Preparation of alkylene diisocyanates
 Alkylene diisocyanates of the formula OCN-R-NCO are prepared by heating a compound of the formula ##EQU1## at a temperature of about 200.degree. to about 500.degree. C. wherein --R-- is dimethylene, trimethylene or tetramethylene which may bear lower alkyl substituents. For example, ethylene diisocyanate is prepared by heating ethylene urea N,N'-dicarbonyl chloride at about 350.degree.C. 
The Dow Chemical Company
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inventional inventional inventional
Laurence I. Michael J.
Peterson VanEyck