Patent GB-821120-A (GB)
Title: Process for the preparation of mixtures of alkyl benzene sulphonic acids and mixtures of salts thereof
IPC: C11D1/22
Filed: 1957-07-24
Abstract: Detergent compositions comprise mixtures of alkylbenzene sulphonates wherein the alkyl radicals contain all the successive numbers of carbon atoms from 8 to a maximum of at least 11 and not more than 13 (see Group IV (b)).  Alkali metal pyro- or poly-phosphates, silicates, carbonates, sulphates, borates, sodium carboxymethyl cellulose or other soluble derivatives of cellulose or starch, persulphates, perborates, percarbonates, optical bleaching agents, foam-forming and foam-stabilizing substances may also be incorporated.  Specification 783,469 is referred to.ALSO:Mixtures of alkyl benzene sulphonic acids are prepared by sulphonating a mixture of alkyl benzenes produced by the alkylation of benzene with a mixture of olefines, at least 90% by weight of which olefines are obtained by cracking higher paraffinic hydrocarbons to give cracked-products comprising molecules which contain all the successive numbers of carbon atoms from 8 to a maximum of at least 11 and not more than 13.  The paraffinic hydrocarbons may be various paraffinic distillates or residues of mineral oil, paraffinic oils obtained by hydrogenating mineral oil, coal or tar, products of the reaction of hydrogen with carbon monoxide, petrolatum, ceresine, ozokerite, montan wax, solid paraffin wax, crude paraffin wax, sweet oil and paraffin-containing oils derived from brown coal.  The cracking is preferably carried out in the vapour phase in the presence of steam.  The catalyst used for the alkylation may be hydrofluoric acid, sulphuric acid, oleum, aluminium chloride or activated clay. In order to prevent the formation of di-alkyl benzene the olefine is preferably reacted with an excess of benzene.  A molar ratio of benzene to olefine between 4 and 12 is generally preferred at the beginning of the reaction.  Sulphonation is generally carried out with oleum containing 5 to 50% by weight of free sulphur trioxide. It is advisable to keep the molar ratio of total SO3 to alkylated benzene between 1 and 2.  The sulphonation temperature is maintained between 5 DEG  and 60 DEG  C., usually 10-20 DEG  C., by external cooling of the reaction vessel.  The mixed sulphonic acids may be neutralized with the hydroxides of the alkali metals, ammonia or organic bases such as the ethanolamines.  The mixed salts may be used as components of detergents.  Solutions containing high concentrations of the mixed sodium salts may be prepared, and they remain clear with fluctuations of temperature. The salts may be mixed with other surface-active agents, and also alkali pyro or polyphosphates, silicates, carbonates, sulphates, borates, sodium carboxymethyl cellulose or other soluble derivatives of cellulose or starch, persulphates, perborates, percarbonates, optical bleaching agents, foam-forming and foam-stabilizing substances.  In an example a mixture containing 90% by weight of olefines having contiguous numbers of carbon atoms from 8 to 13, in which the average molecular weight is 147, is obtained by thermal cracking paraffin wax in the vapour state. The olefine mixture is mixed with benzene and sulphuric acid, with stirring, while the temperature is maintained at 5 DEG  C. After about 1 1/2 hours, the hydrocarbons are separated from the acid, and boiled under reflux with dilute caustic soda containing isopropanol.  After separation from the aqueous liquor and washing with saturated salt solution, the benzene is distilled off from the hydrocarbon mixture, and the alkyl benzenes are rectified in vacuo. The alkyl benzenes are sulphonated with oleum at 25 DEG  C.; and then water is added to remove the residual sulphuric acid from the sulphonic acids.  The sulphonic acids are dissolved in an equivalent quantity of 10% NaOH solution giving a solution having a clear point of only 5 DEG  C., and satisfactory foaming qualities. Specification 783,469 is referred to.