COOC2Hs C2HsONa COOC2Hs -CH CH3CH2Br CH3CH2CH COOC2H5 COOC2Hs COOC2Hs COOH 1)C2HsONa 1)OH CH3CH2C-CH3 →CH3CH2CCH3 -CO2 CH3CH2CHCOOH 2)CH3I 2)H COOC2Hs COOH CH3 2CH2(C00C2H)2 C2HsONa 2 CH(COOC2Hs)2 BrCH2CH2Br CH2CH(COOC2Hs)2 1)OH △ CH2CH2COOH CH2CH(COOC2Hs)22)H* -C02 CH2CH2COOH