${\mathrm{CH}}_3\mathrm{COOH}\stackrel{{\mathrm{LiAIH}}_4}{\to }\mathrm{X}\underset{300°\mathrm{C}}{\overset{\mathrm{Cu}}{\to }}\mathrm{Y}\underset{\mathrm{NaOH}}{\overset{\mathrm{dilute}}{\to }} \mathrm{Z}$ .

In the above reaction $\mathrm{Z}$ is 

${\mathrm{CH}}_3\mathrm{COOH}\stackrel{{\mathrm{LiAlH}}_4}{\to }\underset{\mathrm{X}}{{\mathrm{CH}}_3{\mathrm{CH}}_2\mathrm{OH}}\underset{300°\mathrm{C}}{\overset{\mathrm{Cu}}{\to }}$

${\mathrm{CH}}_3\mathrm{CHO}\stackrel{\text{ dill }\mathrm{NaOH}}{\to }{\mathrm{CH}}_3-\underset{\underset{\mathrm{Z}}{\underset{\mathrm{OH}}{\mathrm{l}}}}{\mathrm{CH}}-{\mathrm{CH}}_2\mathrm{CHO}$

.Acetaldehyde $\left(\mathrm{Y}\right)$ undergoes aldol condensation in presence of dilute caustic alkali to form aldol.