Disulfides from sulfinic acids

Reduction of sulfur compounds by hydrazine Sym. disulfides from sulfinic acid esters... 

Disulfides are obtained from sulfinic acids on reduction by hydrogen bromide in acetic acid solution 553,555-557... 

Sulfonic acid chlorides from disulfides via sulfinic acids s. 18, 561 SOgH SO2GI... 

Thiolsulfonic acid esters from sulfinic acids and disulfides... 

Sulfinyl chlorides may be prepared from the corresponding thiols or disulfides by oxidative reactions rather than by reductions of sulfonyl compounds. A recent example, which improves the earlier procedure of Douglass, is given by equation (3)50. The chemistry of sulfinic acids and their derivatives has been reviewed51 52,53. 

A very surprising sulfone formation has been investigated by Oae and coworkers . On heating p-toluenesulfinic acid with dimethylaniline in ethanol for 15 h, the reaction mixture shown in equation 100 has been obtained. Obviously, the observed products arise from an equilibrium between the sulfinic acid and its pseudo-anhydride (disulfide trioxide), which is able to attack the amine nitrogen and degrade the tertiary amine corresponding to a Polonovsky reaction . 

Methyl methanethiosulfonate (MMTS) is a small reversible blocking agent for sulfhydryl groups (Thermo Fisher, Toronto Research). It reacts with free thiols to form a dithiomethane modification with release of sulfinic acid (Figure 1.122). The sulfinic acid component decomposes into volatile products, which don t affect the disulfide formed from the MMTS reaction Alkylthiosulfonates react rapidly with thiols under mild conditions at physiological pH. The MMTS compound is a liquid at 10.6 M concentration and is conveniently added to a reaction medium by pipette. Complete thiol modifications of available cysteine residues in proteins can... 

Sulfenyl cldorides, sulfinic acids and sulfinyl chlorides were reduced in good yields by lithium aluminum hydride to disulfides [680], The same products were obtained from sodium or lithium salts of sulfinic acids on treatment with sodium hypophosphite or ethyl hypophosphite [507]. Sulfoxy-sulfones are intermediates in the latter reaction [507]. 

Thiazolyl sulfamic acids, rearrangement of sulfonic acid, 70 rearrangement to sulfonic acid, 75 by sulfonation, 75 2-Thiazolyl sulfenyl chloride, transformation to, thiazolyl disulfides. 412 2-Thiazolyl sulfide, in hydrocarbon synthesis, 406 oxidation of, with m-chloroperbenzoic acid, 415 with CrOj, 415 with Hj02,405,415 with KMn04,415 physical properties, infrared, 405 NMR, 404 pKa, 404 ultraviolet, 404 preparation of, from 2-halothiazoles and 5-Thiazolyl sulfides, bis-5-thiazolyl sulfide, oxidation of, 415 general, 418 5-(2-hydroxythiazolyl)phenyl sulfide case, 418 physical properties, 418 preparation of, 417-418 table of compounds, 493-496 uses of. 442 2-Thiazolyl sulfinic acid, decomposition of, 413 preparation of, from 2-acetamidothiazole sulfonyl chloride, 413 from A-4-thiazoline-2-thione and H, 0, 393,413 table of compounds, 472-473 5-Thiazolyl sulfinic add, preparation of,... 

The interest in papain increased enormously after the publication by Kimmel and Smith [9] of a modification of the purification procedure of Balls and Lineweaver [5]. This modification permitted the isolation of pure papain from papaya dried latex and was used for many years as the standard method for the production of papain. The crystalline papain of Kimmel and Smith consists of three components active papain, reversibly oxidized papain, and irreversibly oxidized papain. Reversibly oxidized papain can be converted into active papain by reduction of the active-site thiol by low molecular weight thiols [10], sodium borohydride [11], or CN- [12]. In active papain, the Cys-25, which is essential for catalytic activity, is present in a reduced form, while in reversibly oxidized papain the Cys-25 forms a mixed disulfide with cysteine. Drenth et al. reported that in irreversibly oxidized papain the Cys-25 has been oxidized to the sulfinic acid... 

Oxidative desulfurization can be effected by ozonolysis (Scheme 74). 2-Thiol-4(3//)-quinazolinone on ozonolysis in dry dichloromethane yields the disulfide (448) which is resistant to further oxidation under the reaction conditions. In acetic acid, desulfurization results with hydrogen substitution (449). Rationalization of the reaction in acetic acid involves formation of an unstable sulfinic acid which loses SO2 with replacement by hydrogen. In dichloromethane containing ethanol, the 2-ethoxy product (450) formed, corresponding to nucleophilic substitution of the reactive sulfinic acid from the oxidation. Similarly, ozonolysis of pyrimidine-2-thione acid gave bis-2-pyrimidinyl disulfide in dry dichloromethane and 2-ethoxypyrimidine in the presence of ethanol <93TL1631>. 

Sulfuric acid may be reduced to the level of sulfide and is then an important building stone of L-cysteine (see below). L-Cysteine, (S)- x-amino-/ -thiolpropionic acid, is one of the most important sulfur-containing substances in primary metabolism. The secondary products derived from L-cysteine may contain the sulfur in different states of oxidation. Of importance are sulfides (—S—), disulfides (—S—S— ), sulfenic acids (—S—OH), sulfoxides (—SO— ), sulfinic acids (—SO—OH) and sulfonic acids (—SO2—OH). 

Sodium hydroxide (s, a. under H2O2) Sulfinic acids from disulfides 6-Purinesulfinic acids s. 17, 156... 

Hydrogen peroxide sodium hydroxide Sulfinic acids from disulfides s. 18, 561... 

Sodium hydroxide Sulfinic acids from disulfides... 

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