The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 02, 1980
Filed:
Oct. 26, 1978
William Dowd, Midland, MI (US);
Richard C Krauss, Midland, MI (US);
Edward R Freiter, Midland, MI (US);
The Dow Chemical Company, Midland, MI (US);
Abstract
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.