The Dow Chemical Company

Marylu B Gibbs

Daniel W Baugh, Jr

Gordon Y Liu

Robert D Biggs

David W Alsgaard

Sheldon H Messing

D W Calvin

Alan C Kott

Macroporous copolymer particles are prepared via a process wherein phase separating diluent is removed from copolymer particles and isolated (e.g., by distillation). The isolated diluent is purified by eluting the diluent through a column containing a purification agent such as alumina. The recycled diluent can be employed in the further preparation of macroporous copolymer particles.

Controlled macroporous copolymer properties by removal of impurities in

Anion exchange resins having improved anion capacity are prepared using an improved process whereby the reaction medium can be re-employed. The process comprises contacting a haloalkylated copolymer particle with a compound capable of displacing the halogen of the haloalkyl functionality (e.g., dimethylamine) in a reaction medium (e.g., water). Optionally, an ionizable electrolyte is incorporated into the reaction medium. After preparation of anion exchange resins, the reaction medium containing ionizable electrolyte is re-employed in preparing anion exchange resins.

Process for preparing anion exchange resins by amination of

A method for reducing surface-area decay of fluoride-containing fumed silica which comprises the step of providing an atmosphere of inert gas in which the fumed silica is disposed. The method, which can be used at ambient temperature, is particularly effective for the storage of a fluoride-containing fumed silica product prepared by a fluoride process, which fumed silica contains between about 2 and about 4 percent fluoride by weight.

Surface-area stabilization of fumed silica

A process for defluorination of a fluoride-containing fumed silica, which comprises entraining the silica in a high velocity stream of steam at an elevated temperature for a few seconds and then separating the defluorinated silica from the steam, thereby obtaining a fumed silica product with a substantially reduced fluoride content.

Defluorination of fumed silica

A dentifrice in a liquid vehicle containing fumed silica with fluoride sorbed thereon giving free fluoride ions in the composition for the therapeutic treatment of teeth.

Dentifrice compositions containing fumed silica with sorbed fluoride

Methyl ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone react with vaporized aqueous HF in the vapor phase at about 190.degree. C.-400.degree. C. to make the corresponding 2,2-difluoroalkanes.

Fluorination of methyl ketones

Methanol and aqueous HF react in the vapor phase at 250.degree. C.-400.degree. C. in the presence of activated carbon, nickel fluoride, chromium fluoride, aluminum fluoride, or a mixture thereof to produce methyl fluoride plus dimethyl ether as the principal by-product.

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Baton Rouge, LA, United States of America

Marylu B Gibbs