Branched-chain alkylbenzene

Since linear alkylbenzene derivatives are more readily biodegradable than branched ones, the use of branch-chain alkylbenzene sulfonates has sharply declined with the introduction of respective regulations since the mid-1960 s (e.g. the West German Detergents Law of 1962). 

Mean molecular weight 4 acceptable 2 preferable Branched chain alkylbenzenes by mass spectroscopy... 

While infrared spectrophotometry is most useful for the qualitative analysis of surfactants, various quantitative methods have been developed for well-characterized systems. For example, an attenuated total reflectance cell with a ZnSe crystal is useful for direct analysis of aqueous anionic surfactant solutions by FTIR, while avoiding the deleterious effects of water on the usual transmission cells. In this case, the sulfonate absorbance at 1175 cm" , or the sulfate absorbance at 1206-1215 cm , is used for quantification (10,26). In another application, the weak absorption bands in the 1429-1333 cm" region are used to measure the relative amounts of linear and branched chain alkylbenzene sulfonates extracted from environmental waters (27). This is the one advantage of the infrared technique over those that have supplanted it for wastewater analysis its ability to differentiate the straight and branched chain compounds (28). No procedure will be given here, since the cleanup prior to IR analysis can be handled adequately by the method for LAS analysis by desulfona-tion/gas chromatography, described in Chapter 8. 

The following HF alkylation reactions are based on straight-chain olefins. A similar chemistry can be written for the branched-chain process. The main reaction is the alkylation of benzene with the straight-chain olefins to yield a linear alkylbenzene ... 

A binuclear Ir3+ complex used in the reaction of benzene with alkenes induces the formation of straight-chain alkylbenzenes with higher selectivity than in the branched isomers 407 The selectivity, unusual in conventional acid-catalyzed Friedel-Crafts alkylations, is suggested to result from the complex activating the C—H bond of benzene instead of the alkene. 

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... 

A hydrophobic tail may include such structures as straight-or branched-chain alkyl groups, long-chain alkylbenzenes, alkylnaphthalenes, perfluori-nated alkyl groups, polysiloxane groups, and others. 

EC>9-EC10 a variety of alkylbenzenes (propyl-, methylethyl, trimethyl, and branched-chain butyl)... 

In the mid- 1960s branched-chain surfactants were replaced by more biodegradable analogs in all laundry products. In heavy-duty liquids sodium alkylbenzene-sulfonate, derived from an alkylbenzene with a tetrapropylene side chain, was replaced by its straight-chain analog, referred to as sodium linear alkylbenzesul-fonate (LAS). 

Alkylbenzene Sulfonate Branched Chain Hard To Degrade... 

The changes and yields in polymer irradiation are often similar to those found with lower-molecular-weight compounds with similar structural features. The radiolysis of linear polyethylene is similar to that of the -alkanes, polystyrene resembles the alkylbenzenes, and polymethyl methacrylate behaves like a branched chain ester. Lower-molecular-weight compounds are often used to model processes taking place in polymer irradiation. 

With the exception of soaps, commercial anionic surfactants mainly belong to the sulfonate and sulfate families. Sulfonated species include alkylbenzenesulfonates (linear alkylbenzene sulfonate [LAS], with linear alkyl chain for detergence and still, to a much lesser extent, long, branched-chain... 

Ethanolamine soaps obtained from alkylarylsulfonic acids, preferably alkylbenzene sulfonic acids, or from alcohol sulfates are growing steadily in importance and dominate the market for household cleansers. The use of linear alkyl groups instead of branched chains in these products has resulted in greater biodegradability. 

Figure 12.2 Positive-ion FAB mass spectrum of a branched-chain sodium alkylbenzene sulphonate in a glycerol matrix. 

Prior to 1965, alkylbenzene production was synthesized from petroleum tetrapropylene reacted with an aluminium chloride or hydrogen fluoride catalyst and benzene. The resultant alkylate was a hard branched-chain compound that was considered slowly biodegradable. A straight-chain alkylate, termed LAB (linear alkylbenzene), has been produced since 1965 in the United States. Extensive research has demonstrated biodegradation effectiveness in sewage treatment plants in excess of 95 percent. ... 

Chem. Descrip. Alkylbenzene sulfonic acid, branched chain... 

Takada and Ishimatari [20] extracted alkylbenzenes with normal C10-C14 and branched Cn-C13 alkyl chains from marine and coastal sediment and suspended matter in benzene methanol. The extract in benzene was then applied to a Florisil column for removal of copper sulphide and polar materials, and then subjected to silica gel column chromatography. Alkyl benzenes were quantified and identified using gas chromatography with flame ionization detection. The recoveries of alkyl benzenes were 81-94%. 

---