Patent GB-777716-A (GB)
Title: Improvements in and relating to synthetic detergent compositions
IPC: C07C309/31
Filed: 1954-04-09
Abstract: Detergent compositions are produced by sulphonating an alkyl benzene hydrocarbon having one C9-18 alkyl group and no other alkyl groups of more than 2 carbon atoms with either a mixture of an inert gas and 5-30 per cent by weight (based on the total weight of the mixture) of sulphur trioxide or with an oleum containing at least 30 and preferably 40 to 70 per cent by weight of free sulphur trioxide, the action of the sulphonating agent being modified by adding a polyphosphoric acid to the alkylbenzene prior to sulphonation, and the proportion of sulphonating agent present in the reaction mixture being such that the latter contains 1.1-1.4 moles. of sulphur trioxide per mole. of alkylbenzene; the reaction mixture is neutralized, after sulphonation, with an aqueous solution or suspension of an organic or an inorganic base, the nature of the base being such that the neutralized product is watersoluble, and the neutralized product is dried to give a detergent composition comprising a water-soluble polyphosphate, a water-soluble sulphonate and a water-soluble sulphate, the last-named component having been formed by the neutralization of the excess of sulphuric acid and/or sulphur trioxide present in the reaction mixture at the end of the sulphonation step.  The polyphosphoric acid may be pyrophosphoric, tripolyphosphoric, hexametaphosphoric or hypophosphoric acid and the sulphonation may be effected at about 10 DEG  to 60 DEG  C.  The weight ratio of polyphosphoric acid to alkylbenzene hydrocarbon before sulphonation may be about 0.05 to 2 of the former to one of the latter.  There may be added to the neutralized product, before or after drying, a sufficient proportion of a separately prepared alkali metal salt of a polyphosphoric acid and/or of sulphuric acid to reduce the sulphonic acid salt content of the total mixture to 20 to 40 per cent by weight.  Preferred alkyl benzenes have one 9 to 13 carbon atom alkyl group and one methyl group.  The inert carrier gas for sulphur trioxide may be air, nitrogen, sulphur dioxide or a gaseous hydrocarbon such as methane, ethane, propane, or a butane. The neutralizing base may be an alkali or alkaline earth metal hydroxide, ammonia, a mono-, di-, or tri-alkylamine, an aromatic amine such as aniline or an alkanolamine.  In an example, 25 grams of pyrophosphoric acid and 246 grams of dodecylbenzene are sulphonated at 30 DEG  C. with a mixture of 10 per cent by volume of sulphur trioxide and 90 per cent by volume of air in 1.5 hours using 1.2 moles. of sulphur trioxide per mole. of dodecylbenzene, and the product is neutralized with a 20 per cent aqueous solution of caustic soda.  The neutralized mixture is extracted three times with one-fourth its volume of pentane and evaporated to dryness, and sufficient anhydrous sodium sulphate is added to the dry residue to increase the proportion of builder salts to 60 per cent by weight of the composition.  Specification 585,662, [Group III], is referred to.ALSO:Detergent compositions are produced by sulphonating an alkyl benezene hydrocarbon having one C9-18 alkyl group and no other alkyl groups of more than 2 carbon atoms with either a mixture of an inert gas and 5-30 per cent by weight (based on the total weight of the mixture) of sulphur trioxide or with an oleum containing at least 30 and preferably 40 to 70 per cent by weight of free sulphur trioxide, the action of the sulphonating agent being modified by adding a polyphosphoric acid to the alkylbenezene prior to sulphonation, and the proportion of sulphonating agent present in the reaction mixture being such that the latter contains 1.1-1.4 moles of sulphur trioxide per mole of alkylbenzene; the reaction mixture is neutralized after sulphonation, with an aqueous solution or suspension of an organic or inorganic base, the nature of the base being such that the neutralized product is water-soluble, and the neutralized product is dried to give a detergent composition comprising a water-soluble polyphosphate, a water-soluble sulphonate and a water-soluble sulphate, the last-named component having been formed by the neutralization of the excess of sulphuric acid and/or sulphur trioxide present in the reaction mixture at the end of the sulphonation step.  The polyphosphoric acid may be pyrophosphoric, tripolyphosphoric, hexametaphosphoric or hypophosphoric acid and the sulphonation may be effected at about 10 DEG  to 60 DEG C.  The weight ratio of polyphosphoric acid to alkylbenzene hydrocarbon before sulphonation may be about 0.05 to 2 of the former to one of the latter.  There may be added to the neutralized product, before or after drying, a sufficient proportion of a separately prepared alkali metal salt of a polyphosphoric acid and or sulphuric acid to reduce the sulphonic acid salt content of the total mixture to 20 to 40 per cent by weight.  Preferred alkyl benzenes have one 9 to 13 carbon atom alkyl group and one methyl group.  The inert carrier gas for sulphur trioxide may be air, nitrogen, sulphur dioxide or a gaseous hydrocarbon such as methane, ethane, propane, or a butane.  The neutralizing base may be an alkali or alkaline earth metal hydroxide, ammonia, a mono-, di-, or tri-alkylamine, an aromatic amine such as aniline or an alkanol-amine.  In an example, 25 grams of pyrophosphoric acid and 246 grams of dodecylbenzene are sulphonated at 30 DEG C. with a mixture of 10 per cent by volume of sulphur trioxide and 90 per cent by volume of air in 1.5 hours using 1.2 moles of sulphur trioxide per mole of dodecylbenzene, and the product is neutralized with a 20 per cent aqueous solution of caustic soda. The neutralized mixture is extracted three times with one-fourth its volume of pentane and evaporated to dryness, and sufficient anhydrous sodium sulphate is added to the dry residue to increase the proportion of builder salts to 60 per cent by weight of the composition.  Specification 585,662 is referred to.