Synthesis of polyamines and mixture formed thereby, of diprimary polyalkylene polyamines with disubstituted N-adjacent terminal carbon atom(s)

A process for preparing a polyamine comprising,

• (i) mixing a nitroalkane (NA) having the structure ##STR7## wherein, R.sup.1 and R.sup.2 represent H, C.sub.1 -C.sub.20 alkyl, C.sub.5 -C.sub.7 cycloalkyl, C.sub.2 -C.sub.20 alkylether, C.sub.2 -C.sub.20 alkylaminoalkyl, and R.sup.1 together with R.sup.2 may be cyclized forming a ring with from about 5 to about 7 C atoms;
• with an aliphatic amine reactant to form a mixture containing a salt intermediate, said amine reactant being selected from the group consisting of piperazine, substituted piperazines having substituents on the N or C atoms in the ring;
• an acyclic monoamine having a terminal primary amine group;
• a diprimaryamine with both terminal amine groups being primary;
• and, a polyalkylene polyamine (PAPA) with both primary and secondary amine groups, in which PAPA at least one primary or secondary amine group is a terminal group;
• (ii) gradually adding to said mixture an essentially solvent-free aldehyde having the formula R.sup.3 CHO in at least an equimolar amount of the lesser of EDA or NA, wherein, R.sup.3 represents represents H, C.sub.1 -C.sub.20 alkyl, preferably C.sub.1 -C.sub.6 lower alkyl, C.sub.6 aryl, and, C.sub.4 -C.sub.7 cycloalkyl;
• (iii) maintaining the temperature in the range from about 0.degree. C. to about 50.degree. C. while stirring to form a reaction mixture containing a nitroamine having a terminal nitro group;
• and,
• (iv) contacting said reaction mixture with hydrogen in the presence of a catalytically effective amount of Raney Ni at a temperature in the range from about 15.degree. C. to about 50.degree. C. and a pressure in the range from about 50 psig to about 500 psig for a period of time sufficient to hydrogenate essentially all the nitro groups in said compounds;
• whereby the yield of said polyamine is greater than 10 mol % of the nitroalkane converted to polyamines.