Method for isolating acids from chemical reaction mixtures by using 1-alkylimidazoles
AssigneeBASF SE
InventorsMatthias Maase, Oliver Huttenloch
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Abstract
Method of separating acids from reaction mixtures by means of an auxiliary base, where the auxiliary base b) reacts with the acid to form a salt which is liquid at temperatures at which the desired product is not significantly decomposed while the liquid salt is being separated off and c) the salt of the auxiliary base forms two immiscible liquid phases with the desired product or the solution of the desired product in a suitable solvent, in which the auxiliary base used is an alkylmidazole, which has a solubility in 30% strength by weight sodium chloride solution at 25° C. of 10% by weight or less and whose hydrochloride has a melting point below 55° C.
Claims20
A method of separating acids from reaction mixtures comprising the use of an auxiliary base, where the auxiliary base
- A) reacts with the acid to form a salt which is liquid at temperatures at which the desired product is not significantly decomposed while the liquid salt is being separated off and
- B) the salt of the auxiliary base forms two immiscible liquid phases with the desired product or the solution of the desired product in a suitable solvent,
- and wherein the method the auxiliary base used is an alkylimidazole
- which has a solubility in 30% strength by weight sodium chloride solution at 25° C. of 10% by weight or less and
- whose hydrochloride has a melting point below 55° C.;
- which comprises the following steps:
- a) reacting at least one 1-alkylimidazole with at least one acid in the presence of a desired product to form a mixture of at least one salt of the 1-alkylimidazole and the desired product,
- b) separating the salt or salts of the 1-alkylimidazole and the desired product under conditions under which at least two separate phases of which at least one comprises predominantly the salt or salts of the 1-alkylimidazole and at least one other comprises predominantly desired product are formed,
- c) adding at least one base to a phase which has been separated off from (b) and comprises predominantly the salt or salts of the 1-alkylimidazole to form a mixture of the liberated 1-alkylimidazole and the reaction product of base and acid,
- d) separating the mixture of the liberated 1-alkylimidazole and the reaction product of base and acid under conditions under which at least two separate phases of which at least one comprises predominantly the liberated 1-alkylimidazole in crude form and at least one other comprises the reaction product of base and acid are formed,
- e) if appropriate, purifying the 1-alkylimidazole obtained in crude form and
- f) if appropriate, recirculating the optionally purified 1-alkylimidazole to step (a).
Dependencies are inferred from the claim text.