Hydroxyl/halogen carboxylic acids

Carboxyalkylation of cellulose (for instance, the production of CMC) takes place in a BR at a constant temperature under atmospheric pressure. The Na cellulose particles suspended in the solvent (a branched alcohol) react with dissolved a-halogenated carboxylic acid anions leading to the formation of carboxyalkyl cellulose. In each and every glucose unit in a cellulose molecule, there are three (3) hydroxyl groups, HO-2, HO-3, and HO-6, with different reactivities at carbon atoms 2, 3, and 6. In the scheme below, the substitution of HO-6 in Na cellulose with monochloro acetate is illustrated ... 

The pentachloride, trichloride and tribromide of phosphorus are also used for replacing hydroxyl by halogen in phenols, carboxylic acids and sulphonic acids. The use of phosphorus trichloride is to be preferred in the preparation of many acid chlorides, since three molecules of acid chloride are then formed per molecule of phosphorus halide, as against one molecule of acid chloride when the pentachloride is used ... 

The substituted carboxylic acids discussed in this section possess a halogen (X), a hydroxyl group (OH), a keto group (CO), or an amino group (NH2) as the additional function. The location of the substituents may be designated systematically by numerals or by letters of the Greek alphabet. Illustrative representations are given for ... 

Fat- and oil-soluble dyes are also soluble in waxes, resins, lacquers, hydrocarbons, halogenated hydrocarbons, ethers, and alcohols, but not in water. It is not possible to differentiate clearly between them and the alcohol- and ester-soluble dyes. With the exception of blue anthraquinone derivatives, fat- and oil-soluble dyes are azo dyes, generally based on simple components. According to their degree of solubility they usually contain hydroxyl and/or amino groups, but not sulfonic acid and carboxylic acid groups. Examples of fat- and oil-soluble azo dyes are C.I. 

Strains of Pseudomonas putida are very versatile in metabolizing aromatic compounds, particularly to the corresponding 1,2-dihydro-l,2-diols. The hydroxylating enzyme of the P. putida mutant is not strongly substrate specific and alkyl, aryl and halogen functionalities are usually readily tolerated380. Thus, 4-bromobenzoic acid (1, R = Br) is converted to a. v-4-bro-mo-5,6-dihydroxy-l, 3-cyclohexadiene-l-carboxylic acid (2, R = Br) in 80% yield with 98% cc (determined by chiral NMR shift experiments on the 4-nitrobenzyl ester) 375. The absolute stereochemistry, (5R,6R), was determined by a single crystal X-ray analysis. 

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