New method for preparing saturated and unsaturated aliphatic polyurethanes

Saturated and unsaturated aliphatic polyurethane were obtained from three different routes. In route 1, 1,4‐dichloro‐2‐butene, sodium cyanate, and methanol were reacted to give dimethyl 2‐butene‐1,4‐dicarbamate. This is hydrogenated easily to give dimethyl butane‐1,4‐dicarbamate. Ester exchange reaction of this compound with glycol gave saturated aliphatic polyurethane. In another procedure, route 2, 1,4‐dichloro‐2‐butene, sodium cyanate and excess glycol were reacted to give bis(ω‐hydroxyalkyl)‐2‐butene‐1,4‐dicarbamate. This was hydrogenated to give bis(ω‐hydroxyalkyl)‐butane‐1,4‐dicarbamate. A glycol elimination reaction gave poly(polymethylene tetramethyl‐enedicarbamate). By route 3, 1,4‐dichloro‐2‐butene, sodium cyanate, and glycol were reacted to give poly(polymethylene 2‐butene‐1,4‐dicarbamate), a new unsaturated aliphatic polyurethane.