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:
Aug. 12, 1986
Filed:
May. 20, 1985
William B Darlington, Wadsworth, OH (US);
Charles H Hoelscher, Doylestown, OH (US);
PPG Industries, Inc., Pittsburgh, PA (US);
Abstract
Disclosed is a process of producing anhydrous sodium dithionite by contacting sulfur dioxide-containing formamide and sodium amalgam, separating a sodium dithionite-containing formamide solution from the sodium amalgam and precipitating anhydrous sodium dithionite from the product formamide solution by mixing the sodium dithionite-containing formamide solution with isopropanol, n-propanol, gamma-butyrolactone, tetrahydrofuran or N-methyl-2-pyrrolidone. The sulfur dioxide may be contacted countercurrently with the sodium amalgam in a continuous process. A neutralizing agent can optionally be added to the sodium dithionite-containing formamide solution separated from the amalgam to reduce acidic decomposition of the sodium dithionite.