METHOD OF PREPARING DIACID/DIAMINE SALT SOLUTIONS Russian patent published in 2011 - IPC C07C51/41 C07C55/02 C07C55/14 C07C211/09 C07C211/12 

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of preparing diamine and diacid salt solutions, obtained by mixing diacid and diamine, with weight concentration of the salt ranging from 50% to 80%. The method involves obtaining in a first reactor an aqueous solution of diamine and diacid with molar ratio of diacid to diamine ranging from 1.5 to 5 and with concentration of dissolved particles in water ranging from 40 to 75 wt %, by feeding into the said reactor either an aqueous solution with at least 50 vol. % diamine and diacid with molar ratio ranging from 1.5 to 5, or water making up at least 10% of the total amount of water fed into said reactor, a stream containing diacid, a stream containing diamine and, possibly, a stream of water at temperature T₁, where the flow of the fed streams containing acid and the stream containing diamine are is regulated such that temperature of the solution in the reactor constantly remains below the boiling point at operating pressure of the reactor, and molar ratio of diacid to diamine is greater than 1.1, wherein the amount of the fed acid is at least 90% of the total weight of the acid needed to obtain the desired amount of aqueous salt solution; the amount of the fed water is at least 75% of the total weight of the water needed to obtain the desired amount of aqueous salt solution. The aqueous solution obtained in the first reactor is then moved to a second reactor fitted with a condenser and a stream containing diamine is fed into the second reactor to obtain molar ratio of diacid to diamine between 0.9 and 1.1, wherein the temperature of the solution is raised to a value at most equal to boiling point of the solution at operating pressure at least by removing heat released during the reaction between the diamine and diacid and, possibly, the amount of water and/or additional diacid need to obtain a salt solution with the desired concentration and molar ratio of diacid to diamine is used.

EFFECT: method enables to obtain concentrated salt solutions using minimal heat exchange with ambient medium.

20 cl, 2 ex, 2 dwg