Radicals chloro

Termination for the names of many inorganic and organic radicals chloro-, piperidino-... 

Dimethyl iodo(4-pentenyl)malonate (926) undergoes a Pd-catalyzed intramolecular radical-type reaction to form the alkyl iodides 927 and 928. rather than a Heck-type reaction product(775]. The same products are also obtained by a radical reaction promoted by tin hydride(776]. Although yield was low, a similar cyclization of the n-chloro ester 929 to form the seven-membered ring 930 was ob,served(777(. 

As the demand for rubber increased so did the chemical industry s efforts to prepare a synthetic sub stitute One of the first elastomers (a synthetic poly mer that possesses elasticity) to find a commercial niche was neoprene discovered by chemists at Du Pont in 1931 Neoprene is produced by free radical polymerization of 2 chloro 1 3 butadiene and has the greatest variety of applications of any elastomer Some uses include electrical insulation conveyer belts hoses and weather balloons... 

Carbamates. Lower alkyl A/-halo- and W,W-dihalocarbamates are distillable Hquids (70,112). A/-Halo-A/-metallocarbamates are crystalline hygroscopic soHds. A/-Chloro-A/-sodiourethane [17510-52-0] C2H OCONQNa, does not decompose on heating to 250°C (113), but violent decompositions have occurred at room temperature (114). A/-Halocarbamates react with a variety of organic substrates, eg, the free-radical addition of W-chlorourethane [16844-21 -6] C2H OCONHCl, and A,A-dichlorourethane [15698-16-5], C2H OCONCl2, to olefins provides a convenient route to... 

Hydrogen hahdes normally add to form 1,2-dihaLides, though an abnormal addition of hydrogen bromide is known, leading to 3-bromo-l-chloropropane [109-70-6], the reaction is beUeved to proceed by a free-radical mechanism. Water can be added by treatment with sulfuric acid at ambient or lower temperatures, followed by dilution with water. The product is l-chloro-2-propanol [127-00-4]. 

A chlorohydrin has been defined (1) as a compound containing both chloio and hydroxyl radicals, and chlorohydrins have been described as compounds having the chloro and the hydroxyl groups on adjacent carbon atoms (2). Common usage of the term appHes to aUphatic compounds and does not include aromatic compounds. Chlorohydrins are most easily prepared by the reaction of an alkene with chlorine and water, though other methods of preparation ate possible. The principal use of chlorohydrins has been as intermediates in the production of various oxitane compounds through dehydrochlorination. 

Reactions of 3-chloro-6-methoxypyridazine with ketone enolates in liquid ammonia exhibit characteristics consistent with a radical chain mechanism for substitution (8UOC294). 

In the pyrrole series, ester groups a to nitrogen are more readily hydrolyzed by alkali, but those in a /3 position more readily by acid. A methoxycarbonyl group in the 2-positlon is meta directing thus bromination yields mainly 4-bromo-2-methoxycarbonylpyrrole. Free radical chlorination with f-butylhypochlorite gives the 5-chloro derivative. 

The use of free-radical reactions for this mode of ring formation has received rather more attention. The preparation of benzo[Z)]thiophenes by pyrolysis of styryl sulfoxides or styryl sulfides undoubtedly proceeds via formation of styrylthiyl radicals and their subsequent intramolecular substitution (Scheme 18a) (75CC704). An analogous example involving an amino radical is provided by the conversion of iV-chloro-iV-methylphenylethylamine to iV-methylindoline on treatment with iron(II) sulfate in concentrated sulfuric acid (Scheme 18b)(66TL2531). 

Irradiation of the A-bromo- or N- chloro-azetidin-2-ones (71) in the presence of alkenes, alkynes or radical donors induces rearrangement to the /3-haloalkyl isocyanates (72) via a... 

Thieno[3,4-d][ 1,2,3]triazole, tetramethyl-synthesis, 6, 1015 Thieno[3,4-c][ 1,2,3]triazoles synthesis, 6, 1042 Thieno[3,4-d][ 1,2,3]triazoles reactions, 6, 1036 synthesis, 6, 1044 Thienyl radicals generation, 4, 832 Thiepane, 2-acetoxy-synthesis, 7, 574 Thiepane, 2-chloro-nucleophilic substitution, 7, 573 synthesis, 7, 574 Thiepane, 2-methyl-synthesis, 7, 573 Thiepane, 2-phenyl-synthesis, 7, 573 Thiepane, 3,3,6,6-tetramethyl-cycloaddition reactions, 7, 574 Thiepanes, 7, 547-592 applications, 7, 591... 

Chemistry of polychloroprene rubber. Polychloroprene elastomers are produced by free-radical emulsion polymerization of the 2-chloro-1,3-butadiene monomer. The monomer is prepared by either addition of hydrogen chloride to monovinyl acetylene or by the vapour phase chlorination of butadiene at 290-300°C. This latter process was developed in 1960 and produces a mixture of 3,4-dichlorobut-l-ene and 1,4-dichlorobut-2-ene, which has to be dehydrochlorinated with alkali to produce chloroprene. 

Carbomethoxymethylenetriphenylphos-phorane, 129 Carbon radicals, 240 Carbonyl-forming fragmentations, 239 2a-Carboxy-A-nor-5a-cholestane, 427 Caro s acid, 152 Chlorineazide, 25, 34, 35 Chloro c lene, 136, 138 A-chloroamine reactions, 257 5a-Chloro-6 -azidocholestan-3/3-ol, 25... 

Primary alkyl chlorides are fairly stable to fluorine displacement. When fluorinated, 1-chloropropane is converted to 1-chloroheptafluoropropane and 1-chloto-2-methylbutane produces 39% l-chlorononafluoro-2-methylbutane and 19% perfluoro-2-methylbutane. Secondary and tertiary alkyl chlorides can undergo 1,2-chlorine shifts to afford perfluonnated primary alkyl chlorides 2-Chloro-2-methylpropane gives l-chlorononafluoro-2-methylpropane, and three products are obtained by the fluorination of 3-chloropentane [7] (equation 1). Aerosol fluorina-tion of dichloromethane produces dichlorodifluoromethane which is isolated in 98% purity [4 (equation 2). If the molecule contains only carbon and halogens, the picture is different. Molecular beam analysis has shown that the reaction of fluorine with carbon tetrachlonde, lodotrichloromethane, or bromotrichloromethane proceeds first by abstraction of halogen to form a trichloromethyl radical [5]... 

A -Halogenated compounds such as iV-chlorotnfluoroacetamide, A -chloro-imidosulfuryl fluonde and N N dichlorotnfluoromethylamine add across C=C bonds to form saturated amides [14] tmidosulfury I fluorides [15] and amines [16], respectively Allylic halogenation also occurs with the use of A-bromo- or A-chIo roperfluoroamides The primary amine A,A-dichlorotrifluororaethylamine selectively affords 11 or 2 1 adducts with either tetrafluoroethylene or chlorotrifluoroethylene [16] (equation 7) The reaction mechanism is believed to involve thermal free radicals, with control achieved principally by reaction temperature The 1 1 adduct is formed even in the presence of a large excess of olefin... 

If every collision of a chlorine atom with a butane molecule resulted in hydrogen abstraction, the n-butyl/5ec-butyl radical ratio and, therefore, the 1-chloro/2-chlorobutane ratio, would be given by the relative numbers of hydrogens in the two equivalent methyl groups of CH3CH2CH2CH3 (six) compared with those in the two equivalent methylene groups (four). The product distribution expected on a statistical basis would be 60% 1-chloro-butane and 40% 2-chlorobutane. The experimentally observed product distribution, however, is 28% 1-chlorobutane and 72% 2-chlorobutane. 5ec-Butyl radical is therefore formed in greater anounts, and n-butyl radical in lesser anounts, than expected statistically. 

First examine the geometry of methyl radical. Is it planar or puckered Examine the geometries of 2-methy 1-2-propyl radical, trifluoromethyl radical, trichloromethyl radical and tricyanomethyl radical. Classify each of the substituents (methyl, fluoro, chloro and cyano) as a n-electron donor or as a Tt-electron acceptor (relative to hydrogen). Does replacement of the hydrogens by 7t-donor groups make the radical center more or less puckered Does replacement by Jt-acceptor groups make the radical center more or less puckered Justify your observations. 

There is an early report that thiophene reacts at the 3-position in phenylation with benzenediazonium chloride and aluminum trichloride, but in the Gomberg reaction thiophene has been found to substitute mainly at the 2-position both with p-tolyl and with p-chloro-phenyl radicals.Bcnzothiazole is phenylated at the 2-position in low yield by dibenzoyl peroxide a small quantity of the 4-isomcr is also obtained. ... 

An acridine with a radically different substitution pattern, interestingly, still exhibits antimalarial activity. Condensation of acetone with diphenylamine in the presence of strong acid affords the partly reduced acridine, 20. Alkylation with 3-chloro-dimethylaminopropane (via the sodium salt of 20) affords dimethacrine (21). ... 

Assume that you have carried out a radical chlorination reaction on (P)-2-chloro-pentane and have isolated (in low yield) 2,4-dichIoropentane. How many stereoisomers of the product are formed and in what ratio Are any of the isomers optically active (See Problem 10.24.)... 

Chlorination. Electrophilic chlorination of quinoline (66) in neutral medium showed a positional selectivity order of 3 > 6 > 8. The 5- and 8-positions should be sterically hindered to some extent. Hammett cr+ values predict an order for electrophilic substitution of 5 > 8 = 6 > 3. Treatment with chlorine at 160-190°C converted quinoline into a mixture of 3-chloro-, 3,4-dichloro-, 3,4,6- and 3,4,8-trichloro-, 3,4,6,8-tetrachloro-, and 3,4,6,7,8-pentachloro-quinolines. At lower temperatures ( 100°C) the major product was 3-chloroquinoline, albeit in low yield. The 4-substituted species may have arisen from an addition-elimination or radical process (70JHC171). 

Both 2-chloro- and 2,6-dichloro-quinoxalines can be made by ring expansion of 1-methylimidazole using trichloromethyl radicals (91MI5). 

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