GB846575A - Improvements in or relating to the purification and vinylation of pyrrolidone-2 - Google Patents

Abstract

Crude 2-pyrrolidone prepared by reacting butyrolactone with ammonia under pressure is purified by treating the pyrrolidone with an amount of alkali metal or its oxide or hydroxide sufficient to react with impurities present but not such as to combine with a substantial amount of the pyrrolidone and subsequently distilling off all of the pyrrolidone after removing any water produced. The amount of alkali used may amount to 1-3% (expressed as metal) based as the pyrrolidone. The pyrrolidone treated may be either the crude reaction product from which a substantial amount of water of reaction has been removed or the distilled product. The purified pyrrolidone may be N-vinylated by further treating the purified pyrrolidone with an amount of from 0,5 to 2% by weight (based on the metal) of an alkali metal or its oxide, hydroxide or alkoxide, where necessary distilling a portion of the pyrrolidone to remove water or alcohol produced in the salt formation and treating the residue with acetylene at elevated temperature and pressure until 80-100% of the pyrrolidone has reacted; the vinylation method described in Specification 799,924 may be used. The purification is stated to prevent formation of polypyrrolidone in the vinylation reaction. Examples describe the purification of a crude pyrrolidone, obtained as above, by adding caustic soda thereto and then distilling to remove an aqueous fore-run and then purified pyrrolidone which is treated with sodium or potassium metal to form a pyrrolidone solution of pyrrolidinosodium or potassium catalyst and then reacted with acetylene at 130-135 DEG C. under 8-10 atmosphere pressure to give N-vinyl pyrrolidone. The Provisional Specification refers broadly to the purification of 2-pyrrolidone by treatment with an alkali metal, its oxide or hydroxide and subsequently distilling of the lactam. Specification 757,406 also is referred to.