Occidental Chemical Corporation

Other

David E Albright, Jr

Jian S Qi

Garra C Lester

Edward A Dietz

Disclosed is a method of reducing the UV absorption of a solvent that comprises water, an ethylene glycol, or a mixture thereof, where the solvent contains at least 0.1 ppm of a dione, particularly 3-methyl-2-hydroxy cyclopent-2-eneone or its tautomer, 3-methyl-1, 2-cyclopentanedione. The solvent is passed through an anionic exchange resin containing strong base sites. The UV absorbance of the effluent from the anionic exchange resin can be monitored and, when it increases, the resin can be reactivated by passing an aqueous solution of a base through it.

Method reducing UV absorption in ethylene glycols, water, and mixtures

Disclosed is a method of determining whether a solvent contains a tautomeric cyclic 1,2-dione. It is first determined whether the pH of the solvent is acidic (&lt;5), basic (&gt;9), or neutral (5 to 9). If the pH is neutral, an acid or a base is added to make the pH acidic or basic, respectively. The UV absorbance at a first wavelength between about 230 nm and about 270 nm and at a second wavelength between about 280 and about 320 nm is determined. If the pH is acid, it is changed to basic and, if it is basic, it is changed to acidic. The UV absorbance at the first and second wavelengths is again determined. The presence of a tautomeric cyclic 1,2-dione is indicated if the absorbance at the first wavelength was greater when the solvent was acidic and the absorbance at the second wavelength was greater when the solvent was basic. The concentration of the tautomeric cyclic 1,2-dione can be determined by multiplying the change in absorbance by a constant.

Method of detecting tautomeric cyclic 1,2-diones

Disclosed is a method of making 3,5-diaminobenzotrifluoride from 4-chloro-3,5-dinitrobenzotrifluoride. A solution of 4-chloro-3,5-dinitrobenzotrifluoride in an alcohol is prepared. Separately, a slurry is prepared of a palladium catalyst on a suitable substrate, at least one equivalent of magnesium oxide per equivalent of 4-chloro-3,5-dinitrobenzotrifluoride, sufficient hydrogen-donating reducing agent to reduce the 4-chloro-3,5-dinitrobenzotrifluoride to 3,5-diaminobenzotrifluoride, and an amount of alcohol sufficient to make the slurry stirrable. The solution is added to the slurry with stirring at a rate that does not exceed the reaction rate of the 4-chloro-3,5-dinitrobenzotrifluoride so that no unreacted 4-chloro-3,5-dinitrobenzotrifluoride accumulates in the slurry. The reaction mixture is heated at about 75.degree. to about 100.degree. C.

Controlled feed process for making 3, 5-diaminobenzotrifluoride

3,5-Diaminobenzotrifluoride can be produced, in a single step, by reacting 4-chloro-3,5-dinitrobenzotrifluoride, in methanol, with hydrogen gas, in the presence of magnesium oxide, and in the presence of a catalyst comprising palladium on a carbon support.

Preparation of 3,5-diaminobenzotrifluoride

3,5-Diaminobenzotrifluoride can be readily separated from 4-chloro-3,5-diaminobenzotrifluoride by the addition of hydrogen chloride. 3,5-Diaminobenzotrifluoride forms hydrochloride salt, while 4-chloro-3,5-diaminobenzotrifluoride does so much less readily.

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Niagara Falls, NY, United States of America

David E Albright, Jr