- Relative Thermodynamic Stabilities of Isomeric Alkyl Allyl and Alkyl (Z)-Propenyl Ethers
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The relative thermodynamic stabilities of ten allyl ethers (ROCH2CH=CH2) and the corresponding isomeric (Z)-propenyl ethers (where R is an alkyl group, or a methoxysubstituted alkyl group) have been determined by chemical equilibration in DMSO solution with t-BuOK as catalyst.From the variation of the equilibrium constant with temperature, the values of the thermodynamic parameters ΔG, ΔH and ΔS of isomerization at 298.15 K were evaluated.The propenyl ethers are highly favored at equilibrium, the values of both ΔG and ΔH for the allyl -> propenyl reaction being ca. -18 to 25 kJ mol-1.The favor of the propenyl ethers is increased by bulky alkyl substituents, and decreased by methoxysubstituted alkyl groups.In most cases the entropy contribution is negligible; however, for R=(MeO)2CH and R=(MeO)3C the values of ΔS are ca. -5 J K-1 mol1-.
- Taskinen, Esko
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p. 11389 - 11394
(2007/10/02)
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- DOUBLE BOND MIGRATION OF ALLYL ETHERS OVER SOLID BASE CATALYSTS
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Double bond migrations of allyl ethers were carried out over various solid base catalysts.Magnesium oxide, CaO, SrO, and La2O3 exhibited high activities.High cis/trans ratios in the products suggest that the reaction proceed via cis-?-allylic anions as intermediates
- Matsuhashi, Hiromi,Hattori, Hideshi,Tanabe, Kozo
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p. 341 - 342
(2007/10/02)
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