Abstract: The present invention relates to a process of producing symmetrically structured difatty acid diamines by reacting mixtures of fatty acids or their esters with diamines, isolating the symmetrical difatty acid diamides from the reaction mixture by making use of their different solubilities and concentrating them by recrystallisation if necessary. The invention also provides for a process of isolating a fatty acid from a mixture of fatty acids wherein the difatty acid diamides produced in the process of the invention are saponified to yield the corresponding free fatty acid.

Abstract: The present invention relates to plastics that can be obtained by reacting unsaturated and/or hydroxyl-group-containing fatty acids or their esters or mixtures of various such fatty acids and esters with bifunctional ester-forming and/or amide-forming compounds and, if necessary, subsequently converting ethylenic double bonds, to give difatty acid diamides, difatty acid diesters, difatty acid amide esters, monofatty acid amide amines or monofatty acid amide alcohols as monomer components which contain at least two reactive groups suited for linkage to give polymers, in particular ethylenic double bonds, hydroxyl groups, epoxy groups or amino groups, and by linking the said compounds in the known way via a second group of bifunctional compounds that are capable of reacting with these free reactive groups to give the desired plastics.