Alkanes From alkyl sulfonates

A class of enzymes capable of removing sulfur from alkane sulfonates exists, which may have relevance in microbial desulfurization of alkyl sulfides. A gene cluster ssuEADCB was identified in E. coli. The enzyme SsuD was capable of conversion of pentane sulfonic acid to pentaldehyde and sulfite. It was reported to be capable of conversion of alkyl sulfonates from C2 to CIO, as well as substituted ethanesulfonates and sulfonated buffers. The SsuE was a flavin-reducing enzyme that provided FMNH2 to the SsuD. 

Apart from alkene production, n-alkanes are applied as feedstock in the technical production of alkyl sulfonate surfactants (see Section 5.3.5 for details about surfactants and their application). Two routes are established for the production of the alkyl sulfonate sodium salts [R-S03]Na from higher alkanes (for this application typical C-numbers are 12-18). In both routes, alkane activation proceeds via alkyl radicals, which are generated by UV-irradiation at room temperature. In the sulfo-chlorination route, the higher alkane is contacted with SO2 and chlorine to form the alkylsulfonyl chloride, which is later neutralized with NaOH to give the... 

Zhou and Pietrzyk [41] found that increasing the mobile-phase ionic strength not only increases the retention of AS and AES on a reversed stationary phase, but also improves the resolution since the peak widths are significantly reduced. The authors achieved baseline separation of a multicomponent alkane sulfonate and alkyl sulfate mixture from C2 to Cis using a mobile-phase gradient whereby acetonitrile concentration increases and LiOH concentration decreases. 

The RP-Cis LC separation of this mixture of aliphatic linear alkane sulfonates (CnH2n+i—SO3) and SAS from an industrial blend in combination with APCI—LC—MS(—) detection is presented as total ion mass trace (Fig. 2.11.2(f)) together with selected mass traces (m/z 277, 291, 305 and 319 for (re +x = 11-14)) in Fig. 2.11.2(b)-(e), respectively. The resolved mass traces proved the presence of large number of isomers of every SAS homologue in this blend. This complexity is generated because of the linear isomer precursor and the mixture of branched alkyl precursor compounds applied to chemical synthesis [22], In parallel to elution behaviour observed in GC the branched isomers of alkylsulfates in LC separation were expected to elute first. 

Thus -alkanes (C10-C14) separated from the kerosene fraction of petroleum (by urea complexation or absorption with molecular sieves) are now used as one source of the alkyl group. Chlorination takes place anywhere along the chain at any secondary carbon. Friedel-Crafts alkylation followed by sulfonation and caustic treatment gives a more linear alkylbenzenesulfonate (LAS) which is soft or biodegradable. The chlorination process is now the source of about 40% of the alkyl group used for the manufacture of LAS detergent. 

Alkylbenzene. Alkylbenzene is an intermediate for the production of alkylbenzene sulfonate. Alkylbenzene consists of a mixture of phenyl substituted n-alkanes of 9 to 14 carbon atoms. Prior to 1965, alkylbenzene was synthesized from propylene tetramer, obtained by oligomerization of propylene. The resulting hard alkylate was a highly branched chain compound. However, the slow biodegradability of propylene tetramer-based materials soon became apparent and by 1965, most of the detergent industry had switched over to linear alkylbenzene. Extensive research has demonstrated... 

Aliphatic hydrocarbons include straight chain and branched structures. Industrial solvents, petroleum hydrocarbons, and the linear alkyl benzene sulfonates (LAS) are the primary sources of aliphatic hydrocarbon pollutants. Many microorganisms utilize aliphatic hydrocarbons as carbon sources. Long-chain -alkanes are utilized more slowly due to the low bioavailability that results from their extremely low solubility in water. In contrast, short-chain rc-alkanes show a higher aqueous solubility. 

Replacing a hydrogen atom in any of the methylene groups by a hydroxide function significantly reduces the retention time. The position of the hydroxide function exerts a noticeable influence on the resulting retention time. Fig. 5-35 shows the separation of two Ci6-hydroxyalkane sulfonates, which are hydroxy-substituted in the 2- and 3-pos-ition of the alkyl chain. In comparison to non-substituted alkane sulfonates, the retention decrease corresponds to the loss of 2 to 3 methylene groups from the solvophobic alkyl groups. 

Effect of Surfactant Concentration. Figure 3 compares results of alkane scans for three concentrations of sodium oleate at constant sodium chloride concentration and pH. The 0.002 M solution is derived from 95% oleic acid, the 0.01 M and the 0.1 M solutions are derived from 99% oleic acid. Both the magnitude and the alkane position of minimum interfacial tension (r = 11) are essentially concentration independent under these conditions. Wade, et al (12) reported a similar invariance in nm with a pure alkyl benzene sulfonate, although there was more change in the minimum value of interfacial tension with the sulfonate concentration than is observed with the carboxylate. The interfacial tension at for 0.01 M sodium oleate is in the range of the values of Table I. Very high interfacial tension (> 10 dynes/cm) was found at 0.0001 M sodium oleate in 0.1 M sodium chloride. 

In contrast to TPS with its branched alkyl chain, n-dodecylbenzene sulfonate exhibits an extremely fast rate of biodegradability. The change-over from a branched to a straight-chain structure is easily achieved, and thus by the use of Ziegler synthesis and molecular-sieve extraction techniques, industrial processes for the production of linear olefines and -alkanes soon became readily available. These are the basic starting materials for the synthesis of linear alkylbenzene derivatives. 

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