Patent GB-758082-A (GB)
Title: Method of manufacture of acyl-sulphonic acid and improvements in method of the manufacture of cellulose acetate or other cellulose esters
IPC: C07C303/02
Filed: 1950-11-07
Abstract: An acyl sulphonic acid, prepared by reaction of sulphur dioxide with a carboxylic acid for 100 hours or more in the presence of 0.1-8, preferably 0.2-2 per cent of water, is used as a catalyst in the esterification of cellulose, the product so obtained being used for filament or film production.  Acetyl sulphonic acid in the product of esterification is decomposed by heat, reduced pressure or hydrolysis into acetic acid and sulphur dioxide or is extracted with a non-solvent for cellulose acetate.  Examples refer to the acetylation of cellulose with acetic anhydride, with or without acetic acid, in the presence of acetyl sulphonic acid and with or without a non-solvent such as benzol or a retarder for the oxidation of sulphur dioxide.  In further examples, absorbent cotton or cotton linters are impregnated with acetic acid containing acetyl sulphonic acid, in one case saturated with sulphur dioxide, and then acetylated by adding acetic anhydride. Mercerized cotton cloth is washed, dried to 5 per cent water content, treated with acetyl sulphonic acid, acetylated in a bath containing acetic anhydride and a non-solvent such as benzol, washed, dried, a softening agent added, and passed through a heated calender.ALSO:An acyl sulphonic acid, presumably of the formula R.CO.SO3H, where R is an alkyl or aryl radical, is prepared by reacting sulphur dioxide with a carboxylic acid for 100 hours or more in the presence of 0.1-8, preferably 0.2-2 per cent of water, based on the weight of the acid.  The reaction is promoted by previous addition of acyl sulphonic acid, by heat, pressure, strong light, radioactive rays or electric waves, and by addition of magnesium halide, aluminium or zinc chloride, dithionic acid or derivatives, silver or mercury acetate.  Acetyl sulphonic acid is soluble in water, alcohol, ether, acetone, benzol, other hydrocarbons and halogenated hydrocarbons.  It is used for treating cellulosic materials particularly as a catalyst in esterifying cellulose (see Group IV (a)).  In examples: (1) acetic acid containing 1 per cent of water (part of which may be replaced by aldehydes) is saturated with SO2 while cooling and reacted for over 1000 hours at below 40 DEG  C. and normal or increased pressure; (2)-(4) reaction time is shortened by heat and pressure and activation or addition of the previously specified catalysts.ALSO:Sulphur dioxide is reacted with a carboxylic acid for 100 hours or more in the presence of 0.1-8, preferably 0.2-2 per cent of water, based on the weight of the acid, to produce an acyl sulphonic acid, presumably of the formula R.CO.SO3H where R is an alkyl or aryl radical.  The reaction is promoted by previous addition of acyl sulphonic acid, by heat, pressure, strong light, radioactive rays or electric waves, and by addition of magnesium halide, aluminium or zinc chloride, dithionic acid or derivatives, silver or mercury acetate.  Acetyl sulphonic acid decomposes on applying heat or reduced pressure or on hydrolysis into acetic acid and sulphur dioxide.