Cellulose with phenyl isocyanate, reaction

In a typical experiment the isocyanate (0.006 moles) was reacted with 1.5 g of the polysaccharide in 150 ml of a 5% LiCl/ N,N-dimethylacetamide solution at 90°C under nitrogen for two hours. The appearance of a strong infrared absorbance at 1705 cm l was an indication of carbamate formation. The derivatized polymer was isolated as a white powder by precipitation of the reaction solution into a nonsolvent such as methanol. Alternatively thin films were cast directly from solution the lithium salt could be removed by rinsing with acetone. Figure 1 illustrates the reaction of cellulose with phenyl isocyanate. 

Cellulose tricarbanilate, obtained by reaction of cellulose with phenyl isocyanate - mostly in DMSO or pyridine as the solvents - has been used widely for the determination of analytical parameters of celluloses by gel permeation chromatography (GPC) in organic solvents, such as THE... 

The reaction of cotton cellulose with phenyl isocyanate, to give a cellulose phenylurethan, has been investigated further. The extent of the reaction depends on the ability of the solvent to swell the cellulose, methyl sulfoxide being the best medium, followed by i r,f T-dimethylformamide and P3Tidine. The reaction is catalyzed by the addition of di-w-butyltin diacetate, but toluene 2,4-diisocyanate and 1,2,4,5-tetramethylbenzene diisocyanate do not show high reactivity. A survey of the relative behavior of chitin and cellulose toward esterification under comparable conditions, mainly to give arylsulfonate esters, concluded that, of the two, chitin is the less reactive. 

Undecorated linear (l->4) diequatorial polysaccharides such as cellulose tend to be insoluble in water, so any attempt at determining a molecular weight distribution first has to solubilise them. A common method is complete reaction with phenyl isocyanate (Ph-N=C=0) in warm ( 80 °C) pyridine which converts all the hydroxyl groups of cellulose into carbanilate (cell-O-CO-NH-Ph) groups. SEC in an organic solvent such as tetrahydrofuran can then, with appropriate standards, give the molecular weight distribution. 

ANILINE, A -PHENYL (122-39-4) Comhustible solid. Dust forms explosive mixture with air. Violent reaction when added to hexachloromelamine, trichloromelamine. Often shipped in liquid form (flash point, liquid 307°F/153°C oc). An organic base. Incompatible with strong acids (forms salts), aldehydes, organic anhydrides, isocyanates, oxidizers. Reacts with nitrogen oxides to form Al-nitrosodiphenylamine and mono- and poly-nitro products. Incompatible with organic anhydrides, acrylates, alcohols, aldehydes, alkylene oxides, substituted allyls, cellulose nitrate, cresols, caprolactam solution, epichlorohydrin, ethylene dichloride, isocyanates, ketones, glycols, nitrates, phenols, vinyl acetate. Exothermic decomposition with maleic anhydride. Increases the explosive sensitivity of nitromethane. Attacks light metals in the presence of moisture. 

Preparation of the previously cited triphenylcarbamates was carried out by reaction of microcrystalline cellulose with the specific phenyl isocyanate in pyridine at 120°C for 6 h, according to the procedure reported by Okamoto et al. [34]. Each product was washed with methanol to remove the unreacted isocyanate. 

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