Home › JEE Advanced › Chemistry › Aldehydes, Ketones and Carboxylic Acids › Reduction of an aldehyde with $\mathrm{NaBH_4}$ …
Reduction of an aldehyde with $\mathrm{NaBH_4}$ or $\mathrm{LiAlH_4}$ produces:
AA carboxylic acid
BA secondary alcohol
CA primary alcohol
DAn alkane
Answer & Solution
Correct answer: C. A primary alcohol
Aldehydes ($\mathrm{R-CHO}$) are reduced to **primary** alcohols ($\mathrm{R-CH_2OH}$) because the carbonyl carbon ends up with just one $\mathrm{R}$ group on it. Ketones ($\mathrm{R_2C=O}$) reduce to *secondary* alcohols (option B) for the symmetric reason.
Neither $\mathrm{NaBH_4}$ nor $\mathrm{LiAlH_4}$ goes all the way to alkane — that requires harsher conditions (Clemmensen, Wolff–Kishner).
Related questions
Against ketones, aldehydes in nucleophilic addition are:Aldehydes and ketones take part in addition that is:Solubility of aldehydes falls as the alkyl chain grows:Methanal, ethanal and propanone mix with water in:Aldehydes boil lower than alcohols of like mass because they lack:Aldehydes boil higher than hydrocarbons of like mass because of:At room temperature methanal exists as a:The carbonyl carbon behaves as a centre that is: