GB1153194A - Polymeric Impurity Removal from an Aqueous Quaternary Ammonium Salt Solution - Google Patents

Abstract

1,153,194. Purification of the electrolyte employed in the electrohydrodimerization of acrylonitrile. MONSANTO CO. 3 May, 1966 [10 May, 1965], No. 19571/66. Heading C2C. Partially hydrolysed polyacrylonitrile is removed from an aqueous solution of a hydro. tropic quaternary ammonium salt when employed as catholyte in the electrohydrodimerization of acrylonitrile by (a) precipitating said polyacrylonitrile by adjusting the salt concentration of said solution to not more than 55 wt. per cent and adjusting the pH of said solution to not more than 7, and (b) separating said polyacrylonitrile from said solution. The solution may be adjusted to a pH not greater than 7 by acidification, preferably with an acid whose anion corresponds to the anion of the quaternary ammonium salt being treated. The quaternary ammonium salt may be a tetraalkylammonium sulphate, a tetraalkylammonium aryl sulphonate or a tetraalkylammonium alkyl sulphate and the process may be performed in batch form or it can be performed upon a continuous stream. In the examples, the quaternary ammonium salts employed are tetramethylammonium toluene sulphonate and tetraethylammonium ethyl sulphate and the products obtained from the electrohydrodimerization are adiponitrile, propionitrile, biscyanoethylether, hydroxypropionitrile, the polyacrylonitrile impurity and other high boiling impurities containing 2-cyanoethyladiponitrile.