反应详情

13 g of diethyl 2,2-dimethyl-3-(2',2'-dichlorovinyl)-cyclopropane-1,1-dicarboxylate were dissolved in 50 g of o-xylene and 20 g of 1,5-diaza-bicyclo[4.3.0]non-5-ene were added. The mixture was then heated to the boil for 8 hours. After cooling, ice-cold dilute hydrochloric acid was added, so that a neutral or weakly acid pH value resulted. The organic phase was separated off and dried with Na2SO4 and the xylene was distilled off in vacuo (boiling point = 35° - 40° C./12 mm Hg). The residue weighed 12.5 g. Fractional distillation gave 4.7 g of 2,2-dimethyl-3-(2',2'-dichlorovinyl)-cyclopropane-1-carboxylic acid ethyl ester, of which 30% was in the cis form and 70% was in the trans form. The boiling point was 65° - 72° C./0.3 mm Hg. The nuclear magnetic resonance spectrum agreed with that given in the literature. 6.5 g of the starting material were recovered. The yield was thus 92%.

1. temperatureThe mixture was then heated to the boil for 8 hours
2. temperatureAfter cooling
3. additionice-cold dilute hydrochloric acid was added
4. customresulted
5. customThe organic phase was separated off
6. dry with materialdried with Na2SO4
7. distillationthe xylene was distilled off in vacuo (boiling point = 35° - 40° C./12 mm Hg)
8. distillationFractional distillation