Molecular Sieves

45 Reactions of Aromatic Compounds with Ammonia over Y Zeolite 1

Downloaded by FUDAN UNIV on March 7, 2017 | http://pubs.acs.org Publication Date: June 1, 1973 | doi: 10.1021/ba-1973-0121.ch045

KOU HATADA, YOSHIOONO,and TOMINAGA KEII Department of Chemical Engineering, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo, Japan

The reactions of chlorobenzene and benzaldehyde with amm over metal Y zeolites have been studied by a pulse techniqu For aniline formation from the reaction of chlorobenzene and ammonia, the transition metal forms of Y zeolites show good ac tivity, but alkali and alkaline earth metal forms do not For CuY, the main products are aniline and benzene. The order of catalytic activity of the metal ions is Cu > Ni > Zn> Cr > Co > Cd > Mn > Mg, Ca, Νa 0. This order has no relation to the order of electrostatic potential or ionic radius, but is closely re lated to the order of electronegativity or ammine complex forma constant of metal cations. For benzonitrile formation from benzaldehyde and ammonia, every cation form of Y zeolite show high activity. G y n t h e t i c zeolites h a v e been used as c a t a l y s t s for m a n y reactions. ^

Their

c a t a l y t i c a c t i v i t y depends s t r o n g l y o n t h e n a t u r e of exchangeable

m e t a l cations.

P i c k e r t a n d c o - w o r k e r s (1) p r o p o s e d t h a t t h e h i g h c a t a l y t i c

a c t i v i t y of zeolites for carboniogenic reactions was caused b y t h e s t r o n g electrostatic field near surface cations, r e s u l t i n g i n p o l a r i z a t i o n of r e a c t a n t molecules. W a r d (2, 8) f o u n d a l i n e a r r e l a t i o n s h i p b e t w e e n t h e B r o n s t e d a c i d i t y a n d t h e m a g n i t u d e of t h e electrostatic field of a l k a l i n e e a r t h m e t a l i o n exchanged zeolites. H e suggested t h a t the field associated w i t h t h e c a t i o n p o l a r i z e d a d s o r b e d w a t e r w h i c h r e s u l t e d i n t h e f o r m a t i o n of acidic h y d r o x y l groups. T h e s e h y d r o x y l groups were t h e n t h e p r i m a r y a c t i v e sites for cumene c r a c k i n g a n d o-xylene i s o m e r i z a t i o n . T h i s i d e a was s u p p o r t e d b y T u r k e v i c h a n d O n o (4) w h o i n v e s t i g a t e d cumene c r a c k i n g a n d o-xylene Present address: Japan. 1

Faculty of Education, Saitama University, Urawa, Saitama, 501

Meier and Uytterhoeven; Molecular Sieves Advances in Chemistry; American Chemical Society: Washington, DC, 1973.

502

MOLECULAR SIEVES

i s o m e r i z a t i o n o n h y d r o g e n Y zeolite a n d c o n c l u d e d t h a t t h e B r o n s t e d sites were responsible for these reactions. O n l y a few a t t e m p t s h a v e been m a d e t o r e l a t e t h e c a t a l y t i c a c t i v i t y t o t h e properties of cations o n t h e t r a n s i t i o n m e t a l - e x c h a n g e d zeolites. C r o s s , K e m b a l l , a n d L e a c h (5) s t u d i e d t h e i s o m e r i z a t i o n of 1-butenes o v e r a series of t h e i o n - e x c h a n g e d X zeolites. T h e i r results w i t h C e X zeolite a n d t h e m a j o r i t y of o t h e r zeolites i n d i c a t e d a c a r b o n i u m i o n m e c h a n i s m ; h o w e v e r a r a d i c a l m e c h a n i s m was o p e r a t i v e w i t h N i X a n d i n some cases with Z n X .


W a r d (3, 6) d e t e r m i n e d t h e a c i d i t y of s e v e r a l t r a n s i t i o n m e t a l X a n d Y zeolites b y i n f r a r e d spectroscopy b u t c o u l d f i n d n o s i m p l e r e l a t i o n s h i p b e t w e e n t h e p r o t o n a c i d c o n c e n t r a t i o n a n d p h y s i c a l p a r a m e t e r s of m e t a l ions or c a t a l y t i c a c t i v i t y for o-xylene i s o m e r i z a t i o n . T h e reactions s t u d i e d so f a r are confined t o those i n d i c a t i v e of t h e f o r m a t i o n of c a r b o n i u m i o n i n t e r m e d i a t e s . F o r these reactions t h e B r o n s t e d a c i d sites u s u a l l y h a v e h i g h c a t a l y t i c a c t i v i t y . T h u s , i t m i g h t be difficult t o o b t a i n i n f o r m a t i o n o n t h e c a t a l y t i c properties of m e t a l ions since t h e c a t a l y s i s b y a c i d sites m a y m a s k t h e c a t a l y s i s b y m e t a l ions. T h e r e f o r e , t o i n v e s t i g a t e c a t a l y t i c properties of m e t a l ions, i t is desirable t o a v o i d t h e carboniogenic reactions a n d t o p o i s o n t h e B r o n s t e d sites. I n t h i s w o r k t h e reactions of a m m o n i a w i t h chlorobenzene a n d b e n z a l d e h y d e over a series of m e t a l i o n - e x c h a n g e d zeolites were i n v e s t i g a t e d b y t h e m i c r o r e a c t o r m e t h o d , a n d a t t e m p t s were m a d e t o relate t h e c a t a l y t i c a c t i v i t y of t h e zeolites t o properties of m e t a l cations. A m m o n i a was a r e a c t a n t a n d a p o i s o n for a c i d i c sites. T o m a n u f a c t u r e a n i l i n e f r o m chlorobenzene a n d a m m o n i a , c u p r o u s oxide or d i a m i n o c u p r o u s c h l o r i d e has been used as t h e c a t a l y s t a n d t h e r e a c t i o n is u s u a l l y c a r r i e d o u t i n t h e l i q u i d phase u n d e r pressure (7). There are few r e p o r t s o n t h e r e a c t i o n i n gas phase. J o n e s (8) f o u n d t h a t C u X was a c t i v e for a n i l i n e f o r m a t i o n w h i l e Z n X l e d t o t h e f o r m a t i o n of d i c h l o robenzenes. T h e r e a c t i o n of b e n z a l d e h y d e w i t h a m m o n i a over zeolite has n e v e r been r e p o r t e d . Experimental C a t a l y s t s . T h e s t a r t i n g m a t e r i a l for a l l c a t a l y s t s was c o m m e r c i a l L i n d e S K - 4 0 ( Y zeolite) p o w d e r , free of c l a y b i n d e r . I n a l l cases, t h e zeol i t e s were p r e p a r e d b y i o n exchange w i t h s a l t s o l u t i o n . T h e degree of exchange was e s t i m a t e d b y g r a v i m e t r i c a n a l y s i s for e l u t e d s o d i u m , u s i n g m a g n e s i u m u r a n y l acetate reagent. T h e degree of exchange for C u Y d e t e r m i n e d b y t h i s m e t h o d agreed s a t i s f a c t o r i l y w i t h t h a t d e t e r m i n e d b y t h e a n a l y s i s of r e s i d u a l salt s o l u t i o n . T h e degree of exchange of zeolite is listed i n Table I. Apparatus a n d Procedure. T h e conventional microreactor was used t o d e t e r m i n e c a t a l y t i c a c t i v i t i e s . T h e reactor w a s a 4 m m i d b o r o s i l i c a t e glass t u b i n g , d i r e c t l y connected t o t h e d u a l c o l u m n gas c h r o m a t o g r a p h


45.

Table I.

Form Na+ Ca Mg Mn Cd Co Cr Zn Ni + Cu

Yield of Aniline and Benzene from Chlorobenzene and Ammonia at 395°C Electro Na negativity Yield of Yield of log βι for Metal Aniline, % Benzene, %

2 +

2 + 2 +

2 +

2 +

3 +

2 +


2

2 +

503

Reactions over Y Zeolite

HATADA ET A L .

73 60 91 92 90 92 89 93

-0.2 0.23 0.8 2.60 2.05 2.27 2.75 4.13

0.9 1.0 1.2 1.5 1.7 1.8 1.6 1.6 1.8 1.9

0 0 0 0.5 1.9 2.8 3.8 4.2 9.7 29.2

0 0 0 0 0 1.7 4.2 0 22.5 9.5

o p e r a t e d a t 100°C. T h e a n a l y t i c a l c o l u m n w a s 2 m l o n g stainless steel t u b i n g (od 6 m m ) p a c k e d w i t h 20 w t % s i l i c o n e o i l D . C . 703 o n 60-80 m e s h Celite545. N e a t a m m o n i a was used as a c a r r i e r gas a n d as a r e a c t a n t . I t was d r i e d b y passage t h r o u g h a s o d i u m h y d r o x i d e c o l u m n before i t e n t e r e d t h e r e a c t o r . T h e flow r a t e of a m m o n i a w a s 60 m l / m i n . T h e c a t a l y s t w a s p l a c e d i n t h e r e a c t o r a n d h e l d b y t w o s m a l l p l u g s of q u a r t z w o o l . P r i o r to t h e r e a c t i o n s , t h e c a t a l y s t s were h e a t e d i n a h e l i u m s t r e a m (60 m l / m i n ) a t 4 5 0 ° C for 30 m i n a n d t h e n h e a t e d i n a n a m m o n i a s t r e a m a t t h e r e a c t i o n t e m p e r a t u r e for 30 m i n . T h e r e a c t i o n t e m p e r a t u r e was measured b y a chromel-alumel thermocouple placed adjacent to the c a t a l y t i c zone of t h e reactor. F o r each pulse, 5 μΐ of t h e r e a c t a n t ( c h l o r o benzene or b e n z a l d e h y d e ) were i n j e c t e d b y a m i c r o s y r i n g e . Results and

Discussion

R e a c t i o n of C h l o r o b e n z e n e w i t h A m m o n i a . P r e l i m i n a r y e x p e r i m e n t s showed t h a t chlorobenzene d i d n o t show a n y r e a c t i o n over zeolites i n a h e l i u m s t r e a m a n d t h a t C u Y zeolites h a v e good a c t i v i t y for a n i l i n e f o r m a t i o n . Therefore, t h e r e a c t i o n o v e r C u Y w a s s t u d i e d i n d e t a i l . T h e effect of t h e c u m u l a t i v e n u m b e r of pulses o n t h e c o n v e r s i o n of chlorobenzene c n C u Y was e x a m i n e d a t 3 9 5 ° C . T h e conversion gradually decreased for t h e first three pulses b u t become a l m o s t i n d e p e n d e n t of pulse n u m b e r thereafter. T h u s , i n t h i s s t u d y , t h e r e s u l t of t h e s i x t h p u l s e of each r u n was a d o p t e d for t h e c o m p a r i s o n of a c t i v i t i e s between samples. T h e m a i n p r o d u c t s were a n i l i n e a n d benzene, a n d a t r a c e of d i c h l o r o benzenes was f o r m e d . T h e y i e l d s of a n i l i n e a n d benzene increased p r o p o r t i o n a l l y w i t h i n c r e a s i n g a m o u n t s of c a t a l y s t . T h i s i n d i c a t e s t h a t b o t h a n i l i n e a n d benzene are f o r m e d i n d e p e n d e n t l y f r o m chlorobenzene a n d ammonia—i.e., one is n o t t h e p r o d u c t of t h e f u r t h e r r e a c t i o n of t h e other. 1.

T h e effect of t e m p e r a t u r e o n t h e r e a c t i o n o v e r C u Y is s h o w n i n F i g u r e T h e y i e l d of a n i l i n e increases o n l y s l i g h t l y w i t h t h e r e a c t i o n t e r n -


504

MOLECULAR SIEVES

80

-

20 Downloaded by FUDAN UNIV on March 7, 2017 | http://pubs.acs.org Publication Date: June 1, 1973 | doi: 10.1021/ba-1973-0121.ch045

C H,Cl e

^

Ο

CONVERSION (mol%)

60

CeHsNHa

ι 400 500 TEMPERATURE (°C)

—Ο"

300

Figure 1. Effect of the reaction tem perature on the conversion of chloro benzene on CuY p e r a t u r e , w h i l e t h e y i e l d of benzene depends s t r o n g l y o n t h e t e m p e r a t u r e . T h e a p p a r e n t a c t i v a t i o n energy of chlorobenzene disappearance i s 5.8 k c a l / m o l e , a n d t h e a c t i v a t i o n energies of t h e f o r m a t i o n of a n i l i n e a n d benzene are 2.2 a n d 14.7 k c a l / m o l e , r e s p e c t i v e l y . A m m o n i a decomposes o n zeolites (9), a n d t h e effect of t h i s d e c o m p o s i t i o n o n t h e chlorobenzene r e a c t i o n m a y b e i m p o r t a n t . T h u s , t h e a c t i v i t y of C u Y zeolite f o r a m m o n i a d e c o m p o s i t i o n was s t u d i e d . H e l i u m was used as a c a r r i e r gas, 1 m l of a m m o n i a was i n j e c t e d , a n d t h e extent of a m m o n i a d e c o m p o s i t i o n w a s d e t e r m i n e d as a f u n c t i o n of t e m p e r a t u r e . T h e d e c o m p o s i t i o n was 2 . 4 % a t 3 5 0 ° C , 7 . 8 % a t 4 5 0 ° C , a n d 2 4 % a t 5 5 0 ° C . T h e a p p a r e n t a c t i v a t i o n energy of a m m o n i a d e c o m p o s i t i o n was e s t i m a t e d a t 13 k c a l / m o l e . T h e a c t i v a t i o n energy of a m m o n i a d e c o m p o s i t i o n i s close t o t h a t of benzene f o r m a t i o n f r o m chlorobenzene a n d a m m o n i a . T h u s , benzene f o r m a t i o n results f r o m t h e r e a c t i o n of chlorobenzene a n d h y d r o g e n f o r m e d b y t h e d e c o m p o s i t i o n of a m m o n i a . T h e c a t a l y t i c a c t i v i t y f o r t h e a n i l i n e f o r m a t i o n f r o m chlorobenzene a n d a m m o n i a of t h e Y zeolites w i t h v a r i o u s cations was s t u d i e d a t 3 9 5 ° C ( T a b l e I ) . I t i s clear t h a t t h e t r a n s i t i o n m e t a l - e x c h a n g e d zeolites h a v e t h e c a t a l y t i c a c t i v i t y for t h e r e a c t i o n , w h i l e a l k a l i m e t a l a n d a l k a l i n e e a r t h m e t a l zeolites d o n o t . T h e fact t h a t a l k a l i n e e a r t h m e t a l - e x c h a n g e d zeolites u s u a l l y h a v e h i g h a c t i v i t y for c a r b o n i u m i o n - t y p e reactions denies t h e p o s s i b i l i t y t h a t B r o n s t e d a c i d sites a r e responsible f o r t h e r e a c t i o n . T h u s , c a t a l y t i c a c t i v i t y of zeolites f o r t h i s r e a c t i o n m a y b e caused b y t h e


45.

HATADA ET A L .

505


d i r e c t i n t e r a c t i o n of m e t a l cations a n d t h e reactants. T o c o n f i r m t h i s , t h e c o r r e l a t i o n b e t w e e n t h e c a t a l y t i c a c t i v i t y a n d t h e v a r i o u s properties of m e t a l cations w a s sought. T h e i o n i c r a d i u s o r t h e electrostatic p o t e n t i a l (e/r) i s often used as t h e measure of t h e p o l a r i z i n g p o w e r of t h e cations (2 8, 6). F o r example, B r o n s t e d a c i d i t y has a good c o r r e l a t i o n w i t h these properties (2). T h e correlation between the catalytic a c t i v i t y i n the aniline formation reaction a n d either i o n i c r a d i u s o r electrostatic p o t e n t i a l w a s v e r y poor.


y

T h e i o n i c r a d i u s o r electrostatic p o t e n t i a l represents t h e p h y s i c a l p r o p e r t y of m e t a l cations a n d does n o t reflect t h e b o n d i n g character. T h e e l e c t r o n e g a t i v i t y of m e t a l cations m a y b e t h e m o r e d i r e c t measure of t h e p o l a r i z i n g p o w e r t h a n t h e i o n i c r a d i u s o r electrostatic field w h e n c h e m i c a l b o n d i n g is expected b e t w e e n m e t a l cations a n d t h e reactants. P a u l i n g ' s v a l u e (10) of e l e c t r o n e g a t i v i t y f o r m e t a l a t o m s w a s p l o t t e d against t h e y i e l d of a n i l i n e ( F i g u r e 2), a n d a g o o d c o r r e l a t i o n w a s o b t a i n e d . T h e larger t h e e l e c t r o n e g a t i v i t y , t h e greater t h e c a t a l y t i c a c t i v i t y f o r a n i l i n e f o r m a t i o n . T h e a l k a l i a n d a l k a l i n e e a r t h cations h a v e s m a l l e r e l e c t r o n e g a t i v i t y a n d show n o c a t a l y t i c a c t i v i t y . T h e use of electroneg a t i v i t y v a l u e s (11) corrected for m e t a l ions i n s t e a d of those for metals does n o t change t h e t r e n d .

ELECTRONEGATIVITY · ( ion Ν/Π7.5 8.0 8.5 9.0 9.5

STABILITY CONSTANT Figure 2. Catalytic activity for aniline for mation as a function of electronegativity and formation constant of ammine complex


506

MOLECULAR SIEVES

Jones a n d L a n d i s (12) a s s u m e d t h e f o r m a t i o n of t h e a m m i n e complexes a n d t h e i r p a r t i c i p a t i o n i n the r e a c t i o n of toluene w i t h a m m o n i a t o f o r m b e n z o n i t r i l e o v e r a v a r i e t y of t r a n s i t i o n m e t a l - e x c h a n g e d X zeolites.


E S R w o r k c o n f i r m e d t h a t copper t e t r a a m m i n e c o m p l e x is f o r m e d w h e n a m m o n i a is a d s o r b e d o n C u Y zeolites a t r o o m t e m p e r a t u r e (13). T h e c o o r d i n a t i o n of a m m o n i a t o m e t a l cations m a y t a k e a n i m p o r t a n t role i n t h e reactions i n v o l v i n g a m m o n i a , a l t h o u g h t h e c o o r d i n a t i o n n u m b e r of a m m o n i a m a y be l o w e r a t higher t e m p e r a t u r e . W i t h t h i s s i t u a t i o n i n m i n d , t h e f o r m a t i o n c o n s t a n t (βι) of t h e first a m m o n i a molecule m a k i n g t h e c o o r d i n a t i o n b o n d w i t h m e t a l cations was t a k e n as t h e measure of t h e ease of a m m o n i a a d s o r p t i o n o n m e t a l s . The v a l u e s of ( & ) were t a k e n f r o m R i n g b o m ' s t a b l e (14)T h e p l o t of t h e c a t a l y t i c a c t i v i t y against f o r m a t i o n constants of a m m i n e complexes is s h o w n i n F i g u r e 2. T h e c o r r e l a t i o n is g o o d except for C d Y . A g a i n , t h e metals w i t h lower formation constant ( N a , C a , M g ) have no a c t i v i t y for chlorobenzene r e a c t i o n . +

+

2 +

W h e n C d Y was h e a t e d a t 450° C i n a h e l i u m s t r e a m , c a d m i u m was r e m o v e d f r o m t h e zeolite c a v i t i e s a n d t h e m e t a l was d e p o s i t e d a t t h e exit of t h e reactor. T h e C d Y t h u s t r e a t e d showed no c a t a l y t i c a c t i v i t y . T h e n the t e m p e r a t u r e of t h e p r e t r e a t m e n t was l o w e r e d t o t h e r e a c t i o n t e m p e r a t u r e of 3 9 5 ° C , a n d t h e c o n v e r s i o n c i t e d i n T a b l e I w a s observed. Even a t t h i s p r e t r e a t m e n t t e m p e r a t u r e , t h e s m a l l a m o u n t of c a d m i u m m e t a l a p peared a t t h e exit of t h e reactor. T h i s m a y be t h e cause of t h e large d e v i a t i o n of C d Y f r o m t h e l i n e a r r e l a t i o n s h i p . T h e order of t h e s t a b i l i t y c o n s t a n t of t h e c o o r d i n a t i o n c o m p o u n d s of d i v a l e n t m e t a l cations w i t h v a r i o u s l i g a n d s f a l l s i n t h e general p a t t e r n k n o w n as t h e I r v i n g - W i l l i a m s order (15) : Cr

2 +

> Mn

2+

< Fe

2+

< Co

2 +

< Ni

2 +

< Cu

2 +

> Zn

2 +

T h i s is t h e same order of t h e c a t a l y t i c a c t i v i t y of t r a n s i t i o n m e t a l i n ex changed

zeolites for a n i l i n e f o r m a t i o n .

I r v i n g a n d W i l l i a m s (15,

16)

p o i n t e d o u t also t h a t t h e r e is a clear c o r r e l a t i o n b e t w e e n c o m p l e x s t a b i l i t y a n d t h e second i o n i z a t i o n p o t e n t i a l .

A s a m a t t e r of fact, a g o o d c o r r e l a

t i o n was f o u n d between t h e c a t a l y t i c a c t i v i t y a n d t h e second i o n i z a t i o n p o t e n t i a l of d i v a l e n t ions.

( W e t h a n k t h e r e v i e w e r for p o i n t i n g o u t t h i s

correlation.) A s described above, t h e c a t a l y t i c a c t i v i t y of m e t a l ion-exchanged zeolites f o r a n i l i n e f o r m a t i o n has a good c o r r e l a t i o n w i t h e l e c t r o n e g a t i v i t y a n d w i t h t h e f o r m a t i o n c o n s t a n t of a m m i n e complexes of m e t a l cations. of t h e a c t i v i t y agrees w i t h t h e I r v i n g - W i l l i a m s order.

T h e order

T h e s e facts give

i r r e f u t a b l e evidence t h a t t h e t r a n s i t i o n m e t a l cations are the a c t i v e centers of t h e r e a c t i o n . T h e g o o d c o r r e l a t i o n of c a t a l y t i c a c t i v i t y a n d t h e f o r m a t i o n c o n s t a n t of t h e a m m i n e c o m p l e x or t h e e l e c t r o n e g a t i v i t y of t h e m e t a l c a t i o n c o u l d


45.

HATADA E T AL.

507



be u n d e r s t o o d i f we assume t h a t t h e r a t e - d e t e r m i n i n g step of t h e r e a c t i o n is either t h e c o o r d i n a t i o n of a m m o n i a t o m e t a l c a t i o n s or t h e a b s t r a c t i o n of a chlorine a t o m f r o m chlorobenzene b y m e t a l cations. I f t h e f o r m e r were t h e case, i t w o u l d be n a t u r a l t h a t t h e c a t a l y t i c a c t i v i t y h a d a g o o d c o r r e l a t i o n w i t h t h e f o r m a t i o n c o n s t a n t of t h e a m m i n e c o m p l e x . If the l a t t e r were t h e case, g o o d c o r r e l a t i o n s h o u l d be e x p e c t e d b e t w e e n t h e c a t a l y t i c a c t i v i t y a n d e l e c t r o n e g a t i v i t y since t h e a b i l i t y of m e t a l cations t o abstract a chlorine a t o m should depend largely on their electronegativity. I n t h i s case t h e c o r r e l a t i o n between t h e c a t a l y t i c a c t i v i t y a n d t h e f o r m a t i o n c o n s t a n t is f o r t u i t o u s . T h i s w o u l d h a p p e n because of t h e n e a r l y p a r a l l e l orders of f o r m a t i o n c o n s t a n t of a m m i n e complexes a n d e l e c t r o n e g a t i v i t y of m e t a l cations. Reactions of Benzaldehyde with Ammonia. W h e n i t w a s i n j e c t e d i n t o a m m o n i a , b e n z a l d e h y d e w a s c o m p l e t e l y consumed e v e n w i t h o u t c a t a l y s t s , b u t no p r o d u c t s were f o u n d i n t h e gas c h r o m a t o g r a p h . T h i s i n d i c a t e s t h e f o r m a t i o n of h i g h b o i l i n g p o i n t p r o d u c t s . S a i t o a n d O t a (17) c o n f i r m e d t h e f o r m a t i o n of 2 , 4 , 5 - t r i p h e n y l i m i d a z o l d u r i n g t h e r e a c t i o n of benzaldehyde and a m m o n i a over a l u m i n a catalysts a n d a t t r i b u t e d its f o r m a t i o n t o t h e f o l l o w i n g homogeneous r e a c t i o n :

Hydrobenzamide Table II.

Yield of Benzonitrile from Benzaldehyde and Ammonia

Form Na Mg Co Cr Cu Zn Mn a

2,4,5-Triphenylimidazol

Temperature, °C 395

445

16.4 — 15.7

18.2 17.6

— — — —

— — — —

490 31.0 26.1 31.7 26.5 21.4» 25.2» 20.2»

495°C.

W h e n zeolites were p l a c e d i n t h e reactor, b e n z a l d e h y d e a g a i n c o m p l e t e l y disappeared, b u t b e n z o n i t r i l e was f o r m e d . I t s y i e l d depended s l i g h t l y o n the r e a c t i o n t e m p e r a t u r e . I n c o n t r a s t t o t h e r e a c t i o n of chlorobenzene a n d a m m o n i a , t h e y i e l d of b e n z o n i t r i l e d e p e n d e d o n l y s l i g h t l y o n t h e k i n d of m e t a l cations, as seen i n T a b l e I I . T h i s suggests t h a t t h e r a t e - d e t e r m i n i n g step of t h e n i t r i l e f o r m a t i o n does n o t i n v o l v e m e t a l cations. The r e a c t i o n m e c h a n i s m is p o s t u l a t e d as follows :


508

MOLECULAR SIEVES


Reaction 1 occurs at room temperature (18) and should be very fast at reaction temperature. Furthermore, benzylideneimine is also postulated as an intermediate of the formation of hydrobenzamide (19). Abstraction of hydrogen from benzylideneimine by the zeolite framework is considered to be the rate-determining step of the reaction. α-AJumina has no activity for this reaction. Literature Cited 1. Pickert, P. E., Rabo, J. Α., Dempsy, E., Schomaker, V., Proc. 3rd Intern. Congr. Catalysis (Amsterdam) (1965) 1, 714. 2. Ward, J. W., J. Catalysis (1968) 10, 34. 3. Ward, J. W., J. Catalysis (1969) 14, 365. 4. Turkevich, J., Ono, Y., ADVAN. CHEM. SER. (1971) 102, 315. 5. Cross, Ν . E., Kemball, C., Leach, H. F., ADVAN. CHEM. SER. (1971) 102, 389. 6. Ward, J. W., J. Catalysis (1971) 22, 237. 7. Groggins, P. H., "Unit Process in Organic Synthesis," 5th ed., pp. 129, 388, McGraw-Hill, New York, 1958 8. Jones, D. G., U. S. Patent 3,231,616 (1966). 9. Frilette, V. J., Rubin, M. K., quoted in Venuto, P. B., Landis, P. S., "Advances in Catalysis and Related Subjects," Vol., 18, p. 259, 1968. 10. Pauling, L., J. Amer. Chem. Soc. (1932) 54, 3570. 11. Tanaka, K., Tamaru, K., J. Catalysis (1967) 8, 1. 12. Jones, D. G., Landis, P. S., U. S. Patent 3,231,600 (1966). 13. Turkevich, J., Ono, Y., J. Catalysis (1972) 25, 44. 14. Ringbom, Α., "Complexation in Analytical Chemistry," (in Appendix) John Wiley & Sons, New York, 1963. 15. Irving, H., Williams, R. J. P., J. Chem. Soc. 1953, 3192. 16. Irving, H., Williams, R. J. P., Nature (1948) 162, 746. 17. Saito, S., Ohta, N., J. Syn. Org., Japan (1964) 22, 472. 18. McLeod, R. K., Crowell, T. I., J. Org. Chem. (1961) 26, 1094. 19. Ogata, Y., Kawasaki, Α., Okumura, N., J. Org. Chem. (1964) 29, 1985. RECEIVED November 27,

1972.


Molecular Sieves

Recommend Documents