Thiols chromium oxide

Chromium(VI) oxide will ako oxidize hydroquinones to quinones, and thiols to disulfides. ... 

Tetrabutylammonium chlorochromate, (C4H9)4XCr03CI, is formed by adding a solution of chromium trioxide in concentrated hydrochloric acid to a solution of tetrabutylammonium hydrogen sulfate in 5 N hydrochloric acid at 0 °C. The dry compound is used in chloroform for the oxidation of alcohols to carbonyl compounds and the oxidative coupling of thiols to disulfides [619],... 

FIGURE 10.5 Potential energy diagram (enthalpy of reaction in kcal/mol) for oxidative addition of thiols. The first step involves the formation of a reversible 19 e coordinated thiol adduct that has an estimated enthalpy of binding of —3 to —6 kcal/mol. The transition state occurs when this is attacked by a second mole of chromium radical. The measured enthalpy of activation is near 0 kcal/mol since the exothermic enthalpy of binding in the first step is canceled by the activation enthalpy of the second step. Adapted with permission from reference 79. Copyright 1996, American Chemical Society. 

Related methods can be used to prepare 5-hetero-substituted compounds isonitriles with A-halo-succinimides and azide give halo derivatives, aryl isothiocyanates with azide give the 5-thiols, ° which can be converted into 5-unsubstituted tetrazoles by oxidation with hydrogen peroxide or chromium trioxide. ... 

Transition metals, such as chromium, manganese, or cerium are able to oxidize organic functional group, such as alcohols, aldehydes, amines, thiols, forming free radicals which can initiate copolymerization ... 

The oxidation of thiols by metal ions is of continuing interest and recently the rapid reaction of penicillamine with chromium(vi) has been investigated. The rate law is found to be of the form... 

The processes involved in these adsorptions are related to coordination chemistry in solution, but occur in two dimensions. Metal smfaces can be viewed as planes of metal atoms having vacant coordination sites. Appropriate ligands coordinate (or, in the terms of surface science, adsorb) to a metal surface and form an ensemble that we and others refer to as a self-assembled monolayer. Adsorbates containing polymethylene chains are the most commonly studied b ause they often form oriented, highly ordered SAMs. Some of the presently available systems that yield SAMs include alkanoic acids on oxidized metal surfaces (especially aluminum) (4), alkyl amines on oxidized surfaces of chromium and platinum (5), isonitriles on platinum (6), sulfides (7), disulfides (8-10), and thiols (11,12), on gold, and thiols on silver (ISIS), All of these systems have analogs in classical coordnation chemistry (16). 

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