GB799199A - Improvements in or relating to methods for the continuous production of sulphonated organic substances - Google Patents

Abstract

<PICT:0799199/IV (b)/1> Organic compounds are sulphonated (this term being used to include also sulphation) by a continuous process employing chlorsulphonic acid or vaporized SO3 comprising continuously cycling acid sulphonated product in liquid phase through a closed circuit, removing continuously or at short-time intervals from the circuit an amount of sulphonated product per hour which ranges from one fifth to one thirtieth by weight of the quantity of product circulated and similarly feeding continuously or at short time intervals into a mixing zone forming part of the closed circuit, at a point remote from the withdrawal point, a quantity, corresponding to the withdrawal rate, of the substance to be sulphonated in the liquid state or dissolved in an inert liquid and of the chlorsulphonic acid or vaporized SO3. A preferred method utilizing SO3 vapour, diluted or not with an inert gas, comprises circulating sulphonated product by a pump 1 through a cooler 2, a duct 3, a packed absorption tower 4 and a return duct 5. Vaporized SO3 is blown into tower 4 via line 9 and the substance to be sulphonated is introduced through valved line 7 counter-currently to the SO3 vapours and sulphonated product is withdrawn through line 6. If desired, parallel-flow operation may be used wherein the vaporized SO3 may be introduced at 10, otherwise provided as a gas vent. When the sulphonated product is very viscous the tower 4 may be replaced by a simple tube in which the reaction mixture is stirred by a spiral or worm screw; in addition, a perforated disc diaphragm may be placed in duct 5 to facilitate the mixing. Sulphonation with chlorsulphonic acid may be effected using the parallel flow method described above, the hydrogen chloride formed being removed from the tower or in a suitably disposed degasifier, the chlorsulphonic acid may be diluted with an inert solvent. The withdrawn acid sulphonated product may be neutralized by a continuous method analogous to the closed circuit sulphonation wherein already neutralized product is cycled through the circuit, a fraction amounting by weight to 3 1/2 to 20 per cent thereof being withdrawn per hour continuously or at short spaced intervals and acid sulphonation product and a neutralizing amount of alkaline solution, together equal in weight to that of the product withdrawn, correspondingly introduced into the circuit at a point remote from the withdrawal point and the illustrated sulphonation apparatus may be used for this neutralization. Examples describe the sulphonation of C8-C18 primary fatty alcohols, dodecyl benzene and technical lauric ethanolamide using chlorsulphonic acid or a mixture of SO3 vapours and air; the sulphated alcohols are neutralized, after degasification, by the continuous method above described. Specification 680,629 is referred to.