QUE: WHAT IS ALDOL CONDENSATION ?

ANS: Aldehydes which have alpha hydrogen condense to give beta hydroxy aldehyde is called aldol condensation.

mechanism : aldol condensation can be both base as well as acid catalzed
base catalyzed mech is given below.
step 1: base first remove alpha hydrogen result into generation of enolate  .
step 2: enolate attacks at carbonyl carbon which is electrophillic centre .

Base catalyzed mechanism of aldol condensation

Ketone can also give aldol condensation however yield is very poor as effect of two R group decrease the electrophillicity of carbonyl carbon.