Write the structural formulas and names of the four possible aldol condensation products from propanal and butanal. In each case,indicate which aldehyde acts as the nucleophile and which acts as the electrophile.

(N/A) Propanal $(CH_3CH_2CHO)$ and butanal $(CH_3CH_2CH_2CHO)$ both contain $\alpha$-hydrogen atoms. Therefore,they undergo both self-aldol and cross-aldol condensation to give a mixture of four products. The products are formed as follows:

$1$. Propanal (Electrophile) + Propanal (Nucleophile)	$CH_3CH_2CH=C(CH_3)CHO$ ($2$-methylpent$-2-$enal)
$2$. Butanal (Electrophile) + Butanal (Nucleophile)	$CH_3CH_2CH_2CH=C(C_2H_5)CHO$ ($2$-ethylhex$-2-$enal)
$3$. Propanal (Electrophile) + Butanal (Nucleophile)	$CH_3CH_2CH=C(C_2H_5)CHO$ ($2$-ethylpent$-2-$enal)
$4$. Butanal (Electrophile) + Propanal (Nucleophile)	$CH_3CH_2CH_2CH=C(CH_3)CHO$ ($2$-methylhex$-2-$enal)