GB793427A - Process for the production of surface active agents - Google Patents

Abstract

Surface-tension reducing agents are prepared by reacting organic substances such as hydrocarbons, fatty alcohols, organic acids, esters or phenols in the liquid phase with a gaseous stream consisting chiefly of an inert gas such as air, nitrogen, oxygen or sulphur dioxide, and containing also sulphur trioxide mist, the latter being formed either by the introduction into a gaseous stream containing sulphur trioxide vapour, of water and/or water vapour in an amount of from 1-15 per cent by weight, for instance from 1-10 per cent by weight, and preferably from 2-6 per cent by weight, based on the total amount of sulphur trioxide present, or by forming sulphur trioxide in, or by introducing sulphur trioxide into, a gaseous mixture already containing water vapour, the relative proportions being as above. The water may, if desired, be added at a temperature exceeding 50 DEG C., e.g. 70-500 DEG C., and the gaseous stream subsequently cooled, preferably rapidly, and to a temperature of +40 DEG C. or less, e.g. to -30 DEG to +30 DEG C. The term "sulphur trioxide mist" is used to designate liquid droplets which in contradistinction to sulphur trioxide vapour are retained by a dense mechanical filter, for instance a glass or asbestos filter. Only a part of the sulphur trioxide, e.g. 50-70 per cent, need be present in the mist form. In introducing water or water vapour into a gaseous stream containing sulphur trioxide, it is important that a rapid and intimate mixing occur which may be achieved, for example, by the use of suitable nozzles. The gaseous stream may advantageously be derived from a plant in which sulphur dioxide is converted to sulphur trioxide by catalytic oxidation by means of air or oxygen. By incorporating a suitable amount of humidity in the air, sulphur trioxide mist may be formed by cooling the gases from the reaction. Sulphur trioxide mist may also be produced from liquid or solid sulphur trioxide, or from oleum as by evaporation of sulphur trioxide through heating. The sulphur trioxide is diluted to a suitable concentration with air or other gas and water or water vapour added, or gas may be added directly in connection with the evaporation of the sulphur trioxide. If desired, this gas may contain water vapour so that mist is formed in connection with the evaporation and/or by cooling the gaseous mixture. In general the total amount of sulphur trioxide in the gaseous stream should not exceed 0.5 kg. of SO3 per m.3 of gas at N.T.P. Substances suitable for reaction with the sulphur trioxide mist include aromatic and unsaturated hydrocarbons, especially petroleum fractions, aliphatic, cycloaliphatic or aromatic alcohols, carboxylic acids and esters, hydroxy carboxylic acids and esters, phenols, substituted derivatives of the preceding, e.g. those with halogen or amino substituents, alkylene oxide adducts such as those with nonyl phenol. Aliphatic or cycloaliphatic compounds should, in general, contain 10-30 carbon atoms in the molecule, and aromatic compounds 12-36 carbon atoms. Of particular interest are the products derived from alkyl aryl hydrocarbons having an aliphatic chain of 8-16 carbon atoms such as dodecyl benzene and those from C8-22 fatty alcohols, e.g. the sulphuric acid esters of lauryl, cetyl and oleyl alcohols. The reaction may be carried out in the presence of a solvent such as a chlorinated hydrocarbon, e.g. ethylene dichloride, which may be added to the substance to be sulphonated or introduced into the gaseous stream, possibly along with the water vapour. The reaction may be carried out batchwise or continuously. Reaction times should be as short as possible, e.g. 1 hour, although as long as 12 hours may be permissible. The reaction temperature may be, for example, 0-100 DEG C., preferably 20-80 DEG C., more preferably 50-70 DEG C. The products may be converted to salts, e.g. with sodium hydroxide, carbonate or bicarbonate or with triethanolamine. In examples, sulphur trioxide mist is prepared by the addition of water vapour to a gaseous stream from a contact sulphuric acid plant and used to sulphonate the following, the products being neutralized with NaOH except in (4), where NH4OH is used: (1) castor oil in CCl4 solution; (2) dodecylbenzene; (3) tallow fatty alcohol containing stearyl, cetyl and myristyl alcohols; (4) dodecylphenol hexaethylene glycol; (5) nonylnaphthalene; (6) a commercial olefine mixture obtained as a byproduct in a solvent refining process for producing white paraffin oils.