Q.How will you convert Ethylacetate into Ethylaceto acetate ?

Two molecules of ethyl acetate undergo Claisen condensation, catalysed by sodium ethoxide: the enolate of one molecule attacks the ester carbonyl of the other, kicking out ethoxide to give ethyl acetoacetate.

Ethyl acetate, $CH_3COOC_2H_5$, has alpha-hydrogens on the $CH_3$ group adjacent to the carbonyl, which are acidic enough to be removed by a strong base like sodium ethoxide ($NaOC_2H_5$), generating an ester enolate: $CH_3COOC_2H_5 + NaOC_2H_5 \rightarrow {}^-CH_2COOC_2H_5\ (\text{enolate}) + C_2H_5OH$ This carbanion/enolate then performs a nucleophilic acyl substitution, attacking the carbonyl carbon of a second molecule of ethyl acetate and displacing ethoxide ion: $CH_3COOC_2H_5 + {}^-CH_2COOC_2H_5 \rightarrow CH_3-CO-CH_2-COOC_2H_5 + {}^-OC_2H_5$ After acidic workup, the product is ethyl acetoacet …