Method for purification of 2-alkyl-4-halo-5-formylimidazoles
AssigneeNippon Gohsei Kagaku Kogyo Kabushiki Kaisha
InventorsToshio Yamamoto, Yoshihiro Hibi, Toshimi Ogawa
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Abstract
The invention provides a method of purifying 2-alkyl-4-halo-5-formylimidazoles, which comprises dissolving an 2-alkyl-4-halo-5-formylimidazole in an aqueous solution of a sulfonating agent, adjusting the solution to pH 1-6, and removing the impurity 2-alkyl-4,5-dihaloimidazole by filtration or extraction.
Claims4
A method of purifying a 2-alkyl-4-halo-5-formylimidazole which comprises dissolving a 2-alkyl-4-halo-5-formylimidazole containing the corresponding 2-alkyl-4,5-dihaloimidazole as an impurity in an aqueous solution of a sulfonating agent and adjusting the solution to pH 1-6 to thereby provide an aqueous solution of the sulfonation product and then removing the water-insoluble impurity by filtration or extraction.
A method of purifying a 2-alkyl-4-halo-5-formylimidazole which comprises dissolving a 2-alkyl-4-halo-5-formylimidazole containing the corresponding 2-alkyl-4,5-dihaloimidazole as an impurity in an aqueous solution of a sulfonating agent, adjusting the solution to pH 1-6 to thereby provide an aqueous solution of the sulfonation product, then removing the water-insoluble impurity by filtration or extraction, adjusting the resultant filtrate or extraction residue aqueous layer to pH 6.5-8.2 with an alkali and removing additional precipitated impurity by filtration or extraction.
Dependencies are inferred from the claim text.