(3)脱羧反应 CHCOOH NaOH NaOH-CaO> △ CH4↑+Na2CO3 COOH NaOH NaOH-Cao. △ CH3 CH2=CH-C-COOH △→CH2=CH-CH(CH2+CO2↑ CH3 想想 COOH COOH COOH COOH 02N、 NO2 Br NO2 () (2) (3) (4) 脱羧（由易到难）：（①）>3)>(4>(2) (3)脱羧反应 CH2 CH C COOH CH3 CH3 CH2 CH CH(CH3 ) 2 + CO2 脱羧（由易到难）： (1) > (3) > (4) > (2) CH3 COOH NaOH CH4 Na2 CO3 + + NaOH-CaO COOH + NaOH + Na2 CO3 NaOH-CaO COOH O2N NO2 NO2 COOH COOH NO2 COOH Br (1) (2) (3) (4) 想一想