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Reakcja Dielsa i Aldera w cieczach jonowych z dodatkiem trifluorometanosulfonianów skandu i litu jako katalizatorów

Dramska A., Antoszczyszyn M., Janus E.

Przemysł Chemiczny

2006

T. 85, nr 1

47-49

Przedstawiono wyniki badań doświadczalnych reakcji Dielsa i Aldera przebiegającej w cieczach jonowych, które zastosowano jako nowe możliwe do zawrócenia i przyjazne środowisku naturalnemu medium reakcji. Omówiono również sposoby przeprowadzania reakcji w cieczach jonowych z zastosowaniem dodatku katalizatorów trifluorometanosulfonianów skandu i litu, które użyto po raz pierwszy w reakcji Dielsa i Aldera pomiędzy cyklopentadienem i maleinianem dimetylu w cieczach jonowych.

1-Butyl-3-methylimidazolium triflate (I), tetrafluoroborate, methylsulfate, and 2-(2-ethoxymethoxy)ethylsulfate were studied as recyclable solvent media for the Diels-Alder reactions (24 hrs. at 25°C) of (1/1.5 by moles) diMe maleate–cyclopentadiene, run without and with Sc triflate (or trifluoromethylsulfonimide) and Li triflate (or trifluoromethylsulfonimide) as catalysts. At reactants concns. of 4/6 mols/l., the yields were max. at 78–86% and the endo/exo isomer selectivities were 3.6–4.9; with catalysts used (1 mol% on maleate basis), 87–100% and 5.2–14.7, resp. Active only in I, Sc triflate raised the yield (from 42 to 61%), but not the selectivity. The Li catalysts were inferior. (I) was best as the solvent for the catalysts, and the Sc compds. were best as catalysts and gave the highest yields and selectivities. Products were extd. with Et2O. I was recovered nearly completely and recycled thrice with only minor losses in yield and selectivity.

Ionic liquids as powerful media in lanthanides triflate catalysed Diels-Alder reactions between cyclopentadiene and dimethyl maleate

Dramska A., Janus E.

Polish Journal of Chemical Technology

2006

Vol. 8, nr 2

9-11

1-Butyl-3-methylimidazolium trifluoromethanesulfonate has been tested as a reaction medium in the Diels-Alder reaction between cyclopentadiene and dimethyl maleate. The effect of three Lewis acids - scandium triflate Sc(OTf)3, yttrium triflate Y(OTf)3 and ytterbium triflate Yb(OTf)3 on the yield and the endo/exo product ratio has been investigated. All the catalysts immobilized in [BMIM][OTf] were recycled without a significant decrease in the yields and the endo/exo ratio.