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.$$C{H}_3-C(=O)-NH-CON{H}_2$$

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 $$101g/mol.$$ Its molecular formula can also be written as: $C_3{H}_7{N}_{3}O.$