Dearborn Chemical Company Ltd.

Other

Anne H Kemp

Chih M Hwa

Dionisio G Cuisia

Albert V Thomas

Ramiya H Premchandran

Robert F Keyes

Hemant H Patel

Jane E Quamme

The claimed invention relates to a novel process of preparing N-demethyl-N-alkyl-4'-deoxy erythromycin A and B. The process comprises protecting the 2'-hydroxy or the 2'- and 11-hydroxy of a N-demethyl-4'-deoxy erythromycin derivative having the formula: ##STR1## where R.sub.b is H or OH, with a silyl protecting group and alkylating the N-position of the desosamine sugar.

Process for preparing N-demethyl-N-alkyl erythromycin derivatives

The accumulation of scale in an aqueous system is inhibited by the addition of a composition comprising a copolymer of maleic acid or anhydride and vinyl sulfonic acid and an organic phosphonate such as aminotri(methylene phosphonic acid), hydroxyethylidene diphosphonic acid, or a water soluble salt thereof.

Composition and method for inhibiting scale

An aqueous flocculant solution containing a tannin based polymer compound is produced which is stable and has a shelf life of at least 3-6 months before gelling. The solution is made by reacting at a temperature of from 150.degree.-200.degree. F. a tannin, an amino compound, and an aldehyde under slightly acidic conditions where the pH is less than 7 and where the molar ratio of the primary amine from the amino compound to the tannin repeating unit is from about 1.5:1 to 3.0:1. The intermediate viscosity of the reaction mixture is monitored until the reaction mixture has an intermediate viscosity within the range of the system key intermediate viscosity range. This system key intermediate viscosity range is previously determined for each reactant system to be employed. It is a narrow intermediate viscosity range that is experimentally determined which permits the resulting product to have a long shelf life. The narrow system key intermediate viscosity range will generally be within the range of from about 2-100 cps when measured at 180.degree. F. on a Brookfield LVT viscometer. When this viscosity is reached, the reaction is terminated and the solids content of the liquid is adjusted to about 20% to 60% by weight and the pH is adjusted to a value of less than 3.0.

Stable tannin based polymer compound

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Palatine, IL, United States of America

Anne H Kemp