Thio acids oxidation

The pyridinium chlorochromate (PCC) oxidations of pentaamine cobalt(III)-bound and unbound mandelic and lactic acids have been studied and found to proceed at similar rates.Free-energy relationships in the oxidation of aromatic anils by PCC have been studied. Solvent effects in the oxidation of methionine by PCC and pyridinium bromochromate (PBC) have been investigated the reaction leads to the formation of the corresponding sulfoxide and mechanisms have been proposed. The major product of the acid-catalysed oxidation of a range of diols by PBC is the hydroxyaldehyde. The reaction is first order with respect to the diol and exhibits a substantial primary kinetic isotope effect. Proposed acid-dependent and acid-independent mechanisms involve the rapid formation of a chromate ester in a pre-equilibrium step, followed by rate-determining hydride ion transfer via a cyclic intermediate. PBC oxidation of thio acids has been studied. ... 

Oxidation of thio acids by tetrabutylammonium tribromide showed Michaelis-Menten-type kinetics with respect to the thio acid. The effect of solvent composition was analysed using the Grunwald-Winstein equation. A mechanism involving the formation of an intermediate complex in the pre-equilibrium and its subsequent decomposition in a slow step is proposed.129... 

Hq8 1.4785. It was prepd from thiosemicar-bazide and /S-ethoxypropionyl chloride, followed by nitrous acid oxidation of the intermediate thio (Ref 2)... 

Organotin esters of the oxy- and thio-acids of phosphorus can be prepared inter alia by azeotropic dehydration of a mixture of the organotin hydroxide or oxide and the acid, or by treating a tin alkoxide or tin amide with the acids, or an organotin halide with a salt of the phosphorus acid. By using different molecular ratios of the reactants, products of different compositions can be obtained. Attempts to prepare phosphites may result in an Arbuzov rearrangement to a phosphorus(V) compound (e.g. equation 13-11).47... 

PENTEK (115-77-5) Combustible solid (flash point unknown). Dust cloud forms explosive mixture with air. Incompatible with organic acids, oxidizers. Incompatible with thio-phosphoryl chloride. 

Investigation into new thio-acid compounds from oxide, hydroxide, and sulfide precursors is being excuted. One new compound has recently demonstated lO S/cm at 100°C. 

Earlier, attention was drawn to a novel application of the oxidative desulphurization reaction which occurs between sulphoxides and phosphonothioic acid esters. When 1 mol of the thio acid is allowed to remain in contact with 2 mol of a racemic methyl alkyl sulphoxide for 2 weeks at room temperature, the unreacted sulphoxide is found to be optically active, a result which represents asymmetric deoxygenation of the sulphoxide. The chemical course of the reaction is consistent with Scheme 31. Since the appearance of the initial results, corrections have been made to the configurations of the phosphorus-containing substrates, and hence the stereochemical details and mechanistic arguments require reappraisal neverthless, the fact remains that (-t-)-sulphoxides are obtained by the use of the ( S)-(-)-acids, R (R O)P(S)OH , a feature which can be used to determine the chirality of other like acids. Dialkyl and alkyl aryl sulphoxides are also known to form diastereoisomeric complexes with (5)-(-)-/er butylphenylphosphinothioic acid, distinguishable by their NMR spectra, and through such complexation it is possible to assess the enantiomeric composition of the sulphoxide " ... 

Keywords Ru-pac complex Kinetics Reaction mechanism Catalysis —0—0— bond activation DNA binding DNA cleavage Thio-amino acid oxidation FTP inhibition Dye degradation NO scavenging Redox reactions Biomolecules. 

One group of compounds that have proved to be particularly effective in interfering with DNA synthesis of tumour cells are the mercapto-purines and pyrimidines and their alkyl derivatives 6-mercaptopurine (6-MP) blocks the de novo synthesis of purines 9-(jS-D-arabinofuranosyl)-—9H—purine—6-thiol (ara—6-MP) inhibits the incorporation of L-aspartic acid and orotic acid into DNA cystosine 9-OS-D-xylo-furanosyl)—9H—purine—6-thiol (xyl—6-MP) inhibits the utilization of exogenously administered guanine the periodic acid oxidation product of 9-(/S-D-ribosyl)—6-methyl—thio purine (MMPR—OP) blocks the incorporation of thymidine into DNA . The effective clinical use of thiols... 

Not surprisingly, thio acids (thiolocarboxylic acids, Equation 9.86), prepared by reaction of acyl chlorides with hydrogen sulfide (H2S), are easily oxidized (e.g., on standing in the air) to disulfides (Equation 9.87). 

Sodium salts of a-thio-acids [e.g. (41)] can be decarboxylated oxidatively to give the less thermodynamically stable isomer of the enol thioether product [e.g. (42)] by using V-chlorosuccinimide in dimethoxyethane (cf. 2,49). The rate of... 

The perfluoroalkane sulfonic acids were fkst reported ki 1954. Trifluoromethanesulfonic acid was obtained by the oxidation of bis(ttifluoromethyl thio) mercury with aqueous hydrogen peroxide (1). The preparation of a series of perfluoroalkanesulfonic acids derived from electrochemical fluotination (ECF) of alkane sulfonyl haUdes was also disclosed ki the same year (2). The synthetic operations employed when the perfluoroalkanesulfonic acid is derived from electrochemical fluotination, which is the best method of preparation, are shown ki equations 1—3. 

Folic acid, 5-methyltetrahydro-biological activity, 3, 325 oxidation, 3, 308 Folic acid, iV-nitroso-carcinogenicity, 1, 141 Folic acid, 10-oxa-synthesis, 3, 327 Folic acid, 4-piperidyl-hydrolysis, 3, 294 Folic acid, 5,6,7,8-tetrahydro-chirality, 3, 281 synthesis, 1, 161 Folic acid, 10-thio-synthesis, 3, 327... 

Campaigne et al. have used 3-thenyl bromide obtained by benzoyl peroxide-catalyzed, side-chain bromination of 3-methylthiophene with A -bromosuccinimide, as a starting material for 3-substituted thiophenes. - 22 3-Methylthiophene is now prepared commercially from itaconic acid. The reactive halogen in 3-thenyl bromide could be directly reacted with a variety of nucleophiles, such as cyanide, or malonate, to give more complex 3-substituted compounds. 3-Thenyl bromide was converted by the Sommelet reaction to 3-thio-phenealdehyde which, with silver oxide, was oxidized to 3-thio-... 

Chromi-nydroxyd, n. chromic hydroxide, chro-mium(III) hydroxide, -oxyd, n. chromic oxide, chromium(III) oxide, -rhodanwasser-stoffsMure, /. chromithiocyanic acid, thio-cyanatochromic(III) acid, -salz, n. chromic salt, chromium(III) salt, -suifat, n. chromic sulfate, chromium(III) sulfate, -suifocyan-saure, /. chromithiocyanic acid, thiocyana-tochromic(III) acid, -verbindung,/. chromic compound, chromium(III) compound. 

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