Patent GB-691929-A (GB)
Title: Improvements in or relating to the preparation of higher alkyl sulphates
IPC: C07C305/04
Filed: 1950-06-30
Abstract: Alkyl sulphates are prepared by a process which comprises reacting alkenes containing at least 5 carbon atoms in the molecule with sulphuric acid in the presence of up to 10 percent, based on the weight of the alkenes, of an oxygen-containing compound containing at least one aliphatic group containing at least 5 carbon atoms and selected from the group consisting of aliphatic alcohols, aldehydes, ketones, esters and ether alcohols, carboxylic acids, carboxylic esters and sulphurous esters and aromatic compounds consisting of the condensation products of alkylene oxides with alkyl phenols. Suitable oxygen-containing compounds mentioned are alkanols with more than 6 carbon atoms in the molecule, especially the primary and secondary alkanols with the hydroxyl group in the 1- or 2-position or esters thereof with aliphatic carboxylic acids especially with acids containing not more than 3 carbon atoms in the molecule such as heptanol-1, -2, -3 and -4, octanol-1 and -2, nonanol-1 and -2, decanol-1 and -2, dodecanol-1 and -2, pentadecanol-2, stearyl alcohol, n-octyl acetate, sec.-octyl acetate and n-tetradecyl acetate, aliphatic monocarboxylic acids, especially those with more than 6 carbon atoms in the molecule such as lauric acid, myristic acid, stearic acid and oleic acid and esters thereof including glycerides, aliphatic aldehydes and ketones containing at least 7 carbon atoms in the molecule such as heptanal, octanal, decanal, octanone-2, dodecanone-2 and pentadecanone-2, higher symmetrical and unsymmetrical dialkyl ethers such as dipentyl, dihexyl- and dihexadecyl ethers, methyl pentyl- and ethyl pentyl ethers, ether alcohols such as the monopropyl-, monobutyl- or monopentyl-glycol ethers, the condensation products of alkylene oxides with alkyl-phenols, e.g. ethylene oxide with octyl phenols and dialkyl sulphites such as dioctyl sulphite and didecyl sulphite.  The promoters may be used singly or in admixture, e.g. the mixture of isomeric primary alcohols obtained by the Oxo-synthesis from the higher alkenes or alkene polymers, such as tri-isobutene, or the mixture of so called polymers obtained by converting the sulphonation products of higher alkenes into ester salts and which contain higher secondary alcohols, the primary or secondary alcohols in such mixtures containing at least one aliphatic group of at least 5 carbon atoms.  The alkyl hydrogen sulphates obtained by the process contain a higher proportion of esters in which the sulphate radical is attached to the second carbon atom of the alkene chain than those obtained by normal sulphation in the absence of a reaction promoter. Alkene starting materials mentioned include pure alkenes and hydrocarbon mixtures containing alkenes such as the products or fractions thereof obtained by cracking paraffin wax or other paraffinic hydrocarbon material which consists predominantly of a -alkenes.  The reaction may be carried out batchwise or intermittently but is preferably operated continuously, alkene, sulphuric acid and promoter being passed through a reactor kept at the desired temperature, any unreacted alkene being recirculated. The reaction promoter may be removed from the reaction mixture before working up further.  In examples: (I)-(III) Dodecene-1 is contacted in a film reaction with sulphuric acid to give products containing alkyl hydrogen- and dialkyl sulphates, as promoters decanol-1, oenanthal, pentadecanone-2 and alcohol containing polymers separated during the preparation of sulphuric ester salts from a cracked fraction containing C10-C18 alkenes are respectively employed and n-decyl acetate, stearic acid and dioctyl sulphite are stated to give similar results to pentadecanone-2; (IV) a C10-C18 fraction of a cracked distillate containing alkenes obtained by cracking paraffin wax is sulphonated with sulphuric acid in a film reactor in the presence of dodecanol-1 and sodium alkyl sulphate is obtained by saponification of the product.  The reactor in example (IV) consists of two concentric cylinders, the outer being cooled externally and the reactants, passed through the annular space, are mixed by rotation of the inner cylinder.  The alkyl hydrogen sulphates obtained in examples (II) and (III) contain 2-sulphate.  Runs are made in the absence of promoter for comparison.  The sulphonation of alkenes in the presence of formaldehyde is stated to be known.