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:
Oct. 28, 1980
Filed:
Mar. 22, 1979
Edward T Shawl, Wallingford, PA (US);
Gerald A Bullano, Glen Mills, PA (US);
Atlantic Richfield Company, Los Angeles, CA (US);
Abstract
A method for increasing the 4,4' disubstituted isomer of the diphenylmethane dicarbamates produced by the acid catalyzed condensation of an N-aryl carbamic acid ester, such as ethylphenylcarbamate, with a carbonyl compound, such as formaldehyde, which comprises carrying out the condensation in a single phase system with a dilute solution of the N-aryl carbamic acid ester in an inert solvent having a dielectric constant of at least 20 at 20.degree. C. The solvent must have good solubility for the carbamates, which carbamates are employed in the solvent at concentrations of from about 0.1 to 50 weight percent to provide a product enriched with the 4,4'-diphenylmethane dicarbamate isomer.