1.6- anhydro cellulose

Etherification. Carbohydrates are involved in ether formation, both intramoleculady and intermoleculady (1,13). The cycHc ether, 1,4-sorbitan, an 1,4-anhydroalditol, has already been mentioned. 3,6-Anhydro-a-D-galactopyranosyl units are principal monomer units of the carrageenans. Methyl, ethyl, carboxymethyl, hydroxyethyl, and hydroxypropyl ethers of cellulose (qv) are all commercial materials. The principal starch ethers are the hydroxyethyl and hydroxypropylethers (see Cellulose ethers Starch). 

SCHEME 32. Anhydro sugars obtained by pyrolysis of cellulose. 

J. Piskorz, P. Majerski, D. Radlein, A. Vladars-Usas, and D. S. Scott, Flash pyrolysis of cellulose for production of anhydro-oligomers, J. Anal. Appl. Pyrol., 56 (2000) 145-166. 

D. Fabbri, C. Torri, and V. Baravelli, Effect of zeolites and nanopowder metal oxides on the distribution of chiral anhydro sugars evolved from pyrolysis of cellulose An analytical study, J. Anal. Appl. Pyrolysis, 80 (2007) 24-29. 

The word cellulosan has the disadvantages that (a) it employs an ending ordinarily used for designating simple anhydro-sugars, and (b) that the name implies a relation with cellulose, whereas in fact no relationship is intended and polysaccharides placed in this class are quite different from cellulose in both composition and properties. Their connection with cellulose seems to be only that they occur with cellulose as constituents of the plant cell wall. 

Of other recent experiments in the chemistry of the sugars the preparation of the anhydro-sugar laevoglueosan C6H1005 by the rapid distillation of starch or cellulose in a vacuum may be mentioned (Pictet). This interesting compound possibly has the constitution I. 

Der Mechanismus der Pyrolyse soil ahnlich wie bei der sauren Glykosid-Spaltung sein 26,70,78,153) die Ausbeuten reichen bis zu 25% bei Starke und bis zu 70% bei Cellulose. Bei der Pyrolyse entstehen auBer der 1,6-Anhydro-p-D-glucopyranose die entsprechende 1,6-An-hydro-D-glucofuranose 55,70,75,76,230) ud femer 1,6-3,4-Dianhydroderi-vate sowie Derivate des Furans, welche gaschromatographisch nachge-wiesen werden konnen... 

In the area of waste utilization, Fred s program on the heat content, gasification, and carbonization of forest fuel is now recognized as a major step in our understanding of forest fires. The acid-catalyzed pyrolysis of cellulosic waste to afford l,6-anhydro-3,4-dideoxy-)3-D-g/ycero-hex-3-enopyranos-2-ulose ( levoglucosenone ) pointed the way to another method of chemical conversion of cellulosic wastes similar to cat-cracking in the petrochemical industry. 

It is a naturally occurring horny substance which forms the framework of invertibrates(such as crabs, lobsters other mollusca), and is the animal analog of cellulose of plants. Chitin is considered a polymer, constg of more than 100 units of anhydro-N -acetylglucosamine, a deriv of D-glucose. 

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