Cellulose occurrence

Thus, based on material applications, the following polymers are important natural rubber, coal, asphaltenes (bitumens), cellulose, chitin, starch, lignin, humus, shellac, amber, and certain proteins. Figure 4 shows the primary structures of some of the above polymers. For detailed information on their occurrence, conventional utilization, etc., refer to the references cited previously. 

The synthesis of cellulose by A. xylinum from various polyalcohols14 is accompanied by the formation of carbon dioxide, formic acid, nonvolatile acids, ketoses and sometimes ethanol. The much greater variety of substrates suitable for cellulose synthesis, as compared with the small number for dextran or levan, may account for the widespread natural occurrence of cellulose. 

Occurrence in plant Cell interior Structural tightly bound to cellulose wall of plant cell... 

Tendering Effects. Cellulosic materials dyed with sulfur black have been known to suffer degradation by acid tendering when stored under moist warm conditions. This effect may result from the liberation of small quantities of sulfuric acid which occurs when some of the polysulfide links of the sulfur dye are ruptured. A buffer, such as sodium acetate, or a dilute alkali in the final rinse, especially after oxidation in acidic conditions, may prevent this occurrence. Copper salts should never be used with sulfur black dyes because they catalyze sulfuric acid generation. Few instances of tendering with sulfur dyes other than black occur and the problem is largely confined to cotton. 

Pacsu and coworkers144 have reported the preparation of the sodium alcoholatc of cellulose by treating either cotton or viscose rayon with either sodium methoxide or sodium 1-butoxide in anhydrous alcoholic media, at temperatures ranging from 25 to 120°. No proof of formation of alcoholate was offered. However, there is little reason to doubt its occurrence at the higher reaction temperatures. The ratio of sodium to D-glucose... 

B. Lindberg and O. Theander, The occurrence of 3-oxoglucose units in oxidised cellulose, Acta Chem. Scand., 11 (1957) 1355-1358. 

In this context, heterogeneity refers to the occurrence of the chemical reaction in two phases—liquid (solvent) and solid (cellulose). The reaction is homogeneous if the two reacting phases are completely miscible. 

Harbour JR, Hopper MA, Marchessault RH, Dobbin CJ, Anczurowski E (1985) Photoacoustic spectroscopy of cellulose, paper and wood J Pulp Pap Sci 11 J42-J47 Hauser M, Oelichmann J (1988) A critical comparison of solid sample preparation techniques in infrared spectroscopy Microchim Acta (Wien), Spec Issue, I 39-43 Hergert HL (1971) Infared spectra In Sarkanen KV, Ludwig CH (eds) Lignins Occurrence, formation, structure and reactions Wiley-Interscience, New York, 267-293 Hirschfeld T (1987) In McClure GL (ed) Computerized quantitative infrared analysis ASTM, Philadelphia, 169-179... 

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