Question

what will happen if benzaldehyde react with hydrazine hydrate

Answer 1

Carbonyl compounds generally react with hydrazine to form immines. Benzaldehyde being no different.

The reaction mechanism is actually quite complicated (atleast for me, lol). In a nutshell, the C=O group reacts with H2NNH2 (hydrazine) forming C=N bond otherwise called immines.

Think of the O in C=O being replaced by N and the H2 and O reacting to form H2O.

NOTE- This is not what actually happens but for ease of understanding u can think of it that way.

Answer 2

Phenylhydrazone is formed upon the reaction of benzaldehyde with hydrazine hydrate

• Hydrazine hydrate has the formula of H₆N₂O. Basically, it is the hydrated form of hydrazine
• Hydrazine will react with benzaldehyde to form phenylhydrazone as follows:

                            NH₂NH₂ + ArCHO ⇒ ArCN-NH₂

• The C=O bond which is present in the carbonyl compound benzaldehyde reacts with the hydrazine molecule resulting in the formation of a CN bond which leads to the formation of phenylhydrazone

Thus, if benzaldehyde reacts with hydrazine hydrate, phenylhydrazone will be formed.