Über die Acetylierung der Cellulose

Abstract

Angewandte Chede I 47. Jahrg. 1934. Nr. 4 , Kriiger u. Roman: Ober die Acetylierung der Cellulose ~_ _ -58 dritten Achse slmtliche 92 Elemente anfiigt und in die Raumtabelle die Kombination eintragt. Stellt man die sechs Raumtabellen nicht neben-, sondern ubereinander, dann kann man entweder die Salze oder die Nichtmetallmolekule oder die Metalle ubereinanderstellen und in einem einzigen Raumkorper vereinigen. Die raumlichen Modelle lassen erkennen, daD zwischen den verschiedenen Stoffklassen G r e n z f 1 a c h e n existieren mussen, deren Festlegung Aufgabe der experimentalen Forschung sein wird. 111. Neue Aufgaben. Die Aufgaben, die sich aus der mitgeteilten Systematik ergeben, sind nanientlich folgende:1. Es ist darnach zu forschen, ob es aufier den in den Tabellen 1 und 2 genannten Bindungsklassen noch andere gibt, insbesondere auch noch unbekannte Kombinationen von mehreren Bindungsarten.2. Die Untersuchungsmethoden zur Kennzeichnung der einzelnen Stofflrlassen und zur Unterscheidung der verschiedenen Klassen voneinander sind auszubauen, u. a. auch, um festzustellen, ob es zwischen den verschiedenen Bindungsarten scharfe Grenzen oder allmiihliche ubergange oder beide Falle gibt.3. Die Lage der in vielen Fallen heute schon anzunehmenden scharf en Grenzen zwischen den Bereichen der verschiedenen Stoffklassen ist festzustellen; auf3erdem ist die Abhangigkeit der Lage dieser Grenzen vom Bau der Verbindungen zu ermitteln.

Studies on Cellulose Acetate

“…respectively, appeared in C ellulosechelll1'e 18, 109 (1940) and Cellulosechemie 19, 137 ( 1941 ) .others, but the behavior of sulfuric acid throughout the acetylation has not been interpreted adequately.In Part I of this series [1] ] the present author reported on the behavior of sulfuric acid throughout the course of acetylation, and indicated that a large amount of sulfuric acid is taken up chemically by cellulose at the beginning of acetylation and then gradually split off from cellulose, showing that the sulfuric acid group is gradually replaced by acetyl.Such behavior of sulfuric acid suggests that catalysis by sulfuric acid in the acetylation of cellulose is more complicated than expected according to the theory of normal catalysis due to proton activity supported by Krueger et al [5].In the present work, the relationship between the amount of combined sulfuric acid and the acetylation at East Carolina University on June 29, 2015 trj.sagepub.com Downloaded from …”

“…The mechanism of acetylation by these catalysts has been discussed by many authors; the theory of normal catalysis by proton activity [5] ] has been generally accepted as the most probable. However, there exists some speciality in the mode of acetylation of macromolecular substances such as cellulose, starch, agar-agar, etc., in which the formation of a sulfate ester intermediate is observed.…”

“…Such behavior of sulfuric acid suggests that catalysis by sulfuric acid in the acetylation of cellulose is more complicated than expected according to the theory of normal catalysis due to proton activity supported by Krueger et al [5].…”

Electrophilic Additions toanti-Sesquinorbornene. Br2in Methanol and the Addition of Acetic Acid

“…Because of the low dielectric constant of acetic acid (6.2), salts and mineral acids may be substantially ionized into M + X - pairs, but are largely undissociated even at low concentrations. , Cristol 21 has reported that NaClO 4 has a catalytic effect in promoting the addition of HOAc to norbornadiene (the effect being reversed by the addition of NaOAc) and attributed this to an enhancement of the apparent acidity of weak acids in HOAc. The effect was noted as early as 1934 when the efficacy of H 3 PO 4 or HCl in HOAc in promoting acetylation of cellulose was enhanced by the addition of perchlorate salts in the laboratories of R. C. Fahey noted the ability of LiClO 4 to enhance the catalytic effect of HCl in promoting the addition of HOAc to various olefins including cyclohexene, tert -butylethylene, and styrene.…”

Thermometric Determination of Water and Acetic Anhydride in Acetic Acid

“…Comparisons of catalysts for the hydration of the anhydride (7,8,14,19,22,35) have shown that perchloric acid is among the most powerful. The facility of control of that reaction made possible by that catalysis is the basis of the analytical methods proposed here.…”