Which reactive intermediate is formed during the condensation reaction between acetaldehyde and formaldehyde ?

Options

A. `overset(-)CH_(2)CHO`
B. `overset(+)(C )H_(2)CHO`
C. `overset(+)CH_(2)OH`
D. `overset(-)CHCHO`

Answer

A

Explanation

The `alpha`- hydrogen atoms of of acetaldehyde du to `-E` effect of group is slightly acidi in nature. In crossed aldol condensation between formaldehyde and acetaldehyde in the first step `OH^(-)` (from the base added ) abstracts one of these acidic `alpha`-hydrogens to form carbonion or enolate ion which is stabilised by reasonance.
`HO^(-)+H-CH_(2)-overset(O)overset(||)C-Hoverset("Slow")hArrH_(2)O+:overset(-)CH_(2)-overset(O)overset(||)C-H`