Formation of 3,6-diphenylpyridazine and 2,5- diphenylpyrrole from alpha-styryl azid

Boyer, J. H.

Krueger, W. E.

Modler, R.

English

NASA Technical Reports Server

I 
= 
(CATEGORY) 
P THE FORMATION OF 2,6-DIPHENYLPYRIDAZINE AND 
A ‘  2,5-DIPHENYLPYRROLE FROM a-STYRYL A Z I D E  
(pc)- 3@ 
Lr’ 
J. H.  Boyer, W. E .  Krueger and R. Modler 
Department of  Chemistry, Un ive r s i ty  o f  I l l i n o i s  . 
Chicago C i r c l e  Campus, Chicago, I l l i n o i s  60680 
U 
Two new the rma l  r e a c t i o n s  of n e a t  a - s t y r y l  a z i d e  have been observed. A f t e r  
one month at  room tempera ture  i n  a t i g h t l y  c l o s e d  screw-cap brown g l a s s  b o t t l e ,  
121.0 g. ( 0 . 1 4  mole) o f  n e a t  a - s t y r y l  az ide  (l), 2, i s  t ransformed i n t o  2-phenyl- 
a z i r i n e  (l), - 2 ( c a .  1 0 % )  ( 2 ) ,  3 ,6-diphenylpyridazine,  m.p. 221-223OC (31,  3, 
0.7 g.  (0 .003 mole) (7%)  and 2,5-diphenylpyrrole ,  m.p. 137.5-141.5OC ( 4 ) ,  - 4 ,  3 . 0  g. 
(0 .013 mole) (32%) .  Yie lds  a r e  based  on 8.5 g.  (0.06 mole) (40%) recovered  
a - s t y r y l  a z i d e .  Each day t h e  b o t t l e  was opened t o  a l low accumulated gas  t o  escape .  
By t h e  end of  the first; week an apprec i ab le  q u a n t i t y  o f  i n s o l u b l e  3 was no ted ;  r 
;both 2 and -_ 4 remained i n  s o l u t i o n .  
I 1 
7 
2 - 3 
-, 
- 4 
4 N e i t h e r  ‘2,5-diphenylpyrazine,  5 ,  n o r  i t s  3 ,6-d ihydroder iva t ive  ,- - 6 ,  t h e  
known ( 5 )  d imer  o f  2-phenylaz i r ine ,  - 2 ( o r  its valence  tautomer,  a - s t y r y l n i t r e n e ,  
- 71, was d e t e c t e d .  S ince  - 2 does n o t  dimerize t o  8, an e x p l a n a t i o n  f o r  t h e  f o r -  
mat ion o f  a n i t r o g e n  t o . n i t r o g e n  bond r e q u i r e s  t h e  i n i t i a l  format.ion o f  azo-a- 
s t y r e n e ,  5 by an i n t e r a c t i o n  between two molecules of 1. Ring-closure by va lence  
i s e m e r i z a t i o n  t ransforms - 9 i n t o  -- 8 and a romat i za t ion  produces 3. 
I 
https://ntrs.nasa.gov/search.jsp?R=19680022716 2020-03-12T10:08:23+00:00Z
Y 
t 
- 2 N 2  
2 1  - > 
. .  
?6H6 
6 
C S H S  
7 - 8 - 
I Azostyrene, 9, appa ren t ly  i s  no t  formed from an i n t e r a c t i o n  between - 7 ( o r  - 2 )  
and .1 .  - From a mixture  of 2 .9  g .  (0.02 mole) of  - 1 and 2 . 3  g. ( 0 . 0 2  mole) o f  - 2 i n  
a c losed  brown b o t t l e  f o r  one month, a 67% y i e l d  of  6 ,  a b r i g h t  r e d  s o l i d ,  was 
I ob ta ined .  A i r  o x i d a t i o n  d u r i n g  r e c r y s t a l l i z a t i o n  from e t h a n o l  produces 5, m.p. 
. 192-195' ( 5 ) ,  a yellow compound. The presence of 2 ,5-diphenylpyrrole ,  ?-, was 
! 
d e t e c t e d  by i . r .  and n.m.r. b u t  was not  i s o l a t e d  and o t h e r  p roduc t s ,  u n i d e n t i f i e d ,  
were ob ta ined .  
Whether o r  n o t  t h e  t r ans fo rma t ions  1 -t 3 and 1, -t - 4 have ( a )  common in te rmedi -  
a t e ( s )  has  n o t  been determined. It i s  conceivable  t ha t  r educ t ion  of - 9 t o  t h e  
hydraz ine  10 occur s  as - 8 i s  dehydrogenated t o  - 3. 
- 10 -+ -3 11 c y c l i z a t i o n  w i t h  t h e  e l i m i n a t i o n  of ammonia a f f o r d s  t h e  p y r r o l e  - 4 .  
Following a Cope rearrangemgnt , 
- r 
7 G H 6  YsH6 
, C\. /.C 
i 9 => I _3 I 
'C' 
> 4  CH2 -m3 
0 m- CH2 Hi' ' 
- HN HN ,CH2 N C / C H 2  
I 
-3 1 -  - 
sH5 C6H6 
11 -.- l o  -
~~~~~ ___ 
On t h e  o t h e r  hand, t h e  format ion  o f  %may be independent of  t h e  format ion  
of L. The formation o f  2 ,4-diphenylpyrrole ,  l2, from - 2 and acetophenone, i n  t h e  
1 presence  of s u l f i n a t e  an ion  w a s  r e c e n t l y  r e p o r t e d  (6) .  Apparent ly  e i t h e r  t h e  
e n o l  o r  t h e  e n o l a t e  anion a t t a c k s  t h e  e l e c t r o n  d e f i c i e n t  n i t r o g e n  o f  
va lence  tautomer o f  2. A s  shown below, a comparable r e a c t i o n  between two 
t h e  
1 . - -.. - -  
molecules  of a - s t y r y l  a z i d e  may be i n i t i a t e d  i n  a n u c l e o p h i l i c  a t t a c k  by a t e r -  
mina l  a z i d o  n i t r o g e n  upon t h e  a-carbon o f  a - s t y r y l  a z i d e .  Nitrogen e l i m i n a t i o n  
may be conce r t ed  w i t h  new bond formations.  
a z i d e  would produce 4. 
Subsequent e l i m i n a t i o n  of hydrogen 
. .  
Acknowledgement: F i n a n c i a l  suppor t  was r ece ived  from NASA grant  No. NGR 
14-012-004. 
References 
l y s i s  o f  - 1 a t  350-360° (0.1-0.3 mm.) i n  80% y i e l d .  
subs t ance  assumed t o  be C6H,N=C=CH2 was a l s o  obta ined  bu t  has n o t  been de- 
About 5% of  an u n s t a b l e  
I 
t e c t e d  i n  t h e  p r e s e n t  work. 
2, Obtained t o g e t h e r  w i t h  recoversd I on e l u t i o n  w i t h  hexane from an cllumina 
column t o  which t h e  l i q u i d  p o r t i o n  o f  t h e  r e a c t i o n  mixture  (2, was s e p a r a t e d  
by f i l t r a t i o n )  had beon a p p l i e d .  
- 
By nmr a n a l y s i s  it was determined t h a t  t h e  
3 .  
14. 
I 
I .  
H. K e l l e r ,  R. Pas t e rnak  and H. V. Halban, Helv. Chim. Acta 29, 512 (1946). 
A mixture  mop. of 2 w i t h  a u t h e n t i c  material showed no d e p r e s s i o n .  
'Obtained on f u r t h e r  e l u t i o n  wi th  e t h e r  o f  t h e  l i q u i d  p o r t i o n  o f  t h e  r e a c t i o n  
-I -  * 
mixture on alumina. G. A. Kreutzberger  and P .  A. K a l t e r ,  J. Org. Chsm. Z& 
554 (1960) r e p o r t  m.p. 143-14.4°C, 
t h a t  r e p o r t e d  by G. A. Kreutzberger  and P. A .  K a l t e r ,  J. Phgs. Chem, & 624 
(1961). The nmr spectrum of 
s p i k e s  a t  6.52 ppm (ZH, spac ing  of 3 c p s ) ,  a m u l t i p l e t  c e n t e r e d  a t  7.40 ppm 
- 
I n f r a r e d  a b s o r p t i o n  for ,& agreed wi th  
- 
i n  deuterochloroform c o n s i s t e d  o f  a p a i r  o f  
(1OH) and a broad f l a t  peak a t  ca. 8.43 pprn (1H exchangeable w i t h  DzO) .  E l e -  
menta l  a n a l y s i s  for 4: C a l c f d .  for C16H13N: C,  
mow. 219.3. Found: C, 87.56; H, 6.06; N, 6.35; 
5. L. Horner, A. Christman and A .  Gross, Cham. Ber.  
I 
r 
6 .  S. S a t o ,  H .  Kato' and M. Ohta, B u l l .  Chem. S O ~ .  Japan 4 0 ,  1014 ( 1 9 6 7 ) .  -


The formation of 3,6-diphenylpyridazine and 2,5-diphenylpyrrole from alpha-styryl azide

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