Polyurethane formation from bis-chloroformates

Polyurethanes have frequently been prepared in the laboratory from diamines and bis-chloroformates, using interfacial or solution techniques. The processes have not been widely used in industry, however. The general considerations of interfacial and solution processes described in Section 3 apply to polyurethane preparations by these methods. Specific 

Kinetic measurements of the reaction between chloroformates and amines are difficult because of the great speed of the reactions. Rate coefficients have been estimated [118] to be about 10 to 10 Imole sec . Reaction times have been of the order of five minutes at 0—5°C in benzene-water systems [173], and 10—30 minutes at 60°C in order to get high molecular weights when using piperazine [174]. 

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