Propanenitrile reacts with stannous chloride and hydrochloric acid followed by hydrolysis via Stephen reaction to give propanal.
But-2-ene on ozonolysis followed by hydrolysis gives two moles of ethanal.
Thus, x = propanal and y = ethanal.
When one mole of propanal and one mole of ethanal react in presence of alkali followed by heating, crossed aldol condensation occurs.
Possible aldol condensation products after dehydration are:
• Pent-2-enal • 2-Methylbut-2-enal • 2-Methylpent-2-enal
Formation of 3-Methylbut-2-enal is not possible from this combination.
Hence, the product not obtained is:
$$ \boxed{\text{3-Methylbut-2-enal}} $$
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