Influencing factors of disinfection byproducts formation during chloramination of Cyclops metabolite solutions.

Effects of reaction time, chlorine dosage, pH and temperature on the formation of disinfection byproducts (DBPs), were investigated during the chloramination of Cyclops metabolite solutions. The results showed that some species of DBPs like trichloromethane (TCM), dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) could accumulate to their respective stable values with a progressive elevation in reaction time and monochloramine concentration. And 1,1,1-2-trichloropropanone (1,1,1-TCP) content decreased correspondingly with a continuous increase of reaction time. The amounts of chloral hydrate (CH), chloropicrin (TCNM), 1,1,1-TCP and DCAA firstly increased and then decreased with increasing monochloramine doses. Higher temperature resulted in a decrease of CH, dichloroacetonitrile (DCAN), 1,1-dichloropropanone (1,1-DCP), 1,1,1-TCP, DCAA and TCAA concentration. pH affected the formation of the different DBPs distinctly. TCM accumulateded with the increase of pH under 9, and DCAA, TCAA, CH and 1,1-DCP decreased continuously with increasing pH from 5 to 10, and other DBPs had the maximum concentrations at pH 6-7.

[Photogenerator of trichloroacetic acid--a perspective detritylation agent for microchip oligonucleotide synthesis].

For the purpose of new detritylation agents search for microarray oligonucleotide synthesis we investigated applicability of [4-(4-methoxyphenyl)-2,6-dinitro-phenyl](phenyl)methyl 2,2,2-trichloroacetate for 4,4'-dimethoxytrityl group detritylation during oligonucleotide syntheses generating trichloroacetic acid at radiation by light with a length of wave of 405 nanometers. [4-(4-Methoxyphenyl)-2,6-dinitro-phenyl](phenyl)methyl 2,2,2-trichloroacetate has been successfully used for solid-phase oligonucleotide synthesis of desired oligonucleotides.

Synthesis, growth, spectral and thermal properties of a new organic crystal: 2-carboxypyridin-1-ium trichloroacetate.

A novel organic optical material complex of 2-carboxypyridin-1-ium trichloroacetate has been synthesized and crystals were grown from aqueous solution employing the technique of controlled evaporation. The crystal structure has been determined using single crystal X-ray diffraction studies. The single crystals were successfully grown by the slow evaporation method with dimensions 12 × 8 × 3 mm(3). FT IR spectral investigation has been carried out to identify the various functional groups present in the grown crystal. Molecular structure was confirmed by NMR spectral analysis. Melting point was found using thermal measurements.

Translocation versus cyclisation in radicals derived from N-3-alkenyl trichloroacetamides.

Under radical reaction conditions, two different and competitive reaction pathways were observed for N-(α-methylbenzyl)trichloroacetamides with a N-3-cyclohexenyl substituent: 1,4-hydrogen translocation and radical addition to a double bond. However, for radicals with an acyclic alkenyl side chain, the direct cyclisation process was exclusively observed. The dichotomy between translocation and direct radical cyclisation in these substrates has been theoretically studied using density functional theory (DFT) methods at the B3LYP/6-31G** computational level.

Electrospinning of matrigel to deposit a basal lamina-like nanofiber surface.

Schwann cell basal lamina is a nanometer-thin extracellular matrix layer that separates the axon-bound Schwann cells from the endoneurium of the peripheral nerve. It is implicated in the promotion of nerve regeneration after transection injury by allowing Schwann cell colonization and axonal guidance. Hence, it is desired to mimic the native basal lamina for neural tissue engineering applications. In this study, basal lamina proteins from BD Matrigel (growth factor-reduced) were extracted and electrospun to deposit nonwoven nanofiber mats. Adjustment of solute protein concentration, potential difference, air gap distance and flow rate produced a basal lamina-like construct with an average surface roughness of 23 nm and composed of 100-nm-thick irregular and relatively discontinuous fibers. Culture of embryonic chick dorsal root ganglion explants demonstrated that the fabricated nanofiber layer supported explant attachment, elongation of neurites, and migration of satellite Schwann cells in a similar fashion compared to electrospun collagen type-I fibers. Furthermore, the presence of nanorough surface features significantly increased the neurite spreading and Schwann cell growth. Sciatic nerve segment incubation also showed that the construct is promigratory to nerve Schwann cells. Results, therefore, suggest that the synthetic basal lamina fibers can be utilized as a biomaterial for induction of peripheral nerve repair.

On the origin of the regioselectivity in glycosylation reactions of 1,2-diols.

The assistance of neighboring protecting groups with different orientations in 1,2-diol acceptors and the reactivity of both reaction partners, the donor and the acceptor, have been evaluated as factors that determine the regioselectivity of glycosylation reactions. It has been established, by experimental and theoretical studies, that the regioselectivity for the glycosylation of a given OH group can be considerably increased by the presence of groups able to form a hydrogen bond with that OH group. Moreover higher regioselectivities are observed when armed donor/activated acceptor combinations are avoided.

A study on the influence of the structure of the glycosyl acceptors on the stereochemistry of the glycosylation reactions with 2-azido-2-deoxy-hexopyranosyl trichloroacetimidates.

The stereochemical outcome of glycosylations with 2-azido-2-deoxy-D-gluco- and D-galactopyranosyl trichloroacetimidates as glycosyl donors has been investigated by using a series of chiro-inositol derivatives as glycosyl acceptors. The influence of the absolute configuration, the conformation and the conformational flexibility of the glycosyl acceptor has been studied by using different glycosyl donors under similar pre-established experimental conditions. Although the structure of the acceptor may play a role in governing the stereochemistry of these glycosylations, the results show that, in general terms, the relative influence of these factors is difficult to evaluate. For a given set of experimental conditions, the stereochemical course of these glycosylations depends on structural features of both glycosyl donor and glycosyl acceptor. It is a balance of these factors, where the structure of the glycosyl donor always plays a major role, which determines the stereochemistry of the coupling reaction. Therefore, the examples reported in the literature in which the structure of the glycosyl acceptor appears to be crucial in determining the stereochemistry of the reaction constitute particularly favorable cases which do not presently allow any further generalization.

Concerning the origin of the high beta-selectivity of glycosidation reactions of 2-deoxy-2-iodo-glucopyranosyl trichloroacetimidates.

[structure: see text] Studies on the glycosidation reactions of conformationally constrained glycosyl imidates 8a and 8b were performed to evaluate the possible involvement of "conformationally inverted" oxonium ion intermediates in glycosidation reactions with 2-deoxy-2-iodo-glucopyranosyl donors. The mechanistic implications of this study are discussed, and intermediates 23 and 24 are invoked to rationalize the observed beta-selectivities.

Photochemical reaction monitoring by ultra-violet spectrophotometry.

Within the framework of the monitoring of the trichloroacetylchloride (TCAC) photosynthesis, ultra-violet (UV) spectrophotometry is proposed as a simple and rapid tool allowing, in real time, the control of the process efficiency. A good correlation has been obtained between the results acquired by this alternative method and the standard gas chromatography.

Standardizing chemical peel solution formulations to avoid mishaps. Great fluctuations in actual concentrations of trichloroacetic acid.

BACKGROUND: Chemical peeling using trichloroacetic acid (TCA) is a popular and long utilized procedure in dermatology and cosmetic surgery. OBJECTIVE: To determine the actual concentration of TCA in four disparate methods of preparation of solutions, expressed in the standard pharmaceutical method of weight to volume (wt/vol). METHODS: Method I was wt/vol, method II was weight to weight (wt/wt), method III was grams of TCA added to 100 cc water, and method IV was the usage of saturated TCA, and calling it 100%, then making appropriate dilutions. The amounts of TCA in each solution for methods II, III, and IV were converted, by calculation, to the wt/vol method. RESULTS: The relative concentrations of TCA, ranked by the wt/vol pharmaceutical standard, showed that from strongest to weakest: method IV > method II > method I > method III. CONCLUSIONS: Tremendous variations were found in the relative concentrations of TCA in these solutions. To avoid mishaps and complications, the wt/vol method should be used.