of potassium iodide in water. The suspension 
was warmed and treated with sodium bisulfite to remove 





. t : ' 13x10 

: . ' : ' t ... ■ . • •-.. X ; <. 

x ' ' • : ' ' x 


. <-» . . .. . . 

- ~ 

. 

/ \ . i ■ . ■ r 

v X - - • : 7 . .X. X ' .X. XX 




• . J. 








, , y .. J 

C: ' . f; .. ■; : r ■. ;;: :: : c .0 






X -j.... .V :„ ; X ' :i . 


. - 




■ . ... . _ v; 


r 


'J. 

O ’ 




» V 






o : , , 

.7 •: .0 




■ 

. 0. • r ■ t : ••• x -■ 7- J ■ ' XX - Xc ' 




- 

. . 

‘ • A ' V*-) 

‘..x; r i x x 

- - 

• 

. . . 


•' .: r X X ; .. 

• ; . -X .X • ;\ r , - ' ■ ' xc “a 

: ■ - : 7 ' 






- . .... 


. 

. j , ; j. -• 










. . . ■ 

. i'x ■: g .■ ■ .' 

. X .. ’ : ■ .. .; '.X X 7: X'. X 

7 " ' ■ ' x x xx ; . ' x 7: /" x .7 

; 7 x x! :x 





» V W -«> »*- - . \J 4 


5 


•> • ' ' . * • 

(, ... ... 






xc. ‘ X' j 


xx 








.... • .. . . .. . . ■ 
* .. w ■!. -v' . , t j 





10 


iodine. The crude l-iodo-2-nitro~naphthalene was 
filtered off, and recrystallized from ethanol. It 
melted at 108°. The purified yield was at least 1 g. 

per gram of nitro-amine diazotized. 

/ / 

Preparation of 2,2 -dinitro-1-1 -dinaphthyl 
by means of the Ullmann reaction .- Cumming and Howie 14 
state that Ullmann’s generalizations regarding the Ullmann 
reaction (heating aromatic halogeno-compounds with finely 
divided copper to form diaryls) are correct, namely 

1- The order of reactivity of the halogen is 

1 > Br >C1. 

2. The halogen is activated by the presence of 
an acidic group, particularly a nitro-group, in the ortho 
position. 

3. Only homonuclear derivatives afford dinaphthyls. 
Hodgson and Elliot 12 state that dinaphthyl formation 

by the Ullmann reaction appears to depend on the ability of 
the copper to form covalent cuprous iodide with the 
substituted iodine, since Cumming and Howie 14 found that 
sodium did not effect condensation even in the case of 
ortho compounds. The Ullmann reaction thus differs from 
the Fittig reaction, where sodium, acting as metal or in 
sodium alkoxide, releases one of its electrons to the carbon 
and so enables ionic iodine to separate. Consequently, 
radical formation will depend upon the ease of detachment 
of neutral iodine from neutral carbon, e.g. 2 RI + Cu —■► 

2 R* + Cu 2 I 2 .—*■/?/? 

Hodgson and Elliot 12 believe that the adjacent 












~ . — — . — 

• ; 

- 



' ■ . .•! . 


. 


f/ 

J 



Id,; 









- 








; ■ . 

.. 

, . . 

; ;., i. . : . .•: ■ • ■: 

: ' ; ... : . d ; *, . d. I. I'~ 

: . : ; r » I 






' - I 




C , ... 


* ' J 


1 




. 


■ ; , ': • ■ 




' 










d .. - 














•- . - , 

.. . . id :oe'... c' . 

. .. £ .II • . 

' ; . /■ . ; : -r . : c . . : : :.•! r .. . I 1 ' 

. . i . . : i . dd,.i 

■: ... o . .' I 

I oc . :c 

i r - ? ;d J ■' !■ .II d„ '■ 

. . ; ; • ; ; •. 

. f.: - ...; ■ .c . . . 

... I :J r 




£ 3 

< - L ■ 








4 '. ( 




















11 


nucleus exerts considerable influence also. The unsub¬ 
stituted nucleus has been found to have a restraining 
(electron-attracting) influence in numerous naphthalene 
derivatives. Iodine is more easily detached from 3-iodo- 
1-nitro-naphthalene than from l-iodo-3-nitro-naphthalene 14 , 
which is additional evidence of this kationoid effect. 

Thus, the generalization regarding activation of the 
halogen by groups in ortho position must be modified by 
taking into account the effect of the unsubstituted nucleus 
which will depend on the position of the iodine. This is 
illustrated by the fact that in a relatively inert medium 
such as nitrobenzene, the 4-iodine (meta to the nitro-group) 
was removed by copper from 1,4-diiodo-S-nitro-naphthalene 
instead of the 1-iodine as would be expected. Dry heating 
of copper with 1,4-diiodo-2-nitro-naphthalene resulted 
mainly in the formation of 1-iodo-3-nitro-naphthalene, and 
a little 1-iodo-2-nitro-naphthalene. The production and 

preservation of both the previous compounds under such 
drastic reactions testify to the strength of the bond 
between the iodine and the alpha- carbon atom. 

Hodgson and Crook synthesized 8,8-dinitro- 

✓ 

1,1-dinaphthyl using the Ullmann reaction, thus proving 
that the nitro-group and the iodine need not be in the same 
ring for enhanced halogen reactivity. A lower yield was 
obtained than in the case of condensation of 1-iodo-2-nitro- 
naphthalene, but the result indicates considerable activation 
of the iodine in the 1- position by the peri- (8-) nitro 
group, which the authors believe exerts a direct effect 





s 


. .' 














F, 



~ J . V ; ..... . 3 . O V. .... V. 







3 "... . ’.: 








3 :: 


■. j 





























12 


through space, rather than a relayed induotive effect via 
the carbon atoms of the nucleus. This latter statement 
vis also supported by the fact that 8-nitro-l-naphthylamine 
can be diazotized in dilute sulfuric acid, whereas 2- 
and 4-nitro-naphthylamines cannot. 

1-Iodo-2-nitro-naphthalene (30 g.) was placed 
in a 150 oc. beaker suspended in a paraffin bath, heated 
at 120-130°. Activated copper bronze (15 g.) was added, 
with stirring, in small quantities during an hour. After 
all the copper had been added, the temperature was 
gradually raised to 150°, and maintained at this temperature 
during an hour. Several extractions of the reaction 
product with benzene were made, most of the benzene was 
then evaporated off and the dinitro-dinaphthyl crystallized 
as small light-yellow crystals. Recrystallized from 
benzene or glacial acetic acid using norite, the compound 
melted at 183-4° (uncorr.). T he theoretical yield from 
10 g. 1-iodo-2-nitro-naphthalene is 5.8 g. The purified 
yield obtained was 4.4 g. 

The copper bronze was activated according to the 
method of Kleiderer and Adams**. Copper bronze (100 g.) 
was treated with 200 cc. of a 2 fo solution of iodine in 
acetone, for 10 minutes, during which time the solution 
was decolorized. The copper was then filtered off, and 
washed with a solution of 10 cc. concentrated hydrochloric 
acid in 100 cc. acetone until all the cuprous iodide had 
been washed out from the copper, and the filtrate was clear. 
The copper was then dried in a desiccator. Yield, 97 g. 







- 

a:o 3 ; rcc.'xoc o. 
; f o 3; ■:: ■ o lo- 




j ' : 


..j 3 '.; /U : 


\ r ., , ,* - • 

... . ... s. .... • - • 

*» 

: ..' - ■ ' 

- ■ ; - - . -. 

' 1 303 ' ■ tf ■ " 3 

: - ' . • . .3/ v / o 

. : : . : : . ■, ' : ' - ■ ' 


. 


. r . 

v.! 


.? ■ 


■ 1 " ‘ . ■ ■ '■ 


. . . . ' :• r 
■ : J / ■ ‘v... f ' ' ; 


•; • : 


, • :: o \ • ■ - 3/: o :. ; - '■ ' x 




: ; . ... v. ; .. . o':,;-; ': r ..-J . ■ V- -o.';. 3 "j; :■ 

O ... ' . OV: .1... : 

• . • 






. . 

. ■ . J c 3 . . ■- •- -:g go 

. ■ - O ' 3 ’ ... " - r !■ ■ - - 

■ . . ... • , - . ■ ... — • - - • • 

- ~ 






■ 

' . . ■ J : . 3 



. • . ; : • 

• .3 : ' 




I V:.'3..' . 



j 3 *00 

■ • 

. : 



■ - 

; o :.. . .. 


:. - 

- • o .r. ■ ■. 

" '. ; . 

. 



o . no . . . ..' : C ; 



• 0$ 

t o 3 - 

• ■ , :.r . J".v .0 . '.-..o' 


i . • 


•. [ t q • 












13 


/ / 

Reduction of 2,2 -dinitro-1,1 -dinaphthyl .- 
Cumming and Howie* 5 , following the work of Vesely 16 , 
reduced the above compound to 1,1 -imino-2,2 -dinaphthyl 
(I), by heating with zinc and acetic acid for one-half 
hour. (This compound, which is also 3,4,5,6-dibenz- 
carbazole (II), has been shown to be carcinogenic .) If 
the time of heating is shorter, e.g., 3 minutes, Cumming 

is it 

and Howie were able to isolate 2,2 -diamino-1,1 -di- 
naphthyl (III). Reduction of the dinitro-compound in 
ammoniacal alcohol in the presence of sodium sulfide and 
the solution saturated with hydrogen sulfide, resulted in 
the formation of the nitro-amine (IV)Tauber has 

reduced 2,2 -dinitro-1,1 -diphenyl with sodium amalgam 

/ x 7 

to form cyclic 2,2 -azo-diphenyl (V). Houben Weyl 

2 M&OU + 

mentions sodium amalgam, and sodium zincate as the usual 
reagents for the preparation of azo compounds by the 
reduction of nitro-compounds. 

















. . ■ . 


- c " 


0 




c 


1 




. :• ■ - : 

. 

o . ... ; r , ".' ■'■'io' - '. , 
: i . , c ■ < .. 

. . . . . : . . - / ...0 
. 3 J : 3 u-'. . I 3 I.; ; 't 

:. - 3 ,/ .■:i*..: ... 

■ :. :. . .. ■ . ....; o . * ! ■ • - . I sr. 

■ ■' ' •; -j ; .. '. ■: I .'. c ; ;i: i ■ 1 iv 


o > 


> ..... 


.... . .j 


O. w .:. { ‘ 


■ ■ • c. , ’ ' •/' ‘ vJ. J7;. r . -. 3. 3 


a ■ i 






- 




- . 


o 


■ •; r : 




% 

■ ' . ■ ~ ■ < ' : . 

v & 

: v 3/ .3 


.. • . . . ' . t ■ r; ' ;• : 1 .. 

■■ ■ - 3. 3 3 ' ■ 3 3 






























14 


/ / 

The reduction of 2,2 -dinitro-1,1 -dinaphthyl 

with 3 c /o sodium amalgam in methanol resulted in the 

formation of the diamine (III), m.p. 191°. Sodium 

methylate heated with the dinitro-compound in alcoholic 

solution for 4 hours had no reducing effect. However, 

the following procedures were found to be effective: 

/ / 

Preparation of cyclic 2,2 -azo-1.1 -dinaphthyl 

* t 

One gram of 2,2 -dinitro-1,1 -dinaphthyl was dissolved 
in 125 cc. of 95$ ethanol, and alkaline sodium stannite 
added, (2 g. SnCl 2 .2H 2 0 dissolved in the minimum amount 
of water, and 40$ sodium hydroxide added in sufficient 
amount to dissolve the stannous hydroxide formed by 
hydrolysis). This mixture was refluxed for about 3 hours, 
during which time the azo-compound partly separated. The 
remainder of the azo compound could be obtained by 
diluting the ethanol. 

* / 

Two grams of 2,2 -dinitro-1,1 -dinaphthyl 
dissolved in 250 cc. of ethanol was refluxed 3 hours with 
20 cc. of 4 Q°/o sodium hydroxide, and 7 g. of zinc dust was 
added in small portions. The azo compound was formed, 
and recovered as before. 

The crude yield in these reductions was about 
60$. The azo compound was recrystallized from benzene or 

glacial acetic acid, m.p. 262° (uncorr.). (Pound: c, 85.64, 
85.55; H, 4.43, 4.51. C 20 Hi 2 N 2 requires C, 85.71; H, 4.28$.) 
Heating on the water-bath with sodium stannite rather than 
refluxing, and for a shorter length of time, 2 hours, gave 
a compound melting 247-8° (uncorr.), which is possibly the 






-• ■ r ’ ' / ir*. ■* - -\ <*<• »*•’, • i ‘ 

. . ... . V.- - - - • 

’ 

\ 


jc jc r/j . ■: 

- ■ v _ . _ ; 

:• r /:. 


. 


- 


v . ' 


.'Q 


_. 


. • 1 ./ ' -. 

■.. • 

.. .J. •, 

J ... 


, !- 

; 

r»* . »T 

... .. : 

J 

■: 

' 

• • • 


O * 


v -■* Sf. 

•• '• :: 


> J 

' ■ ■ ■ • : J 


' 

. 

. : . 

5 

• vy v.‘ 


: 3 










,Lv .. . 




.' ' ■ . . ' • : V : J ;i. v: 

• ! =: '.:r ' 




c - 




... r■ ■ 

. J J JL . 


1 <; 

o or..: ©j 




.o . •: v:v 

oo • > j .1. \rS. \ : 

.cc . 

- 

: \ c 

: .. :' . c a .*: 






. • r f 


. J „ . . . J 








J u 


■ v c . •/ ; 




. ... ’ J j Li ■ 

. .. . ' .: . , 



15 


azoxy compound. 

Attempts to determine nitrogen by modified 
Kjeldahl methods were unsuccessful, as it was very 
difficult to reduce the azo compound. 

/ / 

Attempted synthesis of cyclic 1,1 -azo-2,2 - 

dinaphthyl The same general procedure was followed as 

/ / 

with cyclic 2,2 -azo-1,1 -dinaphthyl. However, the 
separation of the nitro-^ -acenaphthalides was carried 
out by fractional crystallization, rather than by the 
separation of the unacetylated nitro-naphthylamines. 

Also, the isomer desired, l-nitro-2-naphthylamine, was 
obtained in much greater yield (approximately 50 fo compared 
with 25/a in the case of 2-nitro-l-naphthylamine). Di- 
azotization in acetic acid solution proved to be a simpler 
procedure, and gave better yields than did diazotization 
in concentrated sulfuric acid. 

Although most of the ^ -naphthylamine derivatives 
isolated were more soluble than the corresponding 

i 

oC-naphthylamine derivatives, unfortunately the 1,1 -di- 
nitro-2,2 -dinaphthyl was soluble only in a high boiling 
solvent such as nitrobenzene. This very low solubility 
partially accounts for our failures to date in attempting 
to reduce it to the desired cyclic azo compound. 

The accompanying flow sheet indicates the steps 
involved in the attempted synthesis of this second azo 
compound. 






■ J. 


• . ... 








fL . , ' ■ 




........ 


: • 1 


- 




■ - 




- . 








: • - ■ ■ • 




. ■ 


( 

. . . * ... • 




a . 


: ' •: . 1 . c 


- ■■ 


* ' , . v» V, - v- ^ 

* . v 


/: : , 


- ■ : 




' • 






o 


' 






. . v - 1 / . -* 




f. 


.: . ■ v j . Zi: ■ : ■ ■ : 


■ ■' ' . ■ ■ : 

- .... ... ■ ... - w .. 


* ' t ■ - ' ■ 

' , .. . - . . • - 


. . • i' 

ft , . ■■ ’ 4 * 


... v . ..... 


t — 


. • 








. . . .. 


• - r <*' 


' *. . .... v. 


. 

V 










































16 





PR£PAR£D 


Pre-paration of 1-nitro-2-nauhthylamine .- 
4^-Naphthylamine (Eastman technical grade), (232 g. in 500 
cc. glacial acetic acid and 225 cc. acetic anhydride), was 
acylated as in the case of oC -naphthylamine, by heating 
at 100° for 20 minutes, and allowing to cool. This gave 
300 g. of the acylated amine for the nitration 1 ®. The 
solution was cooled to room temperature, provided with a 
mechanical stirrer, and the container set in a cooling 
bath. Two hundred grams of concentrated nitric acid 
(s.g. 1.4) was added dropwise, the temperature toeing kept 
below 40°. The temperature was generally in the neighbor¬ 
hood of 30°, and no trouble was experienced with 
crystallization unless stirring was quite vigorous. At 
























f. t i ' 






















- • V 



















; . - - . . - 

. ■ {■■... : .. ■ ■/■■/; "/I'/I/-- 

o I o co 

.: o /r ? -■/ .:I\C.O 








j IIj . ... ' : 3 




- : o »» :< 

■ Solo . 

* 

. : •: " ' / .. .:: : : .V . .. c .. .1 

8 0 

* • 

/,/ o / •/ : : r::sj Gil. »/ •' -.JQl'JL 

■ J ? SI 

. - ■ :I I 11/.'1; : o 














17 


times, the phenomenon of crystallization described 1 '®, was 
observed. Stirring was continued for some time after all 
the nitric acid had been added, until crystallization 
had commenced, the container then being set in the ice-box 
for several hours. The yellow crystalline paste was 
filtered off, washed with acetic acid, and water, the 
washings being used to dilute the filtrate, which contained 
5- and 8-nitro-2-acetylaminonaphthalene. The crude dry 
solid was refluxed with 1700 cc. of benzene for 20 minutes, 
the solution allowed to cool, and then filtered through 
a large Buchner funnel, the temperature being 40-45°. 

The residue is a mixture of sparingly-soluble isomers, 
chiefly 5- and 8-nitro-2-acetylaminonaphthalene. On 
further cooling of the filtered solution, l-nitro-2- 
acetylaminonaphthalene separated as li^it brown crystals. 

It was filtered off, and recrystallized from alcohol and 
norite. The total yield of crude 1-nitno-2-acetylamino- 
naphthalene, (a) crystallized from benzene, (b) recovered 
by twice extracting with benzene the 5- and 8-nitro-2- 
acetylaminonaphthalene residues, and (c) from the evaporated 
benzene mother-liquors, was 250 g., melting at 117-20°. 

After one recrystallization, l-nitro-2-acetyl- 
aminonaphthalene melted at 122-3° (uncorr.). 

Hydrolysis of mixed acetvlated nitro-ff -naphthyl- 
amines .- One part of the mixed acetylated nitro-<^- 
naphthylamines in 4 parts of ethanol was hydrolyzed by 
refluxing 4 hours, with one part of concentrated hydrochloric 
acid. The reaction mixture was poured into water, and the 








: : -J e. -, 


J 

... . ; : ' : • • ' 
, bh ■' 












J - ; : 9 ' c ... s oc bB& 


r -'i. -I.; o:.-:: 


:uoi .'. f : \ 


. ; / . 


• c ■ , , .. , . .. : j.‘i 










- ; • . :,' J; - 

., . c . : . ... . ,. . : ... . . • 




' .. : . .. . - . . .. 


- v.' 


. c . ; . cm/i . ■ j : 3l 


: .. : - ' 

. . c - ~ -• :.. - ; ... .' .0 


.. 


■ . ..".:. . .. ' v ; 


.: .' ' : :.. ‘ , .;;: /. ■: \ .. o.c 

- : < . . . ... ■ . v.; ;) ’. 


. • . . - 




•: ■ .* ; 1 . : .,'v. . ?: ZI'CCjt 

111b c { . . & . { . 

. ■ ■ J o ■; . : c \> r 

t • i : . ... r jcb 

I .:.: 








- 


- — 


rr 


;:c 


. . V J 


. . ; . : :• ;• ...' ;. 7 ' 




.J - .... 


V. 7: , •: : ■ . .. - - -■.".; : 3. 












. , : 


. . 








a e 


. . -w *w . ^ _ V. . — 







18 


l-nitro-2-naphthylamine Miidi separated was filtered off. 

It melted at 126-7° and the yield of crude material was 
95 jo. The filtrate was made alkaline wi th sodium hydroxide. 

The resulting precipitate was filtered off, and treated 
with hot ethanol. 6-Nitro-2-naphthylamine is insoluble 
in hot ethanol, but 8-nitro-2-naphthylamine is soluble 
and may be recovered by evaporation of the ethanol. 

Preparation of l-nitro-2-iodo-naphthalene .- 
Fifty grams of l-nitro-2-naphthylamine was dissolved in 
600 cc. of hot glacial acetic acid 21 , and the solution 
cooled rapidly by shaking under the cold water tap. This 
suspension was then added slowly to a cold solution of 20 
g. (10/6 excess) of sodium nitrite dissolved in 140 cc. of 
concentrated sulfuric acid, the temperature being kept 
below 20°. Urea was added to destroy excess nitrous 
acid, and the solution of the diazonium salt v/as added to 
a saturated solution of 44 g. of potassium iodide in water. 
The resulting mixture was allowed to stand for at least an 
hour, and was then poured into water. The crude yield 
was consistently 74.5 g. (theoretical yield, 79 g.). After 
one recrystallization from ethanol, l-nitro-2-iodo- 

naphthalene melted at 89-90°. 

/ / 

Preparation of 1.l-dinitro-2,2-dinaphthvl .- 
1-Nitro-2-iodonaphthalene was melted in a 150 cc. beaker, 
suspended in a paraffin bath heated at 120-30°, and one-half 
its weight of activated copper bronze was added in small 
portions, with stirring, during an hour. The temperature 
was then raised to 165°, and stirring was continued at 










- ~ • 








... 


' 




i r.j .. ■ .. i 

.. . - 

. . ... 




■ . i 

i 

' 

- 



~ — - — 




- - 




. ... . . : . 




, 






1 




•V .. ' • 






< / ... j ...n. ,o 


• : :. o 


w. . - .< . . ... ‘ • • • ' • - 






. w • 






. . . J • B 

' 

: ooo o ’ ‘ ’... nr,: 

. ' ... . : 

:. ; . d 

... . . . r :• : . . 

' roY......: .. .'.m. 




•- fL*J T 

", ;r Y 'V. 



C- 

r c- YO 










. ' no 

.. :.' ... 


.. .. 

• 

'.. 









■ 




: 




■ 

V . . . . . • V - 1 J 
















J J. - 0 


*i J. * 









19 


intervals. The reaction mixture gradually solidified. 

It was finely ground, and extracted with hot nitrobenzene. 
The dinitro-dinaphthyl was recrystallized from nitrobenzene. 
The yield was 4 g. from 10 g. of iodo-nitro-naphthalene, 
and the melting point was 287-8°, with decomposition. If 
the reaction mixture were first extracted with benzene, 
any unchanged iodo-nitro-naphthalene could be recovered. 

Attempted preparation of cyclic l.l-azo-2.2- 

/ / 

dinanhthvl .- Cyclic 1,1-azo-2,2-dinaphthyl has not yet 

/ / 

been prepared from 1,1-dinitro-2,2-dinaphthyl. Reduction 

of the dinitro compound with sodium amalgam, sodium 
stannite, zinc and alkali, and sodium benzylate has been 
tried. In most cases, color intensification from yellow 
to orange was observed at some time during the reaction, 
but only colorless substances melting over a range, at 
comparatively low temperatures, were isolated, along with 
unchanged dinitro-compound. 






. -. 



.'u,. %. -> 








• .... C -j.'.- 




: - r V 

- 

• 

a aw 


' 

: I ' J s; ’ 

. i . 

: J. J 

• • : : . . ■’ ■ c ■. : J' 

■ . . : :C : 

. - - ; t . ; . .. . , , 






, 1 V 











.• 




j 








c 


■ - c - . ~ c : a 





' 





: 


l 

■J' ^0 






t ■ 

a. . . ... 

. - ■ 



. • 

-- 

■ . 

-«• J. - i ■ .'«•'• V - 


: .f . 


. • 

. 




... .... 

c a 

_.W 

• 


. a. : -;:r 


• r 


’ 

J • 

era: 

j. 

j 


v : 




a' -a . ac ad' 

* r - ■ 


• 

; 


. 



. j j ... 

:o 

.. t 



. 




: 



■ : 

. 



i . 

.. ... . c 








■ ' 

- 

j 

Lb 










Summary 


/ / 

1. Cyclic 2,2 -azo-1,1 -dinaphthyl has been 

prepared. 

2. An unsuccessful attempt has been made to 

* * 

prepare cyclic 1,1 -azo-2,2-dinaphthyl. 







21 


References (Part I) 

1. Hodgson and Walker, J.C.S. 1205, (1933). 

2. Hodgson and Kilner, ibid. 807, (1924). 

3. Hodgson and Kilner, ibid. 6, (1926). 

4. Lelleman and Remy, Ber. 1£, 797, (1886). 

5. Morgan and Micklethwaite, J.C.S. 928, (1905). 

6. Schoepfle, J.A.C.S. 45, 1571, (1923). 

7. Meldola, J.C.S. 519, (1885). 

8. Saunders and Hamilton, J.A.C.S. 54, 637, (1932). 

9. Sandin and Liskear, ibid. J57, 1304, (1935). 

10. Eranzen and Helwert, Ber. 53, 319, (1920). 

11. Kleiderer and Adams, J.A.C.S. 5j5, 4425, (1933). 

12. Hodgson and Elliott, J.C.S. 123, (1937). 

13. Hodgson and Crook, ibid. 571, (1937). 

14. Cumming and Howie, ibid. 3179, (1931). 

15. Cumming and Howie, ibid. 528, (1932). 

16. Vesely, Ber. 38, 136, (1905). 

17. Houben-Weyl, Die Methoden der Grganischen Chemie , 

Leipzig 1922/Georg Thleme, II, 345. 

18. Tauber, Ber. 24, 3081, (1891). 

19. Organic Synthesis, XIII, 72, Hartman and Smith. 

20. Cook et al, Amer.J.Cancer, 29., 219, (1937). 

21. Hodgson and Walker, J.C.S. 1621, (1933). 











. . . - . I 

■ 

* ... 



; : 

: - 

• 

/ 


i, : - 

. oK 

*. • .* 




• 

• - 


» * .. • 

; . d ‘ t 

■ : 








* ... - , 

. • Y . ; . 'o 

- - .. 

-0 





» 



. i ■ 



; 

, Q 

■ 



■ .. 



' 

■ - 



. 


! 

, 

. : . x . X Y::Y 

. oi. 


v. :, . \ 

- 

. 


: : .- 

■- C.C 
: ■ . :■ Y • ' . 


. - . . ; ' - • - • 
j . Y 






■ 




t 



... 


, x.:\ x 


■ - H 
\ 

. x 

v. 

• - 

1 . : ... 



■ 


xx :'o:"C 

> 


• ; 3 ; 











22 


PART II 

THE STRUCTURE OF NAPHTHALENE, TETRaLIN AND HYDRINDENE 

The structure of naphthalene has been the subject 
of many critical investigations, and has been attacked 
from several different viewpoints. The problem cannot 
be regarded as solved, although chemical evidence is q.uite 
unanimous. 

When 1-nitro-naphthalene is oxidized, 3-nitro 
phthalic acid is formed, whereas the oxidation of 
°C- naphthyl amine produces simply phthalic acid. 





Therefore, naphthalene consists of two fused benzene rings. 

The fact that 2 ,6-dichloro-naphthalene has no 
dipole moment indicates that the two lings in naphthalene 
are coplanar. 

If resonance, as occurs with benzene, 



be taken into account, three possible structures are 
suggested for naphthalene. 












. .. 




. . ' - . 



V • CJ s e:V.. 

:. ' •" : - : • 

. .■ ■ - 
. . ■ - ■ ; • • 

»a/joiftxfifin/j 




• . ' - 










.. : - ' . ' ' - 

. . j - : J . : ; 

" r • 

.* c < : j. ' 

































• - ;r i' ■ cJ 

.. . !■ . :«• !£:./ ' 




23 



Some workers believe that an equilibrium between these 
three structures affords the most satisfactory explanation 
of the properties of naphthalene derivatives. However, 
most of the chemical evidence indicates that resonance is 
not involved, and favors structure II. 

The chemical evidence rests chiefly on the 
reactivity of the 1-position, and the non-reactivity of 
the 3-position in 2-substituted naphthalene compounds. 

This is explained by the presence of a double bond between 
Ci and C 2 , and a single bond between C 2 and C 3 . 

The failure of the coupling reaction in certain 
specific instances favors the Erlenmeyer formula (II) for 
naphthalene. & -Naphthol couples at position 1, but if 
this position is blocked by a stable group (alkyl), as 
shown below (IV), no coupling with diazotized amines occurs. 
A less stable group (carboxyl, halogen) at the 1-position 
is displaced by the reagent, and in no case is the other 
ortho position attacked. 


. A 3 


OH 

fVr 

f 

yV 

Uv 


V 

3 £ 


C « 3 

X 


The failure of IY to react cannot be ascribed to the known 














. 

. 

■ 

• J . '■ c ■ - ■' 

■ , c. ■ : ; ' ‘i " o 301T- 







. . .J . • ' . -V. . \ 

s ; 

ISS-S 

: : iJoBai 

- 

■ 

l.-: : . b . < C : . ;x 

■’ ■ : “ • J-’- 

■ ; . I C . i < ' 10 l 

. c _ r . .. ; • - V . ' ■- 

. ' ; : . ■ ■ - . ' .. . . - ; -c,.:. 

. . . . • o.elo; J.h .. J: 

v.... ... I .• ■ : :c 

























.. .. 1 . 






24 


lower degree of reactivity of the €? -positions of 
naphthalene in comparison with the oC -positions, for 
4-methyl-l-naphthol (V) couples easily in the $ -position, 
C 2 . It is not merely a difference in the degree of 
reactivity which is involved, but a difference in kind, 
and the only plausible explanation is that the double bond 
required in some way for the coupling is available at one 
position and not at the other. 

The pyridine ring produced in the Skraup reaction 
of $ -naphthylamine with glycerol, sulfuric acid, and an 
oxidizing agent, extends to position 1, and not 3, and in 
similarly constituted compounds, a methyl group at 
position 1 prevents the reaction while a bromine atom may 
be displaced. In general, cyclization occurs in such a 
way that the new ring includes a double bond of the 
original ring system. 



The establishment of the positions of the un¬ 
saturated centers in one part of the naphthalene molecule 
does not settle the problem of the complete bond structure. 
The facts cited may be explained on the basis of either 
the symmetrical Erlenmeyer formula, or the unsymmetrical 
structure. To determine the bond structure of the second 
ring, Fieser and Lothrop 1 extended to 2,6- or 2,7-dihydroxy- 
naphthalene methods of investigation employed successfully 



. o ■; • . 

o • ■: : ;■ r: 

c / ' •. .' ■ '' ' c ... :: 

■ ■ . . 'y . 






■' ; : ■ i : ' - 


: ■; . . : ; I. j. ;: ■ 

. ■ . : 

■ • . ' ■: .. . 

c ; ' . ... . J. ... J .;. i : 

■ . - - .. ■■/ 'J ■ ' ■' '.'J J. 

" • • ' j/j; . • 

i «I . 

;o 







; • . 

u . v . 

•' c . o 

< ■ 

•’ ' •’ ■" - v v:: ; \ [; . ■ c -'j...; - m 








25 


in the case of the coupling of S -naphthol. If 2,7-di- 
hydroxynaphthalene has the fixed symmetrical structure VI, 
it should be attacked by substituting agents at the two 
enolic ortho positions 1 and 8, but if it has the unsym- 
metrical structure VII, the disubsti tution should occur 
at the 1- and 6-positions. 

"TO" 

32X 

Actually, coupling occurs at the 1- and 8-positions, but 
although this observation supports formula VI, it does not 
exclude the alternate formula. One can reconcile the 
observation with the unsymmetrical foimula by supposing 
that the first substituent enters at Ci and that the bonds 
then shift to the alternate unsymmetrical arrangement and 
provide an enolic group at C 7 -C 8 for the entrance of the 
next azo group. 

In order to settle the matter, Fieser and Lothrop 
investigated various 1,8-dialkyl derivatives of 2,7-di- 
hydroxynaphthalene. If such a compound has the symmetrical 
structure VIII, it should be incapable of ortho substitutions 
in the free positions 3 and 6, but if it exists in the form 
IX, or if it can tautomerize to this form having an avail¬ 
able enolic ortho position at C 6 , monosubstitution should be 
possible. Compounds of this type, as well as various 
l,5-dialkyl-2,6-dihydroxynaphthalenes, were tested for 
phenolic properties with entirely negative results. They 










- , . 


• ; •O' 0 

i . : : ; 


■ • 


. - ; - - 


; ' . • • . : a 

■ ■ iBOi 



















Dr... 




r ■ . . 


I t bI .• ■ ■ - . i ■ ' [j ? 

' >. : : : eiU r/xo 

- ■ ■ ’ v ;.\:vv:cs 

. 

; . „ 'j 


^ _ 

; _ c .'. : ' : ; c. to ; 

. :x:j : : x 

..' ' . :..." to nl 

* • r - * • 

£ V. ........ 

r . • * - * ' - -v , - 

• .... , . v . : .. - t . - v... w 

. C ’ . O .. . . ' . X.i J . f ... C ! ’ ’ •'/C 

Oi 

■ / ; o. J.. j r : o V 








: : 


. . 






: ... •: " :cC 

' •. * _ _ ‘ " r ’ 

• . ^ ^ . . 

: 9vi • : j ■ oiloix 





do not couple, even with particularly active diazo 
components. 


HR HR 




This evidence clearly indicates that the naphthols 
have the symmetrical structure of the Erlenmeyer formula 
and that the arrangement of the bonds represents a 
condition of considerable rigidity. A tautomerism to 
an unsymmetrical form does not appear to occur to any 
appreciable extent. Since there is no reason to suppose 
that naphthalene itself differs from the naphthols, the 
evidence regarding the hydroxy compounds can be accepted 
as applying to the hydrocarbon, i.e. naphthalene has the 
symmetrical structure suggested by Erlenmeyer, and it 
differs- from benzene in having a more rigid and more 
reactive conjugated system of linkages. 

The physical evidence as to the structure of 
naphthalene is conflicting. Hampson and Weissberger 2 
conclude, as a result of the measuranent of the dipole 
moments of chlorinated naphthalenes, that the C-Cl bonds 
are directed as from the center of the rings, and that 
if there is any fixation of the single and double bonds 
in naphthalene it is not revealed in the direction of the 
substituents. On the other hand, Bergmann and 
Hirshberg 3 , from the dissociation constants of the 
chloronaphthoic acids, infer that the bond Ci to C 2 is not 







■ 




- • : 


- - ~ '• 

. . J- 



















. . ' ■' 


. : : •; • : :: ~; ; . , ~ ov 

- . . '• : ... . • : . ... : . ‘ • - ./ 






:0 

. . . • ■ . : : • J:.: t r . . ; ' : 

. . .' . . J 

t ' , . . , ■■ . .: . •: r .:. ; .' :. . - r '. 

. : . . . r 

. . • , ..' c -• . 

• • ... J..' :. : J. >•>;. 









, . , ' ' ... . .... :. o 

... .' . :. 

■ 


. : .;. ' .. ' • /, 


- * . . .... . *• • 


■ 








;/ ;.. .. 


.. I:: [ 





' .' « • C J: . . r C. r . C 

’. ■ -] 












27 


identical with the bond C 2 to C 3 , while the optical 
properties of naphthalene indicate that the symmetrical 
structure is most probably correct. 

On the basis of the Mills-Nixon hypothesis, 
the unsymmetrical structure of naphthalene probably would 
be in a state of somewhat less strain than the symmetrical 
form, and consequently the strong tendency of the hydro¬ 
carbon to exist in the Erlenmeyer form is not due to 
steric factors. The fact that naphthalene shows little 
tendency to exist in the unsymmetrical form may be because 
one of the rings would then have to depart from the 
aromatic condition and acquire the bond structure of the 
highly reactive o-benzoquinone, or the character of the 
thermodynamically unstable 1,2-dihydrobenzene. 



ft 

fY° 


V 

u 



unstable 

veactiye 

uv*sfab/e 


The resistance to the acquisition of quinonoid or dihydride 
characteristics accounts for the lack of stability of this 
structure. In the Erlenmeyer formula, neither ring is 
an entirely true benzenoid nucleus because the central 
bond is shared between the two rings and conjugated in 
different directions, but each approaches as nearly as 
possible the stable condition of an isolated benzene ring. 
The tendency to approach this condition, which appears to 
be the most important feature characteristic of the aromatic 
state, results, in the case of naphthalene, in the 




i 











< 

- 

- ... 

- 

: Itf* • - ' 

....... . 3 ' foe?: C<J ^ C L '• -Xi-'w3 

- ' • - 
. .. - < ■- ■■ - - • 0 : - 













- ® ; " 

: Vj : • : : ■ r ' 

t 31 i ssretael^ v - * •' '• : 

■ ■ ' ■ ^ " : ;X ; • •’ : -' :: 

- ■ : w. • ■ 1 - •' X 

• - - ■ ' Si: - ;r - : - 
33 jsc i t a d : 















28 


suppression of oscillation. 

The enhanced reactivity or unsaturation of 
naphthalene, e.g. susceptibility to oxidation and reduction, 
as compared with benzene, is manifested particularly in 
the °C-positions of the molecule. The @ -positions seem 
to exhibit only slightly greater reactivity than the 
positions of the benzene ring. This point is further 
demonstrated in competitive reactions, for example, the 
condensation of naphthalene with phthalic anhydride can be 
conducted in benzene solution with no appreciable 
contamination of the naphthoyl-benzoic acid with benzoyl- 
benzoic acid. A possible explanation may be that the 
fixed double bond shared between the rings is subject to 
valence claim from two directions, and an equalization of 
valence in the two rings cannot be attained as fully as in 
an isolated benzenoid ring, so that the two nuclei are 
less aromatic and more unsaturated than true benzene rings. 

The mere proximity of the oC -position in one 
nucleus, but not of the $ -position, to an adjoining 
aromatic ring, may be a factor of some importance in 
contributing to the reactivity at this position, and such 
an effect would not necessarily be associated with the bond 
fixation. Halogenation experiments indicate that in 
ethylbenzene or tetralin, the cC -position, but not the 
-position, of the side chain or alicyclic ring is 
activated by the unsaturated benzenoid nucleus. Some 

-activation may also be possible in the case of naphthalene. 

Mills and Nixon 4 believed that the attachment of 












... J:.. C c -nc' ; 

; : v-' • . r ' •> f. 

. J-.. " j .. " < ■ . . A'-sr -yy c- 

. ' . . i i 

■ . 

;. ; ;: ... . /■. . •: y '-.v- -Vic ’$- ; o s.iCBJ a 

J ■ j . / - - ' 0 • . M i • 

: . < ■ - ; 

- 

j . . ., ■ . . V-'i ' • . 

; i ' 

- J i ■ 

... ^lefiesog - ■ •' 

x a r i.B£i& t( - - 

;. . . .■ . •: ■: : - • ■■ v 


■ - : - - Ei • . - 


■ . < . j. •- 

. . ... -: ...■ J . . .. -jj \ :u .: ,, : 

- ’ • • • 

























. 


) I ' J V [ ' : 






• ; • j '. . ; . ': . r:.. :.. c ~ 

. ;.. v ' : ,; '0 

. . , - 

■ i. i q alii 








29 


an alicyclic 5-membered ring might stabilize one of the 
possible Kekule forms, or result in a fixation of the 
bond structure in the benzenoid nucleus. According to 
the van’t Hoff model, the free bonds in the system >0=0^ 
of an aliphatic compound lie in a plane, and the angle oC 
between each pair of single bonds is the same as that 
between the carbon valences of methane (109.5°). The 
angle $ which the single bonds make with the plane of the 
double bond is then l/2(36G° - 109.5°) = 125.25° (See 
Fig. 1). The angles $ and Y are in this case identical 
and they are considerably greater than the angle cK . Ytfhen 
the double bond becomes incorporated into the Kekule ring 
(Fig. 2) the situation is altered slightly, for the 
internal angle Y is reduced from 125.25° to 120° to 
accommodate ring formation, and oC + 0 consequently is 
increased by 5.25°. Regardless of the distribution of 
this increment, $ will remain appreciably larger than . 
Thus, the external valences in the Kekule ring are not 
directed toward the center of the hexagon but are inclined 

9 

at a greater angle from the double bonds of the ring than 
from the single bonds. Mills and Nixon reasoned further 
that a 5-membered ring can be fused to the Kekule structure 
with little distortion of the normal tetrahedral angle 

if it is attached to ortho carbon atoms joined by a single 

« 

bond (position 1, Fig. 2), for two of the smaller angles 
are then incorporated in the new ring. If, however, the 
attachment were made to doubly bound carbon atoms, 

(position 2), the new ring including the angles would 












- ■ ■ ' 







. 3. '" f J . :•. ; 




' 

- 

• . - . ' 










£ . 0 . 

'■ ■ • - 


0 . :■£ 7: c 




i 


. C 1 . ... 3 3 V 





-• ■ - . : ' ■ r - 
■ V' - •- • - . ‘ - ’ • -- 

. '.: 0 : 





. • . 




. > • 


o *v. . .X) 


* • ■ . . 


• .• - • 

>. v v. . : v- . :v* 




cJ , as. e%£ N nrtrs b I 






c* 


• • . s : 1 ' c : . . . 




■■ - • - •' : : c_ . . jJ; 3 

t 




' . i . ...... , 




. r . ; /. " 


:> ■ k 








' : . ;;' ... 




i 

' ■ • V ... \:o. J: 


■ r.:\:c : , .'a,' 


- . - J ■ ■ >Lb : . . 


; . X . ■ : • •• . t:' .j . co-.c 




- r 


Kerri ... . . . ■. : s ,jb 




: .. 


• . . - . ’ .' . . . :• 






z ::c vl 


.j..J J\ ..V. 






• . .. 




/ . 


. 






.'. .::c 

or-:, a ::'X :: : ; 

. 

;■ 'n i ; .r; ,. - • 
























30 


be under considerable strain. Tims, the form of 
hydrindene in which the carbon atoms common to the two 
rings are joined by a single bond should be more free from 
strain, or more stable, than the alternate form in which 
there is a double linkage between the rings. 



As a means of testing this prediction of the 
stereochemical theory, Mills and Nixon investigated the 
diazo coupling and the bromination of 5-hydroxyhydrinderte, 
the two Kekule forms of which are shown (X, XI). Since 
these reactions of phenols are closely related to similar 
reactions of aliphatic enols, it can be inferred that the 
ortho coupling and ortho bromination of phenols involve 
substitution at the carbon atom connected to that carrying 
the hydroxyl group by a double linkage, rather than at the 
alternate ortho position. Thus, if structure X is 
correct, substitution should occur at 6, and if structure 
XI is correct, substitution should occur at 4. The 
substance is attacked very largely in the 6-position. 








.tea oo. 

i 

• ' . . ' . ' : ' 

J ‘ • 





























. ' ' ' 

. i i allii . ; .. . . • i : . - 

■ . " :r t c c n 

: ■ . ■ ' ; J:: •; - • /. ; .. 

[on o 2d 1:1 ■ 

• v " . : 

' / ; ' 

B ;cf ■ \ $ 

t ' • . •. i.. . j • . • c 

c , i ': .. ', . • . 

tjb! . . . tta il ■ ' cf 







31 





However, as-o-xylenol (XII) yields similar substitution 
products. It is therefore possible that the chemical 
effect of the alicyclic ring is sufficient, without 
assistance from a steric factor, to direct substitution 
largely into one of the two available ortho positions. 

A double bond shared between the two rings in tetralin 
is indicated, since 6-hydroxy tetralin couples in position 
5 (XIII). 

Fieser and Lothrop* state that the preferential 
coupling at one of two available ortho positions may be 
the result of a moderate preponderance of one of the 
tautomeric Kekule forms, or of a slight difference in 
reactivity. To investigate bond fixation further, these 
authors tried coupling diazotized p-nitroaniline with 

tnd 

5-hydroxy-6-methylhynd:rene (XIV) , in which the 6-position 
is blocked and only the alternate ortho position 4 is 






' 



: '.1 ' 


.... ' c 






■ ./ . 7. ;• r r.o'X ■: ., * : ' ; o :c v{ 

; ; .. . . 7 7 - ■ • ■ 7 /. 

. ; _ . 6j J leg t . 


3 in' / 

■ 

. (■: .... 

lav 1 - ' o 

■ 

■ 

. ' ', v 1 • > '' 0 

i ■ 

7- ■ 

< ■ ~ - 

:ojI ■ [ b\ b .. c £c 







32 


available, and with XV, where the situation is reversed. 
The latter coupled readily, whereas XIV did not in 
moderately alkaline solutions. Thus, a single bond 
between the two rings is indicated. However, in very 
weakly alkaline solutions, XIV did couple, which would 
tend to indicate that the bonds are not fixed so rigidly 
in the position shown in formula XIV that the linkage 
extending from the hydroxylated carbon atom to the 
4-position cannot under certain conditions acquire double 
bond characteristics. 



The behavior of 6-hydroxytetralin in the same 
test is characteristic of ordinary alkylated phenols. 

No evidence was found of a relative fixation of one or 
the other bond structures. Thus each ortho position can 
function as a part of an enolic group. The introduction 
of a blocking methyl group at the 7-position (XVI) does 
not interfere with coupling at position 5, while the 
5~substituted derivative (XVII) is attacked readily at 
the free position 7. 


CH3 




m MET 





, ' 

■ ■ •, . .. - -: . ;/■' c . 0.7 

■ . 1 il 

. i ' « 

. 

. - - ’ ■' : 

. : ■ . . . : . : . :■ -i:. ; - ; :c ; ■ :: 

: ;• . :: .■ . 7 - ■ ( 








.• • ; ' ■'" •: .. * . 













; . . ;—‘ ,o . 

' . V. - .. ' orl 

. . . r./j v. :: 7 

• ' ■ flOltOfli 




'• o'.v' : .' . - ■; 

* < ' 

"_ ",. .:. . / : j, jj: ~ ■ 









. ■ .. .. ...: 


. 









33 


From a study of dipole moments, Sidgwick and 
Springall have come to the same conclusions. The 
moment of the group Br-C-C-Br in 6,7-dibromotetralin was 
found experimentally to be 2.13, whereas the calculated 
value on the assumption that there is no fixation, is 
2.12. With 5,6-dibromhydrindene, the moment observed 
for the group was only 1.78, which was close to the 
value calculated on the basis of the Mills-Nixon 
hypothesis that bond fixation results in an abnormally 
large angle between the ortho linkages joined to the 
bromine atoms, as compared with the situation in tetralin. 

The formation of a chelate ring may determine 
the Kekule structure to a detectable extent. From a 
study of various o-hydroxyacetophenones, Baker 6 came to 
the conclusion that the fonnation of a ,6-membered chelate 
ring containing coordinately linked hydrogen, as shown 
in formula XVIII is dependent upon the presence of a 


/°\ 
<f H 

I l 

CH3 


= e 

i 

— c 




H 


\c' 


ch 3 


XZZ2T XJK 

double bond betwe-en the carbon atoms bearing the hydroxyl 
and acetyl groups. The conjugation of this double bond 
with that of the acetyl group apparently stabilizes the 
coordinate linkage, and if no double bond is available 
at this position, as in XIX, chelation does not occur. 

This fact furnishes a new method for the detection of a 
fixed double or single link in a simple aromatic structure. 



















.. 


. 


c . . . •: -../ •' 

:±\l-3l.U ■ ' ■ 






■ " . :: . a : ■: . ■ • •" 

■. j ; ■> ;: . * ■' ■■■ - - ' j ■■ 






: • \j : r . ;. r : : - ' ' - ‘ - X ■ ' ■ ' X 

.. ■. . '. >i. J';ji .• : : xlT 


. ■ , , - v r' x ' •.$ . .■ •: •- : - 

■ ' v.''. i . - ■' - •' . - ; 

- . sin-e.B 1 fioi ': ' . ' * o 

• ; '/ c ■ :: 

■ ; ■ "■' i ■’ • ’ ■•J.'!- ' /; 










. 






■ IZ . X .' X . .' ■ - 




: ■ ..... .. 






. ;• D' ’■?: : j'. iU ix 

i 

. 

' • W ' ' • : • 

: : . . : , -:x c. x .. 






34 


Baker 6 also examined 5-hydroxy-6-acetylhydrindene (XX), 
and 5-hydroxy-4-acetylhydrindene (XXI), and found both 
to be chelated, but XX to be more highly chelated, 

(e.g. by determinations of melting points, solubility, 
volatility with steam, and critical solution temperatures). 



Using the same method, Baker 7 investigated the 
properties of the isomeric hydroxyacetylnaphthalenes 
(XXII-XXV). As expected, XXII and XXIII proved to be 

chelated, and XXV non-chelated, but XXIV also proved to 
be chelated. 



The interpretation of this latter result may mean that 


















- - . a f 

■ i - - . . - 

: s : i . . - - t 

■ : . ; • . . : : < • ■ 

. air./ v;:i:Xiaa^Go', 













■ 


' : v : . i \ c- ' a : . : 

a: : ■ ■: ; . : ■ . •: 

\ a : .. i. a .: aj-f ;■ ac: r ■ ■ ; vx ; a. j . a... ; 

. he'saltdo a if 









. 






35 


chelation between the hydroxyl and acetyl group is 
sufficiently powerful to overcome the normal symmetrical 
arrangement of the naphthalene valencies, so that the 
molecule must assume the asymmetrical distribution of 
the bonds as shown in XXVI, in which one of the rings 
is o-quinonoid. This is not indicated chemically, and 
resonance may be the explanation. 

The reactivity of the bromine atom in aromatic 
bromonitro-compounds is also a method for detecting both 
the presence and the position of double bonds in aromatic 
compounds, and has been applied by McLeish and Campbell 1 2 * * * * * 8 
to bromonitro-derivatives of naphthalene, hydrindene, 
and tetralin. They report the following semi-quantitative 
results (halogen being removed with pyridine at 45°)*. 


1 - Br omo- 2- ni t r onapht hale ne 

2 - Br omo -1 - ni t r onaph th ale ne 
4-Bromo-l-nit ronaphthalene 

5 - Br orao -1 - ni t r onaphth ale n e 

6 - Br omo - 2- ni t ro na phtha le ne 

5,8-Bibromo-l-nitronaphthalene 

3- Bromo-2-nitronaphthalene 

1- Chloro-2-nitronaphthalene 

2- Chloro-l-nitronaphthalene 

4- Chloro-l-nitronaphthalene 
8-Chloro-l-nitronaphthalene 
4-Bromo-5-nitrohydrindene 


Percentage removal 
of bromine 


0.5 hour 

91 

65 

60 

0 

0 

0 

51 

46 

43 


20 hours 

101 

100 

98 

0 

0 

0 

0 


0 

5 




. . - ■ ... . - . -V ' 

. ■ ; ; • '' ' .. ‘. . : / " ‘-'o 

• "... ::. ' ...' ' ' - 

i .. ; hI me . . : 5 ' . • 



- 

•j-Y j 








;■ : ■ 


’ . "" ' ' 


a 

* 

« : . 

: . : - 

X 


e. 

: c. c;.: 

• 

i . 














■ : *i ■ . ' 

. 

U ..... 



... . <*.w *■’ 

r ‘ ' 

. ■. -• • - 

s;Ij 

• 


. 

: . ■ '': ■; 




.. 

. : ' : 


■ 






■ : ; /...• J . . -i. ■ - - 






■ J ~ . 

- ■ 

r 




~ 





* * 


— 


.' •• 

~ : 

- 



- 

— 

- 




;. -. 





. : 

— • 



_ , 

: . 


< 


- - 

. 

~~ 



. -•. > 

: IyO 





f 

; .. 

__ 






• ' - ’ 







36 


6-Bromo-5-nitrohydrindene 

- - 

72 

6-Bromo-7-nitrotetralin 

5 

51 

6-Bromo-5-nitrotetralin 

0 

0 


If the Erlenmeyer formula is correct, the bromine 
atom in l-bromo-2-nitronaphthalene, 2-bromo-l-nitro- 
naphthalene, and 4-bromo-l-nitronaphthalene should be 
reactive, and in the other naphthalene compounds it should 
be non-reactive. The same applies to the corresponding 
chloronitro-compounds. If, on the other hand, equilibrium 
between the three possible naphthalene structures is 
possible, 3-bromo-2-nitronaphthalene also must be reactive. 
The results listed above indicate that the Erlenmeyer 
structure is the one that actually occurs, and substantiate 
other results, thus ruling out the possibility that the 
introduction of polar groups such as nitro- and bromo-groups 
into the naphthalene nucleus produces an unsymmetrical 
formula. If might be expected that 6-bromo-2-nitro- 
naphthalene would contain reactive bromine, as the bromine 
and the nitro-group are separated by a conjugated system 
of three double bonds. The fact that no reactivity was 
observed is another proof that the double bond shared by 
the two rings does not function normally. With 8-chloro- 
1-nitronaphthalene, and 5,8-dibromo-l-nitronaphthalene, 
no reactivity was observed, although each contains a 
halogeno- and a nitro-group ortho to one another. It is 
clear that mere proximity of the groups is not sufficient 
to produce reactivity. 

These results also indicate that the shared bond 


■ J 






• - 




- - - ~ : ' - ~ - 

' - - . : 


. 

- -. . • V , .... , r . V ^, V. 1 ’ 


U’' 


... 


‘ l :.. 


- ' ‘ . , • - • ■?. 

: • ' '■ ■ " j . _ ■. .‘ ■_ ■■ :• ... , : . ' , 

c ‘ . • ' - 

: ' .. ; .. / j .. v- .' - 


i. : ..... 


■,..V 






i 

- - - ‘. ., '-.A v; 

' 

- . 


... .. ... ..... 



c c- . ■ ; 

• -** 

c 

: v.v.;.;.. j r -• ;■ 


~ . -.cc-;; o . 

• ■' '• - . . ' ‘ . : : .'.o ; : - : ' . o \ r c r :;r 

. ‘ . ....... 

- ' e .. c-C '. .’. ' J 




: Jo. : . . : 

■ % 

. ■ : ■ . 




* 

* . • ■ 


. ' : ... . 



- 


. . 





■ ■ 

■ 





— 









: 

,. r . c .. . c 




; 













37 


in hydrindene is single, but that the bonds in tetralin 
derivatives are not fixed, i.e., the shared bond in 
tetralin is also single. It may be that the presence 
of the bromo- and the nitro-group does stabilize the 
molecule in this way, or it is possible that the reduced 
ring has some inhibiting effect on the bromine reactivity. 

In the work in our laboratory, an attempt has 
been made to correlate a fixation of the Kekule ring 
with the reactivity or non-reactivity of a halogen 
present in 4U amino-derivative of naphthalene, tetralin 
or hydrindene. 

It is a well known fact that a halogen such as 
bromine or iodine in ortho or para position to an amino- 
group present in a benzene ring acquires oxidizing powers. 
This type of halogen can be reduced by stannous chloride, 
and can be replaced by hydrogen. It is to be noted that 
the location of the halogen with respect to the amino- 
group must be at the end of a double bond or at the end 
of a conjugated system of double bonds. Because of the 
resonance structures of benzene, the ortho positions are 
equivalent. However, if the bonds in naphthalene, 
tetralin, and hydrindene are fixed, the two ortho positions 
should be different. One ortho halogen should be reactive, 
and the other non-reactive. 

To deteimine the reactivity or the non-reactivity 
of the halogen, the compound in question was refluxed with 
a solution of stannous chloride in glacial acetic acid and 
concentrated hydrochloric acid. At the end of several 
hours’ refluxing, the reaction mixture was made strongly 


t 61 . J J: . 

. 

- - 

i ' i ; i [ I 

■ iJ ' J : : 

e 

• •' ’-/r:: J •" :: •••'C- v : . 

~ • • ' ; J. 


- £ : 

; ", 

J. v'-. 

J. ■ -o ' 1 ' 

~ ; •. : .-.j r ;r-: . ' ;:c . ;• •••: J l 1 

l . f 

i beobI 

' 

‘ . ; ■ ■ ■ . J . . 









... 








* •' : 


. . ' 

. 




: : .. J” : 

■ ■' ' i 

- 

; 

■ ; - 






38 


acid with, concentrated hydrochloric acid. At this stage, 
the hydrochloride of the amine usually precipitated, and 
the free amine was liberated by treating the salt with 
excess sodium hydroxide. 

The following page gives a summary of the results 

obtained. 






' j "■ ■ . ■ v : .• -‘O'. 


. 




' ; '' 1‘-a .sn;/ 

. : -1 . I 




. 

I 








J 














' 































































































69 


CD d 
fe: iH 


• 

ft 









• 









ft • 









0 CaD 

to 

CO 

o 


CO 

CO 



d 








o* 

O d 

o 


in 

CO 


CO 



0 *H 









d 









Eh 









-P 









*8) tt> 


1—1 

o 


co 

CO 




• 







o* 

0 C 

to 

CO 

CO 

CO 


Cv2 



-tH 

• 












o 

o 

o 

o 



• 

o 

o 

«—1 

05 

05 

1-1 



ft 

CO 

o 

1 

1 

1 

1 

o 

c- 

• 


LO 

o 

CO 

CO 

o 






1—1 

cO 

CO 

LO 






<—1 

rH 

1 -1 




• 






0 









d 







0 

0 

0 








d 

d 



d 





•H 

d 



0 




a 

a 

•rH 



d 




0 

0 

a 



0 




rH 

i—i 

d 



> 




>4 


t>> 



o 

O 

0 

0 

0 

5 


d 

o 



0 

d 

d 

0 

d 

d 

d 



d 

•H 

•H 

•H 

ft 

ft 

•d 

c* 

o 


a 

a 

R 

0 

0 

a 



d 

3 

0 

0 

0 

d 

0 



H 

*—1 

H 

1—1 

1 

i 

1 



P 

>4 


>> 

CO 

CO 

in 



o 

d 

d 

d 

1 

1 

i 



ft 

•p 

-p 

4-5 

o 

o 

o 



a 

d 

d 

d 

a 

a 

a 



o 

ft 

ft 

ft 

o 

o 

o 



o 

0 

0 

0 

d 

d 

d 





S25 


m 

pq 

pq 




i 

1 

| 

i 

i 

i 




rH 

rH 

CO 

CO 

CO 




-p 



cO 

CO 

CO 

in 

CO 

co 

d • 



• 

% 

• 

• 

* 

• 

CiD ttf) 

o 

05 

cO 



d 1 

CO 

CO 

•H 

I—1 









• 

o 

0 

o 

O 

o 

o 

o 

0 

ft 

CO 

CJN- 

CO 

CO 

05 

r- 

o 

O 

• 

O 

1 

cO 

1 

1 

1 

1 

1 


i—1 



05 

CO 

o 

cO 

cO 





rH 

CO 

o 

in 

CO 





H 

1—1 



1 — 1 







0 

d 







d 


•rH 



0 

0 


0 

rH 



d 


d 


d 

0 



•r- 


•rH 


d 


d 

03 




a 


•tr 


ft 

1—1 

0 

CC 

0 

0 

0 

H 

d 

0 

d o 

d 

i — 


i — 1 

d 

d 

•rH 

ft 

d d 

*d 

> 

> -H 

>5 

•H 

> 

} rH 

O 

d co 

R 

d 

H 

d 

a 

d 

0 

d 

o 

0 

ft 

CO 

ft 

0 

o 

d 

rj 

ft d 

r—1 

d 

rH 

d 

i — i 

d 

ft 

a 

a -p 

>4 

ft ^ 

ft 

r4 

•r- 

0 

0 

O *H 

d 

0 d 

0 

d 


ft 

•—i 

O & 

ft 

C 

ft 

d 

ft 


O 

1=4 


d 

t 

d 

i 

d 

1 

d 

■p 

rH d 

ft 

t—i 

ft 

CO 

ft 

in ft 

0 

0 0 

0 

! 

0 

i 

0 

i 

•H 

O 

d 

d 

O 

d 

o 

d 

o 

d 

0 

•h d 

i 

a 

i 

a 


a 

i 

1 

taD i—1 

rH 

0 

CO 

o 

CO 

o 

£> 

cO 

•H ft 

1 

d 


d 

i 

d 

1 

1 

d 0 

o 

d 

o 

d 

o 

d 

O 

O 

O d 

a 

•P" 

a 

•pH 

a 

*r~ 

a 

a 


o 

P 

o 

p 

o 

P 

o 

o 


d 

1 

d 

i 

d 

i 

d 

d 


cq 

d* CQ 

CO 

pq 

cO 

pq 

pq 

















- [ 


! 


0 






:•» 













* 

■ .. 











■. . 





■ 





K* 






t 

i 


- T 

C ' 




s—, 

• • - 















< ! 







9 




' r 



















f.:. 














. ■ 








> 




: 

1 

l 

f 

t 

i 













9 

4» 

• 

> 






G> 




• . 


o 

, . 


r..:. 

' • 














! 

! 

1 

. ‘I 

r i 





























■ 



• . 
















< , 







■ . 












ry 

















I 





1 









1 - 

c i. 
















r 


. 1 • 

. 

■ . 


i 























40 


The first five results indicate that naphthalene 
has a fixed system of double bonds, i.e., the Erlenmeyer 
structure (XI). It is a very significant experimental 
fact that 3-bromo-2-naphthylamine contains a stable 
halogen, and remains unchanged after ten hours* further 
refluxing with stannous chloride. No definite result has 
yet been obtained with the tetralin derivatives , due 

to lack of time, but no fixation of the double bonds in 
the Kekule ling is indicated. The result with 4,6-di- 
bromo-5-aminohydrindene indicates that the bond shared 
between the rings is a single bond. 

Preparation of 4-bromo-l-naphthylamine 9 Aceto- 
o(,-naphthalide was treated with one nfolecular proportion of 
bromine dissolved in glacial acetic acid. The resulting 
4-brom-o(-naphthalide was crystallizred from the same solvent, 
and then hydrolyzed to 4-brom-l-naphthylamine by means of 
alcoholic sodium hydroxide. 4-Brom-1-naphthyl amine was 

recrystallized from ethanol, and melted at 103°. 

Preparation of 2,4-dibromo-l-naphthylamine .- 
This compound was prepared by a procedure similar to that 
used for the preparation of 4-bromo-l-naphthylamine. The 
only difference was that two molecular equivalents of 
bromine were used. 2,4-Dibromo-l-naphthylamine melted 
at 118-9°. 

Preparation of l-bromo-^-naphthylamine 10 .- 
Bromine (26 g.) dissolved in glacial acetic acid was added 
slowly to 30 g. of aceto-j?-naphthalide dissolved in 7 parts 







\' ■: A" v. v-v: 

- < 

. - - ' ~ : 

" . ' . ■ ' , : ' ■ ■ " ' ' ' 

- . X 1 .. -> J« 

‘ . . ’. > ' ' ; 

. . ■ —' 

. . - - . 

. ' ‘ . . • : ' “■*-■■■ 

; ' - - - 

. ... 

to ' B It J . ■ ■ 

' I \'".C - " ~ : 

... '• . . . - c 

- ~ - ■ • ' j ' 

... t . , : . ■ . : x ; 



- 


: 

■ 


■ 



• 







- “ 

‘L. r ,•"> 

- C 


- 



- . S. 


~ - 

— 




• 

: . vniiTl XS 






— — i 

















41 


of glacial acetic acid, and the mixture was agitated 
continuously. The precipitate of l-bromo-2-aoeto- 
naphthalide, which separated after the addition of the 
bromine, was collected, washed with acetic acid, dissolved 
in alcohol, and hydrolyzed by boiling with concentrated 
hydrochloric acid until the precipitation of the hydro¬ 
chloride of l-bromo-2-naphthylamine was complete. The 
base obtained by decomposing the salt with sodium hydroxide 
melted at 63°. 

Preparation of l,3-dibromo-2-naphthylamine 
Bromine (5 g.) was added dropwise to a solution of 
p-toluenesulfon-2-naphthalide (5 g.) in pyridine. After 
12 hours, the mixture was poured into dilute hydrochloric 
acid, and the resultant gummy material rendered solid by 
rubbing with alcohol. It melted at 163°. 1,3-Dibromo- 
2-naphthylamine,obtained by solution of the above p-toluene 
sulfonyl derivative in sulfuric acid, crystallized from 
alcohol in needles, and melted at 119°. 

Preparation of 4,6-dibromo-5-aminohydrindene .- 
5-Acetylhydrindene (b.p. 169° (7 mm.)) was prepared from 

hydrindene and acetyl chloride by means of a Friedel-Craft 

1 2 

reaction, using anhydrous aluminium chloride as catalyst 
The oxime (m.p. 117-8°) of 5-acetylhydrindene was converted 
into 5-acetamidohydrindene by means of the Beckmann re- 

JL 3 * 

arrangement, using phosphorus pentachloride . 5-Acetamido- 
hydrindene was hydrolyzed with alcoholic hydrochloric acid 
to 5-aminohydrindene. 13 The latter was brominated in 
chloroform solution 14 , yielding 4,6-dibromo-5-aminohydrindene 
(m.p. 70-1°). 


















42 


Preparation of 6-bromo-7-nitrotetralin .- 
6-Acetyltetralin (b.p. 140-5° (2 mm.)) was prepared from 
tetralin by a Friedel-Craft reaction 18 . The oxime of 

6- acetyltetralin was converted into 6-acetamidotetralin 
(m.p. 106-7°), by means of the Beckmann rearrangement, 
using benzenesulfonyl chloride 8 . 6-Acetamidotetralin was 
nitrated in acetic acid solution 16 , and the resulting 

7- nitro-6-acetamidotetralin (m.p. 134-5°) was hydrolyzed, 
using alcoholic hydrochloric acid 16 , to 7-nitro-6-amino- 
tetralin (m.p. 124-5°). The latter was diazotized in 
glacial acetic acid, and treated with cuprous bromide 
dissolved in hydrobromic acid, to form 6-bromo-7-nitro- 
tetralin (m.p. 56-7°). 

metv/ X7 

Preparation of 5-bromo- and 8-bromo-6-xaminotetralins 
Five grams of 6-acetamidotetralin was dissolved in 15 g. of 
glacial acetic acid, and 4 g. of bromine dissolved in 10 g. 
of T the same solvent, was added slowly, the temperature being 
maintained at 50-60°. About one-half hour later, the 
reaction mixture was heated on a water-bath for a few minutes, 
and then allowed to cool. 5-Bromo-6-acetylaminotetralin 
separated, and was crystallized several times from ethanol. 

It melted at 126-7° (uncorr.). 8-Bromo-6-acetylaminotetralin 
precipitated from the acetic acid mother liquor on the addition 
of water. It was crystallized from ethanol, and melted 


at 151° . 







' 



- 


- . • : , . : , , 

■ . J . . •• 

- - - : : ' . . 'J 

. ■ ■ ,■ . c - .. : ■■ ... :.:■■■ , / .. : 

: .. ' :: ' .. . ',.. • \r . , 


: n 




V/ 




, ■■■■•' - * ' 'O.-L ‘ 1 ■ ■' ' ■ J.., :j 

; ■ c ° ; ;; '. lor c .rrre - rj; oo:i ; r:i 

■' - - . r -• ~ : -• 

' ■ .' ■ ■ 


- 






,/ ■" f • - 








. , c 

f. . : 1 . . 


“ >■ - 


; - 

. • 


. ;. .. r 

i 







' 

v. 

W 

• 

~ 




. - 

; 



. . 




or 

- 







- ■ 

o ' ■ -r - r 





< . ■■ 















‘ ' 



■■■■; . 





. 

- ^ 


. " r o.i 






. • 





- 


- - 



i *— 

^ .■ v . . 







J c 





. 






L. ' -i . «.• 


11 



































43 


Summary 

1. The reactivity of the halogen in certain 

halogeno-derivatives of c^-naphthylamine -naphthylamine , 

aminohydrindene, and aminotetralin has been ascertained 
by means of stannous chloride. 

2. Experimental evidence indicates bond fix¬ 
ation in the case of naphthalene and hydrindene . 






. 

» .. oj; ;io ■ j 


■ 


. ... ; • 

: .L, r;; ; :o 


' 















44 


References (Part II) 

1. Gilman, Organic Chemistry (John Wiley & Sons, Inc., 

New York (1938)), Chapter II - Fieser, Theory 
of the Structure and Reactions of Aromatic 
Compounds. 

2. Hampson and Weissberger, J.C.S., 393, (1936). 

3. Bergmann and Hirshberg, ibid, 331, (1936). 

4. Mills and Nixon, ibid, 2510, (1930). 

5. Baker, ibid, 1684, (1934). 

6. Baker, ibid, 476, (1937). 

7. Baker and Carruthers, ibid, 479, (1937). 

8. McLeish and Campbell, ibid, 1103, (1937). 

9. Morgan, Miclclethwait and Winfield, ibid, 750, (1904). 

10. Morgan, ibid, 814, (1900). 

11. Bell, ibid, 2733, (1932). 

12. Braun, Kirschbaum and Schuhmann, Ber. 53, 1163, (1920). 

13. Borsche and John, ibid, 57 . 658, (1924). 

14. Borsche and Bodenstein, ibid, 5£, 1914, (1926). 

15. Barbot, Bull.soc.chim. (4), 47, 1314, (1930). 

16. Schroeter, Ann. 426 , 65,0<?2// 

Smith, J.C.S., 85, 730, (1904). 


17. 







, ■ 0;f O^Si 


:.. ■ • :0 
t - . : : , { ( ■ - - 

• i j c ;:o 






f 

, \ •. 


c • • • • •: r 

. 

. ..Jy.' < ' .. 

. , . * . , . . 

' . . v - ' . 

'v:’:.y .• - ■ 

• ' ; . ' ■ , . //■ < - . 

: ..... - ■ ■ t - 

- ■ c • •• • . t -i' ... - o y 

: . .. . . ._. . ’ - c..: . ■ 








«• > 






<. ~ 
s 


. 


.. 


Vt ;■ 

i . 






1 ,