Isotopic Studies of Thermally Induced Reactions of Coal and Coal

12 Isotopic Studies of Thermally Induced Reactions of Coal and Coal-Like Structures CLAIR J. COLLINS, BEN M. BENJAMIN, VERNON F. RAAEN, PAUL H. MAUPIN, and W. H . ROARK (1)

Downloaded by UNIV LAVAL on July 11, 2016 | http://pubs.acs.org Publication Date: June 1, 1978 | doi: 10.1021/bk-1978-0071.ch012

Chemistry Division, Oak Ridge National Laboratory, Oak Ridge, T N 37830

We r e c e n t l y (2) reported that under c o n d i t i o n s o f coal conv e r s i o n (tetralin, 400°) several d i a r y l a l k a n e s undergo carbon-carbon cleavage, and that the scission o f carbon-carbon bonds must t h e r e f o r e be considered as an important process i n asphaltene formation ( 3 ) . We also reported (2) t h a t vitrinite (from Illinois No. 6 c o a l ) was a " b e t t e r hydrogen t r a n s f e r agent" than tetralin itself f o r the hydrogenolysis o f 1 , 1 , 2 - t r i p h e n y l e t h a n e t o diphenylmethane and toluene. We have now extended these s t u d i e s to e s t a b l i s h a) t h a t vitrinite i s indeed a b e t t e r hydrogen donor than tetralin toward several organic s t r u c t u r e s ; b) that tetralin, i n a d d i t i o n t o its f u n c t i o n as a hydrogen donor, can undergo c e r t a i n other r e a c t i o n s w i t h coal and coal-like s t r u c t u r e s which i n v o l v e both carbon-carbon bond formation and bond cleavage. A Comparison o f T etralin an d V itrinite as H-donors When 1 , 2 - d i p h e n y l - 1 - p - t o l y l e t h a n e i s heated a t 400° ( e i t h e r i n g l a s s capillaries or i n s t a i n l e s s s t e e l tubes) w i t h an excess of tetralin, the major products are toluene and phenyl-p-tolylmethane. The same products are obtained when 1 , 2 - d i p h e n y l - l - p t o l y l e t h a n e i s heated a t 400° i n the presence o f an excess o f v i t r i n i t e (handpicked from I l l i n o i s No. 6 c o a l ) . Given i n Table I i s a comparison o f the extent r e a c t i o n - as determined by g . c . a n a l y s i s o f the products - a f t e r various contact times with t e t r a l i n or w i t h v i t r i n i t e . Another d i a r y l a l k a n e which i s e a s i l y decomposed i n the presence o f excess t e t r a l i n o r excess v i t r i n i t e i s 1,3-diphenylpropane. The major products i n both cases are toluene and e t h y l benzene, although a m u l t i p l i c i t y o f minor products are produced. Also given i n Table I are comparisons o f the extent r e a c t i o n o f 1,3-diphenylpropane (400° f o r 30 minutes) a) with excess t e t r a l i n ; b) with excess t e t r a l i n and v i t r i n i t e ; and c) with excess v i t r i n i t e . The extent r e a c t i o n i n each case was estimated from the g . c . t r a c e .

0-8412-0427-6/78/47-071-165$05.00/0 © 1978 American Chemical Society Larsen; Organic Chemistry of Coal ACS Symposium Series; American Chemical Society: Washington, DC, 1978.

166

ORGANIC CHEMISTRY OF COAL

Table I A Comparison o f T e t r a l i n and I l l i n o i s No. 6 V i t r i n i t e as Hydrogen Donors

Reactants


1,2-Diphenyl-1-ptolylethane

Conditions 400°, 5 min tetralin

Percent Reaction 2%

a

II

4 0 0 ° , 30 m i n tetralin

II

400°, 5 min vitrinite 4 0 0 ° , 30 m i n tetralin

b

50%

a

1 , 3 - d i p h e n y l propane

b

23%

b

43%

b

65%

II

4 0 0 ° , 30 m i n tetralin & vitrinite

II

4 0 0 ° , 30 m i n vitrinite

The oven was a t 4 0 0 ° , b u t t h e warm-up t i m e i s 15 m i n u t e s , t h e a c t u a l t e m p e r a t u r e was c o n s i d e r a b l y l e s s t h a n 4 0 0 ° . b

94%

thus

3 0 m i η i n c l u d e d warm up t i m e .

S i n c e t h e r e a c t i o n s were m o n i t o r e d by g . c , w h i c h would d e t e c t n e i t h e r n o n v o l a t i l e polymeric m a t e r i a l , nor high molecular weight products o f r e a c t i o n with v i t r i n i t e , i t i s p o s s i b l e t h a t t h e v i t r i n i t e i s a c t i n g n o t as a hydrogen d o n o r , b u t m e r e l y as a c a t a l y s t , and t h a t t h e s o u r c e o f t h e h y d r o g e n f o r t h e h y d r o g e n o l y s e s comes f r o m t h e 1 , 2 - d i p h e n y l - l - £ - t o l y l e t h a n e or from the 1,3-diphenylpropane. To c i r c u m v e n t t h i s p r o b l e m , we h e a t e d benzophenone t o 4 0 0 ° f o r one hour a) i n t h e p r e s e n c e o f e x c e s s t e t r a l i n , and b) i n t h e p r e s e n c e o f e x c e s s v i t r i n i t e . The m a j o r p r o d u c t s a r e d i p h e n y l m e t h a n e and w a t e r , w i t h t r a c e s o f t o l u e n e and benzene. The r e a c t i o n i n t e t r a l i n p r o c e e d e d t o t h e e x t e n t o f o n l y 12%, whereas i n t h e p r e s e n c e o f v i t r i n i t e 35% r e a c t i o n had o c c u r r e d . (6,7) R e a c t i o n s o f T e t r a l i n o t h e r t h a n Hydrogen D o n a t i o n T e t r a l i n - l - ^ C r e a c t s w i t h Wyodak c o a l a t 4 0 0 ° (1 hour) t o the extent t h a t the p y r i d i n e - i n s o l u b l e r e s i d u e c o n t a i n s c h e m i c a l l y bound c a r b o n - 1 4 e q u i v a l e n t t o 5% t e t r a l i n by w e i g h t . F u r t h e r , when t h e r e s i d u e was r e h e a t e d i n normal t e t r a l i n ( 4 0 0 ° , one h o u r ) t h e r e i s o l a t e d s o l v e n t c o n t a i n e d no m e a s u r a b l e amount o f e i t h e r

Larsen; Organic Chemistry of Coal ACS Symposium Series; American Chemical Society: Washington, DC, 1978.

12.

Isotopic

COLLINS ET AL.

Studies of Thermally


l l f

Induced

Reactions

167

ll

t e t r a l i n - C o r o f n a p h t h a l e n e - * C . T h e r e were, however, t r a c e s o f l a b e l e d a l k y l a t e d n a p h t h a l e n e s , w h i c h were i d e n t i f i e d by g.c. r e t e n t i o n t i m e s as 1- and 2 - s u b s t i t u t e d m e t h y l - and e t h y l n a p h t h a l e n e s . These p r o d u c t s u n d o u b t e d l y a r i s e as a r e s u l t o f f r e e r a d i c a l i n t e r m e d i a t e s . We t h e r e f o r e i n v e s t i g a t e d t h e p o s s i b i l i t y t h a t m e t h y l - o r e t h y l n a p h t h a l e n e s c o u l d be p r o d u c e d by t h e r e a c tion of t e t r a l i n with structures containing aromatic moieties s e p a r a t e d by two o r more m e t h y l e n e g r o u p s , o r w i t h a r y l a l k y l e t h e r s . Both t y p e s o f s t r u c t u r e (4,5) a r e known t o be p r e s e n t i n d i f f e r e n t k i n d s and r a n k s o f c o a l . We h e a t e d s e v e r a l d i a r y l a l k a n e s and a r y l a l k y l o r a r a l k y l e t h e r s t o 4 0 0 ° i n t e t r a l i n f o r v a r y i n g p e r i o d s o f t i m e . Many o f t h e s e r e a c t i o n s y i e l d e d m e a s u r a b l e q u a n t i t i e s o f m e t h y l - and ethyl naphthalenes i n a d d i t i o n to other products. Typical are the r e a c t i o n s o f 1 , 3 - d i p h e n y l p r o p a n e and o f p h e n e t o l e , b o t h o f w h i c h were i n v e s t i g a t e d w i t h c a r b o n - 1 4 — l a b e l e d s p e c i e s . The p r o d u c t s were a n a l y z e d a) by gas c h r o m a t o g r a p h y combined w i t h r a d i o a c t i v i t y m o n i t o r i n g o f c a r b o n - 1 4 — l a b e l e d p r o d u c t s ; b) by gas c h r o m a t o g r a phy e q u i p p e d w i t h mass s p e c t r o g r a p h s a n a l y z e r s ; and c ) by i s o l a t i o n o f s p e c i f i c p r o d u c t s u s i n g p r e p a r a t i v e g.c. f o l l o w e d by nmr a n a l y s i s ( V a r i a n XL-100 S p e c t r o m e t e r ) . G i v e n i n T a b l e s II and I I I a r e t h e m a j o r p r o d u c t s o b t a i n e d - t o g e t h e r w i t h a p p r o p r i a t e y i e l d s - f r o m t h e r e a c t i o n s o f 1 , 3 - d i p h e n y l propane and phenetole, respectively, with t e t r a l i n . T a b l e II 3

M a j o r P r o d u c t s and Y i e l d s O b t a i n e d on H e a t i n g 1 , 3 - D i p h e n y l propane w i t h T e t r a l i n One Hour a t 4 0 0 °

Toluene E t h y l benzene 1- and 2 - ( 2 - P h e n y l e t h y l ) t e t r a l i n s 1,4-Diphenylbutane 1- and 2 - M e t h y l n a p h t h a l e n e s Styrene 1,3-Diphenylpropene Methyldi hydronaphthalenes 1,2-Diphenylethane 1- and 2 - ( 2 - P h e n y l e t h y l ) n a p h t h a l e n e s Other a

B a s e d on 1 , 3 - d i p h e n y l p r o p a n e

28% 19 8 5 3 1. 1. 34

consumed.

The 1- and 2 - m e t h y l n a p h t h a ! e n e s were i s o l a t e d and i d e n t i f i e d by nmr a n a l y s i s . T h e i r g e n e s i s f r o m t h e r e a c t i o n o f 1 , 3 - d i p h e n y l p r o p a n e - 2 - C ( C=*) and t e t r a l i n was d e t e r m i n e d as follows: lif

llf


168


CH P h C H C H C H P h + (0Q 2

2

-

2

00}

CH CH Ph

3

2

+

2

00)

Table III


M a j o r P r o d u c t s and Y i e l d s O b t a i n e d on H e a t i n g P h e n e t o l e w i t h T e t r a l i n E i g h t e e n Hours a t 4 0 0 °

Phenol M e t h y l n a p h t h a l enes Toluene E t h y l benzene Ethylnaphthalenes Methyltetralins Ethyl phenol Ethyltetralins E t h y l m e t h y l benzene Methylindane B u t y l benzene

37J » 7 ' 7

3 / 0

4 3 3 %

From D e c o m p o s i t i o n of Tetralin

The m i x t u r e o f e t h y l n a p h t h a l e n e s was i d e n t i f i e d by g . c . r e t e n t i o n t i m e s and r a d i o a c t i v i t y a s s a y by means o f t h e g . c . r a d i o a c t i v i t y m o n i t o r . T r a c e s o f m e t h y l i n d a n e and o f b u t y l benzene were a l w a y s p r e s e n t a f t e r r e a c t a n t s were h e a t e d w i t h t e t r a l i n . T h a t t h e s e l a t t e r two p r o d u c t s were d e r i v e d f r o m t e t r a l i n was d e m o n s t r a t e d by t h e f a c t t h a t t h e y c o n t a i n e d c a r b o n - 1 4 when t e t r a l i n - * C was u s e d i n t h e r e a c t i o n . In l i k e manner, l a b e l e d p h e n e t o l e and t e t r a l i n were s u b j e c t e d t o t h e c o n d i t i o n s o f r e a c t i o n w i t h t h e f o l l o w i n g results: l l

It i s c l e a r from the i s o t o p i c l a b e l i n g experiments t h a t t e t r a l i n has e n t e r e d i n t o t h e r e a c t i o n b o t h w i t h 1 , 3 - d i p h e n y l p r o p a n e and w i t h p h e n e t o l e . The r e s u l t s a r e n i c e l y accommodated by t h e p o s t u l a t i o n o f r a d i c a l i n t e r m e d i a t e s . A p o s s i b l e mechanism f o r t h e r e a c t i o n o f 1 , 3 - d i p h e n y l p r o p a n e i s i n d i c a t e d i n T a b l e IV.


COLLINS ET AL.

12.

Isotopic Studies of Thermally Induced Reactions

169

TABLE IV P o s s i b l e Mechanism f o r t h e R e a c t i o n o f T e t r a l i n w i t h 1 , 3 - D i p h e n y l propane PhCH CH CH Ph

>• PhCH -

+

PhCH -

*

+

2

2

2

+

2

PhCH

3

PhCH CH - +

*• PhC,H CH

2PhCH CH -

*~

2

2

2


2

2

2

(00

PhCH CH - + 2

2

CH CH Ph 2

2

-CH CH Ph 2

2

+

3

PhCH CH CH CH Ph 2

2

2

2

CH CH Ph

-

®3 ©0

2

2

CH '

?

2

+

PhCH 2

α & g

€0

CH 2

+

.

CH

0D - OO^eO ^ .CHs 3

a

α,β A c k n o w l e d g e m e n t s : We a c k n o w l e d g e w i t h t h a n k s t h e a s s i s t a n c e o f Mr. L. L. Brown i n r u n n i n g t h e nmr s p e c t r a , and o f Dr. W. T. R a i n e y , Mr. Ε. H. McBay and Mr. D. C. Canada o f t h e A n a l y t i c a l C h e m i s t r y D i v i s i o n , f o r c a p i l l a r y g . c . a n d mass s p e c t r o g r a p h ! c a n a l y s e s o f s e v e r a l o f t h e h y d r o g e n o l y s i s p r o d u c t s . We thank t h e S a h a r a M i n i n g Co., H a r r i s o n b u r g , 111., f o r a g e n e r o u s sample o f I l l i n o i s No. 6 c o a l ; t h a n k s a r e a l s o due D r s . L. A. H a r r i s and A. S. Dworkin f o r a f i e l d t r i p t o t h e mine s i t e .

Literature Cited 1. 2.

Research sponsored by the Division o f Basic Energy Sciences of the Department o f Energy under contract with the Union Carbide Corporation. C o l l i n s , C. J., Raaen, V. F., Benjamin, Β. M . , and Kabalka, G. W., Fuel (1977), 56, 107.


170

3.

4. 5. 6.


7.


S e e also S h o z d a , R. J., Depp, Ε. Α . , Stevens, C. Μ . , and Neuworth, M. B., J. Amer. Chem. S o c . ( 1 9 5 6 ) , 78, 1716; Depp, Ε . Α . , Stevens, C. Μ . , and Neuworth, M. B., Fuel ( 1 9 5 6 ) , 35, 437. H e r é d y , L. Α . , K o s t y o , A. E . , and Neuworth, M. B., Fuel ( 1 9 6 5 ) , 44, 125. Brücker, R. a n d Kölling, G., Brennst. Chem. ( 1 9 6 5 ) , 46, 4 1 ; Kölling, G. a n d H a u s i g k , D., ibid. (1969) 50, 1. For information on "Catalylic D e h y d r o g e n a t i o n of Coal" s e e R e g g e l , L . , Wender, I., a n d Raymond, R., Fuel ( 1 9 7 3 ) , 52. 162-163 (1973) a n d the previous six papers in this series cited therein. C o a l s have previously been d e h y d r o g e n a t e d w i t h p - b e n z o q u i n o n e , P e o v e r , M. E . , J. Chem. S o c . (London) ( 1 9 6 0 ) , 5020.

RECEIVED February 10,

1978


Isotopic Studies of Thermally Induced Reactions of Coal and Coal

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