- The functionalization of saturated hydrocarbons. Part 23. Gif-type bromination and chlorination of saturated hydrocarbons: A non-radical reaction
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The bromination of saturated hydrocarbons was studied in the GoAggIII system using CBrCl3 and other polyhaloalkanes. This bromination reaction was compared to free radical processes by (i) evaluating the rates of reactions for a series of polyhaloalkanes, by (ii) measuring the selectivity of the different systems towards various saturated hydrocarbons and by (iii) analyzing the product distribution arising from the bromination of cyclohexyl bromide under both the GoAggIII type conditions and from known processes for alkyl radical generation. Some chlorine containing reagents were also examined for C - Cl bond formation in the GoAggIII system. All the experimental findings support a mechanism for the reaction that is different from one involving free radicals. This non-radical pathway is common in all Gif-type systems, as seen in common patterns of selectivity, conditions is in agreement with a non-radical reaction pathway for the Gif-type bromination and chlorination reactions.
- Barton, Derek H. R.,Csuhai, Eva,Doller, Dario
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- Preparation method of heteroatom-containing cyclohexene halide
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The invention discloses a preparation method of a heteroatom-containing cyclohexene halide, belonging to the field of synthesis of fine chemical intermediates. According to the preparation method, cyclohexanone containing heteroatoms is used as a raw material, and gem-dihalide or alkenyl halide is mainly generated in a halogenating reagent; and after an additive is added into organic alkali, and hydrogen halide is removed to generate cyclohexene halide containing heteroatoms. The method is simple in process; the operation of purifying a mixture in traditional methods is avoided; and a productis fully utilized. Under close-to-elimination condition of gem-dibromide, an additive is added to overcome the problem of difficulties in gem-dichloride elimination is by adding, and the purpose of controlling regioselectivity is achieved through steric hindrance of different alkalis.
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Paragraph 0051-0053
(2019/12/25)
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- The functionalization of saturated hydrocarbons. Part 25. Ionic substitution reactions in GoAggIV chemistry: The formation of carbon-halogen bonds
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GoAggIV chemistry (Fe (III) species, tert-butyl hydroperoxide in a mixture of pyridine and acetic acid) in the presence of LiCl can transform saturated hydrocarbons efficiently into the corresponding alkyl chlorides. The transformation into monosubstituted alkyl derivatives by "ionic trapping" reagents arising from the interception of the first intermediate of the system supports the presence of a high valent VFe-C species. Mechanistic studies suggest a possible pathway operating via an Fe-centered ligand coupling. In addition, the production of alkyl chlorides and alkyl bromides could also be achieved employing this system in the presence of halogenating reagents such as CCl4 and BrCCl3.
- Barton, Derek H. R.,Beviere, Stephane D.,Chavasiri, Warinthorn
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- Studies on the Synthesis of Heterocyclic Compounds. XIV. Cleavage of 1,3-Benzoxathioles by Magnesium Bromide-Acetic Anhydride
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The cleavage reaction of some 1,3-benzoxathioles with magnesium bromide and acetic anhydride has been studied.In all the 1,3-benzoxathioles studied, the opening of the heterocyclic ring occurs first with cleavage of the C-O bond and formation of bromides and their corresponding products of hydrolysis.Successively also the cleavage of the C-S bond can occur.The competitive electrophilic substitution on the benzene ring becomes appreciable only in the 1,3-benzoxathioles-2,2-disubstituted with sterically demanding groups.The structure of newly prepared compounds has been determined by analytical and spectroscopic data and when possible by comparison with authentic samples.
- Bonsignore, Leonardo,Fadda, Anna Maria,Loy, Giuseppe,Maccioni, Anna Maria,Marongiu, Enrica,Podda, Gianni
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p. 573 - 576
(2007/10/02)
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- Dibromocarbonyl Ylides. Deoxygenation of Aldehydes and Ketones by Dibromocarbene
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The reaction of phenyl(tribromomethyl)mercury (4) with benzaldehyde-α-13C results in benzal-α-13C bromide and CO.The generality of this deoxygenation was shown by treatment of other aldehydes and ketones with mercurial 4 (1.8:1, benzene, 80 deg C, 4 h): , Ph (46), Et (35), i-Pr (39), t-Bu (19); Ph, Ph (6), Ph, Me (15), Me, Me (16), Et, n-Bu (19), Me, c-C3H5 (20), c-C3H5, c-C3H5 (20), cyclohexanone (38), cyclopentanone (19), norcamphor (46).Additional products in selected cases include (for acetophenone) α-bromostyrene, (for cyclohexanone) 1-bromocyclohexene and 1,1-dibromocyclohexane, (for norcamphor) 2,2-dibromonorbornane, 1,2-dibromonorbornane, 2-bromo-2-norbornene and 1-bromonorbornene, and (for pivaldehyde) 1,1-dibromo-2,2-dimethylpropane.The yields of CO from the treatment of a series of benzaldehydes with mercurial 4 (1.8:1 benzene, 80 deg C, 20 h) are given in parentheses: ArCHO (percent CO), 4-MeO (81), 4-Me (61), 3-Me (55), H (50), 4-F (46), 3-MeO (58), 4-Cl (46), 4-Br (47), 3-Cl (34), 3,4-Cl2 (27).A Hammett-type correlation of log (yield)/(yield)0 vs. ? gave ρ = -0.50 (r = 0.94).
- Huan, Zhenwei,Landgrebe, John A.,Peterson, Kimberly
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p. 4519 - 4523
(2007/10/02)
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