Alkylbenzenes, branched

Of interest is the relative composition of the LABs, particularly the different amount of 2-phenyl isomer and of nonlinear alkylates, given in Table 8. Branched alkylbenzene (BAB) formed by the AlCl3-catalyzed reaction between propylene, condensed to its tetramer, and benzene are less biodegradable and are termed biologically hard. LABs have to a large extent replaced BABs in the domestic markets because of their improved biodegradability. 

Branch and bound techniques, discrete optimization via, 26 1023 Branched aliphatic solvents, 23 104 Branched alkylbenzene (BAB), 77 725 Branched copolymers, 7 610t Branched epoxies, 70 364 Branched olefins, 77 724, 726 Branched polycarbonates, 79 805 Branched polymers, 20 391 Branched primary alcohols, synthetic processes for, 2 2 7t Branching... 

Tong and Tan [18] have performed a simultaneous determination of branched alkylbenzene sulfonates (ABSs) and LASs by HPLC using a C48 column. The elution of ABS produced one large wide peak representing the elution of the compounds with high molecular weight, with the same retention time of the CnLAS. 

Dated sediment layers (1939-1991) of a small German river were studied for their LAS concentrations and the gathered data were related to political, economic and technical developments in Germany [14]. As expected the sediments corresponding to the period 1939-1945 contained no LAS, since at that time soap was the most important surfactant used for laundry washing. A significantly different picture was obtained in sediments from 1949 to 1951 when a particular LAS was used along with soap. The values determined in the two core samples amounted to 1.4 and 1.3 mg kg-1, respectively. In the sediment horizons from 1954 to 1956 no LASs were detected, which is in accordance with the fact that the less expensive branched alkylbenzene sulfonate (ABS) had replaced the linear one. In the years from 1959 to... 

ABS AE AE/P AES AG AOS APEO APG AS BiAS BM c6(EO)3 CNPEC CTAS D DATS DCPEG DEEDMAC branched alkylbenzene sulfonate alcohol ethoxylate alcohol ethoxylate/propoxylate alkylether sulfate alkyl glucamide a-olefin sulfonate alkylphenol ethoxylate alkyl polyglucoside alkyl sulfate bismuth active substances alkyldimethylbenzyl ammonium triethylene glycol monohexyl ether carboxylated nonylphenoxy carboxylates cobalt thiocyanate active substances R2S10(o.5)2 dialkyl tetralinsulfonate dicarboxylated PEG ditallow ester of di(hydroxyethyl)dimethyl ammonium chloride... 

It is common practice to put the experimentally obtained values for biodegradation and aquatic toxicity into a kind of matrix, as is illustrated by Fig. 2. The shaded areas in the matrix are the approved areas . Out of the six product types discussed above linear alkylbenzene sulfonates, alcohol ethoxylates, and ester quats lie within the shaded areas, while branched alkylbenzene sulfonates, alkylphenol ethoxylates and stable quats do not. 

Disproportionation (transalkylation) and positional isomerization usually take place simultaneously when either linear or branched alkylbenzenes are treated with conventional Friedel-Crafts catalysts or with Nafion-H. The reactivity of alkyl groups to participate in transalkylation increases in the order ethyl, propyl < isopropyl < tert-butyl.117 207 217... 

Figure 9.7. Typical visible absorption spectra for the glass-sandwiched viologen V2 2ArS032 upon UV irradiation Curves 1 and 1 indicate the spectra of films composed of highly branched alkylbenzene sulfonate after irradiation, and before irradiation or after complete recovery curves 2 and 2 are those of n-C14 H29. Absorption spectra given qualitatively as for absorbance in order to make comparisons easier.

No applications before 1974 (to avoid possible confusion with branched alkylbenzene sulphonates). 

Benzene is also alkylated with 1-olefins (e.g., where R is C10H21) to prepare detergent alkylate for sulfonation to make detergents. A UOP/Petresa process, using a fluorided silica-alumina catalyst, gave 92% linear alkylbenzene and 6% branched alkylbenzene at 97% conversion with a cata-... 

The branched alkylbenzenes exhibited considerable variation in behavior. With teri-butylbenzene the effluent contained 71.9 mole % isopentane, the highest concentration produced with any of the additives tested. 

The synthetic detergent iadustry has become one of the largest chemical process iadustries (see Detergency). Sales ia 1989 were estimated at more than 4 billion ia the United States alone. As of 1989, the worldwide annual production of linear alkylbenzene (LAB) and branched alkylbenzene (DDB) was estimated to be about 1.8 million tons and 230,000 tons, respectively (71,72). 

The branched alkylbenzenes, produced predominantly between 1950 and 1970, were obtained from propylene tetramer and benzene at temperatures from 20 to 50 °C, with a reaction time of a few minutes, using Friedel-Crafts catalysts (HF or AICI3). To avoid polyalkylation as far as possible, the operation was carried out with a 5 to 10-fold excess of benzene. The yield of dodecylbenzene was 70 to 80%. 

Of all the various surfactants used in detergent formulations, alkylbenzene sulfonates are by far the most widely used. As a result, alkylbenzenes are the most widely used surfactant raw materials. There are two basic types of alkylbenzenes used in surfactant manufacturing linear alkylbenzenes (LAB) and branched alkylbenzenes (BAB). Both types of alkylbenzenes are homolog mixtures. Typical homolog representatives of LAB and BAB are depicted in Figures 2.1 and 2.2, respectively. 

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