Question

The starting raw material for synthesis of lignocaine is:

• A. 2,6-Xylidine
• B. p-Nitroacetophenone
• C. 4-Amino-3-Nitroanisole
• D. 4-Chlorobenzyl cyanide

Hint:

Lignocaine synthesis begins with aromatic amines like 2,6-Xylidine that are modified through various chemical processes to form the anesthetic agent.

Answer 1

The Correct Option is A

The starting raw material for the synthesis of lignocaine (also known as lidocaine) is 2,6-Xylidine. This compound undergoes a series of reactions to form the final anesthetic compound.

Answer 2

Working out a drug's starting material means tracing its synthesis route backward to the simplest building block. Checking each candidate against known synthesis routes:

1. 2,6-Xylidine: 2,6-Xylidine, also called 2,6-dimethylaniline, is the aromatic amine used to build lignocaine (lidocaine). It is first reacted with chloroacetyl chloride to form an intermediate amide, which is then treated with diethylamine to install the tertiary amine side chain, giving the finished local anaesthetic. This route directly connects 2,6-xylidine to lignocaine.
2. p-Nitroacetophenone: This compound is a known starting material in the synthesis of chloramphenicol, an antibiotic, where the nitro and ketone groups are elaborated into the drug's characteristic structure. It has no role in building the anilide backbone of lignocaine.
3. 4-Amino-3-Nitroanisole: This nitroaniline derivative is more typically associated with dye and pigment synthesis, where its amino and nitro groups are used to build coloured azo compounds. It is not part of the lignocaine synthesis pathway.
4. 4-Chlorobenzyl cyanide: This nitrile is a known building block in the synthesis of certain antihistamines, where the cyanide group is later converted into an amine side chain. It does not connect to the aniline-based route used for lignocaine.

Since lignocaine's structure is built around a 2,6-dimethyl substituted aniline ring carrying an amide and a diethylamino side chain, only the starting material that already has that dimethylaniline core can be the correct precursor.

So the correct answer is 2,6-Xylidine.