Relative thermodynamic stabilities of isomeric alkyl allyl and alkyl (Z)-propenyl ethers
作者:Esko Taskinen
DOI:10.1016/s0040-4020(01)81820-2
日期:1993.1
were evaluated. The propenyl ethers are highly favored at equilibrium, the values of both ΔGΘ and ΔHΘ 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 methoxy-substituted alkyl groups. In most cases the entropy contribution is negligible; however, for R = (MeO)2CH and R = (MeO)3C the values of
十种烯丙基醚(ROCH 2 CH = CH 2)和相应的异构体(Z)-丙烯基醚(其中R为烷基或甲氧基取代的烷基)的相对热力学稳定性已通过DMSO溶液中的化学平衡确定。以t- BuOK为催化剂。从平衡常数随温度的变化,评估了在298.15 K下异构化的热力学参数ΔGΘ,ΔHΘ和ΔSΘ的值。丙烯醚在平衡时非常受青睐,烯丙基→丙烯基反应的ΔGΘ和ΔHΘ均为ca。-18至-25 kJ mol -1。庞大的烷基取代基增加了丙烯基醚的支持,而甲氧基取代的烷基则减少了丙烯基醚的支持。在大多数情况下,熵的贡献可以忽略不计。然而,对于R =(MeO)2 CH和R =(MeO)3 C,ΔSΘ的值约为。-5 JK -1 mol -1。