4935-93-7

This study evaluated the effects and related mechanisms of natural organic matter (NOM) on the photolysis of methyltriclosan (MTCS), a metabolite of triclosan. Addition of two representative NOM isolates, Pony Lake fulvic acid (PLFA-microbial origin) and Suwannee River fulvic acid (SRFA-terrestrial origin), significantly inhibited the direct photolytic rate of MTCS by ～70%. The MTCS photolytic rate in the presence of PLFA was greater than for SRFA. NOM not only suppressed photolysis by light-shielding, but also produced ROS to oxidatively degrade MTCS and/or triplet NOM (3NOM?) to sensitize degradation. The dual effects of light-screening and photo-sensitization led to an overall decrease in photolysis of MTCS with a positive concentration-dependence. Upon addition of NOM, EPR documented the occurrence of 1O2 and OH in the photolytic process, and the bimolecular k value for the reaction of 1O2 with MTCS was 1.86 × 106 M-1 s-1. ROS-quenching experiments indicated that the contribution of OH (19.1-29.5%) to indirect photolysis of MTCS was lower than for 1O2 (38.3-58.7%). Experiments with D2O further demonstrated that 1O2 participated in MTCS photodegradation. Moreover, the addition of sorbic acid and O2 gas to the reaction confirmed the participation of 3NOM? as a key reactant in the photochemical transformation of MTCS. This is the first comprehensive analysis of NOM effects on the indirect photolysis of MTCS, which provides new insights for understanding the environmental fate of MTCS in natural environments.

The invention relates to a preparation method of triclosan methyl ester, wherein the preparation method comprises the steps: fully dissolving triclosan in acetone, adding sodium hydroxide, uniformly mixing, adding methyl iodide, stirring at room temperature for 15 min, heating to 40 DEG C-55 DEG C in a closed stirring state, and carrying out reflux reaction for 2-4 h; after the reaction is finished, dissolving with dichloromethane for multiple times, cleaning, filtering, dewatering and concentrating to obtain a yellow viscous concentrated solution; separating and purifying the concentrated solution by adopting medium-pressure preparative chromatography, collecting a product according to an ultraviolet absorption signal of a medium-pressure preparative chromatography detector, carrying outrotary evaporation and nitrogen blowing on the collected product, and thoroughly drying to obtain colorless syrup-like triclosan methyl ester. According to the method, the methylation efficiency of triclosan is effectively improved, the post-treatment steps are simplified, meanwhile, the post-treatment purification method is suitable for purification of constant samples, the accuracy of target component separation is high, and the purity and yield of products are guaranteed.

Exploration of triclosan analogs has led to novel diaryl ureas with significant potency against in vitro cultures of drug-resistant and drug-sensitive strains of the human malaria parasite Plasmodium falciparum. Compound 18 demonstrated EC50 values of 37 and 55 nM versus in vitro cultured parasite strains and promising in vivo efficacy in a Plasmodium berghei antimalarial mouse model, with >50% survival at day 31 post-treatment when administered subcutaneously at 256 mg/kg. This series of compounds provides a chemical scaffold of novel architecture, as validated by cheminformatics analysis, to pursue antimalarial drug discovery efforts.

A sensitive method for the determination of triclosan in plasma and milk is presented. Following hydrolysis of possible conjugates, triclosan is extracted with n-hexane/acetone, partitioned into alcoholic potassium hydroxide, and converted into its pentafluorobenzoyl ester. After sulfuric acid cleanup, sample extracts are analyzed by gas chromatography/electron capture negative ionization mass spectrometry. The limit of quantification was 0.009 ng/g for a 5-g plasma sample and 0.018 ng/g for a 3-g milk sample. The coefficient of variation for the method was 6%. The method was tested on more than 70 human plasma and milk samples, of which all plasma samples and more than half of the milk samples were above the limit of quantification. The presented method has lowered the limit of quantification for triclosan in human matrixes significantly as compared to previous methods and makes possible the analysis of triclosan in humans under normal exposure conditions.

The bactericide triclosan and methyl triclosan, an environmental transformation product thereof, have been previously detected in lakes and a river in Switzerland. Both compounds are emitted via wastewater treatment plants (WWTPs), with methyl triclosan probably being formed by biological methylation. Passive sampling with semi-permeable membrane devices (SPMDs) showed the presence of methyl triclosan in some lakes, suggesting some potential for bioaccumulation of the compound. In this study, we report the presence of methyl triclosan in fish (white fish, coregonus sp.; roach, rutilus rutilus) from various lakes in Switzerland receiving inputs from WWTPs. Identification of the compound was based on mass spectral (MS) evidence including MS/MS data. The concentrations of methyl triclosan in the fish were up to 35 ng g-1 on a wet weight basis and up to 365 ng g -1 on a lipid basis with concentrations in a relatively narrow range for fish from the same lake (Thunersee, 4-6 ng g-1 Zuerichsee, 32-62 ng g-1; Pfaeffikersee, 43-56 ng g-1; Greifensee, 165-365 ng g-1, lipid basis). No methyl triclosan (-1, lipid basis) was detected in fish (lake trout, salmo trutta) from a remote lake in Sweden (Haebberstjaernen) and in fish (roach) from a small lake in Switzerland with no input from WWTPs (Huettnersee, -1, lipid basis). The concentrations of methyl triclosan in fish correlated (r2 = 0.85) with the ratio of population in the watershed to water throughflow of the lakes (P/Q ratio), which is considered to be a measure for the domestic burden from WWTPs to a lake. Passive sampling with SPMDs confirmed the presence of methyl triclosan in lakes and a river (Zuerichsee and Greifensee; Limmat) but not in a remote mountain lake (Joerisee) and in Huettnersee. The bioconcentration factor (BCF) of methyl triclosan estimated from the fish data and SPMD-derived water concentrations was in the order of 1-2.6 × 105 (lipid basis) and thus in the range of other persistent organic pollutants. SPMDs were found to be reliable for monitoring low concentrations of methyl triclosan in surface water. Methyl triclosan appears to be a suitable marker for WWTP-derived lipophilic contaminants in the aquatic environment and fish.

A process is disclosed for the synthesis of 2,4,4'-trichloro-2'-methoxydiphenyl ether, and it's precursor 2,4,4'-trichloro-2'-bromodiphenyl ether, a novel compound.

Several polychlorinated phenoxyphenols with three to nine chlorine atoms were examined as their methyl ethers by electron capture negative ion and positive ion chemical ionization and electron impact mass spectrometry.In chemical ionization studies methane, hydrogen, nitrogen, helium and argon were used as reagent gases.Selected compounds were also examined with deuteriomethane, ammonia and deuterioammonia as reagent gases.Utilization of chemical ionization spectra in conjunction with electron impact spectra provides substantial structural information about these compounds.Chemical ionization spectra provide information about chlorine atom substitution.The position of phenoxy substitution can be established from electron capture negative ion and positive ion spectra.

The methyl ethers of a number of hydroxylated (poly)chlorodibenzo-p-dioxins, chlorodibenzofurans, chlorodiphenyl ethers and chloronaphthalenes, representing all different hydroxy substitutions, were synthesized and their mass spectra investigated. With the exception of the methoxy derivatives of the chlorodibenzofurans, it appeared that the mass fragmentation patterns of the structural isomers of each class of compounds were very specific and allowed unambiguous assignment of the position of the methoxy group in the molecule. The different fragmentation patterns can be explained in terms of plausible mechanisms resulting in stable charge delocalized (oxonium) ions. Because of its diagnostic value, this method is useful in the structure elucidation of hydroxylated metabolites of pure isomers of chlorodibenzo-p-dioxins, chlorodiphenyl ethers and chloronaphthalenes.