GB658422A - A process for the preparation of polyamines - Google Patents

Abstract

Polyamines such as 1.3-alkanediamines and/or polyalkylene polyamines are prepared by reacting in the liquid state a a ,b - unsaturated aldehyde with ammonia or a primary aliphatic mono-amine present in a proportion of at least 4, preferably from 4 to 100, mols. of ammonia or amine per mol. of the unsaturated aldehyde, and subsequently subjecting the mixture to catalytic hydrogenation under conditions of temperature and pressure of hydrogen which favour the hydrogenation reaction. The general reaction when ammonia is employed is represented by the equation <FORM:0658422/IV (b)/1> in which R represents either a hydrogen atom or an organic group such as alkyl and aralkyl, alkaryl or cycloalkyl group. Depending on the particular conditions of the reaction, particularly on the amount of excess ammonia present during the hydrogenation stage, varying amounts of polyalkylene polyamines containing small amounts of oxygen may also be formed. Primary amines, preferably primary aliphatic mono-amines, may be used instead of ammonia. Preferred starting materials are those with the formula <FORM:0658422/IV (b)/2> where R1 represents either a hydrogen atom or an alkyl group and are, for example, acrolein, methacrolein, a -ethylacrolein, a -propylacrolein, a -isopropylacrolein and a -butylacroleins. The reaction between the unsaturated aldehyde and the ammonia or primary amine may be effected by dissolving either or both of the reactants in an inert organic solvent such as alcohol, an ether or a saturated or aromatic hydrocarbon. A limited amount of water may be present in the mixture. The temperature during the first step of the process should be such that both reactants can exist in the liquid phase. Hydrogenation catalysts, which may be used in the second step, are Ni, Co, Fe, Mn, V, Sb, Ti, Te, Sn and Pb. The free metals or mixtures or alloys thereof or their oxides or sulphides may be used. The catalyst may be supported on kieselguhr, pumice or carbon. The preferred catalyst is Raney nickel catalyst. The treatment with molecular hydrogen is effected at a temperature in the range 50-200 DEG C. under super-atmospheric pressure of hydrogen. When the treatment with hydrogen is complete the organic components of the mixture may be separated by fractional distillation or other suitable means. The 1,3-alkane diamines are useful as wetting agents, antioxidants, gas absorbents and as biological agents. The polyalkylene polyamines may be reacted with higher fatty acids, e.g. oleic acid, to form adhesive and binding agents for asphalt emulsions, and they may be used for the preparation of stabilizing agents for synthetic greases. In the examples acrolein is treated with ammonia or isopropylamine and then hydrogenated. Specification 365,214 and U.S.A. Specifications 1,966,478 and 2,045,574 are referred to.ALSO:Polyamines, prepared by reacting in the liquid state a a ,b -unsaturated aldehyde with ammonia or a primary aliphatic monoamine present in a large excess over the amount theoretically required and subsequently subjecting the mixture to hydrogenation, are used in the preparation of stabilizing agents for synthetic greases, e.g. silica gel greases.