Alkenes sulphonation

The properties of the two species are very different in terms of their solubility, viscosity and detergency. The alkene sulphonate is the better performing surfactant and the manufacturing process is developed to maximise this more desirable product. The sulphonation process is significantly more exothermic than LAB sulphonation, requiring careful control of reactor temperatures and more dilute S03 which often results in lower reactor loadings and hence lower productivity, compared to LAB. Low product colours can be achieved but require very careful control of sulphonation, neutralisation and hydrolysis. Earlier processes relied heavily... 

Another class of sulphonates is the a-olefin sulphonates which are prepared by reacting linear a-olefin with sulphur trioxide, typically yielding a mixture of alkene sulphonates (60-70%), 3- and 4-hydroxyalkane sulphonates ( 30%), and some disulphonates and other species. The two main a-olefin fractions used as starting material are C 2 ie Fatty acid and ester sulphonates are produced... 

The enhanced sulphonating activity of sulphuric acid derivatives allows them to be used for the sulphonation of alkenes (this reaction is not possible with sulphuric acid). Thus, alkenic sulphonic acids are formed by the replacement of a vinyl hydrogen atom by the sulphonic acid group, as shown in equation ll98. 

Sulphur trioxide and its adducts usually react with terminal alkenes to produce quantitative yields of the terminal alkenic sulphonic acid (equation 16)140"145. However in a few instances it has been reported that a mixture of products is obtained146"150, as shown in equation 17, or else addition across the double bond takes place141,144, as shown in equation 18. Polyfluorovinyl ethers react with sulphur trioxide to give, upon hydrolysis, / -ketosulphonic acids in excellent yield151. 

The abnormal behaviour of an oc,/ -disulphonyl chloride has been reported to lead to an alkene sulphonate ester, as shown in equation 82375. 

Neutralisation/hydrolysis of alkene sulphonic acid and sultones... 

The combination of neutralisation/hydrolysis gives a product containing about 55-65% alkene sulphonates and 25-35% hydroxy alkane sulphonates and 5-15% disulphonates. The C(l,3) sultones and D(l,4) sultones have virtually disappeared in the plug flow reactor with a residence time of 30 minutes at HO C. The ratio between initial and final concentration of delta (1,4) sultones will be ... 

Alkene monosulphonates may be extracted as the sulphonic acids from strongly acid solution and determined by titration with alkali. Under these conditions the hydroxyalkane sulphonates are converted back to the sultones from which they were derived, and although these are also extracted, they are not titrated by alkali. Alternatively the alkene sulphonates in the extract may be titrated with benzethonium chloride. The hydroxyalkane sulphonates may be determined by alkaline hydrolysis followed either by measurement of the alkali consumed or by a second titration with benzethonium chloride. The following method is adapted from those of Ranky and Battaglini [20] and Martinsson and Nilsson [21]. The alkali used for hydrolysis of the sultones is alcoholic simply to prevent excessive foaming. 

Add 50 ml ethanol and titrate to phenolphthalein with 0.1 M ethanolic sodium hydroxide. Calculate the percentage of alkene sulphonate. 

As a check, the sum of the alkene sulphonates and hydroxyalkane sulphonates in mol/1 may be determined on the original sample by titration with benzethonium chloride. The result includes any 2-hydroxy-alkane sulphonate, which is not converted to the sultone by the acid treatment described, and so may differ slightly from the sum of the... 

Several papers are concerned with motions of polymers containing backbone sulphur atoms. - > In poly(phenyl thiirane), it is found that backbone correlation times are an order of magnitude shorter than in polystyrene. An unusual feature > of relaxation in poly(alkene sulphones) is that C Ti s are independent of molecular weight whereas dielectric relaxation times are not. This has been rationalized in terms of specific conformational transitions which re-orient C—H bonds but not the sulphone dipole. 

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