Why does not formaldehyde take part in aldol condensation?

Explanation

Aldol condensation involvses the nucleophile attrack to carbanion generated by one molecular of a particular carbonyl `3*5`). In case the medium is srongly acidic (`p_(H)` close to `1`). then the ammonia derivates will be also protonated and will not be able to act as a nucleophile.