Selective chlorination

An economic synthesis of (3) has been patented (74,91). The process iavolves (/) synthesis of sucrose 6-acetate by way of sucrose 4,6-cychc orthoacetate (2), and (2) selective chlorination usiag thionyl chloride—pyridine—1,1,2-trichloroethane, followed by removal of the acetate group. 

In the hquid-phase chlorination, 1,3-dichlorobenzene is found only in a small quantity, and 1,3,5-trichlorobenzene and 1,2,3,5-tetrachlorobenzene are undetectable. The ratios of 1,4- to 1,2-dichlorobenzene with various catalysts are shown in Table 3. Iodine plus antimony trichloride is effective in selectively chlorinating 1,2,4-trichlorobenzene to 1,2,4,5-tetrachlorobenzene (22), however, 1,2,4,5-tetrachlorobenzene is of limited commercial significance. 

Selective chlorination of the 3-position of thietane 1,1-dioxide may be a consequence of hydrogen atom abstraction by a chlorine atom. Such reactions of chlorine atoms are believed to be influenced by polar effects, preferential hydrogen abstraction occurring remotely from an electron withdrawing group. The free radical chain reaction may be propagated by attack of the 3-thietanyl 1,1-dioxide radical on molecular chlorine. 

Where fumes or deposits which act as anti-oxidants are present, no orthodox paint which dries by oxidation can give satisfactory service. Instead, a coating which dries either by evaporation (e.g. a selected chlorinated rubber paint), or by a cross-linking reaction (e.g. a catalysed epoxy or two-component polyurethane paint) must be used. 

Morphology of the anionically synthesized triblock copolymers of polyfp-methyl-styrene) and PDMS and their derivatives obtained by the selective chlorination of the hard segments were investigated by TEM 146). Samples with low PDMS content (12%) showed spherical domains of PDMS in a poly(p-methylstyrene) matrix. Samples with nearly equimolar composition showed a continuous lamellar morphology. In both cases the domain structure was very fine, indicating sharp interfaces. Domain sizes were estimated to be of the order of 50-300 A. 

Jeffers PM, Ward LM, Woytowitch LM, et al. 1989. Homogenous hydrolysis rate constants for selected chlorinated methanes, ethanes, ethenes and propanes. Environmental Science and Technology 23 965-969. 

Figure 5.3. The selective chlorination of anisole in the presence of cyclodextrin (Breslow, 1982).

Edney, E.O., Kleindienst, T.E., Corse, E.W. (1986) Room temperature rate constants for the reaction of OH with selected chlorinated and oxygenated hydrocarbons. Int J. Chem. Kinet. 18, 1355-1371. 

Liu, K., Dickhut, R.M. (1994) Saturation vapor pressures and thermodynamic properties of benzene and selected chlorinated benzenes at environmental temperatures. Chemosphere 29, 581-589. 

Many other glycosides have been subjected to selective chlorination with sulfuryl chloride. Methyl /3-L-arabinopyranoside afforded methyl 4-chloro-4-deoxy-a-D-xylopyranoside 2,3-di(chlorosulfate) in 29% yield, whereas the a-L anomer gave357 methyl 3,4-dichloro-3,4-dideoxy-/3-i)-ribopyranoside 2-(chlorosulfate) (30%). Methyl /3-d-ribopyranoside was converted into methyl 3,4-dichloro-3,4-dideoxy-a-L-arabinopyranoside through the action of pyridine hydrochloride on its 2,3,4-tri(chlorosulfate).358 Methyl a-D-lyxopyranoside gave only the 2,3,4-tri(chlorosulfate),353 as would be expected from the disposition of its hydroxyl groups, similar to that in the rhamno- and manno-pyranosides. Methyl a-D-altropyranoside was transformed into the 6-chloro-6-deoxy 2,3,4-tri(chlorosulfate) derivative in 80% yield.353... 

Law, L.M. and D.F. Goerlitz. 1974. Selected chlorinated hydrocarbons in bottom material from streams tributary to San Francisco Bay. Pestic. Monitor. Jour. 8 33-36. 

Wendell Dunn A family of chlorine beneficiation processes based on selective chlorination of ores in a fluidized bed. Developed by W. E. Dunn of Chlorine Technology in Australia in the 1970s, primarily for beneficiating ilmenite. The first such commercial ilmenite beneficiation plant, completed in 1991, was that of Bene-Chlor Chemicals Private, Madras. 

Murray HE, Beck JN. 1990. Concentrations of selected chlorinated pesticides in shrimp collected from the Calcasieu River/Lake complex, Louisiana. Bull Environ Contain Toxicol 44 798-804. 

Hill DW, McCarty PL. 1967. Anaerobic degradation of selected chlorinated hydrocarbon pesticides. 

Hill, D.W. and McCarty, P.L. Anaerobic degradation of selected chlorinated hydrocarbon pesticides, J. Water PoIIut. Control Fed, 39 1259-1277, 1967. 

Leigh, W. Degradation of selected chlorinated hydrocarbon insecticides, J. Water PoUut. Control Fed., 41(11) R450-R460, 1969. 

Van Warmerdam EM, Erape SK, Aravena R, Drimmie RJ, Elatt H, Cherry JA (1995) Stable chlorine and carbon isotope measurements of selected chlorinated organic solvents. Appl Geochem 10 547-552... 

Richardson and Hough s efforts on the chlorination of sucrose ran in parallel with their studies on the selective chlorination of other readily available disaccharides. One notable piece of work done with Philippe L. Durette involved a study of the regioselective chlorination of methyl (S-maltoside (Scheme 31), which was undertaken with the long-term objective of possibly developing a future synthesis of the natural antitumor agent, amicetin. 

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