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:
Sep. 06, 1983
Filed:
Mar. 15, 1982
John A Donohue, Elmhurst, IL (US);
Standard Oil Company Indiana, Chicago, IL (US);
Abstract
Terephthalic acid is electrochemically reduced to p-hydroxymethylbenzoic acid and 4-carboxybenzaldehyde content is decreased by a process in a two-compartment electrolysis cell in which (a) the cathode is solid and metal with a mercury amalgam surface and with a hydrogen overvoltage which is greater than the potential for the reduction of terephthalic acid to p-hydroxymethylbenzoic acid, (b) the separating diaphragm is a cation exchange membrane, (c) the catholyte comprises a solution of terephthalic acid, ammonia, an ammonium salt and a soluble salt of mercury, (d) the temperature of the catholyte is between 0.degree. C. and 100.degree. C., (e) the current density is within the range of 1 to 200 A/dm.sup.2, (f) the concentration of the said soluble salt of the mercury metal is within the range of 5 to 500 ppm expressed as the metal, (g) the reduction of terephthalic acid to p-hydroxymethylbenzoic acid is performed at a voltage of about at least 6 volts with current efficiency being maintained at a level of at least 80%, and (h) reduction of 4-carboxybenzaldehyde is performed at a voltage not greater than 4 volts.