in a seconde reaction stage into the high molecular weight polyurethane by means of suitable chain lengthening agents all the processes mentioned for the preparation of polyurethanes using diisocyanates according to this invention are applicable in particular to the lacquer sector i e for the production of one component and two component polyurethane lacquers the percentages given in the following examples are percentages by weight all indications of pressure given with the boiling points are in mbar the following unsaturated amines are used in the examples which follow 605 g of 4 5 cyano 1 methylcyclohexane were dissolved in 500 ml of liquid ammonia in a stirrer autoclave and hydrogenated under a hydrogen pressure of 100 bar over 40 g of raney nickel iron at 90 u00b0 c after evaporation of the ammonia the product was filtered from the catalyst and distilled under vacuum 550 g 88 of 4 5 amino methyl methylcyclohexene bp 10 78 u00b0 80 u00b0 c were obtained the proportions by weight of the 4 and 5 isomers was approximately 80 20 830 g of 3 1 methylcyclohexen 4 yl butyr aldehyde were dissolved in 800 ml of liquid ammonia in stirrer autoclave and hydrogenated under a hydrogen pressure of 100 bar over 50 g of raney nickel iron at 90 u00b0 c after evaporation of the solvent the product was filtered from the catalyst and distilled under vacuum 720 g 86 of 3 1methylcyclohexen 4 yl butylamine bp 10 120 u00b0 c were obtained 620 g of campholene aldehyde were dissolved in 600 ml of liquid ammonia in a stirrer autoclave and hydrogenated under a hydrogen pressure of 100 bar 50 g of raney nickel iron at 90 u00b0 c after evaporation of the ammonia the.