CH3COONa→CH3-CH3-CH2-CH2-CH₂Br- CH₂Br→ CH=CH-KOOC - COOK

The reaction you have described is a substitution reaction where sodium acetate (CH3COONa) is reacted with 1,4-dibromobutane (CH3-CH2-CH2-CH2-Br2) to form 1,4-dibromobutane. This is then reacted with potassium ethoxide (CH3CH=CHKOOC) to form potassium diethyl maleate (CH3CH=CHCOOK). The overall reaction can be represented as follows:

CH3COONa + CH3-CH2-CH2-CH2-Br2 → CH3-CH2-CH2-CH2-CH2-Br + NaOAc
CH3-CH2-CH2-CH2-CH2-Br + CH3CH=CHKOOC → CH3CH=CHCOOK + CH3-CH2-CH2-CH2-COOC2H5

The final product is potassium diethyl maleate.