The Dupont Merck Pharmaceutical Company

E.i. Dupont De Nemours and Company

James H Jensen

Matthew Ernst Voss

Timothy D Costello

Leon De Brabander, Jr

Lynn E Applegate

George F Huhn

Polycyclic cognition enhancers having the general formula (1a), (1b) or (1c) are provided: ##STR1## wherein: R.sub.1 is a heterocyclic aromatic moiety such as a 4-pyridyl, 2-pyridyl, 4-pyrimidyl, or pyrazinyl group;

Disubstituted polycyclic systems and preparative methods therefor

This invention is a process for purifying nucleoside-5'-diphosphates containing substituents other than primary amines (hereinafter designated as NDPs) from complex mixtures by contacting the aqueous solution mixture with a strongly basic ion exchange resin in the chloride form, eluting certain absorbed impurities with an alkali metal salt solution, converting the column to the hydroxide form by contacting the resin with an alkali metal hydroxide solution such that the effluent becomes basic, and eluting absorbed NDP with a weakly acidic alkali metal salt solution such that solutions of highly pure NDP are obtained in basic effluent fractions. The new process is particularly valuable for purification of NDPs directly from chemical synthesis reaction media.

Process for purifying nucleoside-5'-diphosphates

The water flux rate (i.e., rate of water flow) through an aromatic nitrogen-linked synthetic organic polymer membrane in separation processes, such as reverse osmosis, is improved by incorporating a selected non-ionic, anionic or ampholytic surfactant into the rinse medium used to quench and extract salts and solvent from the membrane during preparation. The surfactant can be, inter alia, a water-soluble polyethylene glycol ester. The surfactant is effective in improving water flux in amounts ranging from between about 50 p.p.m. to about 10,000 p.p.m. based on rinse medium.

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Wilmington, DE, United States of America

James H Jensen