introduction water quality refers to the chemical, physical and biological characteristics of water. it is a measure of the condition of water relative to the requirements of one or more biotic species and or to any human need or purpose. it is most frequently used by reference to a set of standards against which compliance can be assessed. the most common standards used to assess water quality...

During the course of recent studies on the formation of functionalized cyclopropanes via diazoketones, we required a safe, scalable alternative to diazomethane in the Arndt–Eistert synthesis of diazoketones.1 Trimethylsilyldiazomethane is often touted as a safe alternative to diazomethane, but the opportunity still exists for the in situ generation of diazomethane when using this reagent. Furth...

[reaction: see text] The Heck reaction of aryl chlorides was investigated in the presence of defined monocarbenepalladium(0) complexes. Activated and nonactivated aryl chlorides provide the corresponding cinnamic esters and stilbenes in (n)Bu(4)NBr as a ionic liquid in good to excellent yields.

A catalyst based on a new biarylphosphine ligand (3) for the Pd-catalyzed cross-coupling reactions of amides and aryl chlorides is described. This system shows the highest turnover frequencies reported to date for these reactions, especially for aryl chloride substrates bearing an ortho substituent. An array of amides and aryl chlorides were successfully reacted in good to excellent yields.

An efficient method for the synthesis of aryl and heteroaryl chlorides is described. The reactions of aryl and heteroaryl bromides with tetramethylammonium chloride proceeded smoothly in the presence of a copper catalyst under mild reaction conditions to produce the corresponding chlorides in satisfactory to excellent yields.

[equation: see text] An efficient one-pot route to unsymmetrical diorganyl selenides has been developed by ruthenium(III) chloride catalyzed reactions of dibenzyl or diphenyl diselenides with alkyl halides in the presence of zinc. Organic iodides, bromides, and activated chlorides underwent the reactions efficiently. Unreactive organic chlorides also underwent the same type of selenation with s...

The objective of this study was to determine the in vitro transdermal permeation through human epidermis of zalcitabine, lamivudine and the synthesised N-acyl lamivudine esters, with and without the use of Pheroid as delivery system and to establish a correlation, if any, with selected physicochemical properties. Six N-acyl lamivudine esters were prepared by acylation of lamivudine with six dif...

A sequence of Michael addition of a primary amine onto methyl 2-chloro-2-cyclopropylidene-acetate (1), acylation of the adduct with alpha-bromo acid chlorides under modified Schotten-Baumann conditions and ring-closing twofold nucleophilic substitution on the thus formed bishalides 3a-e with aliphatic or aromatic amines according to a very simple protocol with final acid/base extraction or filt...

A new series of 2-[N-(Tosor Pht-)aminoacylp-substituted phenylmethyleneamino]pyrimdines (V-XII) was synthesized via the reaction of Schiff bases, 2-(4-substituted benzylidene)aminopyrimdines (I,II) with the requisite tosyl or phthalylaminoacyl chlorides. Elongation of these amino acid derivatives to form the corresponding dipeptides (XVII-XXIV) were synthesized starting with 2-[glycyl or Dl-val...