Reactivity of Hydrogens in Saturated Compounds

The reactivity of hydrogens at various positions of aliphatic and alicychc hydrocarbons and their derivatives in various reactions is successfully interpreted by the theoretical indices. Dr and fr, mentioned in Chap. 6. Most of the results obtained were reviewed in reference 16 and are not repeated here. 

The HO and LU MO of propane are available from the result of calculation by Katagiri and Sandorfy 2S) which is based on the method already mentioned in Chap. 1. Fig. 7.19 indicates the result. Both HO and LU localize more at secondary CH bonds than at primary CH bonds, reflecting the reactivity of CsHg- 

The reactivity of hydrogens in norbomane towards abstraction is of interest since the difference between two hydrogen atoms attached to the same carbon atom of position 2 can well be explained. The frontier electron density values u 5) are in accord with the reactive exo hydrogen (Fig. 7.20). 

AdamarUane pe cage hydrocarbons have become a new target of theoretical investigation. The tertiary hydrogens which are known to be 

The important role of LU MO in the nucleophilic reactions of saturated hydrocarbons bearing nucleophilic substituents (halogens, alkoxy-, acyloxy , RS020, etc.) in the molecule has been pointed out 122,123). 

---

Reactivity of Hydrogens in Saturated Compounds 7.4 Reactivity of Hydrogens in Saturated Compounds... 

Their physical properties are essentially those of the alkanes. It is the unsaturated linkages that dominate the chemistry and the main reaction is one of addition (e.g. hydrogen, halogen, and hydrogen halides) across the double bond to produce saturated compounds. This reactivity is utilized in the manufacture of long-chain polymers, e.g. polyethylene and polypropylene. 

Al-Sheikhly Ml, Schuchmann H-P, von Sonntag C (1985) y-Radiolysis of N20-saturated formate solutions. A chain reaction. Int J Radiat Biol 47 457-462 An bar M, Meyerstein D (1964) Isotope effects in the hydrogen abstraction from aliphatic compounds by radiolytically produced hydrogen atoms in aqueous solutions. J Phys Chem 68 3184-3167 Anbar M, Meyerstein D, Neta P (1966) Reactivity of aliphatic compounds towards hydroxyl radicals. J Chem Soc Perkin Trans 2 742-747... 

Under the usual commercial hydrodesulfurization conditions (elevated temperatures and pressures, high hydrogen-to-feedstock ratios, and the presence of a catalyst), the various reactions that result in the removal of sulfur from the organic feedstock (Table 4-3) occur. Thus, thiols as well as open chain and cyclic sulfides are converted to saturated and/or aromatic compounds depending, of course, on the nature of the particular sulfur compound involved. Benzothio-phenes are converted to alkyl aromatics, while dibenzothiophenes are usually converted to biphenyl derivatives. In fact, the major reactions that occur as part of the hydrodesulfurization process involve carbon-sulfur bond rupture and saturation of the reactive fragments (as well as saturation of olefins). 

The rate and selectivity of a surface-catalyzed reaction can be affected by the existence of concentration or temperature gradients in the quiescent layer of fluid which surrounds the catalyst particle or is contained within its pores upon whose surface much of the exposed active material is distributed. The reactants in the bulk phase reach the reactive sites by diffusion through these regions of the fluid, and they affect the kinetics when the rates of the surface-catalyzed reactions are fast relative to the rate of transport of reactants to the catalytic sites. In the hydrogenation of unsaturated liquids or compounds in solution, the agitation of the liquid-catalyst mixture must be adequate to assure that the solution remains saturated with hydrogen. 

The single bonds between carbon and hydrogen atoms in organic compounds are not highly reactive. However, these compounds do participate in a variety of chemical reactions, one of which is called a substitution reaction. A substitution reaction is a reaction in which one or more atoms replace another atom or group of atoms in a molecule. Another type of reaction involving organic compounds is an addition reaction in which an atom or molecule is added to an unsaturated molecule and increases the saturation of the molecule. 

As saturated hydrocarbons, the alkanes have the lowest chemical reactivity of organic compounds. However, under certain conditions these compounds can undergo substitution reactions, especially with the halogens. An example of such a reaction is that between an alkane, such as methane, and a halogen, such as chlorine. In this substitution reaction, a chlorine atom replaces a hydrogen atom on the methane molecule. 

We have prepared and characterized a series of cobalt complexes representing substantially all of the species shown in eq. 1. This series of compounds provides a unique view of the stepwise transformation of O2 from an unreactive molecule into a highly reactive species capable of abstracting hydrogen from saturated alkyl groups. 

---