1. A process for the preparation of Allopurinol (1) having purity greater than
99.5% by HPLC.
5 comprising the steps of:
a) reacting 2-cyanoacetamide (5)
with triethoxymethane (4)
10 in the presence of morpholine to obtain 2-cyano-3-morpholino acrylamide
(3);
b) reacting 2-cyano-3-morpholino acrylamide (3) with hydrazine hydrate in
presence of an acid to obtain 3-amino-4-pyrazolecarboxamide (2); and
15
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c) cyclizing 3-amino-4-pyrazolecarboxamide (2) with formamide in the
presence of a base to obtain crude Allopurinol (1), and
d) purifying crude Allopurinol (1) to obtain pure Allopurinol (1).
Wherein the purification of Allopurinol (1) comprises of
5 i. dissolving allopurinol in aqueous sodium hydroxide solution;
ii. adding neutral charcoal and heating to 40-45°C;
iii. filtering and adjusting pH of the filtrate to 4.5 using suitable
organic acid; and
iv. isolating pure Allopurinol.
10 2. The process as claimed in claim 1, wherein the acid used in step b) is selected
from sulfuric acid or hydrochloric acid.
3. The process as claimed in claim 1, wherein the base used in step c) is selected
from the group comprising “alkali hydroxides” such as sodium hydroxide,
potassium hydroxide, lithium hydroxide and the like.
15 4. The process as claimed in claim 1, wherein the suitable organic acid used is
acetic acid.