BULLETIN DE L'ACADEMIE
POLONAISE DES SCIENCES
Serie des sci. chim., geol.
et geogr. —Vol. VII, No. 2, 1959
ORGANIC
CHEMISTRY
On Nitration of Dimethylaniline
i n Presence of Acetic A c i d or Acetic Anhydride
by
A. S E M E N C Z U K and T. U R B A N S K I
Communicated by T. URBANSKI
at the meeting of November 24, 195S
I t has been s t a t e d b y O r t o n [1] t h a t d i m e t h y l a n i l i n e , w h e n n i t r a t e d
w i t h m i x t u r e s of n i t r i c a c i d w i t h acetic a n h y d r i d e a n d acetic a c i d , does
n o t f u r n i s h N - n i t r o d e r i v a t i v e s a n d solely 2 . 4 - d i n i t r o d i m e t h y l a n i l i n e i s
p r o d u c e d . Therefore, i t a p p e a r e d t h a t f o r m a t i o n of N , 2,4,6-tetranitrom e t h y l a n i l i n e (tetryl) does n o t occur, w h e n n i t r a t i n g d i m e t h y l a n i l i n e
w i t h the above mentioned m i x t u r e .
P r e v i o u s l y w e f o u n d [2] [3] t h a t t e t r y l c a n be p r o d u c e d b y a c t i n g
o n d i m e t h y l a n i l i n e w i t h n i t r i c a c i d alone o r i n presence of a n i n e r t solv e n t . S u b s e q u e n t l y , t h e w o r k b y O r t o n c o u l d suggest t h a t acetic a n h y d r i d e o r acetic a c i d m a y a c t as i n h i b i t o r of t h e r e a c t i o n of n i t r a t i n g
d i m e t h y l a n i l i n e t o t e t r y l . T h i s suggestion is r a t h e r u n e x p e c t e d a n d w e
c o n s i d e r e d i t necessary t o f i n d t o w h a t e x t e n t t h e s t a t e m e n t of O r t o n
is c o n c l u s i v e .
W e c a r r i e d o u t a n u m b e r of e x p e r i m e n t s o n n i t r a t i o n of d i m e t h y l a n i l i n e w i t h m i x t u r e of n i t r i c a c i d (d 1.5) c o n t a i n i n g c a . 0 . 3 % N 0 a n d
2
t ric
ac
acetic a c i d o r acetic a n h y d r i d e . V a r i o u s r a t i o s -—-.——.
'^—-^-^r- were
acetic acid or anhydride
used.
T o m o d e r a t e t h e t r e n d of t h e r e a c t i o n a n i n e r t s o l v e n t , s u c h as
c h l o r o f o r m , c a n also be used.
T h e spontaneous reaction w h i c h o c c u r r e d after introducing dimethyla n i l i n e i n t o t h e n i t r a t i n g m i x t u r e p r o d u c e d a n increase of t h e t e m p e r a t u r e t o c. 40° C. A f t e r t h e reaction subsided, i t was necessary t o w a r m
the reacting m i x t u r e a n d to keep i t at c. 80° 0 u n t i l t h e reaction w a s
]
J
completed.
W a t e r was added to the cooled reaction solution a n d pure N,2,4,6tetranitromethylaniline precipitated.
T h u s , t h e s t a t e m e n t of O r t o n s h o u l d p r o b a b l y be l i m i t e d t o specific e x p e r i m e n t a l c o n d i t i o n s a p p l i e d b y t h i s a u t h o r . W h e n t h e r e a c t i o n
[91]
A. Seineiiezuk and T. Urbanski
913
of n i t r a t i o n i n presence of acetic a n h y d r i d e or acetic a c i d is r u n i n c o n d i t i o n s d e s c r i b e d i n the present paper, p a r t i c u l a r l y w i t h r e g a r d to the
t e m p e r a t u r e , N , 2 , 4 , 6 - t e t r a n i t r o m e t h y l a n i l i n e is f o r m e d .
I t has also been f o u n d t h a t the best y i e l d a n d the p u r i t y of the
p r o d u c t , s i m i l a r to those r e a c h e d w i t h n i t r i c a c i d alone, were o b t a i n e d
tr
10
a c
d
w h e n the v o l u m e r a t i o — . — — . ,
' . , . , was 5 0 : 5 0 .
acetic acid or anhydride
A l o w e r r a t i o r e q u i r e d a longer r e a c t i o n t i m e , a n d the y i e l d a n d
the p u r i t y of the p r o d u c t were n o t so h i g h .
T h e c o n s u m p t i o n of n i t r i c a c i d , wdien the m e t h o d d e s c r i b e d i n the
present p a p e r was a p p l i e d , is l o w e r t h a n i n o u r m e t h o d s w i t h n i t r i c
a c i d [2] [3].
r
Experimental
N i t r a t i o n i n presence of a c e t i c a n h y d r i d e . The nitrating solution was
prepared by mixing 60 ml. of nitric acid (d 1.5), 60 ml. of acetic anhydride and 60 m l .
of chloroform. The solution was cooled below 0°C and with vigorous stirring the solution of 6 g of dimethylaniline in 60 ml. chloroform was introduced. The temperature
was kept below 0°C. After all the dimethylaniline was introduced, the cooling medium
was removed and the reacting mixture spontaneously reached the temperature of 40°C.
A copious evolution of nitrogen dioxide occurred at this stage. The vigorous reaction
lasted c. 20 min. and after that the temperature began to fall. The reacting mixture
was then warmed gently on water bath until the temperature rose to 80° C. Chloroform distilled off and the mixture was warmed until nitrogen dioxide ceased to evolve,
and the solution acquired a light orange colour. A l l this lasted c. 8 hours.
The reaction solution was cooled to room temperature, diluted with 150 ml. of
water. The precipitated product was collected and crystallized from acetone. The yield
was 12.8 g. (90°/o of theoretical), m . p . 129°C.
N i t r a t i o n i n presence of a c e t i c a c i d . The nitrating solution was prepared
of 60 ml. of nitric acid (d 1.5), 60 ml. of acetic acid and 60 ml. of chloroform.
The reaction was carried out in the same way, as previously described with acetic
anhydride.
After the reaction was terminated, 100 ml. of water were added to the light orange
solution. Precipitated tetryl was collected and crystallized from acetone. The yield
and purity of the product was the same as in the previous method.
MILITARY T E C H N I C A L C O L L E G E , WARSAW
(WOJSKOWA A K A D E M I A T E C H N I C Z N A , WARSZAWA)
REFERENCES
[1] K . J . P . O r t o n , Ber. 40 (1907), 370.
[2] T. U r b a n s k i and A . S e m e n c z u k , Bull. Acad. Polon. Sci., CI. I l l , 5
(1957), 649.
[3] A . S e m e n c z u k and T. U r b a i i s k i , Bull. Acad. Polon. Sci., Serie des Sci.
chim., geol. et geogr., CI. I l l , 6 (1958), 309.