Patent GB-462573-A (GB)
Title: Improvements in and relating to substituted barbituric acids
Filed: 1936-01-24
Abstract: Aqueous solutions of alkali metal salts of barbituric acids of the formula <FORM:0462573/IV/1> in which R1 represents an olefine radicle halogenated at the double bond, R2 an aliphatic or alicyclic radicle and R3 an aliphatic radicle, are stabilized for therapeutic purposes by the addition of a water-soluble pyrazolone, e.g. 1 - phenyl - 2 : 3 - dimethyl - 5 - pyrazolone or 1-phenyl-2 : 3-dimethyl-4-methoxy-5-pyrazolone.  The barbiturate is dissolved in an aqueous solution of the pyrazolone or vice versa, or the free acid is treated in the presence of the pyrazolone with the requisite amount of aqueous caustic alkali.  In the latter case the acid is preferably made into a paste with a polyhydric alcohol such as glycol or glycerine before adding the alkali solution. According to the examples: (1) sodium sec - butyl - b  - chlorallyl - N - ethyl-barbiturate is dissolved in an aqueous solution of 1 - phenyl - 2 : 3 - dimethyl - 4 - methoxy - 5 - pyrazolone; (2) sec - amyl - b - bromallyl-barbituric acid is N-methylated with dimethyl sulphate, made into a paste with glycol, dissolved in caustic soda solution and an aqueous solution of 1-phenyl-2 : 3-dimethyl-5-pyrazolone then added; (3) isopropyl-b -bromallyl-N-methyl-barbituric acid is stirred with glycerine, dissolved in caustic soda solution and added to an aqueous solution of 1-phenyl-2 : 3-dimethyl-5-pyrazolone.  An aqueous solution containing sodium isopropyl-b -chlorallyl-N - methyl - barbiturate and 1 - phenyl - 2 : 3-dimethyl-5-pyrazolone is also referred to.  A sample has been furnished under Sect. 2 (5) of an aqueous solution of sodium isopropyl-b -bromcrotyl - N - methyl - barbiturate containing 1 - phenyl - 2 : 3 - dimethyl - 5 - pyrazolone.  The barbituric acid is prepared by heating sodium isopropylbarbiturate with 1 : 2-dibrombutene-2 in aqueous solution and treating the product with dimethyl sulphate.ALSO:Aqueous solutions of alkali metal salts of barbituric acids of the formula <FORM:0462573/VI/1> in which R1 represents an olefine radicle halogenated at the double bond, R2 an aliphatic or alicyclic radicle and R3 an aliphatic radicle, are stabilized for therapeutic purposes by the addition of a water-soluble pyrazolone.  The barbiturate is dissolved in an aqueous solution of the pyrazolone or vice versa, or the free acid is treated in the presence of the pyrazolone with the requisite amount of aqueous caustic alkali. In the latter case the acid is preferably made into a paste with a polyhydric alcohol such as glycol or glycerine before adding the alkali solution.  Examples describe the preparation of an aqueous solution of sodium secbutyl-b -chlorallyl-N-ethyl-barbiturate containing 1 - phenyl - 2 : 3 - dimethyl - 4 - methoxy - 5 - pyrazolone, and of aqueous solutions of sodium sec - amyl - b  - bromallyl - N - methyl - barbiturate and of isopropyl - b  - bromallyl - N - methylbarbiturate containing 1-phenyl-2 : 3-dimethyl-5-pyrazolone. The sample furnished under Sect. 2 (5) comprises an aqueous solution of sodium isopropyl-b -bromcrotyl-N-methyl-barbiturate containing 1 - phenyl - 2 : 3 - dimethyl - 5 - pyrazolone.