Studies on Cellulose Acetate

Araki, Tsunao

doi:10.1177/004051755202201002

Cited by 5 publications

(3 citation statements)

References 4 publications

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“…A study has been made of the conditions affecting the amount of combined sulfuric acid (7). Dry cellulose treated with benzenesulfone chloride in pyridine took up two PhS02-groups per glucose unit (190).…”

Section: Boric Estersmentioning

confidence: 99%

Esterification

Reid¹

1953

Ind. Eng. Chem.

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This year's novelty is the appearance on the cover of Chemical and Engineering News of a chemist for work on esterification, E. F. Izard, Schoelikopf medal ist. The year brings many articles and a host of patents on the various ways of making esters, so many that only a part can be mentioned and those briefly. As last year, the chief attention has been given to kinetics.A comprehensive correlation of such data is needed. Catalysts for high temperature, 200°C. and above, continue to be mentioned but information as to their performance is still lacking. Interest continues in silicic, phosphoric, and polymeric linear esters. THE formation of oxonium complexes as a part of the mechanism of esterification has been considered (258). Experiments indicate that esters of p-toluene sulfonic acid are not intermediates when this acid is an esterification catalyst (204). The effect of ultrasonic irradiation has been investigated ( 105).The effects of branching of the chain of an aliphatic acid on its esterification velocity has been investigated further (150). Unsaturation in the alcohol affects the saponification rates of acetates. The influence of the ethynyl group is greater than that of the vinyl which exceeds that of the ethyl (186). The esters of ß, y-unsaturated acids in a mixture can be saponified without touching those of a, /3-unsaturated acids (273). INDUSTRIAL AND ENGINEERING CHEMISTRYVol. 45, No. 9 COURTESY HERCULES POWER CO.

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Section: Boric Estersmentioning

confidence: 99%

Esterification

Reid¹

1953

Ind. Eng. Chem.

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“…The heavy concentration of catalyst on the fiber surfaces then favors the topochemical reaction path. Cellulose acetylation has been studied by a number of investigators (1)(2)(3)(4)(5)(6)(7)(8)(9). These studies generally have been qualitative nature.…”

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confidence: 99%

“…W Frith (5) also measured an energy of activation using perchloric acid äs a catalyst. In the present study additional values of activation energy were determined Brought to you by | University of Glasgow Library Authenticated Download Date | 6/30/15 9:28 PM from the data of Araki (6) and plant and laboratory data (7). All of the activation energies together with the pertinent variables are listed in Table i. The eifect of agitation can be shown by considcring cases 6 and 8 of Table i.…”

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confidence: 99%

Effect of Wood Pulp Characterization Factors and Other Variables on the Temperature Behavior of the Acetylation of Cellulose

Griskey¹

1965

Holzforschung

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The manufacture of cellulose acetate has been an important industrial process for over forty years. During this span of time the industry has grown to be one of the leading consumers of wood pulp. The result is that Information relating to cellulose acetylation is in turn important to the wood pulp industry.In the present study the possible effect of a number of variables upon the Arrhenius activation energy associated with the acetylation of cellulose (i. e. relation of variables to the temperature behavior of the acetylation reaction) was investigated. The following variables were considered:1) Wood pulp characterization factors 2) Reaction medium -homogeneous or heterogeneous \ 3) Catalyst type and amount used 4) Reaction path 5) Agitation • The variables of agitation and catalyst type and amount used require no further clarification. However, certain of the other variables such äs wood pulp characterization factors, reaction medium and reaction path require definition.Wood pulp characterization factors are the per cent alpha cellulose, alcohol-benzene solubles, raw pulp viscosity and transmission of the wood pulp itself. In addition, factors relating to cellulose acetate made from the pulp such äs plugging value (relative filterability) and viscosity ratio (ratio of a 27% cellulose acetate solution viscosity to a 6% cellulose acetate solution viscosity) are also included under variable i.Reaction medium äs used in this study refers to whether the reaction was carried out in a heterogeneous medium (fibers suspended in a liquid medium) or a homogeneous medium (a liquid solution).Variable 4, reaction path, indicates the manner in which the acetylation reaction proceeds -either permutoidally, that is, uniformly throughout the cellulose fibers or eise topochemicaÜy, that is, the reaction initiales on the fiber surface and proceeds radially into the fiber.These difFerences in reaction path result from the method used to contact the cellulose and commonly used catalyst, sulfuric acid. If the cellulose and catalyst are contacted during a pretreatment Operation and then added to the acetic anhydride the reaction path is permutoidal. On the other hand the reaction path is topochemical if the sulfuric acid contacts the cellulose in the presence of the acetic anhydride.Explanation for the differences in reaction paths have been furnished by White and Rosenthal (i). In the absence of acetic anhydride (see figure i) the sulfuric acid is reversibly adsorbed on the cellulose (2) and ultimately distributed throughout the cellulose fibers.In this case the reaction path is permutoidal because of the excellent catalyst distribution. The presence of acetic anhydride (see figure i) during the contacting of the cellulose and sulfuric acid results in rapid chemical bonding of the catalyst to the fiber surfaces (3). The heavy concentration of catalyst on the fiber surfaces then favors the topochemical reaction path. H 2 S0 4 ADDED WITH ANHYDRIDE ADDED BEFORE ANHYDRIDE BEFORE ANHYDRIDE AFTER ANHYDRIDE Fig. i. Effect of method of conta...

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