Mechanisms of hydrogenation

We can gam a general understanding of the mechanism of hydrogen halide addi tion to alkenes by extending some of the principles of reaction mechanisms introduced earlier In Section 5 12 we pointed out that carbocations are the conjugate acids of alkenes Therefore strong acids such as HCI HBr and HI can protonate the double bond of an alkene to form a carbocation... 

The stereochemistry of metal-ammonia reduction of alkynes differs from that of catalytic hydrogenation because the mechanisms of the two reactions are different The mechanism of hydrogenation of alkynes is similar to that of catalytic hydrogenation of alkenes (Sections 6 1-6 3) A mechanism for metal-ammonia reduction of alkynes is outlined m Figure 9 4... 

Ca.ta.lysis, The mechanism of hydrogen abstraction from alcohols to form aldehydes (qv) over silver has been elucidated (11). Silver is the principal catalyst for the production of formaldehyde (qv), the U.S. production of which was 4 x 10 metric tons in 1993. The catalytic oxidation of... 

These data suggest that both die chain reactions and die biinolecular reactions occur simultaneously in all systems but that the biinolecular reaction, which dominates the formation of HI, occurs only to a minor extent in the formation of HCl and HBr. To analyse the difference between these alternate mechanisms of hydrogen-halogen reactions, we should first consider die relative energies of each of the chain reaction steps for each system. The results for for... 

Scheme 3 Mechanism of hydrogenation of NBR catalyzed by [Pd(OAc)(2-benzoyl pyridinejL. Source Ref. 79.

Figure 4-437. The simplified mechanism of hydrogen damage. (From Ref. [191].)...

Despite the major technical importance of hydrogen embrittlement, and the wealth of research work on the subject, the mechanism (or perhaps mechanisms) of hydrogen embrittlement remains uncertain. Much of the book edited by Oriani, Hirth and Smialowski is concerned with mechanistic aspects of hydrogen embrittlement, and the reader is referred in particular to the summary by Thomson and Lin . 

Stereochemistry and Mechanism of Hydrogenation of Naphthalenes on Transition Metal Catalysts and Conformational Analysis of the Products A. W. Weitkamp... 

Bockris, J. O M. and Potter, E. C. (1952) The mechanism of hydrogen evolution at nickel cathodes in aqueous solutions. 

Kobayashi, K., Salathe, M., Pratt, M.M., Cartagena, N.J., Soloni, F., Seybold, Z.V. and Wanner, A. (1992). Mechanism of hydrogen peroxide induced inhibition of sheep airway cilia. Am. J. Respir. Cell Mol. Biol. 6, 667-673. 

The mechanism of hydrogen sulfide toxicity is in part similar to that of cyanide. Like cyanide, hydrogen sulfide can inhibit the enzyme cytochrome oxidase resulting in tissue hypoxia. Specific health effects are discussed in greater detail below. 

Visualizing Reaction Intermediates and the Mechanism of Hydrogen Oxidation... 

The mechanism of hydrogen exchange in the benzene ring was developed further by Harper and Kemball in their account of the exchange and... 

Birnbaum, H.K., Roberson, I.M., Sofronis, P., and Teter, D. Mechanisms of Hydrogen Related Fracture—A Review, in Corrosion-Deformation Interactions, CDI 96, T. Magnin (Ed), The Institute of Mining, Materials, London, 1997, pp. 172-195. 

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