Цепочки осуществить реакцию
CH3CH2COOH+Br2=CH3CHBrCOOH+HBr CH3CHBrCOOH+KOH=CH3CHOHCOOH+KBr CH3CHOHCOOH=CH3CHO+H2O+CO CH3CHO+H2=C2H5OH CH3COOH+C2H5OH=CH3COOC2H5+H2O