Direct and indirect reduction

Abdel-Magid, A. F. Carson, K. G. Harris, B. D. Maryanoff, C. A. Shah, R. D. Reductive Amination of Aldehydes and Ketones with Sodium Triace-toxyborohydride. Studies on Direct and Indirect Reductive Amination Procedures, J. Org. Chem. 1996, 67, 3849. 

In the absence of protons the deprotection is complicated by nucleophilic attack of RO on the tosylate ester with formation of the ether, ROR [Eq. (60)]. This side reaction can be suppressed on addition of a proton donor, such as acetic acid. In that case aromatic radical anions cannot be used as catalyst and Ni(acacen) was used. The difference in yield of deprotected alcohol from direct and indirect reduction was insignificant [249]. 

Many of the direct and indirect reduction methods retain the chiral nature of the starting material. A good general rule is if the production method does not use boiling acids, racemization does not occur. One can then conclude that only the direct reduction with palladium black, and the hydroiodic acid and red phosphorus methods lead to racemization of the starting material. 

II. ELECTROREDUCTION OF SULPHONIC ESTERS A. Direct and Indirect Reductions... 

Impurities present in coke (moisture, volatile matter, ash, sulfur, phosphorous, and alkali contents) affect its performance in the blast furnace by decreasing its role as a fuel in terms of amounts of carbon available for direct and indirect reduction roles and also its role as a permeable support. 

Hauquier F, Matrab T, Kanoufi F, Combellas C (2009) Local direct and indirect reduction of electrografted aryldiazonium/gold surfaces for polymer brushes patterning. Electrochim Acta 54 (22) 5127-5136. doi 10.1016/j.electacta.2009.01.059... 

The impact of price subsidy programs on consumers real income is equivalent to the sum of direct and indirect reductions in the prices of the commodities consumed, which depends greatly on the incidence of participation as measured by actual consumption levels. 

One purpose of this investigation was to determine whether the rate determining step for CT and TCE reduction involves electron transfer. A second goal of this research was to determine the contribution of direct and indirect reduction mechanisms to the overall rate of TCE and CT dechlorination. 

Results from this study indicate that reduction of CT involves direct electron transfer, and that the rate of electron transfer controls the CT dechlorination rate. In contrast, reaction of TCE involves both direct and indirect reduction mechanisms, and the rate determining step does not involve electron transfer. The indirect reduction mechanism for TCE is faster than the direct mechanism, but its contribution to the overall rate of dechlorination decreases with increasing concentration. 

All the evidence gathered so far points to the conclusion that the RX radicals are intermediates in the reductive cleavage of aryl halides by outer sphere electron donors in polar solvents. This was an already established conclusion for the reduction of several aryl halides in the gas phase (Steelhammer and Wentworth, 1969 Wentworth et al., 1967), and for iodobenzene in apolar or weakly polar matrixes from y-irradiation studies with esr detection at low temperatures (Symons, 1981). It might, however, not have been true in the polar media used in direct and indirect electro-... 

At this point, it can be concluded that the direct and indirect electrochemical approach of the reaction in the case of aryl halides has provided a quantitative kinetic demonstration of the mechanism and the establishment of the nature of the side-reactions (termination steps in the chain process). In poor H-atom donor solvents, the latter involve electron-transfer reduction of the aryl radical. 

In healthy patients, propofol produces a greater reduction in systemic blood pressure than equivalent doses of barbiturates. This hypotension is a consequence of both direct and indirect effects, namely, direct myocardial depression. 

Until it could be proved that the source of the gain in weight of calcined metals was due to combination with a definite and weighable constituent of the air, and that this constituent of the air takes part in all cases of combustion and calcination, the phlogistic philosophy—as elaborated by Stahl, his pupils, and adherents—offered to chemists the first coherent and plausible explanation of all those phenomena which are now known as oxidation and reduction, direct and indirect. 

Reductive eliminations have been employed as models for electron-transfer reactions. The stereochemical differences between direct and indirect... 

Under this heading a few borderline cases between direct and indirect electrochemical reactions can be included. Dihalocarbenes are probably intermediates in the cathodic reduction of certain polyhalogenated compounds172) as an example, cathodic reduction of carbon tetrachloride at a mercury cathode in acetonitrile-tetrabutylammonium bromide in the presence of tetramethylethylene gave a low yield of l,l-dichloro-2,2,3,3-tetramethylcyclopropane ... 

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