Patent GB-666642-A (GB)
Title: Process for the sulfonation of alkyl aromatic hydrocarbons
Inventor: BLOCH HERMAN S
IPC: C07C309/28
Filed: 1948-09-07
Abstract: Alkyl aromatic sulphonic acids for use as detergents are prepared from alkyl aromatic hydrocarbons having an alkyl group of at least 5 carbon atoms by introducing such an hydrocarbon from an extraneous source into a reaction zone and into contact therein with a sulphonating agent comprising at least 30 per cent by weight of free sulphur trioxide in a proportion of said agent to said hydrocarbon corresponding to at least 0.8 and not more than 1.6 moles. of free sulphur trioxide to one mole of hydrocarbon and in the presence of an inert diluent boiling substantially within the range of from - 42 DEG to 126 DEG  C. and consisting essentially of at least one member from the group consisting of the inert paraffinic and cycloparaffinic hydrocarbons of at least 3 and not more than 8 carbon atoms per molecule, and the inert halogenated hydrocarbons of not more than 8 carbon atoms per molecule, effecting the sulphonation reaction during said contact and in the presence of said diluent in a quantity and at a pressure which assure that at least a portion of said diluent is maintained in the liquid phase in the reaction mixture and thereafter separating the inert diluent from the sulphonation products.  The sulphonating agent may be oleum containing at least 30 per cent and, preferably at least 60 per cent free sulphur trioxide, and desirably an amount of such oleum corresponding to 0.9 to 1.3 moles free sulphur trioxide per mole. hydrocarbon is then used. Also, free sulphur trioxide itself in the a , b  or g  forms may be employed as the sulphonating agent, the preferred amount being about 1.1 moles per mole. hydrocarbon.  The inert diluent is preferably one which boils normally at a temperature approximately equal to or below the maximum desired reaction temperature or one which can be induced by suitable pressure regulation to boil at such a temperature; as a result, when the reaction temperature tends to rise above such a pre-determined maximum, a portion of the diluent is vaporized whereby excess heat is dissipated as heat of vaporization and the reaction temperature controlled. Specified inert diluents include liquefied propane, butane, pentane, the cyclopentanes and cyclohexanes, the mono- and polygenated hydrocarbons containing up to 8 carbon atoms such as trichloroethane, dichlordifluoromethane, carbon tetrachloride, perfluoropropane and perfluorobutane.  Preferably more than 1.5 volumes of inert diluent per volume of alkyl aryl hydrocarbon are employed in the sulphonation.  The sulphonation temperature is generally within the range of from - 20 DEG  to +20 DEG  C.  The sulphonation may be carried out batchwise or continuously. Suitable alkyl aryl hydrocarbons specified for use as starting materials comprise alkylated naphthalenes, diphenyls, phenanthrenes and anthracenes wherein the alkyl group contains from 5 to 10 carbon atoms such as amyl methyl naphthalene and nonyl naphthalene, and alkyl benzenoid hydrocarbons especially those containing at least two alkyl groups not more than one of which is an alkyl group having from 9 to 18 carbon atoms and the remaining alkyl groups having not more than 2 carbon atoms.  The alkylated benzenes may be obtained by condensing, for example, benzene, toluene, xylene, methylethyl benzene or diethyl benzene with an alkylating agent furnishing a C9-18 alkyl group, with the aid of an alkylation or condensating catalyst.  As alkylating agents may be employed olefinic hydrocarbon fractions obtained, for example, by the polymerization of such lower molecular weight olefines as propylene and/or butylene or obtained from cracked petroleum products such as a pressure distillate fraction boiling from about 140-300 DEG  C.; alternatively, a halogenated alkane such as a chlorinated kerosene may be used. The crude alkylate is distilled to isolate the desired alkylate containing a C9-18 alkyl group.  In an example: toluene is continuously fed together with a propylene tetramer fraction (produced by polymerization of a propanepropylene mixture over a catalyst formed by calcining a mixture of kieselguhr and pyrophosphoric acid) into an autoclave wherein it is contacted with sulphuric acid at 2.5 DEG  C. at atmospheric pressure and the alkylation product flowing from the autoclave is separated from acid and distilled to yield an alkylate B.P. about 275-345 DEG  C.; the alkylate fraction is dissolved in n-butane and the temperature maintained at about 0 DEG  C. by allowing the butane to reflux while sulphonation is effected, utilizing 1.8 moles of 65 per cent oleum per mole alkylate; the product is distilled to remove the solvent, neutralized with aqueous caustic soda, sodium sulphate added to increase the content thereof as builder and the solution spray-dried. Data is given wherein the results of sulphonation according to the process of the invention are compared with those obtained by sulphonating with 24 and 60 per cent oleum in the absence of an inert diluent and with 60 per cent oleum, in the presence of a diluent but using less oleum than corresponds to 0.8 mole. free sulphur trioxide per mole. of alkylate.  It is stated that the process according to the invention results in substantially complete conversion of the alkylate into the monosulphonic acid with the use of less sulphonating agent and yields a product which does not contain a large excess of sulphuric acid.  Specification 666,643 is referred to.  The Specification as open to inspection under Sect. 91 includes the use of alkyl aromatic hydrocarbons in general as starting materials and is not limited to the process wherein the hydrocarbon is introduced from an extraneous source into the reaction vessel. This subject-matter does not appear in the Specification as accepted.