Patent GB-727648-A (GB)
Title: Improvements in or relating to diaryl sulphones and their manufacture
Inventor: LEE ROBERT J
IPC: C07C317/14
Filed: 1951-03-22
Abstract: Materials which can be incorporated in adhesive compositions and plastic compositions such as those of polyvinyl chloride/polyvinyl acetate copolymers, comprise a mixture of sulphone isomers that is in the super-cooled state when at room temperatures.  Each isomer has a pair of 8-carbon-membered alkylaryl radicals and is obtained by reacting a mixture of the four aromatic hydrocarbon isomers having 8 carbon atoms per molecule and containing at least 5 per cent by volume of o-xylene and/or ethylbenzene with a sulphonating compound. Alternatively one alkylphenyl group in each isomer is derived from such a hydrocarbon mixture, and the other alkylphenyl group is one containing 7 or 8 carbon atoms.  The preparation and properties of the sulphone mixtures are given (see Group IV (b)).ALSO:The invention comprises a composition of matter comprising essentially a mixture of sulphone isomers that is in the supercooled state when at room temperatures, each isomer having a pair of 8-carbon-membered alkyl aryl radicals, obtained by reacting a mixture of the four aromatic hydrocarbon isomers having 8 carbon atoms per molecule and containing at least 5 per cent by volume of o-xylene and/or ethyl benzene with a sulphonating compound.  It also comprises a composition of matter comprising a mixture of alkylphenyl sulphone isomers that is a supercooled liquid when at room temperatures, one alkylphenyl group in each isomer containing 8 carbon atoms and being derived from a mixture containing the four C8 alkylbenzenes containing at least 5 per cent by volume of o-xylene or ethylbenzene, the other alkylphenyl group containing 7 or 8 carbon atoms.  A process of preparing such a mixture comprises heating a mixture of the four alkylbenzenes having 8 carbon atoms per molecule including at least 5 per cent by volume of ortho-xylene or ethylbenzene at a temperature between 275 DEG  and 350 DEG  F. with a sulphonating agent. In a modification the four alkybenzenes are heated with an aryl sulphonic acid, e.g. toluene sulphonic acid.  The reaction is preferably effected by heating two moles of the alkylbenzenes with one mole of 98 per cent sulphuric acid with a reflux condenser and a trap for removing water from the condensed vapours.  Initially the process is one of sulphonation, and then sulphone formation takes place.  The rate of the reaction depends on the reflux rate. Before returning the xylene reflux to the reaction vessel it may be cooled and/or dried, e.g. with alumina, to increase the rate of removal of water.  Preferably a reflux ratio of 1 1/2 to 2 pounds per hour per pound of xylene charged is employed. It is preferred, in order to avoid the formation of undesired products, to discontinue the reaction when 70 to 45 per cent of the sulphonic acid first formed has been converted to sulphone.  A graph shows the relationship between the actual sulphone yield, the theoretical yield, and the per cent disappearance of sulphonic acid. The minimum of water to give two phases is added to the product, the aqueous layer, containing sulphonic acids, being recharged to the reactor together with the necessary amount of sulphuric acid, for reaction with further xylene.  Any entrained sulphone can be extracted with xylene.  Emulsion formation during the water-extraction can be prevented by adding aromatic hydrocarbons. The crude sulphone is neutralized, purified by distillation, and treated in solution in benzene or other solvent to eliminate odour. A table shows the effect of time and temperature of reaction, refluxing rates, the use of excess xylenes, the use of a drying agent to remove water from the reflux stream, and the relationship between the actual and theoretical sulphone yields for a given conversion of xylene sulphonic acid, in 13 runs employing four different xylene mixtures within the above definition, the products being liquid. In a comparison run, using xylene containing no ortho xylene and only 3.3 per cent ethyl benzene a solid product is obtained. Further tables show the results of analyses of the unconverted xylenes compared with the feed, the distribution of the different isomers in the products, and the percentage conversion, for three runs.  In an example of a modification, a liquid mixture of xylyl-tolyl sulphones is prepared by reacting equimolecular proportions of commercial xylene and technical toluene sulphonic acid.  The products may be incorporated in adhesive and synthetic resinous compositions.