Preparing 2-chlorobenzylamine from 2-chlorobenzylchloride via

Abstract

2-Chlorobenzylamine is prepared from 2-chlorobenzylchloride in a two-step process. In the first step, 2-chlorobenzylchloride is reacted with alkali metal phthalimide, preferably formed in situ from potassium carbonate and phthalimide, to form the novel intermediate 2-chlorobenzylphthalimide. In the second step, the phthalimide ring of the 2-chlorobenzylphthalimide is cleaved to form 2-chlorobenzylamine. The first step is preferably carried out in an unreactive solvent at 60.degree. C. to reflux temperature, for example, for 1 to 10 hours. The solvent is very preferably dimethylformamide which is advantageously recovered and used again as solvent in the conversion of 2-chlorobenzylchloride to 2-chlorobenzylphthalimide. The second step consists essentially, for example, of hydrazinolysis or hydrolysis. When the second step consists essentially of hydrazinolysis, the 2-chlorobenzylphthalimide is reacted with hydrazine to form 2-chlorobenzylamine and phthalylhydrazide, and the 2-chlorobenzylamine is separated by reacting with acid to form soluble amine salt, filtering out the phthalylhydrazide and then reacting the amine salt with base to convert it to the free amine. When the second step consists essentially of hydrolysis, the hydrolysis can be carried out in one step with alkali metal hydroxide or inorganic acid or in two steps, for example, with hydrolysis with alkali metal hydroxide followed by hydrolysis with inorganic acid. The hydrolysis is suitably carried out at temperatures of 60.degree. C. to reflux temperature utilizing base and acid strengths ranging from 5% to saturated. Preferred hyrdolyzing agents are 40-60% aqueous KOH for one step base hydrolysis, 40-60% aqueous sulfuric acid for one step acid hydrolysis and 10-30% aqueous KOH followed by a mixture of water and concentrated HCl in a volume ratio ranging from 0.5:1 to 2:1 for the two-step base/acid hydrolysis. A second step consisting essentially of hydrolysis is preferred over a second step consisting essentially of hydrazinolysis not only for safety reasons but also because phthalic acid or a mixture of this with 2-chlorobeznylphthalamic acid can be recovered as by-product or by-product derivative which, contrary to the hydrazinolysis by product, phthalylhydrazide, are readily, respectively, converted to phthalimide and 2-chlorobenzylphthalimide by reaction with concentrated aqueous ammonium hydroxide. The phthalimide is useful in the in situ reaction in the first step to form 2-chlorobenzylphthal-imide. 2-Chlorobenzylphthalimide which is introduced with phthalimide into said first step becomes part of the product of the first step.