Patent ID: 7632953
Filing Date: 2009-12-15
Classification: C07D

Abstract:
1. A process for the preparation of gabalactam of formula 1 which comprises (i) preparing an aqueous solution of an alkali or alkaline earth metal hydroxide at a concentration in a range from 10 to 20% by weight, adding bromine to the aqueous solution to yield a corresponding alkali or alkaline earth metal hypobromite solution having a concentration in a range from 5 to 10% by weight, (ii) adding 1 part by weight of an amide of the formula 4 to 7.5 to 9.5 parts by weight of the hypobromite solution during a period in a range from 1 to 4 hours, at a temperature in a range from −10 to +10 degrees C. to form a mixture, (iii) aging the mixture from step (ii) at a temperature in a range from −10 to +10 degrees C. for a period in a range from 0.5 to 2 hours, (iv) heating the mixture from step (iii) gradually at a temperature in a range from 80 to 100 degrees C., for a period in a range of 3 to 8 hours and aging for a period in a range from 5 to 8 hours to yield gabalactam, (v) cooling the mixture of step (iv) at a temperature in a range from 30 to 50 degrees C., (vi) extracting the mixture of step (v) using a nonpolar organic solvent or a mixture of nonpolar organic solvents to yield an organic layer containing gabalactam, (vii) subjecting the resulting aqueous layer to the steps of (iv) to (vi) defined above to yield additional organic layers containing gabalactam, (viii) combining the organic layers obtained in steps (vi) & (vii) together, (ix) washing the combined organic layers with water at a temperature in a range from 30 to 35 degrees C., and (x) distilling of the nonpolar organic solvent or the mixture of nonpolar organic solvents at a temperature in a range from 60 to 110 degrees C., under reduced pressure to yield gabalactam.