Complete reaction of acetaldehyde with excess | vedclass

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Question

(C) The reaction of acetaldehyde $(CH_3CHO)$ with excess formaldehyde $(HCHO)$ in the presence of conc. $NaOH$ is an aldol condensation followed by Ca

Vedclass · Accepted Answer

$18$

Vedclass · Answer

(C) The reaction of acetaldehyde $(CH_3CHO)$ with excess formaldehyde $(HCHO)$ in the presence of conc. $NaOH$ is an aldol condensation followed by Cannizzaro reaction,yielding pentaerythritol ($P$,$C(CH_2OH)_4$) and sodium formate ($Q$,$HCOONa$).$P$ is $C(CH_2OH)_4$,which has no aldehyde group and does not give Tollens' test.$Q$ is $HCOONa$,which upon acidification gives formic acid $(HCOOH)$,which gives a positive Tollens' test.Reaction of $P$ with excess cyclohexanone in the presence of $PTSA$ forms an acetal $R$ (a spiro-compound).The structure of $R$ is $C(CH_2O)_2(C_6H_{10})_2$.In $R$,there are $12$ methylene groups from two cyclohexanone rings and $2$ methylene groups from the central carbon's substituents,totaling $14$ methylene groups $(-CH_2-)$.There are $4$ oxygen atoms in the two acetal linkages.Sum $= 14 + 4 = 18$.

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