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Alkylation behavior of WCl6, MoCl5 and the methathesis cocatalyst system WCl6-C2H5AlCl2
TetrahedronLettersNo.11, pp. 707-700,1971. PergamonPress. Printed in Great Britain.
ALKYLATIONBEliAVIOR OF WCle, MoClz AND THE -IS
CCCA!MLYSTSYSTE?4WCle-C&AlCls
James FL Grahsm and Iynn Ii.Slaugh Shell DevelopmentCuapany,IQaneryville, California 94608 (Receivedin USA 15 February 1971; receivedin UK for publication25 February1971) Recently,Calderon and co-workersreported (1) the intriguingdiscoverythat WCle treated with C&AlCl,
in benzene catalyzesolefin methathesis. For example,2-penteneis
convertedto a mixture of 25% 2-butene,50% 2-pentene,and 25% J-hexene. Kothari and Tazuma (2) observed an unexpectedbehavior of the WC&,-C&AlCla catalystwhen it was preformedin toluene: upon additionof 2-pentene,Friedel-Craftsalkylationof toluene resultedinsteadof the anticipatedmethathesisreactionwhich occurs when the catalyst is prepared in toluene in the preseme of an olefin. Benzene alkylationproceededmore slowly and was accanpauiedby an wen slower 2-pentenemethathesis. We wish to report data that illuminatethe alkylationproperties of WCls, MoClz and WCle-C&AlCls and show that WCle can promote alkylationunder certain conditionsin the absence of CzHzAIC1a. meten
herachloridein the absence of Cs.HsAIC1a readily promotesthe alkylationof
benzenewithpromlene at150'. * With 40% of the benzene convertedthe alkylatedproduct consistedof 55% cumene, 31% diisopropylbenzene (mixtureof isaaers),and 14% triisopropylbenzene. Slow all@ation occurs at 100". Similarly,alkylationof benzene occurs with 1-psntene. The catalyst exhibitsselectivityfor substitutedolefins. With an equimolar mixture of ethyleneand 1-buteneand with 31% of the benzene converted,the allqvlation product consistedof 13% ethylbenzene,58% -see-butylbenzene, and 29% di-E-butylbenzene. The reactiontakes a different'coursewith ethyleneas shown by the data in Table I. wCatalystconcentrationusually was 1.3 x 10-s molar. WCle was purifiedas describedelsewhere (1). All reagentswere carefullydried.The olefin was always added to the autoclavelast.
707
788
No.11 a) Table I. WCle-PROmTED ALKYLATIONOF BENZENEWITH ETHYIENE ReactionTime, hr.
0.25
1.0
3.2
6
20
0
0
5
14.6
-set-Butylbenzene
2.0
4.5
9
12.6
di-set-Butylbenzene -
0.4
1.5
6
Benzene
Conversion,$ mole
2.0
5.0
34
Yields, '$ Ethylbenzene
6.8 ’
a) Conditions:benzene, 2'7g, WCle concentration,1.26 x 10 5 moles/l.;temperature,16O"C, ethylenepressure,&Cl psi. Tungstenhexachloridepmnotes the dimeri%ationof ethyleneto butenes which subsequently alkylatebenzene. In an inert solvent (diethylether) with benzene absent, ethylenewas shown to dimerizeas the catalystsolutionwae heated to the temperatureemployedfor allqylation. The butenes,being more reactive,canpetemore favorablythan does ethylenefor benzene; consequently,mainly see-butylbenaenes are producedduring the early stages of the alkylation reaction.* As the reactionproceeds,the dimerizationactivityappearsto abate and alkylation with ethylenebecomesmore predominant. In some instances,small amour&e of polymer also were concomitantlyformed fmn ethylene.
Ethylaluminumdichlorideenhancesthe rate of alkylation. With only one mole of Ca.H.+UClz present for 2.5 moles of WC%, the rate of alkylationof benzene with ethyleneat 60" was roughlythe same as that observedat QCJ" when C,H&Cl,
was not present. Perhaps,the very
active alkylationcatalystAlC13 was producedin situ from the reactionof C&&Cl~ Molybdenumpentachlorideis a more active alkylationcatalystthan WCb.
with WCb. Like the
latter, it producesmainly set-butylbenzene at low benzene conversionsbut tends to form more polymericby-productfrau the ethyleneco-reactant. Tungstenhexachloridealso is a transalkylation catalyst. When WCle was contacted ethylbenzeneand diet&vlben%enes was with ethylbenzeneat 160" for 17 hr., a mixture of berxsene, reactionbetweenbenzene and xylenes. produced. WC&, is ineffectivefor the transalkylation References. 1. N. Calderon,E. A. Ofstead,J. P. Ward, W. A. Judy and K. W. Scott, J. Am. Chem. Sot., a 4133 (1968). 2. V. M. Kothari and J. J. Tasuma, Absts., 160th NationalMeeting of the AmericanChemical Society, Chicago,Ill., Sept. 1970, Inorg. 025. 3. J. Tsuji, T. Nogi, and M. Morikawa,Bul. Chem. Sot. Japan, 2, 714 (1966). *ec-Butylbenzenefran benzene and ethylenealso results in the presenceof rhenium pentachloride(3).
ALKYLATIONBEliAVIOR OF WCle, MoClz AND THE -IS
CCCA!MLYSTSYSTE?4WCle-C&AlCls
James FL Grahsm and Iynn Ii.Slaugh Shell DevelopmentCuapany,IQaneryville, California 94608 (Receivedin USA 15 February 1971; receivedin UK for publication25 February1971) Recently,Calderon and co-workersreported (1) the intriguingdiscoverythat WCle treated with C&AlCl,
in benzene catalyzesolefin methathesis. For example,2-penteneis
convertedto a mixture of 25% 2-butene,50% 2-pentene,and 25% J-hexene. Kothari and Tazuma (2) observed an unexpectedbehavior of the WC&,-C&AlCla catalystwhen it was preformedin toluene: upon additionof 2-pentene,Friedel-Craftsalkylationof toluene resultedinsteadof the anticipatedmethathesisreactionwhich occurs when the catalyst is prepared in toluene in the preseme of an olefin. Benzene alkylationproceededmore slowly and was accanpauiedby an wen slower 2-pentenemethathesis. We wish to report data that illuminatethe alkylationproperties of WCls, MoClz and WCle-C&AlCls and show that WCle can promote alkylationunder certain conditionsin the absence of CzHzAIC1a. meten
herachloridein the absence of Cs.HsAIC1a readily promotesthe alkylationof
benzenewithpromlene at150'. * With 40% of the benzene convertedthe alkylatedproduct consistedof 55% cumene, 31% diisopropylbenzene (mixtureof isaaers),and 14% triisopropylbenzene. Slow all@ation occurs at 100". Similarly,alkylationof benzene occurs with 1-psntene. The catalyst exhibitsselectivityfor substitutedolefins. With an equimolar mixture of ethyleneand 1-buteneand with 31% of the benzene converted,the allqvlation product consistedof 13% ethylbenzene,58% -see-butylbenzene, and 29% di-E-butylbenzene. The reactiontakes a different'coursewith ethyleneas shown by the data in Table I. wCatalystconcentrationusually was 1.3 x 10-s molar. WCle was purifiedas describedelsewhere (1). All reagentswere carefullydried.The olefin was always added to the autoclavelast.
707
788
No.11 a) Table I. WCle-PROmTED ALKYLATIONOF BENZENEWITH ETHYIENE ReactionTime, hr.
0.25
1.0
3.2
6
20
0
0
5
14.6
-set-Butylbenzene
2.0
4.5
9
12.6
di-set-Butylbenzene -
0.4
1.5
6
Benzene
Conversion,$ mole
2.0
5.0
34
Yields, '$ Ethylbenzene
6.8 ’
a) Conditions:benzene, 2'7g, WCle concentration,1.26 x 10 5 moles/l.;temperature,16O"C, ethylenepressure,&Cl psi. Tungstenhexachloridepmnotes the dimeri%ationof ethyleneto butenes which subsequently alkylatebenzene. In an inert solvent (diethylether) with benzene absent, ethylenewas shown to dimerizeas the catalystsolutionwae heated to the temperatureemployedfor allqylation. The butenes,being more reactive,canpetemore favorablythan does ethylenefor benzene; consequently,mainly see-butylbenaenes are producedduring the early stages of the alkylation reaction.* As the reactionproceeds,the dimerizationactivityappearsto abate and alkylation with ethylenebecomesmore predominant. In some instances,small amour&e of polymer also were concomitantlyformed fmn ethylene.
Ethylaluminumdichlorideenhancesthe rate of alkylation. With only one mole of Ca.H.+UClz present for 2.5 moles of WC%, the rate of alkylationof benzene with ethyleneat 60" was roughlythe same as that observedat QCJ" when C,H&Cl,
was not present. Perhaps,the very
active alkylationcatalystAlC13 was producedin situ from the reactionof C&&Cl~ Molybdenumpentachlorideis a more active alkylationcatalystthan WCb.
with WCb. Like the
latter, it producesmainly set-butylbenzene at low benzene conversionsbut tends to form more polymericby-productfrau the ethyleneco-reactant. Tungstenhexachloridealso is a transalkylation catalyst. When WCle was contacted ethylbenzeneand diet&vlben%enes was with ethylbenzeneat 160" for 17 hr., a mixture of berxsene, reactionbetweenbenzene and xylenes. produced. WC&, is ineffectivefor the transalkylation References. 1. N. Calderon,E. A. Ofstead,J. P. Ward, W. A. Judy and K. W. Scott, J. Am. Chem. Sot., a 4133 (1968). 2. V. M. Kothari and J. J. Tasuma, Absts., 160th NationalMeeting of the AmericanChemical Society, Chicago,Ill., Sept. 1970, Inorg. 025. 3. J. Tsuji, T. Nogi, and M. Morikawa,Bul. Chem. Sot. Japan, 2, 714 (1966). *ec-Butylbenzenefran benzene and ethylenealso results in the presenceof rhenium pentachloride(3).