Question

Acetaldehyde reacts with semicarbazide, product will be:
A.\[C{{H}_{3}}CH=NNH-CO-N{{H}_{2}}\]
B.\[C{{H}_{3}}CH=NCONHN{{H}_{2}}\]
C.\[C{{H}_{3}}CH=NHN{{H}_{2}}\]
D.\[C{{H}_{3}}-C\left( =O \right)-NH-CON{{H}_{2}}\]

Answer 1

Hint: We know that Semicarbazone are derivatives of imines and formed by the condensation reaction between an aldehyde or ketone and semicarbazide. Chemical formula of semicarbazide is $N{{H}_{2}}(CONH)N{{H}_{2}}$ the condensation reaction between acetaldehyde $\left( C{{H}_{3}}CHO \right)$ and semicarbazide to get the molecular formula of acetaldehyde semicarbazone.

Complete answer:
Acetaldehyde semicarbazone belongs to the group of semicarbazones. Semicarbazones are formed by the condensation reaction between an aldehyde or ketone and semicarbazide. A condensation reaction proceeds with the loss of a water molecule. So, to form acetaldehyde semicarbazone, we need to do the condensation reaction of aldehyde, which is acetaldehyde here, with semicarbazide. Semicarbazide is a derivative of urea.

Some semicarbazones have antiseptic properties. Nitrofurazone (trade name as Furacin) is such an example. Thiosemicarbazone is a semicarbazone which contains sulphur atoms (thio group) in the place of oxygen atoms. It possesses anti-viral, anti-malarial and anti-cancer activities.

Therefore, the correct answer is option A.

Note:
Remember that Semicarbazones are crystalline solids and they are very useful for the identification of aldehydes and ketones by the melting point analysis method. Molecular weight of acetaldehyde semicarbazone is \[101\text{ }g/mol.\] Its molecular formula can also be written as: ${{C}_{3}}{{H}_{7}}{{N}_{3}}O.$