Hydrogen substituent, cellulosics

The influence of substituents on the rates of degradation of arylazo reactive dyes based on H acid, caused by the action of hydrogen peroxide in aqueous solution and on cellulose, has been investigated [43]. The results suggested that the oxidative mechanism involves attack of the dissociated form of the o-hydroxyazo grouping by the perhydroxyl radical ion [ OOH]. The mechanism of oxidation of sulphonated amino- and hydroxyarylazo dyes in sodium percarbonate solution at pH 10.6 and various temperatures has also been examined. The initial rate and apparent activation energy of these reactions were determined. The ketohydrazone form of such dyes is more susceptible to attack than the hydroxyazo tautomer [44]. 

Hydroxyalkylcellulose. Reaction of cellulose with ethylene or propylene oxides produces hydroxyethyl or hydroxypropyl derivatives. By forming the hydroxyethyl derivative about the same ratio of hydrogen bonding sites to carbon atoms is provided as in the underivatized cellulose, but the substituent groups reduce the fit between polymer chains so that the derivative can be dissolved in water to produce stable solutions. The cellulose derivative has many of the solution properties of guaran. 

The review by Neely tabulated the characteristic frequencies of several common, substituent groups that are of interest in carbohydrate chemistry, and discussed in detail the results of the structural analysis - of pyranose derivatives in the region 730-960 cm.-. In addition, brief outlines were also given of a similar analysis (see Ref. 69) of furanose derivatives (less fruitful than that of pyranose derivatives) and of the investigations of variation in hydrogen bonding in celluloses. 

Cellulose derivatives are formed by replacing the hydrogen of the primary and secondary hydroxyl groups of cellulose with such groups as methyl, ethyl, hydroxyethyl, carboxymethyl, etc. The resulting cellulose ethers are very stable the substituent groups are not readily removed by enzymatic means. 

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