ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Acetylation of wood cellulose

V. Ríša, M. Jambrich, and A. Pikler

Slovak Technical University, Bratislava

Abstract: Favorable conditions for acetylation (I) of wood cellulose and the changes during reaction were studied microscopically and by the decrease of acidity. Lower homologs of cellulose and hemicellulose (sol. in 18% NaOH) are acetylated immediately in the first phases of the reaction and dissolved in AcOH with rapidly decreasing acidity. The intermicelle area is loosened and the speed of diffusion of Ac₂O into the fibrils is increased in accordance with Fick's law: dn = -Dq(Sc/Sx)tdt, where dn is the amt. of diffused matter. Soln. of acetylcellulose (II) can be expressed as: dc/dt = kO(C₈ - C), where C₈ is decrease in II, C is concn. of AcOH, and O is area of reaction surface. The reaction surface is directly related to the speed of II. soln. The concn. of lower polymers is related to the speed of I, but only in the 1st hr. of I. Later on as the concn. of Ac₂O is decreased there is increase in II, and retarding effect on I by lower polymers is noticeable. In the 4th hr., a sulfoester, formed in the first phase of reaction, is sapond. Thereafter the reaction mechanism is changed and the speed of sapon. of sulfoester increases. The reaction const. for wood cellulose, contg. 91.7% α-cellulose and 8.3% lower polymers at 35°, is: K = 1627 × 10^-6.

Full paper in Portable Document Format: 86a356.pdf (in Slovak)

Chemical Papers 8 (6) 356–366 (1954)