Patent ID: 6610888
Filing Date: 2003-08-26
Classification: C07B,C07C

Abstract:
A method of increasing the concentration of one or more compounds in a solution comprising a mixture of at least two chemical compounds which are in chemical equilibrium with one another, with the exception of the reaction of a formaldehyde solution with aniline in the presence of acid catalysts, wherein the formaldehyde solution comprises polyoxymethylene glycols or polyoxymethylene glycols and monomeric formaldehyde or polyoxymethylene glycols and methylene glycol or polyoxymethylene glycols and monomeric formaldehyde and methylene glycol, which method comprises the following steps:(a) fractionating the solution by means of a separation method to give at least two fractions in which different chemical compounds of the mixture are present in increased concentrations compared to the chemical equilibrium; and (b) reacting at least one of the compounds of increased concentration with a further chemical compound or compounds before the chemical equilibrium is fully reestablished in at least one of the fractions, and recovering the desired compound(s).