Question

The reagent with which both acetaldehyde and acetone react easily is

• A. Fehling's reagent
• B. Grignard reagent
• C. Schiff's reagent
• D. Tollen's reagent

Answer 1

The correct option is B Grignard reagent

(a) Aliphatic aldehyde on warming with Fehling solution A give a red precipitate of cuprous oxide. Benzaldehyde and ketones give negative Fehling's test.

(b) Grignard reagents react both with aldehydes and ketones.

(c) The Schiff test is a chemical test used to check for the presence of aldehydes in a given analyte. This is done by reacting the analyte with a small quantity of a Schiff reagent. It does not react with ketones.

(d) Tollen's reagent refers to the chemical reagent which is used in the detection of an aldehyde functional group, an aromatic aldehyde functional group, or an alpha hydroxy ketone functional group in a given test substance.
Ketones don't give silver mirror with Tollens' reagent.
Tollen's reagent is a solution of silver nitrate $\left(AgN{O}_3\right)$ and Ammonia $\left(N{H}_3\right)$.
A postive test gives precipitate of elements silver.$RCHO+2\left[Ag\right(N{H}_3{)}_2{]}^{+}+3O{H}^{-}\to RCO{O}^{-}+2Ag\downarrow +2H_{2}O+4N{H}_3\text{Aldehyde}\text{Tollen's Reagent}\text{Carboxylate ion}\text{Silver mirror}$

Fehling solution, Schiff's reagent & Tollen's reagent react only with aldehydes but Grignard reagents react both with aldehydes and ketones Hence, the correct answer is option (b).