Reaction addition with organic compounds

Sulfur dichloride undergoes many of the same reactions with organic compounds as described for sulfur monochloride. Addition to olefins affords a route to bis(2-chloroalkyl) sulfides and, ia certain cases, heterocycHc sulfides (159,160). 

Reactions with Organic Compounds. The addition of biomine to unsatuiated carbon compounds occurs readily. 

In reactions with organic compounds, the acid may act not only as an oxidizer (see above) but also as a chlorinating agent (in the case of saturated compounds) or the addition of HO-C1 to the double linkage C=C to form a chlorhydrin ... 

The reactions of OH with organic compounds can be classified into three major types (1) hydroxyl addition, (2) hydrogen abstraction, and (3) electron transfer. Which type of reaction takes place depends upon the nature of the substrates present in the medium. Organic compounds containing aromatic ring or carbon-carbon multiple bonds undergo hydroxylation due to the rich n-electron cloud on the aromatic ring. For example ... 

A kinetic study of direct photolytic decomposition of organics showed that in aqueous solution organic substrates can be decomposed by UV radiation emitted by a polychromatic source. In UV/H202 photolytic destruction, the reaction between the organic compound and the hydroxyl radicals generated in the H202 photodecomposition is dominant. In addition, the kinetics must consider the reaction of hydroxyl radicals with the radical scavengers if they are present. The Arrhenius correlation was proposed to express the rate constants of the reaction between hydroxyl radicals and bentazone as a function of the temperature ... 

The method is based on the observations that gas-phase OH radical reactions with organic compounds proceed by four reaction pathways, assumed to be additive H-atom abstraction from C-H and O-H bonds, OH radical addition to >C=C< and -C=C-bonds, OH radical addition to aromatic rings, and OH radical "interaction" with N-, S-, and P-atoms and with more complex structural units such as ->P=S, >NC(0)S- and >NC(0)0- groups. The total rate constant is assumed to be the sum of the rate constants for these four reaction pathways (Atkinson, 1986). The OH radical reactions with many organic compounds proceed by more than one of these pathways estimation of rate constants for the four pathways follow. Section 14.3.5 gives examples of calculations of the OH radical reaction rate constants for the "standard" compounds lindane (y-hexachlorocyclohexane), trichloroethene, anthracene, 2,6-di-ferf-butylphenol, and chloropyrofos. 

Atkinson (1987) developed very reliable fragment additivity SARs for estimating kHO(air) from molecular structure using more than 400 compounds in the database (Chapter 14 describes procedures for using these SARs). SARs for HO are based on the premise that rate constants for each of the several different classes of reactions of HO with organic compounds — abstraction of H- atom (kH), addition to double, triple or aromatic bonds (kE), and reaction with S or N atoms (kA) — can be estimated separately and then summed to give the total molecular rate constant, kHO ... 

Peroxy radicals(R02) react with organic compounds either by H-atom transfer or addition to a double bond. These reactions have rate constants ranging from <0.01 to 300 M 1 s 1 at 25°C (Howard, 1972 Hendry et al., 1974 Neta et al., 1990) and are rarely important under environmental conditions because of the low average concentration of R02 in surface waters (Table 15.5). However, H-atom transfers from phenol OH or aniline NH have large... 

Triplet oxygen is a stable and surprisingly unreactive electrophilic diradical. Its reactions with organic compounds (autoxidation) include abstraction of hydrogen atoms or single electrons and addition to reactive C-C double bonds (Scheme 3.14). 

From its E° value, 2.02 V, hydroxyl radical would be expected to show strongly oxidizing properties. It sometimes does, but the major pathway for its reactions with organic compounds is bond formation, either by addition or hydrogen-atom abstraction. The calculation for benzene assumes A(OH / OH-) < 20 kcal moC1 and A(PhH+ /PhH) = 10 kcal mol-1 both of which are probably maximum values. Clearly, nonbonded electron transfer is not feasible in this case. 

Transition metals have already established a prominent role in synthetic silicon chemistry [1 - 5]. This is well illustrated by the Direct Process, which is a copper-mediated combination of elemental silicon and methyl chloride to produce methylchlorosilanes, and primarily dimethyldichlorosilane. This process is practiced on a large, worldwide scale, and is the basis for the silicones industry [6]. Other transition metal-catalyzed reactions that have proven to be synthetically usefiil include hydrosilation [7], silane alcdiolysis [8], and additions of Si-Si bonds to alkenes [9]. However, transition metal catalysis still holds considerable promise for enabling the production of new silicon-based compounds and materials. For example, transition metal-based catalysts may promote the direct conversion of elemental silicon to organosilanes via reactions with organic compounds such as ethers. In addition, they may play a strong role in the future... 

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