LAS (Linear Alkylbenzene Sulphonate) shows relatively high aquatic toxicity in hard freshwater or seawater. In this paper, we studied the effect of adsorbent on the aquatic toxicity of LAS in hard freshwater and seawater. Daphnia magna and Artemia salina were used for acute aquatic toxicity test in freshwater and seawater, respectively. Kaolin was used as a model adsorbent and toxic surface tension (g tox ) was used as an indicator of toxic condition. Results showed that the values of g tox of LAS to D. magna and A. salina were about 45-55 mN/m and 35-40 mN/m, respectively. Surface tension of LAS solution decreased and its aquatic toxicity increased with increasing the water hardness or the salinity. By adding adsorbent into the solutions, the surface activity and the aquatic toxicity were decreased greatly, and the effect of water hardness or salinity on surface tension and aquatic toxicity were removed. That is to say, the surface tension curve of soft freshwater corresponds with that of hard freshwater containing adsorbent and the surface tension curve at low salinity corresponds with that obtained for high salinity solutions containing the adsorbent. Therefore, our experimental data leads to the conclusion that the relatively high aquatic toxicity of LAS in concentrated solution of inorganic salts disappears in the presence of adsorbents. This is an important viewpoint in conducting environmental risk assessment of surfactants. (lethal concentration 50%); the concentration of a chemical in air or water that kills 50% of the test animals in a given time. **EC 50 (effective concentration 50%, harf maximal effective concentration); the concentration of a chemical where 50% of its maximal effect on the test animals is observed. In a toxicity test with D. magna, the effect means the inhibition of swimming ability.

The stereoselective Horner-Wadsworth-Emmons reaction of aldehydes with bis-(2,2,2-trifluoroethyl)phosphonoacetic acid utilizing i-PrMgBr afforded (E)-α,β-unsaturated carboxylic acids as the major products. bis-(2,2,2-Trifluoroethyl)phosphonoacetic acid was prepared by enzymatic hydrolysis of the corresponding methyl ester with porcine liver esterase.

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Asymmetric Horner-Wadsworth-Emmons (HWE) reaction of prochiral cyclic ketones is of current interest.1-4) Several useful chiral HWE reagents such as phosphonates, [5][6][7][8][9] phosphonoamides, 10) and phosphonoamidates 11) have been developed for the synthesis of olefins possessing an axis of chirality. However, most of these reagents are restricted to the compounds with non-stereogenic phosphorus atom. Although Motoyoshiya et al. reported geometrical selectivity of HWE reactions of aldehydes with racemic phosphonoacetates, 12) the asymmetric HWE reaction of P-stereogenic phosphonoacetates has never been established. Herein we describe a facile synthesis of novel chiral phosphonoacetates bearing a stereogenic phosphorus atom utilizing the enzymecatalyzed kinetic resolution of racemic phosphonoacetates derived from two kinds of Z-selective HWE reagents, methyl bis(2,2,2-trifluoroehtyl)phosphonoacetate (Still's reagent, 1)13) and ethyl diphenylphosphonoacetate (2). 14)Recently, we reported a new and efficient stereoselective HWE reaction of aldehydes and ketones with bis(2,2,2-trifluoroehtyl)phosphonoacetic acid and found oxophilicity of a phosphorus atom of phosphonoacetate 1. 15,16) That is to say, the phosphonate moiety of 1 was found to be more easily hydrolyzed than the ester moiety of 1 under aqueous alkaline conditions. Thus, the phosphonoacetic acid was readily prepared by enzymatic hydrolysis of 1 with porcine liver esterase (PLE). Although attempts to hydrolyze the ester moiety of 1 under aqueous alkaline conditions were unsuccessful, reactions of 1 with various alcohols in the presence of triethylamine or 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) gave the corresponding phosphonoacetate rac-3a-d as the major product (Chart 1). The similar transformation of 2 using various alcohols gave rac-4a-d as shown in Chart 2. Attempts to hydrolyze 2 under aqueous alkaline conditions were also unsuccessful, though phosphonoacetates 4a and 5-7 were obtained (Chart 2). It can be concluded that the high oxophilicity of phosphorus atoms of these HWE reagents 1 and 2 appears to be necessary for Z-selective HWE reaction with aldehydes. [17][18][19] The phosphonoacetates rac-3a-d were subjected to enzymatic hydrolysis utilizing PLE (Sigma, E-2884), as follows. Phosphonoacetates rac-3a-d were dissolved in 1/15 M phosphate buffer solution (pH 7.4) and acetone (9 : 1). After addition of PLE (800 units/mmol), the mixture was stirred at room temperature for the appropriate time. The reaction mixture was treated with 10% HCl and then extracted with AcOEt. After evaporation of the extraction in vacuo, the residue was purified on a silica gel column with CHCl 3 -MeOH as eluent to give the corresponding carboxylic acid 8 and unreacted ester 3. The enantiomeric excess of resolution product 8 was determined by means of HPLC analysis with chiral-stationary-phase (CSP) after methylation with (trimethylsilyl)diazomethane (TMSCHN 2 ). 20) Unreacted resolution compound 3 was also subjected to HPLC analysis with CSP. As the result of enz...

Carboxylic acid estersCarboxylic acid esters Q 0530 (E)-Selective Horner-Wadsworth-Emmons Reaction of Aryl Alkyl Ketones with Bis(2,2,2-trifluoroethyl)phosphonacetic Acid. -In contrast to the corresponding methyl ester, the phosphonoacetic acid (I) reacts highly (E)-selectively with alkyl aryl ketones (II) utilizing lithium hexamethyldisilazide in DMF. -(SANO*, S.; TAKEMOTO, Y.; NAGAO*, Y.; Tetrahedron Lett. 44 (2003) 49, 8853-8855; Fac. Pharm. Sci., Univ. Tokushima, Sho, Tokushima 770, Japan; Eng.) -Mais 10-095