Allied Chemical Corporation

Allied Corporation

Robert A Wiles

Michael Van Der Puy

David Nalewajek

Richard E Eibeck

Bernard F Sukornick

Louis G Anello

Richard F Sweeney

William J Cunningham

Eugene B Recla

Addison M Smith

Gd.sub.2 O.sub.3 and Ga.sub.2 O.sub.3 are currently used for the fabrication of Gd.sub.3 Ga.sub.5 O.sub.12 (GGG) wafers which are employed as substrates for bubble domain memory devices. In the processing, in the order of 25% of the starting material ends up as process 'saw kerf' contaminated with variable amounts of iron, nickel, magnesium, aluminum, zirconium, iridium and silicon. A process is described whereby the 'saw kerf' can be reprocessed in sufficient purity to be re-used in the process, thereby improving the economics of production of GGG wafers significantly. Gadolinium and gallium oxides are recovered and separated from transition metal impurities introduced during fabrication of GGG wafers. The process 'saw kerf' produced from slicing the crystal boule is dissolved in HCl, treated with H.sub.2 SO.sub.4, and the resulting sulfates separated. Metathesis with (NH.sub.4).sub.2 C.sub.2 O.sub.4 results in conversion of the sulfates to the ammonium oxalates which were calcined at 850.degree. C. to form Ga.sub.2 O.sub.3 and Gd.sub.2 O.sub.3 of purity &gt;99.99%. The process can be extended to include purification and re-use of by-products generated in other grinding and polishing operations which may result in the recycling of the order of 80% of the generated by-products.

Recovery of gadolinium and gallium oxides

The present invention provides a novel process for producing 1,2-dichloro-1,1,2,2-tetrafluoroethane substantially free of the 1,1-isomer. The process includes contacting, in the vapor phase, an organic feed composition containing a major amount of the 1,2-isomer and a minor amount of 1,1-isomer with hydrogen in the presence of a hydrodechlorination catalyst. The process selectively degrades the 1,1-isomer. Also provided is a process for producing high purity 1,2-isomer.

Process for producing 1,2-dichloro-1,1,2,2-tetrafluoroethane

The process for preparing hexafluoroisobutylene which comprises reacting, at elevated temperatures, ketene or a ketene-generating compound with hexafluorothioacetone. Hexafluoroisobutylene is a known valuable monomer, which forms polymers of exceptional thermal, chemical and mechanical properties, particularly when copolymerized, such as with vinylidene fluoride.

Preparation of hexafluoroisobutylene

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Hamburg, NY, United States of America

Robert A Wiles