The Dow Chemical Company

Rohm and Haas Company

Laurence I Peterson

Ralph A Davis

Joseph J Pedjac

Michael J Van Eyck

Ronald G Tigner

Michael J VanEyck

Improved system for delivering a controllable concentration of anesthetic gas to a patient by eluting with a carrier gas a solid polymeric adsorbent previously loaded with an anesthetic, the concentration being dependent only on the adsorbent temperature and the initial quantity of adsorbed anesthetic. Preferred embodiments utilize the polymeric adsorbent's capability of delivering a broad range of concentrations at low flow rates in a recycle delivery system.

Anesthetic delivery system

Compounds of the formula ##STR1## wherein --R-- is di-, tri- or tetramethylene which may bear from 1 to 8 C.sub.1 -C.sub.3 alkyl substituents, and a process for their preparation wherein a reactant of the formula ##STR2## is contacted, at reaction temperature, with COCl.sub.2. For example, 2-imidazolidone is contacted with phosgene to form N,N'-bis(carbonyl chloride)-2-imidazolidone. The compounds may be condensed with polyols, polythiols or polyamines to form useful resins or pyrolyzed to give alkylene diisocyanates.

N,N-di(carbonyl chlorides) of N,N'-alkylene ureas

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.

Preparation of alkylene diisocyanates

Brominated pentaerythritols are prepared at reaction temperatures of from about 85.degree. to 135.degree.C. by reacting pentaerythritol with HBr in the liquid phase employing a solvent medium containing from about 0.8 to about 25 mole percent of an aliphatic carboxylic acid of 2 to 8 carbon atoms and their anhydrides, based on the pentaerythritol. The HBr is fed continuously to the reactor throughout the reaction. The water formed as a result of the reaction remains in the reaction mixture until substantial completion of the reaction. The product can be predominantly dibromoneopentyl glycol or tribromoneopentyl alcohol and is characterized by the absence of tar formation.

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Doylestown, PA, United States of America

Laurence I Peterson