申请人:Hoechst Aktiengesellschaft
公开号:US05663410A1
公开(公告)日:1997-09-02
The present invention relates to the compounds cis-4-(2,2,3,3-tetrafluoropropoxy)cinnamonitrile and trans-4-(2,2,3,3-tetrafluoropropoxy)cinnamonitrile and to a process for their preparation. The process relates to the preparation of cis-4-(2,2,3,3-tetrafluoropropoxy)cinnamonitrile and trans-4-(2,2,3,3-tetrafluoropropoxy)cinnamonitrile or optionally one of these two compounds, by fractionally distilling a mixture containing cis- and trans-4-(2,2,3,3-tetrafluoropropoxy)cinnamonitrile under reduced pressure, separating off a main fraction containing at least 80% by weight of cis-4-(2,2,3,3-tetrafluoropropoxy)cinnamonitrile and a main fraction containing at least 80% by weight of trans-4-(2,2,3,3-tetrafluoropropoxy)cinnamonitrile, further purifying these main fractions by means of fractional crystallization or melt crystallization or adjusting one of these main fractions by isomerization to the cis/trans isomer ratio corresponding to the particular thermodynamic equilibrium and returning it to the process and returning the remaining fractions to the process directly or after isomerization.
本发明涉及化合物顺式-4-(2,2,3,3-四氟丙氧基)肉桂腈和反式-4-(2,2,3,3-四氟丙氧基)肉桂腈以及它们的制备方法。该方法涉及通过在减压下分馏含有顺式和反式-4-(2,2,3,3-四氟丙氧基)肉桂腈的混合物,分离出含有至少80%重量的顺式-4-(2,2,3,3-四氟丙氧基)肉桂腈和含有至少80%重量的反式-4-(2,2,3,3-四氟丙氧基)肉桂腈的主馏分,通过分馏结晶或熔融结晶进一步纯化这些主馏分,或通过异构化调整其中一个主馏分的顺/反异构比以达到特定热力学平衡,并将其返回到过程中,将其余馏分直接或经过异构化返回到过程中。