Industrial and Laboratory Nitrations

23 The Preparation of R D X from 1,3,5-Triacylhexahydro-s-triazines Ε. E. GILBERT, J. R. LECCACORVI, and M . WARMAN Downloaded by MICHIGAN STATE UNIV on February 24, 2015 | http://pubs.acs.org Publication Date: June 1, 1976 | doi: 10.1021/bk-1976-0022.ch023

Explosives Division, Picatinny Arsenal, Dover, N.J. 07801

RDX ( 1 , 3 , 5 - t r i n i t r o h e x a h y d r o - s - t r i a z i n e , 1) has been an important m i l i t a r y e x p l o s i v e s i n c e World War II. I t is made by the nitrolysis of hexamethylenetetramine in the presence of ammonium nitrate and a c e t i c anhydride, about 2 lbs* of anhydride being r e q u i r e d per lb. of RDX. (The equations f o r this process are g i v e n later.)

1, R = N 0

2

2, R = SO 4., R = CH C03

_5, R = C H C O 2

5

17_, R = C H 0 C 0 2

5

20, R = ^ H ^ R ^ S O ^ Another procedure for the p r e p a r a t i o n of RDX, developed i n Germany by Wolfram in the 1 9 3 0 s , i n v o l v e s nitrolysis of the h e x a h y d r o - s - t r i a z i n e d e r i v a t i v e 2 (as the potassium salt) (1). Although good yields of RDX were o b t a i n e d , t h i s method was abandoned as economically inferior to the other approach, cited above. B r i e f attempts in the past to prepare RDX by the nitrolysis of two other h e x a h y d r o - s - t r i a z i n e d e r i v a t i v e s , 17 and 20, ,

327

In Industrial and Laboratory Nitrations; Albright, L., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1976.

INDUSTRIAL AND

Downloaded by MICHIGAN STATE UNIV on February 24, 2015 | http://pubs.acs.org Publication Date: June 1, 1976 | doi: 10.1021/bk-1976-0022.ch023

328

LABORATORY

NITRATIONS

gave none o f t h e d e s i r e d p r o d u c t ( 2 ^ 3) . S p e c u l a t i o n d u r i n g W o r l d War I I as t o t h e p o s s i b l e r e a c t i o n s e q u e n c e o c c u r r i n g d u r i n g the p r e p a r a t i o n o f RDX f r o m h e x a m e t h y l e n e t e t r a m i n e and a c e t i c a n h y d r i d e , by t h e method c i t e d a b o v e , l e d t o t h e t h o u g h t t h a t compound 4_ m i g h t be t h e k e y i n t e r m e d i a t e (3). T h i s i d e a c o u l d n o t be t e s t e d a t t h e t i m e , s i n c e 4^was a c t u a l l y unknown u n t i l s e v e r a l y e a r s l a t e r , when a s i m p l e method f o r p r e p a r i n g i t and some a n a l o g u e s was d e v e l o p e d . Then, D.N* T h a t c h e r d i d i n d e e d show (4) t h a t RDX c o u l d be p r e p a r e d by t h e n i t r o l y s i s o f 4· o r 5^ ( I t s h o u l d be m e n t i o n e d t h a t , e v e n t h o u g h _4 can be n i t r o l y z e d t o RDX, and e v e n t h o u g h we h a v e shown t h a t 4_ can be made by r e a c t i n g h e x a m e t h y l e n e t e t r a m i n e w i t h a c e t i c a n h y d r i d e (_5), 4 i s no l o n g e r c o n s i d e r e d t o be an i n t e r m e d i a t e i n the p r e p a r a t i o n o f RDX by t h e d i r e c t n i t r o l y s i s o f h e x a m e t h y l e n e tetramine i n the presence of a c e t i c anhydride.) S i n c e a p r o c e s s o f t h i s t y p e - i n v o l v i n g the use o f 4^, 5^, o r s i m i l a r compounds, as i n t e r m e d i a t e s - a p p e a r e d t o us t o be o f p o t e n t i a l i n t e r e s t f o r p r e p a r i n g RDX on a l a r g e s c a l e , i t seemed d e s i r a b l e to study the n i t r o l y s i s o f other h e x a h y d r o - s - t r i a z i n e s t o e s t a b l i s h t h e optimum s t r u c t u r e o f R. We r e p o r t h e r e i n t h e r e s u l t s of such a s t u d y , i n v o l v i n g the n i t r o l y s i s o f a s e r i e s o f known h e x a d y d r o - s - t r i a z i n e d e r i v a t i v e s , as w e l l as o f a number p r e v i o u s l y unknown; a l l o f t h e s e a r e l i s t e d i n T a b l e I . I n a d d i t i o n , we have s t u d i e d v a r i a t i o n s i n t h e n i t r o l y s i s p r o c e d u r e f o r compounds o f s p e c i a l i n t e r e s t , t o w a r d d e v e l o p i n g an optimum p r e p a r a t i v e a p p r o a c h f o r I. The c o n c l u s i o n s r e a c h e d a f t e r an e c o n o m i c a n a l y s i s o f t h i s method, i n c o m p a r i s o n w i t h t h e e s t a b l i s h e d method, a r e a l s o s u m m a r i z e d . Screening

o f C a n d i d a t e T r i a z i n e Compounds

In c o n s i d e r i n g n i t r o l y s i s reagents s u i t a b l e f o r t h i s study, r e f e r e n c e was made t o the f a i r l y e x t e n s i v e p u b l i s h e d d a t a on t h e s y n t h e s i s o f s e c o n d a r y n i t r a m i n e s by the S^.2 n i t r o l y s i s o f Ν,Ν-disubstituted amides and s u l f o n a m i d e s (6,7_,8) :

t

1

R NCOR R NS0 R 2

2

f

> >

R NN0 R NN0 2

2

2

2

+ +

RCOOH R'SC^OH

Reagents used i n these s t u d i e s i n c l u d e : a b s o l u t e n i t r i c a c i d , n i t r i c acid-phosphorus pentoxide, n i t r i c a c i d - t r i f l u o r o a c e t i c a n h y d r i d e , n i t r i c a c i d - a c e t i c a n h y d r i d e , and n i t r o g e n p e n t o x i d e . F o r o u r p u r p o s e s , the l a s t two r e a g e n t s w e r e e l i m i n a t e d , s i n c e t h e f o r m e r gave p o o r y i e l d s , and t h e l a t t e r i s somewhat i n c o n v i e n t f o r r o u t i n e l a b o r a t o r y use. The n i t r i c a c i d - p h o s p h o r u s p e n t o x i d e a p p r o a c h was r e t a i n e d , s i n c e i t was r e p o r t e d t o g i v e an 84% y i e l d o f f r o m !2 ( 1 ) , e v e n t h o u g h p o o r r e s u l t s w e r e n o t e d b y o t h e r s (7) i n t h e n i t r o l y s i s o f d i ( n - b u t y l ) formamide w i t h t h i s reagent.



23.

GILBERT

E T AL.

Preparation

of

RDX

329

The n i t r i c - t r i f l u o r o a c e t i c a n h y d r i d e s y s t e m was o f s p e c i a l i n t e r e s t , s i n c e i t was r e p o r t e d t o g i v e o u t s t a n d i n g r e s u l t s i n t h e n i t r o l y s i s o f o p e n - c h a i n amides (.6,7^8) . P a s t w o r k w i t h t h i s s y s t e m h a s a l w a y s e n t a i l e d t h e u s e o f 1.1 m o l e s o r l e s s o f n i t r i c a c i d per mole o f anhydride. When a p p l y i n g t h i s s t o i c h i o m e t r y i n t h e n i t r o l y s i s o f 4 , o n l y two o f t h e t h r e e a c e t y l g r o u p s were n i t r o l y s e d , l e a d i n g t o t h e p r e c i p i t a t i o n o f l - a c e t y l - 3 , 5 d i n i t r o h e x a h y d r o - s - t r i a z i n e ("TAX"). ( T h i s c o m p r i s e s a new a n d i m p r o v e d p r o c e d u r e f o r p r e p a r i n g TAX, a s d e s c r i b e d i n t h e Experimental Section.) I t was t h e n f o u n d t h a t u s e o f 4.8 m o l e s o f n i t r i c a c i d p e r m o l e o f a n h y d r i d e gave n e a r l y c o m p l e t e n i t r o l y s i s o f _1, s i n c e t h e e x c e s s n i t r i c a c i d a p p a r e n t l y f u n c t i o n s a s a reaction solvent, i n contrast to trifluoroacetic acid (9). T h i s s t o i c h i o m e t r y was t h e r e f o r e u s e d t h r o u g h o u t i n our s t u d i e s . The n i t r o l y s e s , a l l e f f e c t e d w i t h l a r g e e x c e s s e s o f t h e r e a g e n t s , gave t h e r e s u l t s summarized i n T a b l e I . N i t r i c a c i d a l o n e c o n s i s t e n t l y gave t h e l o w e s t y i e l d s , and n i t r i c a c i d - t r i f l u o r o a c e t i c a n h y d r i d e g a v e t h e b e s t , e x c e p t i n t h e c a s e o f 4^ The n i t r o l y s i s a p p e a r s q u i t e s e n s i t i v e t o s t r u c t u r a l f a c t o r s , and ( e x c e p t f o r 1 8 ) i s s p e c i f i c f o r R = a l k a n o y l a s b e i n g t h e o n l y s u b s t i t u t i n g g r o u p y i e l d i n g jL. L e n g t h e n i n g t h e c h a i n Cas i n 5^, j ) , and 7) g i v e s d e c r e a s i n g y i e l d s w i t h a l l t h r e e r e a g e n t s . Also n o t e w o r t h y i s t h e f a c t t h a t 3_ g a v e no 1_, s i n c e s e v e r a l Ν,Ν-dîalk y l f o r m a m i d e s h a v e been shown (7) t o g i v e good y i e l d s o f n i t r a m v ines, e s p e c i a l l y w i t h n i t r i c a c i d - t r i f l u o r o a c e t i c anhydride. However, no n i t r a m i n e s c o u l d b e o b t a i n e d f r o m Ν,Ν-dialkylformam i d e s w i t h b u l k y a l k y l groups ( 6 ) . Branching the c h a i n i n t h e p o s i t i o n o f R b y i n c r e a s i n g t h e number o f m e t h y l g r o u p s ( a s i n _5, 8^ a n d 9) l e a d s t o a s h a r p d e c r e a s e i n y i e l d , w i t h l i t t l e o r no 1_ b e i n g f o r m e d f r o m t h e most h i g h l y s u b s t i t u t e d compound 9_. A s i m i l a r s t e r i c e f f e c t was n o t e d p r e v i o u s l y i n a s t u d y o f t h e n i t r o l y s i s of N,N-dialkylamides (j6) . I t i s n o t e w o r t h y t h a t t h e n i t r i c - t r i f l u o r o a c e t i c anhydride system i s l e s s s e n s i t i v e t o s t e r i c f a c t o r s t h a n t h e o t h e r two, a n d , i n f a c t , g a v e a l o w y i e l d o f 1^ f r o m i n c o n t r a s t t o the other systems, w h i c h gave none. The p r e s e n c e o f e l e c t r o n - w i t h d r a w i n g g r o u p s Ci*e. C l i n 1Q, and CHICHI i n 13) p r e v e n t e d t h e f o r m a t i o n o f 1_. R o h s o n a n d R e i n h a r t (j6) n o t e d a s i m i l a r e f f e c t i n t h e n i t r o l y s i s o f N,N^

(CH^NNC^

i f s i m i l a r reasoning i s a p p l i e d t o the n i t r o l y s i s o f 18, i n t e r m e d i a c y o f t h e t r i n i t r a t e o f (-CH NE-) would b e i n v o l v e d . T h i s t r i a z i n e has never been i s o l a t e d , b u t i t i s thought t o b e an i n t e r m e d i a t e i n t h e r e a c t i o n o f f o r m a l d e h y d e w i t h ammonia t o form hexamethylenetetramine ( 1 8 ) , w h i c h i s known t o g i v e 1^ u p o n nitrolysis. A n o t h e r p o s s i b l e r o u t e f o r t h e f o r m a t i o n o f 1^ f r o m 18 w o u l d o f c o u r s e i n v o l v e d i r e c t n i t r o n i u m i o n a t t a c k , w i t h e x p u l s i o n o f t h e n e u t r a l m o l e c u l e C0~. U n l i k e t h e o t h e r a p p r o a c h e s t o 1^ d e s c r i b e d h e r e i n , t h e n i t r o l y s i s o f 1 £ w o u l d u n i q u e l y i n v o l v e c l e a v a g e o f a n ΝτΟ b o n d . I n a d d i t i o n t o o u r s t a n d a r d n i t r o l y s i s p r o c e d u r e s , we a l s o em p l o y e d t r e a t m e n t o f 1 £ w i t h l i q u i d N 0 ( 1 9 ) , a n d w i t h aqueous n i t r o u s a c i d , b y a n a l o g y t o a known (t) p r o c e d u r e s f o r g e n e r ^ a t i n g t h e n i t r i m i n o group: 2

3

2

^NOH

+

HN0

2

»NN0

2

+

^0

None o f t h e s e a p p r o a c h e s y i e l d e d 1^.



332

INDUSTRIAL AND LABORATORY NITRATIONS

The n i t r o l y s i s o f t h e N-S bond i s a n e s t a b l i s h e d method f o r p r e p a r i n g n i t r a m i n e s i n good y i e l d s f r o m t h e Ν,Ν-dialkylsulfona m i d e s o f b o t h a l i p h a t i c and a r o m a t i c s u l f o n i c a c i d s ( $ ) . I n a d d i t i o n , 2 f o r m s JL i n good y i e l d , a n d , i n f a c t , was s e r i o u s l y c o n s i d e r e d a t one t i m e f o r t h e p r o d u c t i o n o f 1 o n a l a r g e s c a l e . Compounds 2£ and 2 1 , h o w e v e r , g a v e no 1^, w h i c h i n t h e f o r m e r c a s e was n o t e d b y o t h e r s ( 3 ) . We c o n c l u d e f r o m t h e a b o v e s t u d y t h a t t h e p r e p a r a t i o n o f _1 f r o m 1 , 3 , 5 - t r i a c y l h e x a h y d r o - s - t r i a z i n e s a n d r e l a t e d compounds i s a n a p p r o a c h l i m i t e d , o n t h e one h a n d , b y t h e same s t e r i c a n d i n d u c t i v e f a c t o r s a l r e a d y known t o l i m i t t h e p r e p a r a t i o n o f n i t r a m i n e s f r o m Ν,Ν-dialkylamides, a n d , i n a d d i t i o n , b y t h e l a b i l i t y of the t r i a z i n e r i n g . D e t a i l e d S t u d y o f P r e f e r r e d Compounds A. and The good y i e l d s o f JL o b t a i n e d f r o m 4^ a n d 5_ i n t h e p r e l i m i - r n a r y t e s t s summarized i n T a b l e I l e d u s t o make a more d e t a i l e d study of t h e i r n i t r o l y s i s , the r e s u l t s of which a r e reported i n T a b l e I I . I t i s n o t e d t h a t _5 a l w a y s y i e l d s p u r e L, w h i l e 4^ a l w a y s g i v e s a m i x t u r e o f 1_ a n d TAX, e x c e p t when u s i n g n i t r i c acid-phosphorus pentoxide. This d i f f i c u l t y i n removing t h e l a s t a l k a n o y l g r o u p i n t h e c o n v e r s i o n o f 4 t o 1 was i n f a c t u n i q u e among t h i s g r o u p o f compounds, s i n c e a l l o f t h e o t h e r s (5 — 9^ i n c l u s i v e ) gave o n l y p u r e 1^. T h i s much g r e a t e r e a s e o f r e m o v a l of t h e p r o p i o n y l v s . t h e a c e t y l group i s e s p e c i a l l y noteworthy i n the f i v e - m i n u t e runs u s i n g n i t r i c a c i d - t r i f l u o r o a c e t i c anhy d r i d e , where t h e r e s p e c t i v e y i e l d s o f JL w e r e 92 a n d 4 4 % | t h e same was n o t e d u s i n g n i t r i c a c i d a l o n e (55 and 1 5 % ) . I t i sclear t h a t 1^ c a n b e o b t a i n e d f r o m 4_ o r 5_, b y a s u i t a b l e c h o i c e o f c o n d i t i o n s , i n good t o e x c e l l e n t y i e l d s , We h a v e no e x p l a n a t i o n a s y e t f o r t h e h i g h d e g r e e o f v a r i a t i o n i n t h e y i e l d s o f 1^ f r o m J5 when u s i n g n i t r i c a c i d - p o l y p h o s p h o r i c a c i d o r n i t r i c a c i d sulfur trioxide. P r e l i m i n a r y Economic Comparison The o v e r a l l p r o c e s s f o r p r e p a r i n g JL v i a 4 o r 5^would i n v o l v e r e c o v e r y o f a c e t i c o r p r o p i o n i c a c i d s and t h e i r r e c y c l e . One p r o c e d u r e f o r d o i n g t h i s i n v o l v e s t h e f o l l o w i n g S e q u e n c e A, w i t h y i e l d s given p a r e n t h e t i c a l l y : (1)

4

(2)

3 CH COOH

+

3 NH

(3)

3 CH CN

+

3 CH 0

Adding

+

3

HN0

3

3

^ > 1

3

+

3

CILjCQOIL

> 3 CH^CN

3

(85%) +

6 H 0 2

>^

2

(85%)

( 1 ) , ( 2 ) , and ( 3 ) , we h a v e :

(4)

3 HN0

3

+

3 NH

3

+

3 0Η 0 £

(94%)

>1

+

6

E 0 2


23.

GILBERT E T A L .

Preparation

of RDX

333

R e a c t i o n ( 2 ) i s w e l l known ( 2 0 ) . R e a c t i o n s (1) a n d C3) w e r e s t u d i e d f o r u s under c o n t r a c t ( 2 1 ) : t h e l a t e r r e a c t i o n i s known ( 2 2 ) . A v a r i a t i o n o n t h e a b o v e i s t h e f o l l o w i n g S e q u e n c e B; (1)

4


(5)

+

3 HN0

3 CH C00H

+

3

P 3

P

A

y i

3

+

3

CILjCOOH.

» 3 C^CONH^

+

(85%)

3 1^0

(95%)

Table I I N i t r o l y s i s Studies of (-CH N(COCH )-) 2

3

3

( 4 ) , and ( - C H N ( C O C H ) - ) ( 5 ) 2

Minutes

Temp.

5

3

P e r c e n t Crude Y i e l d o f _1 f r o m

Reaction Conditions

Reagent

2

(°C.)

4

a

-

60

50

87(96)

30

50

87(92)

5

50

58(76)

HNO Alone

30

50

20(75)°'

HN0 -P 0

15

65

15

70

87(98)

30

50

70(92)

120

27

-

HN0 -(F CC0) 0 3

3

2

3

3

2

HN0 -PPA

5

f

3

H N 0

N

3" 2°5

HN0.-S0

f Q

C

98° 92 d

5

5

c

80 g

e

74-93 92 40-93

Parenthetical figures indicate the content of 1 in the crude, the remainder being T A X . * Pure 1 in all cases. These data are from Table I. R e f . 21 noted 28-37% yields of crude 1, containing 16-24% T A X , using other conditions. Ref. 21 noted 67-83% yields of crude 1, containing 4-54% T A X , using other conditions. These experiments were run by D r . R. W . Hutchinson of this laboratory; PPA = polyphosphoric acid. ' Ref. 21 noted 58-83% yields of crude 1 containing traces to 80% T A X , using other conditions. a

c

d

e

1



334

(6)

3 CH CONH 3

+

2

3

CH 0

>4

2

+

3 H^O

(85%)


Adding ( 1 ) , (5) and (6) a g a i n g i v e s e q u a t i o n ( 4 ) . R e a c t i o n (6) was i m p r o v e d f r o m a l o w - y i e l d t o a h i g h - y i e l d p r o c e s s u n d e r a c o n t r a c t s t u d y ( 2 3 ) ; r e a c t i o n ( 5 ) i s known t o p r o c e e d i n good yield. I t i s n o t e d t h a t S e q u e n c e s A and Β d i f f e r i n w h e t h e r n i t r i l e o r a m i d e i s u s e d a s i n t e r m e d i a t e , and a s t o w h e t h e r w a t e r r e m o v a l i s e f f e c t e d i n two s t a g e s o r o n e . A t h i r d S e q u e n c e , C, i s t h a t now u s e d t o make 1 o n a l a r g e scale: (7)

1/2 ( C H ) . N , + N H , N 0 + 2 H N 0 + 3 ( C H . C 0 ) 0 — * 1 + 6 CH-COOH 2 6 4 4 3 3 3 2 3 o

o

o

Q

o

c

(8)

6

CH COOH

(9)

2 NH

*.3 ( C H C O ) 0

3

3

+

3

3

2

CH 0

+

3

& 0 2

6

3

%

)

(95%)

2

> l / 2 (CH ) N

2

g

4

+

3 1^0 (95%)

A d d i n g ( 7 ) , ( 8 ) , and ( 9 ) , a g a i n g i v e s ( 4 ) . I n t h i s c a s e , t h e w a t e r i s removed a t two p o i n t s and t h e r e c o v e r e d a c e t i c a c i d i s r e c y c l e d as a c e t i c anhydride. I t i s t h e r e f o r e e v i d e n t t h a t i n a l l t h r e e c a s e s , we a r e merely u s i n g d i f f e r e n t o v e r a l l expedients f o r r e a c t i n g formalde h y d e , ammonia, and n i t r i c a c i d , a n d t h a t w h i c h i s t h e m o s t e c o n o m i c method i s d e t e r m i n e d b y t h e e f f i c i e n c y o f t h e i n t e r n mediate r e a c t i o n s . U s i n g a v a i l a b l e d a t a , w h i c h f o r Sequences A and Β a r e o n a l a b o r a t o r y l e v e l , t h e s e t h r e e a p p r o a c h e s h a v e b e e n s u b j e c t e d t o a c o m p a r a t i v e c o s t a n a l y s i s (.24) , w i t h r e s u l t s summarized i n T a b l e I I I . I t i s n o t e d t h a t t h e two t r i a z i n e p r o c e d u r e s a r e c l o s e l y s i m i l a r i n b o t h Permanent I n v e s t m e n t a n d O p e r a t i n g C o s t , a n d t h a t t h e Bachmann P r o c e s s ( S e q u e n c e C i h a s a somewhat h i g h e r P e r m a n e n t I n v e s t m e n t a n d a somewhat l o w e r Operating Cost. Although i t i s f e l t that Operating Costs f o r a l l t h r e e p r o c e d u r e s c a n b e r e d u c e d somewhat w i t h f u r t h e r s t u d y , i t i s c o n c l u d e d t h a t t h e t h r e e methods a r e q u i t e c l o s e l y c o m p e t i t i v e .

Table I I I RDX: Method

Comparative

Cost

Permanent Investment

C (Bachmann) A (Triazine v i a N i t r i l e ) Β ( T r i a z i n e v i a Amide)

1.00 0.83 0.83

* I n c l u d e s raw m a t e r i a l s , l a b o r , u t i l i t i e s ,

Data Operating Cost* 1.Q0 1.15 1.15 and overhead.


23.

GILBERT E T A L .

Preparation

of RDX

335

EXPERIMENTAL SECTION ( 2 5 )


1,3,5-Triformylhexahydro-s-triazine, (3). To a c e t i c - f o r m i c a n h y d r i d e (18.6 g.-0.21 m o l e ) , p r e p a r e d b y a p u b l i s h e d p r o c e d u r e (26) f r o m a c e t i c a n h y d r i d e (21.4 g.-0.21 m o l e ) a n d 98% f o r m i c a c i d ( 9 . 7 g . -0.21 m o l e ) , was added p o r t i o n w i s e w i t h s t i r r i n g a t 10° h e x a m e t h y l e n e t e t r a m i n e ( 6 . 7 g . -0.048 m o l e ) . The v i s c o u s m i x t u r e was a l l o w e d t o warm t o room t e m p e r a t u r e over 2 hours w i t h s t i r r i n g to a t t a i n complete s o l u t i o n . Water (100 m l ) was added s l o w l y t o d e s t r o y e x c e s s a n h y d r i d e , f o l l o w e d by n e u t r a l i z a t i o n w i t h s o l i d potassium carbonate. The s o l u t i o n was e v a p o r a t e d t o d r y n e s s i n v a c u o , and t h e r e s i d u e was d r i e d i n vacuo over sodium h y d r o x i d e . I t was t h e n e x t r a c t e d w i t h 3-250 m l . p o r t i o n s o f c h l o r o f o r m . T h e combined e x t r a c t s w e r e f i l t e r e d and e v a p o r a t e d , y i e l d i n g 5.3g. ( 6 4 % ) , m.p. 169.5-171°. R e c r y s t a l l i z a t i o n f r o m a c e t o n e - w a t e r r a i s e d t h e m.p. t o 171-2°. NMR ( d e u t e r i o c h l o r o f o r m ) : û 5.32s ( 6 H , C H j ; δ 8.20 s (3R,CH0). A n a l . C a l c d , f o r C Η Ν 0 : C,42.1;H,5.3;N,24.6. F o u n d : C,42«2;H,5.3;N,24.3. M o l f wtT: C a l c d . : 1 7 1 . Found: 180 ( o s m o m e t r i c ) , 171 (mass s p e c t r o m e t r i c ) ( 2 7 ) . T r i a z i n e s ]_ NN) C R ) , δ 5.80 ( s , 41L, r e m a i n i n g CH^) , δ 2.27 ( s , 3Η, CH~) . I r (potassium bromide), 3 0 6 0 , 1660 (CH C O N ) 1 5 8 0 (Q.NNJ, 1 4 2 0 , 1 3 7 0 , 1280 (0 N N ) , 1240, 1180, 1030, 9 9 0 , 9 2 0 , 8 8 0 , 8 5 0 , 8 1 0 , 75Q, 6 3 0 , 5 8 5 , a n d 490 c n T l . 2

2

5

Nitrolysis

Procedures

N i t r i c A c i d - P h o s p h o r u s P e n t o x i d e . To p h o s p h o r u s p e n t o x i d e (10.0 g. -0.070 m o l e ) i n a 100 m l . t h r e e - n e c k e d f l a s k , e q u i p p e d w i t h thermometer, magnetic s t i r r e r , and r e f l u x condenser, i s added a l l a t o n c e w i t h s t i r r i n g a t room t e m p e r a t u r e 9 9 % n i t r i c a c i d (30.0 g. -0.480 m o l e (20 m l . ) . No e x t e r n a l c o o l i n g i s used, and an exotherm o c c u r s , t a k i n g t h e r e a c t i o n temperature t o a b o u t 60°. A f t e r c o o l i n g t o 3 5 ° , 1.0 g. o f t h e o r g a n i c compound (0.018 m o l e o r l e s s o f amido g r o u p ) , i s added r a p i d l y with stirring. T h e m i x t u r e i s t h e n h e a t e d r a p i d l y t o 65° a n d h e l d t h e r e f o r 15 m i n u t e s , a f t e r w h i c h i t was q u e n c h e d o n i c e and t h e p r o d u c t f i l t e r e d and d r i e d . The p u r i t y o f t h e 1 o b t a i n e d was e s t a b l i s h e d b y m e l t i n g b e h a v i o r , and b y i r a n d nmr s p e c t r a l d a t a . H i g h l y p u r i f i e d 1_ m e l t s a t 204.5° ( d e c . ) (34.). I r ( p o t a s s i u m b r o m i d e ) : 3060, 3000, 1570 ( 0 N N ) , 1 5 2 5 , 1 4 5 5 , 1 4 2 0 , 1 3 8 0 , 135Q, 1 3 1 0 , 126Q (0 N N ) , 1220, 1035, 9 1 0 , 8 8 0 , 8 4 0 , 7 8 0 , 7 5 0 , 67Q, 5 9 0 , 46Q, 4 1 0 , and 340 cm-1. T h e p r e s e n c e o f - T A X a s a n i m p u r i t y was d e t e c t e d by t h e CHACON p e a k a t 1660 cm . The q u a n t i t y o f TAX i n c r u d e _1 was d e t e r m i n e d b y r e l a t i v e nmr p e a k h e i g h t s . O t h e r s ( 2 1 ) h a v e r e p o r t e d t h e o c c a s i o n a l f o r m a t i o n o f some b y - p r o d u c t 1 , 3 d i a c e t y l - 5 - n i t r o h e x a h y d r o - s - t r i a z i n e f r o m t h e n i t r o l y s i s o f 4^. I t was n o t e d o n l y when TAX f o r m a t i o n was h i g h , t h e q u a n t i t y u s u a l l y b e i n g < 1 0 % b y w e i g h t o f t h e TAX. We e n c o u n t e r e d n o n e 9


338


of this material i n our work. Nmr data for i t (21) are as follows: (DMSO-d.): 6 2.17 (s, 6H, 2CH ), 6 5.27 (s, 2K,AcN-ÇR -NAc), ô 5.70 (s, 4H, -CH N (N0 ) CH -). Nitric Acid. The compound (l.Og. -0.018 mole or less of amido group) i s added quickly to 99% n i t r i c acid (30.0g. -0.480 mole -20ml.) at room temperature i n a flask equipped with a thermometer and magnetic s t i r r e r . The flask is then immersed in a water bath preheated to 70°, and the reaction mixture i s held at this temperature for 15 minutes. The solution is then quenched on ice, and the product is filtered and dried. Nitric Acid-Trifluoroacetic Anhydride. To 99% n i t r i c acid (15.0 g. -234 mole -10 ml.) i s added dropwise at 5-10°, with cooling and s t i r r i n g , trifluoroacetic anhydride (10.Og. -0.048 mole -6.5 ml.). The organic compound (l.Og.) i s added a l l at once, and the flask is then immersed in a water bath preheated to 50°. The mixture i s held at this temperature for 30 minutes, and i s then quenched i n ice water to. precipitate the product, which is filtered and dried. Nitrations of 4 and 5^ with polyphosphoric acid were done at 70° for 15 minutes using 5.0g. compound (corresponding to 0.071 and 0.059 mole amido group, respectively), 9.0 g. (0.140 mole) 99% n i t r i c acid and 10.0 g. polyphosphoric acid C83% P 0^). The nitration of 5. with sulfur trioxide was effected at 27° for 2 hours, using 3.0 g. (0.035 mole amido group), 30.0 g. (0.470 mole) 99% n i t r i c acid and 7.2 g. (0.090 mole) liquid sulfur trioxide; the acids were carefully premixed at 5°.


2

2

2

2

ABSTRACT Nineteen triazines, (-CH N(R)-) , were nitrolyzed by several procedures for preparation of the explosive RDX (R=NO). The reaction succeeds only when R is alkanoyl or KOCO. With R = acetyl, mixtures of RDX and the monoacetyldinitro analogue (TAX) were usually formed; i n all other cases, the product was pure RDX. Nitric acid-trifluoroacetic anhydride gave the best yields (max. 98%), followed successively by n i t r i c acid -P O5 (80%), and n i t r i c acid alone (55%). Three other nitrolysis systems were considered briefly. A preliminary economic comparison of the triazine process with the current Bachmann process, which uses hexamethylenetetramine and acetic anhydride, shows that the former method entails lower plant investment and higher operating cost than the latter. Further improvements appear possible with both procedures. 2

3

2

2

LITERATURE CITED (1)

G.F.Wright, "Methods of Formation of the Nitramine Group, Its Properties and Reactions", i n The Chemistry of the Nitro and Nitroso Groups", Part 1, H.Feuer, E d . , Interscience, New York, 1969, pg. 613 ff.


23.

(2) (3) (4) (5) (6) (7) (8)


(9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (22) (23) (24) (25)

(26) (27) (28) (29) (30)

GILBERT ET AL.

Preparation of RDX

339

A.T.Blomquist, OSRD Report 4134 (1944), pg. 135-6. G.C.Bassler, "The Chemistry of Cyclonite", PhD Thesis, Pennsylvania State University, 1943. D.N.Thatcher, U.S. Patent 3,178,430 (1965). M.Warman, V . I . S i e l e , E.E.Gilbert, J.Het. Chem. 10, 97 (1973) J.H.Robson, J.Reinhart, J.Am.Chem. Soc. 77, 2453 (1955). J.H.Robson, J.Am.Chem. Soc. 77,107 (1955). M.B.Frankel, C.H.Tieman, C.R.Vanneman, M.H.Gold, J.Org. Chem. 25, 744 (1960). This procedure was developed by Mr. V . I . S i e l e of this laboratory. H.A.Levine, U.S. Patent 2,976,152 (1961). E.M.Smolin, L.Rapoport, "s-Triazines and Derivatives", Interscience Publishers, New York, 1959, pg. 533. M.A.Gradsten, M.W.Pollock, J.Am.Chem. Soc. 70, 3079 (1948). R.Wegler, A.Ballauf, Chem. Ber. 81, 527 (1948). B.S.Thyagarajan, K.C.Majumdar, J.Het. Chem. 11,937 (1974). E.E.Gilbert, Int. J. Sulfur Chem. 3(1), 43 (1973). V.Grakauskas, K.Baum, J.Org.Chem. 37 (2), 334 (1972). A.P.N.Franchimont, Rec. Trav. Chim. 3, 216 (1884). Y.Ogata, A.Kawasaki, i n "The Chemistry of the Carbonyl Group", V o l . 2, J.Zabicky, Ed., Interscience, New York, 1970, pg. 51. Private communication, Professor B.S.Thyagarajan, University of Idaho. E.L.Tollefson, R.M.Dicker, C.B.Johnson, Can.J.Eng. 48, 219 (1970). E.I.duPont de Nemours & Co., Dr. C.H.Rolston, Principal Investigator, Contract No. DAAA-21-71-C-0542. M.A.Gradsten, M.W.Pollock, J.Am.Chem. Soc. 70, 3079 (1948). Stanford Research Institute, Dr. C.L.Coon, Principal Investigator, Contract No. DAAA-21-73-C-0487. Stanford Research Institute, Dr. Y.C.Yen, Process Economics Group, Contract No. as i n Ref. 23. Melting points were taken i n capillary tubes i n a Thomas -Hoover apparatus, and are uncorrected. Infrared spectra were determined i n potassium bromide pellets with a Perkin -Elmer Model 457 A spectrophotometer. Nmr spectra were de termined i n the stated solvent on a Varian Τ-60 spectrometer, using tetramethylsilane as internal reference. Microanaly ses and molecular weights were run by Schwarzkopf Micro analytical laboratory, Woodside, N.Y. L.F.Fieser, M.Fieser, "Reagents for Organic Synthesis", Wiley, New York, 1967, pg. 4. We are indebted to Professor T.Axenrod, City University of New York, for this determination. W.Emmons, H.Rolewicz, W.Cannon, R.Ross, J.Am.Chem.Soc. 74, 5524 (1952). W.R.Dunstan, A.L.Bossi, J.Chem. Soc. 73, 353 (1898). H. Kraessig, H.Ringsdorf, Macromol, Chem. 22, 163 (1957).


340


S.D.Jolad, S.Rajagopal, Org. Syn. Coll. Vol. V, H.E.Baumgarten, Ed., Wiley, New York, 1973, pg. 139. (32) W.J.Chute, A.F.McKay, R.H.Mean, G.S.Myers, G.F.Wright, Can. J.Res. 27B, 503 (1949). (33) K.W.Dunning, W.J.Dunning, J.Chem Soc. 1950, 2920. (34) F.Chapman, P.G.Owston, D.Woodcock, J.Chem.Soc. 1949., 1638.


(31)


Industrial and Laboratory Nitrations

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