Cotton acetylation

Method 1. Use the apparatus depicted iu Fig. Ill, 56, 1, but omit the thermometer also attach a cotton wool (or calcium chloride) tube to the side arm of the filter fiask receiver in order to prevent the entrance of moisture into the apparatus. Mount the reaction fiask in a water bath e.g., a large beaker or other convenient vessel). It is important that all the apparatus be perfectly dry, since both phosphorus trichloride and acetyl chloride are decomposed by water. The set-up should be assembled in the fume eupboard. 

Boil a mixture of 10 g. (10 ml.) of o-toluidine and 38 g. (35 ml.) of acetic anhydride in a 75 or 100 ml. Claisen flask fitted with a reflux condenser (Fig. Ill, 28, 1, but with trap replaced by a calcium chloride or cotton wool guard tube) for 1 hour. Arrange the flask for distillation under reduced pressure (compare Fig. II, 20, 1) and distil acetic acid and the excess of acetic anhydride pass over first, followed by the diacetyl derivative at 152-153°/20 mm, some mono-acetyl-o-toluidine (1-2 g.) remains in the flask. The yield of diacetyl-o-toluidine is 14-15 g, it is a colourless, somewhat unstable hquid, which slowly sohdifies to yield crystals, m.p. 18°, To prepare the (mono-) acetyl-o-toluidine, warm a mixture of 5 g. 

Activation of Cellulose. The activation required depends on the source of cellulose (cotton linter or wood pulp), purity, and drying history. Typical specifications for an acetylation-grade cellulose are given in Table 5. Cellulose that has never been dried or has been mildly dried to ca 5% moisture requires Htde, if any, further activation. 

The earliest preparation of cellulose acetate is credited to Schiitzenberger in 1865. The method used was to heat the cotton with acetic anhydride in sealed tubes at 130-140°C. The severe reaction conditions led to a white amorphous polymer but the product would have been severely degraded and the process difficult to control. Subsequent studies made by Liebermann, Francimont, Miles, the Bayer Company and by other workers led to techniques for controlled acetylation under less severe conditions. 

In the so-called Dormagen process developed by IG Farben the cotton was first preheated with 30-40% of its own weight with glacial acetic acid for 1-2 hours. The pretreated material was then fed to the acetylisers, which consisted of horizontal bronze cylinders. For every 100 parts of pretreated cellulose there was added the following acetylating mixture, previously cooled to 15-20°C ... 

It has been found that substitution of cellulose hydroxyls of cotton by acetyl groups, greatly affects the graft yield [45],... 

Cotton linters and viscose grade wood pulp were partially acetylated and carboxymethylated. The samples were grafted under the same conditions with acrylamide. Grafting yield and efficiency depend on several factors, such as the kind of pulp, chemical and physical structure, type of the introduced substituent, and degree of substitution (DS). 

Wood pulp and cotton linters were partially acetylated to different acetyl contents ranging from approximately 6%-13% (0.23-0.54 degree of substitution [D.S.]). The increase of the DS of partially actylated cotton linters from 0.26 to 0.56 causes the percent graft of partially acetylated cotton linters to decrease slightly from 0.93% to 0.6%. In the case of wood pulp, the effect is somewhat different—the percent graft increases with an increasing DS until about 0.48, then the percent graft decreases. 

Barsha and Hibbert16 also demonstrated by meins of methylation, acetylation, acetolysis and hydrolysis experiments that the membranes synthesized by the action of A. xylinum on D-fructose and on glycerol were chemically identical with cotton cellulose. 

Elod and Schmid-Bielenberg86 observed that the speed of acetylation of dry native fibers increases with decreasing degree of micellar (crystallite) orientation. Arranged in order of increasing reactivity the dry native fibers were flax, hemp, ramie and cotton. On being pretreated with water or acetic acid, however, the fibers were alike in rates of reac-... 

Addition of lithiated heterocycles to aldonolactones yields carbon-linked nucleosides (56). Thus, the reaction of 2,3 5,6-di-O-isopropylidene-L-gu-lono-1,4-lactone (9b) or 2,3-O-isopropylidene-D-ribono-l,4-lactone (16a) with various lithiated heterocycles gave gulofuranosyl derivatives 53a-g or ribofuranosyl derivatives 54b,c. Gulonolactols 53a-g and ribonolactols 54b,c were acetylated with acetic anhydride in pyridine to yield their acetyl derivatives. The stereochemistry of compounds 53a-g and 54b,c was discussed in terms of the Cotton effect of circular-dichroism curves of the ring-opened alcohols formed upon reduction by sodium borohydride. The configuration at C-l of 53g was proved by means of X-ray analysis (57,58). 

The manufacture of cellulose acetate involves the acetylation of cellulose from cotton linters or wood pulp by acetic anhydride and acetic acid. Production started about 30 years ago, and early products that were developed include safety photographic films, airplane dopes, and acetate fabrics. It is now also produced in the form of sheeting, rods, and tubes and is widely used as a molding compound. 

Both the square planar bis(acetylacetonato)manganese(II) and the octahedral tris(acetyl-acetonato)manganese(III) have been shown to possess marked fungicidal activity in the protection of cotton and linen.49 Recently, the complex of manganese(II) with 4-(5 -phenyl-l, 3, 4 -oxadiazol-2 -yl)thiosemicarbazide (14) has also been shown to exhibit fungicidal properties.50 The structure of this bis-complex also appears to be unknown at present. 

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