The Dow Chemical Company

Edward R Freiter

Richard C Krauss

William Dowd

1-Aryl-1-hydroxy-2-methylaminopropanes are rearranged from the erythro isomer to the threo isomer by the process of (1) forming the O,N-diacyl derivative of the arylpropanolamine; (2) reacting the product of step (1) with an anhydrous or substantially anhydrous protic acid (thereby forming a novel oxazolinium salt); and (3) reacting the oxazolinium salt from step (2) with an aqueous protic acid. The threo isomer of the arylpropanolamine is thus produced as an amine/acid salt. This salt can be further purified, if desired, by neutralizing the acid/amine salt with caustic isolating the free amine and reprotonating the free base in isopropanol with, for example, anhydrous HCl. This process is particularly applicable to manufacture of d-pseudoephedrine from 1-ephedrine.

Oxazolinium salts and method of preparation

Alpha-diketones, such as 1-phenyl-1,2-propanedione and 1-propyl-1,2-butanedione, are prepared by reacting an acylmethyl ester of a carboxylic acid (e.g., benzoylmethyl acetate or butanoylmethyl propionate) with an aldehyde, such as formaldehyde or acetaldehyde, in the presence of an acid catalyst and water. Such alpha-diketones are also obtained by first refluxing a mixture of an alpha-haloketone and a carboxyl anion source and then reacting the mixture with an aldehyde in the presence of an acid catalyst and water.

Synthesis of alpha-diketones

Coatings having good weatherability characteristics are obtained by curing an epoxy resin which is an adduct of glycidol and an aliphatic or cycloaliphatic diisocyanate such as hexamethylene diisocyanate with an aliphatic or cycloaliphatic acid or anhydride such as tetrahydrophthalic anhydride.

Growing community of inventors

Midland, MI, United States of America

Edward R Freiter