反应详情

A solution of 320 g (1.5 moles) of the ketol prepared in Example 2 in 1000 ml of benzene containing 2 g p-toluene-sulphonic acid is heated in an apparatus for azeotropical water separation (Dean-Stark) till no more water separates. The reaction mixture is washed with a solution of sodium bicarbonate till neutral reaction and dried over anhydrous sodium sulfate. The solvent is removed by distillation at reduced pressure and the residue is distilled through a short Vigreux column. The product, cis, E-1-crotonoyl-2,2,6-trimethyl-cyclohexane (III, contains about 10% of the trans isomer) is collected at 76° C/1 mm; yield 273 g (94%). Recrystallization from pentane gives cis, E-1-crotonoyl-2,2,6-trimethylcyclohexane in high purity (m.p. 27°-28° C).

1. washThe reaction mixture is washed with a solution of sodium bicarbonate till neutral reaction
2. dry with materialdried over anhydrous sodium sulfate
3. customThe solvent is removed by distillation at reduced pressure
4. distillationthe residue is distilled through a short Vigreux column
5. customis collected at 76° C/1 mm
6. customRecrystallization from pentane