INTERACTION WHERE BENZOYL

OF

M = Ca OR

COMPLEX Sr,

CHLORIDE,

WITH

ALANATES

M[A1R4]2,

BENZOPHENONE,

AND ACETIC

ANHYDRIDE

L. I. Z akharkin, L. L. Ivanov, S. Y a . Z a v i z i o n , L. I. Fainshtein, and T. G. Sorokina

UDC 542.91 : 547.631.6:547.281.2

R e a c t i o n s of tetracoordi,nate a l u m i n u m d e r i v a t i v e s with ketones and with organic acid d e r i v a t i v e s have r e c e i v e d little attention [1, 2]. I n f o r m a t i o n r e g a r d i n g i n t e r a c t i o n s of alanates of a l k a l i n e - e a r t h m e t a l s with c a r bonyl compounds is e n t i r e l y lacking. In this study, we have i n v e s t i g a t e d the r e a c t i o n of M[A1R4]2, w h e r e M = C a and Sr, with benzophenone, benzoyl chloride, and acetic anhydride. When a s u s p e n s i o n of Ca[AI(CGH~)4] 2 is mixed with a hexane solution of benzophenone, c o m p l e x f o r m a t i o n o c c u r s , i r r e s p e c t i v e of the ratio of the initial components (Table 1). 20 ~

CaAI2(C6H~)s~ (C6H5)~.C0- - - - > CaAL.(C6Hs)s.(C~H5)2C0 Hexane (I) Compound I was i s o l a t e d in p u r e f o r m and c h a r a c t e r i z e d by e l e m e n t a l a n a l y s i s and IR s p e c t r u m . D i s p l a c e m e n t of the c a r b o n y l band f r o m 1650 c m -1 f o r benzophenone to 1610 c m -1 f o r I indicates that the oxygen a t o m of this group takes p a r t in a d o n o r - a c c e p t e r bond. Until now, the e x i s t e n c e of stable c o m p l e x e s of t e t r a c o o r d i n a t e a l u m i n u m with carbonyl compounds has b e e n unknown. It has b e e n c o n s i d e r e d true [3-5], however, that the f o r m a t i o n of such c o m p l e x e s is the f i r s t step in the i n t e r a c t i o n of all t r i v a l e n t a l u m i n u m compounds with carbonyl compounds. In view of the high r e a c tivity and i n s t a b i l i t y of such c o m p l e x e s , t h e i r e x i s t e n c e g e n e r a l l y has been d e m o n s t r a t e d by ebullioscopic [6] o r I R - s p e c ~ r a l methods [8], o r by the u s e of i n d i c a t o r s [7]. C o m p l e x I is sufficiently stable that its h y d r o l y s i s gives benzophenone in a yield of ~ 100~; however, a f t e r 24 h at 20 ~ t r a c e s of t r i p h e n y l c a r b i n o l a p p e a r e d in the h y d r o l y s i s p r o d u c t s f r o m I, indicating reduction of c o m plex I to the alcoholate II: CaA12(C6Hs)8-(CGHs)~CO ~ CaAI~(C6Hs)~IOC(CeHs)~]

(i)

(Ii)

The yield of t r i p h e n y l c a r b i n o l (46~) obtained on heating Ca[AI(C6Hs)4] 2 with benzophenone in dodecane shows that f o u r of the eight C6H 5 g r o u p s a v a i l a b l e in the c o m p l e x e n t e r into the reaction. It is known [9-12] that m a n y a l k y l - and a r y l a l a n a t e s of alkali and a l k a l i n e - e a r t h m e t a l s f o r m s i m p l e solv a t e s with Lewis b a s e s . Apparently, these compounds a r e d o n o r - a c c e p t e r c o m p l e x e s ; however, in c o n t r a s t to s i m i l a r c o m p l e x e s of t r i v a l e n t aluminum, the a l k a l i n e - e a r t h m e t a l in this case, r a t h e r than the fully c o o r d i nated a l u m i n u m atom, is c o n s i d e r e d [9, 11, 12] to p a r t i c i p a t e in the coordination. I t is a l s o likely that the Ca a t o m p a r t i c i p a t e s in coordination during the f o r m a t i o n of c o m p l e x I f r o m b e n z o phenone, and this l e a d s one to conclude that all f o u r "bridging" phenyt g r o u p s ~ake p a r t in the following reactio~. However, the yield (65~) of methyldiphenylcarbinol which is obtained in the r e a c t i o n of Ca[AI(CH3)4]2 with benzophenone in diglyme t e s t i f i e s to the p a r t i c i p a t i o n of m o r e than five A1-C bonds in the r e a c t i o n leading to the alInstitute of H e t e r o o r g a n i c Compounds, Academy of Sciences of the USSR, Moscow. T r a n s l a t e d f r o m I z v e s t i y a Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2557-2560, N o v e m b e r , 1976. Original a r t i c l e submitted O c t o b e r 28, 1975. This material is protected by copyright registered in the n a m e of Plenum Publishing Corporation, 227 West 17th Street, New York, N. Y. 100]1. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any meanS, electronic, mechamcal, photocopying, microfilming, recording or otherwise, without written permission of the publisher. A copy of this article is available [ram the publisher for $Z50.

I 2380

TABLE

1, Reaction of C alcium B i s t e t r a a l k y l (aryl) alanates with Benzophenone Molar Solvent T Time, Reaction Yield, ratio Ca ~hR. o&,h 1 products ]~2fr. (CoH~hCO CaAI2lZ,

8 ~aAI~(CH~)s

~odecan~ 901 I I~O 2 IHexane It00 6

8

CaAI~(C~H~)s.(C~H~hCO CaAI~(C~Hs)s-(C~H~)~CO Triphenylcarbinol

95 92 46

Methyldiphenylcarbinol

65

T A B L E 2. R e a c t i o n of C a l c i u m and S t r o n t i u m B i s t e t r a a l k y l ( a r y l ) a l a n a t e s with B e n z o y l C h l o r i d e and with Acetic Anhydride* i ISummary of ketone 1N . -

I

Reagent

MAlzl~

CaAl:(CoH~)s CaAl:(C~H~)s

C6H~COCI n

Sr AI=(C~Hs)s

~rAla(C~H~)s

CaAl~(n-CaH:)s

CaAl2(n-CaHT)s

(CHACO)20

I~

Reaction productS

Benzophenone Triphenylcarbmol 65 i Benzophenone rriyhenylcarbmol Propiophenone 0 Ethylphenylcarbinol Diethylphenylcaxbinol 0 i Methyl ethylketom Methylethylcar5inol MethyldiethyIcarSinol 0 i Methyl propyl ketone MethylpropylI carbinol ! Methyldipropylcarbinol 70 [t Methyl propyl ketone Methylpropylcarbinol Methyldipropylcarbinol

L'~=

',~

Trace ~I -22

2,0

2,2

7t I 2,8

5,,2

381 0,8

I,I

19

0,4

0,7

t5

i,2

2,2

0 12 5

1

54 3t 3 4

4

9 6 3 t9

* R e a c t i o n s w e r e c a r r i e d out in hexane with c a l c i u m alanates, in toluene with s t r o n t i u m a l a n a t e s . t i n c a l c u l a t i n g yields, it was taken into a c c o u n t that one A I - C bond of the initial a l a n a t e is involved in the form~tfion of the ketones, and twO s u c h bonds a r e i n v o l v e d in the f o r m a t i o n of the s e c o n d a r y and tertiary alcohols.

kylation of the benzophenone. P e r h a p s this is a c o n s e q u e n c e of the higher solubility and l e s s e r steric hindrance of the b i s t e t r a m e t h y l a l a n a t e s as c o m p a r e d to c a l c i u m bistetraphenylalanate. Ca[AI(C~H5)4] 2 does not react (0 ~ 2 h) in hexane with benzoylchloride, apparently due to its poor solubility in h y d r o c a r b o n s and ethers. At 65 ~ (1 h), two C6H5 groups e n t e r into the reaction: 65 ~

CaA12(C6Hs)s+ 2CsH~COC1 -~ 2(CsHs)aAb(CsH~)~C0+ CaCl~ Hexane (lit)

Complex ]11 u n d e r these conditions hardly r e a c t s with benzoyl chloride, but it is slowly reduced to the alcoholate (CGHs)2A1OC(C6Bs)3 (6% yield of triphenylcarbinol after h y d r o l y s i s ) .

Ethyl alanates are significantly m o r e r e a c t i v e to benzoyl chloride than phenyl alanates. two A1--C bonds of Sr[AI(C2H5)4]2 participate in the reaction in toluene, even at 0~

Thus, m o r e than

2381

SrA12(C~Hh)s + 2C6H5COC1 ~ 2(C2Hh)3A1.CeHhCOC2H5 + SrC12 (iv) (IV) + C6HsCOC1-~ (C2Hh)~A1C1-C~HhCOC2H5 + C6HsCOC2H~ C o m p l e x IV is l e s s s t a b l e than III, a p p a r e n t l y , and t h e r e f o r e benzoyl chloride d i s p l a c e s propiophenone f r o m IV, but does not d i s p l a c e benzophenone f r o m HI. The instability of c o m p l e x IV is also r e s p o n s i b l e f o r the fact that one finds a total of only 12% propiophenone a m o n g the p~:oducts of h y d r o l y s i s of the reaction m i x t u r e f r o m SrA12(C2Hs) 8 a n d b e n z o y l chloride; despite the mild conditions, m o s t of the propiophenone (54%) is conv e r t e d to diethylphenylcarbinol. This m e a n s that the s e c o n d a r y r e a c t i o n - alkylation and reduction of the p r o piophenone - p r o c e e d s at a f a s t e r r a t e than the p r i m a r y r e a c t i o n under these conditions. S i m i l a r l y , we found only an insignificant quantity of methyl propyl ketone among the p r o d u c t s of h y d r o l y sis of the reaction m i x t u r e f r o m Ca[Ai(n-C~HT)4] 2 and (CHaCO)20 at 0% m o s t of the ketone had been alkylated to give the c o r r e s p o n d i n g t e r t i a r y alcohol or reduced to m e t h y l p r o p y l c a r b i n o l . When the t e m p e r a t u r e was inc r e a s e d to 70 ~ the p r o p o r t i o n of these s e c o n d a r y r e a c t i o n p r o d u c t s i n c r e a s e d . Strontium b i s t e t r a e t h y l a l a n a t e showed f a r l e s s tendency toward s e c o n d a r y r e a c t i o n s (Table 2). EXPERIMENTAL All e x p e r i m e n t s w e r e c a r r i e d out u n d e r an a t m o s p h e r e of pure, d r y argon. The initial alanates w e r e obtained a c c o r d i n g to the m e t h o d s of [12, 13]; c a l c i u m b i s t e t r a m e t h y l a l a n a t e was obtained analogously [13]. H y d r o l y s i s p r o d u c t s of the r e a c t i o n m i x t u r e s w e r e analyzed on an LKhM-8MD c h r o m a t o g r a p h with a flow m e t e r , u s i n g a column (2 m • 4 ram) with 5% E-301 on C h r o m a t o n NAWDMCS, column t e m p e r a t u r e 120-160 ~ v a p o r i z a t i o n t e m p e r a t u r e 250-300 ~ and helium c a r r i e r g a s at a flow r a t e of 40 m l / m i n . Reaction

of M[A1R4] 2 with

Benzophenone

P r e p a r a t i o n of the C o m p l e x Ca[AI(C6Hh)4] ~ -(C6H5)2CO (I). To a s t i r r e d suspension of 0.002 m o l e Ca[A1. (C6H~)4]2 in 20 ml hexane w a s added 0.016 m o l e benzophenone in 10 m l hexane at 20-25 ~ Stirring was continued f o r 1 h, and then the p r e c i p i t a t e was f i l t e r e d off, thorougMy washed with pentane (3 • 50 ml), and dried 2 h at 1 t o r r . Yield of c o m p l e x I, 95~; d e c o m p o s i t i o n t e m p e r a t u r e , > 170 ~ Found: Ca 4.70; A1 6.24; benzophenone 19.86~c. C61Hh0A12CaO. Calculated: Ca 4.49; A1 6.04; benzophenone 20.40~. H i g h - T e m p e r a t u r e Reduction of C o m p l e x I: The suspension of c o m p l e x I f r o m the preceding e x p e r i m e n t was s t i r r e d 2 h at 90 ~ and 2 h at 160 ~ The g r a y i s h yellow p r e c i p i t a t e was f i l t e r e d off and washed with hexane to c o m p l e t e l y r e m o v e the benzophenone. Then 30 ml hexane was added to the p r e c i p i t a t e , and it was d e c o m p o s e d by s t i r r i n g with 20~c HC1. The organic l a y e r was s e p a r a t e d . The aqueous l a y e r was e x t r a c t e d with ether, and the e t h e r e x t r a c t s w e r e c o m b i n e d with the organic l a y e r . The solution was d r i e d o v e r Na2SO 4 and e v a p o r a t e d to d r y n e s s u n d e r v a c u u m (1 t o r t ) . After the r e s i d u e was washed ~vith cold hexane and dried, it gave t r i phenylcarbinol (containing t r a c e s of benzophenone) in 46~ yield, mp 160-162 ~ E v a p o r a t i o n of the combined o r galliC f i l t r a t e s gave benzophenone (containing t r a c e s of triphenylcarbinol) in N 100~ yield. Reaction of Ca[AI(CH3)4] 2 and Benzophenone. To a solution of 0.01 m o l e Ca[AI(CH3)4] 2 in 20 ml diglyme was added with s t i r r i n g , o v e r a 5-rain period, a solution of 0.08 mole benzophenone in 50 ml diglyme. The m a s s was heated f o r 6 h at 100 ~ and then d e c o m p o s e d at 0~ with 20~ NaOH. A f t e r extraction, evaporation of the solvent f r o m the e x t r a c t , and r e c r y s t a l l i z a t i o n of the r e s i d u e f r o m hexane, methyldiphenylcarbinol with nap 78 ~ was obtained in 65~ yield; subsequent r e c r y s t a l l i z a t i o n f r o m e t h e r did not change the melting point. Mixture with the authentic m a t e r i a l (rap 78~ which was obtained by reaction of p h e n y l m a g n e s i u m b r o m i d e with acetophenone in e t h e r [14], did not give melting point d e p r e s s i o n . Reaction

of Alanates

with

Benzoyl

Chloride

Strontium b i s t e t r a e t h y l a l a n a t e (0.01 mole in 30 ml toluene) w a s allowed to r e a c t with C6HhCOC1 (0.04 m o l e in 10 1Ill toluene) f o r 2.5 h at 0% H y d r o l y s i s of the reaction m a s s with 5~ HCI o r 20~ NaOH and extraction with e t h e r g a v e t h r e e m a i n products: propiophenone (12~), phenylethytcarbinol (5~), and diethylphenylcarbinol (54~) (GLC analysis). C a l c i u m b i s t e t r a e t h y l a l a n a t e (0.0015 m o l e in 40 ml hexane) was allowed to r e a c t with C6HhCOC1 (0.012 m o l e in 10 m l hexane) f o r 1 h at 65% After analogous workup and s e p a r a t i o n of the p r o d u c t on a 1.5 m • 40 m m silicic acid column (eluted by a m i x t u r e of low-boiling p e t r o l e u m e t h e r and diethyl ether), this g a v e benzophenone (22~), t r i p h e n y l c a r b i n o l (6~), and an unidentified m i x t u r e of p r o d u c t s .

2382

Reaction

of Alanates

with

Acetic

Anhydride

To a solution of 0.01-0.015 m o l e M[AIR4]2 i n 2 0 m l toluene was added a sotution of 0. 02- 0.12 m o l e (CH3CO)20 in 10 ml of the s a m e solvent; the m i x t u r e was s t i r r e d f o r 2 h at e i t h e r 0 ~ o r 70~ The r e a c t i o n m a s s was worked up as indicated above and analyzed by GLC. CONCLUSIONS !.

The c o m p l e x Ca[AI(CsHs)4] 2 - (C6H5)2CO has been isolated and c h a r a c t e r i z e d .

2. Six alkyl g r o u p s (R = CH 3) o r four aryl groups (R = CGH5) p a r t i c i p a t e in the r e a c t i o n of c o m p l e x alanates Ca[A1R4] 2 with benzophenone to give the c o r r e s p o n d i n g t e r t i a r y alcohols. 3. The r e a c t i o n of c o m p l e x alanates M[A1R4] 2, w h e r e M= Ca o r Sr, with benzoyl chloride or acetic anhydride gives the c o r r e s p o n d i n g ketones and their reduction and alkylation p r o d u c t s . LITERATURE 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14.

D . J . P a s t e and R. Snyder, J. O r g . Chem., 3.00, 1634 (1965). G. Wittig and O. Bub, Liebigs Ann. Chem., 566, 113 (1950). T. Mole, Austral. J. Chem., 1/7, 961 (1964). S. P a s y n k i e w i c z and W. Arab~,s, Rocz. Chem., 39, 1393 (1965). C. H a r r i s , T. Mole, and F. D. Looney, T e t r a h e d r o n Lett., 4195 (1966). T. Mole, A u s t r a l . J. Chem., 16, 807 (1963). G . A . R a z u v a e v and A. I. G r a e v s k i i , Zh. Obshch. Khim., 33, 2423 (1963). G. C o s t a and R. Calcinari, Gazz. Chim. Ital., 89, 1415 (1959). H. L e h m t ~ h i , Angew. Chem., 7_~5, 1090 (1963); Angew. Chem. International Edit., 3, 107 (1964). H. Lehmkuhl, Liebigs Ann. Chert., 719, 20 (1968). H. Lehmkuhl and W. Eisenbach, Liebigs Ann. Chem., 705, 42 (1967). L . L . Ivanov, S. Ya. Zavizion, and L. I. Zakharkin, Zh. Obshch. Khim., 4.~_5, 1060 (1975). L . L . Ivanov, S. Ya. Zavizion, and L. I. Zakharkin, Zh. Obshch. Khim., 43_3, 2254 (1973). A . N . K o s t a (editor), P r a c t i c a l Organic C h e m i s t r y [in Russian], Mir (1965), p. 492.

FORMATION BETWEEN AND

CITED

OF THE

TITANIUM

A

Ti--

C

BOND

TRIPHENYLMETHYL

IN

REACTIONS RADICAL

SALTS

S. I. Beilin, N. N. G. N. Bondarenko, and B. A. Dolgoplosk

Eliseeva, G. P. Karpacheva,

UDC 542.91 : 547.632.2 : 541.515 : 546.821--38

The benzyl and silaneopentyl derivatives of titanium are homogeneous polymerization catalysts in solutions [I, 2]. These compounds are usually synthesized by reacting the corresponding organo ~r or Li derivatives with titanium halides. The feasibilityof obtaining organo Ti compounds by a recombination of the (C6H5)3C" radical with Ti2+ and Ti3+ salts was investigated in this paper. EXPERIMEN

TAL

The compound (C6H5)6C2 (HPE), which was synthesized by the method in [3], s e r v e d as the s o u r c e of the f r e e r a d i c a l s . Titanium t r i c h l o r i d e , TIC13, was obtained by reducing TiC14withBuL[ , TiC12 by pyrolyzing TiCI~ A. V. Topchiev Institute of P e t r o c h e m i c a l Synthesis, Academy of Sciences of the USSR, Nioscow. T r a n s lated f r o m I z v e s t i y a Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2561-2563, N o v e m b e r , 1976. O r i g inal a r t i c l e s u b m i t t e d O c t o b e r 24, 1975. This material is protected by copyright registered in the name of Plenum Publishing Corporatton, 227 West 17th Street, New York, N.Y. 10011. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, microfilming, recording or otherwise, without written permission of the publisher. A copy of this article is available from pthe u b l i s h e r for $ 7 . 5 0 ~

2383