Regular copolyamides. I. A facile method for the preparation of diamine‐oxamides

Abstract α,ω‐Diamine‐oxamides with 2–12 CH 2 groups between the two amino groups were obtained by the reaction of the diamines and diethyl or dimethyl oxalate. Diethyl oxalate is added slowly to a substantial excess of diamine in the proper solvent over a period of time under controlled temperature conditions. All variables are very important for each individual diamine in order to obtain optimal conversions to the diamine‐oxamides under the most favorable conditions. Diamine‐oxamides were obtained in approximately 80% yield with only small amounts (5–10%) of the corresponding polyoxamides as the side product. Diamine‐oxamides from diamines with less than six methylene groups are water‐soluble. All diamine‐oxamides show an alternation of their melting points and are useful intermediates for the preparation of regular copolyoxamides.