Ethyl Corporation

Albemarle Corporation

Ronald C Zumstein

W Dirk Klobucar

Thanikavelu Manimaran

Allan A Eisenbraun

Adam Nugent, Jr

Hao V Phan

Robert E Young

Optically active carboxylic acids, salts or esters, such as the profen-type compounds, are racemized in the presence by nitrogenous bases such as methylbenzylamine by heating an aqueous solution of such optically active compounds in the presence of a suitable excess of an alkali metal hydroxide relative to the amount optically active carboxylic compound present in the solution. The process not only enables conversion of inactive or undesirable enantiomers of compounds such as naproxen or ibuprofen into a usable, desirable enantiomers in an efficient and economical manner, but avoids conversion of the nitrogenous base into amide. Thus the deleterious consequences of amide formation are avoided.

Racemization process for optically active carboxylic acids or salts or

Described is a process for producing, in particulate form, aromatic polyimides based on one or more 2,2-bis[4-(aminophenoxy)-phenyl]hexafluoropropanes. The process involves forming, heating and agitating in a medium composed of dipolar aprotic solvent and liquid aromatic hydrocarbon solvent, a homogeneous solution of a polyamic acid derived from a substantially equimolar mixture of (i) an aromatic tetracarboxylic dianhydride and (ii) a 2,2-bis[4-(aminophenoxy)phenyl]hexafluoropropane, such that a separate phase of particulate aromatic polyimide is formed in such medium. The process avoids difficulties caused by the tendency of the wet polyimide polymer to agglomerate into stringy or tacky masses which can foul reactor and agitator surfaces.

Production of particulate polyimide polymers

Described is a process for producing, in particulate form, aromatic polyimides based on one or more 2,2-bis[4-(aminophenoxy)phenyl]hexafluoropropanes. The process involves forming a solution of an equimolar mixture of (1) an aromatic tetracarboxylic dianhydride and (2) a 2,2-bis[4-(aminophenoxy)phenyl]hexafluoropropane as the sole or predominant aromatic diamine in (3) a solvent composed of (i) tetrahydrofuran, or (ii) one or more alkyltetrahydrofurans having a normal boiling point below 100.degree. C., or (iii) a mixture of (i) and (ii), and heating and agitating such solution in a closed reaction system under super-atmospheric pressure such that a separate phase of particulate aromatic polyimide is formed. The process avoids difficulties caused by the tendency of the wet polyimide polymer to agglomerate into stringy or tacky masses which can foul reactor and agitator surfaces.

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Baton Rouge, LA, United States of America

Ronald C Zumstein