反应详情

48.8 parts of 1,1,4-triacetoxy-2-methyl-but-2-ene, consisting, according to NMR analysis, of 46.4% of (E)-isomer and 53.6% of (Z)-isomer, are boiled with 500 parts of glacial acetic acid and 18 parts of water for 2.5 hours. After stripping off the acid and water on a rotary evaporator at from 40° to 50° C. under a waterpump vacuum, fractional distillation of the residue gives 23.2 parts of 4-acetoxy-2-methylcrotonaldehyde (81.6% of theory) of boiling point 102°-103° C./23.9 mbar (nD20 =1.4641). According to NMR analysis (aldehyde protons), the aldehyde obtained consists of 98.0% (E)- and 2.0% (Z)-4-acetoxy-2-methylcrotonaldehyde.

1. customon a rotary evaporator at from 40° to 50° C.
2. distillationunder a waterpump vacuum, fractional distillation of the residue