- Induced Fitting and Polarization of a Bromine Molecule in an Electrophilic Inorganic Molecular Cavity and Its Bromination Reactivity
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Dodecavanadate, [V12O32]4? (V12), possesses a 4.4 ? cavity entrance, and the cavity shows unique electrophilicity. Owing to the high polarizability, Br2 was inserted into V12, inducing the inversion of one of the VO5 square pyramids to form [V12O32(Br2)]4? (V12(Br2)). The inserted Br2 molecule was polarized and showed a peak at 185 cm?1 in the IR spectrum. The reaction of V12(Br2) and toluene yielded bromination of toluene at the ring, showing the electrophilicity of the inserted Br2 molecule. Compound V12(Br2) also reacted with propane, n-butane, and n-pentane to give brominated alkanes. Bromination with V12(Br2) showed high selectivity for 3-bromopentane (64 %) among the monobromopentane products and preferred threo isomer among 2-,3-dibromobutane and 2,3-dibromopenane. The unique inorganic cavity traps Br2 leading the polarization of the diatomic molecule. Owing to its new reaction field, the trapped Br2 shows selective functionalization of alkanes.
- Hayashi, Yoshihito,Inada, Yasuhiro,Katayama, Misaki,Kikukawa, Yuji,Kitajima, Hiromasa,Seto, Kensuke,Watanabe, Daiki,Yamashita, Shohei
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supporting information
p. 14399 - 14403
(2020/07/13)
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- Oxidative bromination of alkenes mediated with nitrite in ionic liquids
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The oxidative bromination of C2-C8 alkenes with HBr-NaNO2-O2 in solutions of BMImBr, HMImBr or BMImBF 4 containing 16-28 wt% H2O was studied using volumetric method, GC-MS analysis, 14N NMR and UV-VIS spectroscopy. The optimal conditions to conduct the reaction at high selectivity for 1,2-dibromoalkanes in BMImBr were determined. The composition of ionic liquid affects the catalytic performance. Although in BMImBF4 the reaction runs with equal rate as in bromide ionic liquid, the fraction of bromohydrin in the reaction products increases to 20 %. Generated from NaNO2, NOx operated as a catalyst in the oxidation of Br- and was oxidized to catalytically inert NO3 - anions when complete conversion of HBr was attained. Graphical Abstract: Oxidative bromination of alkenes [Figure not available: see fulltext.]
- Kuznetsova, Lidia I.,Kuznetsova, Nina I.,Zudin, Vladimir N.,Utkin, Viktor A.,Trebushat, Dmitry V.,Fedotov, Martin A.,Larina, Tatyana V.
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p. 1499 - 1506,8
(2014/11/08)
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- Synthesis of propylene from renewable allyl alcohol by photocatalytic transfer hydrogenolysis
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Photochemical transformation of biomass-derived or renewable substances with promising scalability is an important challenge for promoting green and sustainable chemistry. We report here that photocatalytic transfer hydrogenolysis of allyl alcohol (obtained from glycerol) gives potentially sustainable propylene with high chemo- and redox selectivity, promoted by powdered Pd/TiO2 in CH3OH (obtained from CO2) under near-ultraviolet-visible light irradiation (λ > 365 nm) at ambient temperature.
- Caner, Joaquim,Liu, Zijun,Takada, Yuki,Kudo, Akihiko,Naka, Hiroshi,Saito, Susumu
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p. 4093 - 4098
(2015/02/19)
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- Rhodium-catalyzed reductive allylation of conjugated aldehydes with allyl acetate
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Reductive allylation of aryl and alkenyl aldehydes with allyl acetate catalyzed by the ionic diamine carbonyl rhodium complex, [Rh(TMEDA)(CO) 2][RhCl2(CO)2], under a carbon monoxide atmosphere afforded the corresponding homoallylic alcohols in good isolated yields.
- Vasylyev, Maksym,Alper, Howard
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body text
p. 2710 - 2713
(2010/07/17)
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- An economical and convenient synthesis of vinyl sulfones
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A general process for the efficient synthesis of vinyl sulfones has been developed using commercially available sulfinic acid sodium salts and dibromides. A variety of phenyl and methyl vinyl sulfones have been formed in good yields, in the absence of any catalyst. Georg Thieme Verlag Stuttgart.
- Guan, Zheng-Hui,Zuo, Wei,Zhao, Lian-Biao,Ren, Zhi-Hui,Liang, Yong-Min
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p. 1465 - 1470
(2008/02/05)
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- Synthesis of hydroxylated hydrocarbons
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Ethylene glycol, other diols, triols, and polyols are made in an efficient manner by reacting dibromides with water in the presence of a metal oxide. An integrated process of dibromide formation, alcohol synthesis, metal oxide regeneration, and bromine recycling is also provided.
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Page/Page column 5
(2008/06/13)
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- REACTION OF ORGANIC COMPOUNDS WITH SF4-HF-HALOGENATING SYSTEM VII. REACTIONS OF OLEFINS WITH THE SF4-HF-Cl2(Br2) SYSTEM
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Under the influence of the SF4-HF-Cl2(Br2) system halogen-containing olefins undergo conjugate halogenofluorination.It was shown for the case of (Z)- and (E)- 1,2-dichloroethenes that these reactions take place anti-stereospecifically through the formation of the bromonium ions.The accumulation of chlorine atoms in the olefin molecule hinders electrophilic addition of stoichiometric equivalents of ClF and BrF at the double bond.The SF4-HF-Br2 system is an effective agent for substitutive fluorination of organic compounds containing bromine.Only the bromine atoms situated at the secondary carbon atom are substituted by fluorine.
- Kunshenko, B. V.,Mokhamed, Nagib Mukhtar,Omarov, V. O.,Muratov, N. N.,Yagupol'skii, L. M.
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p. 511 - 518
(2007/10/02)
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- Gas-Phase Pyrolysis of Phenylcyclopropane
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The gas-phase pyrolysis of phenylcyclopropane (5) has been ivestigated in a quartz tubular reactor between 560 and 680 deg C and a contact time of about 1 s.Main reaction is the thermal isomerization to allylbenzene (4) as well as to cis-(1b) and trans--β-methylstyrene (3b).Besides 1, 3, and 4, indene (8) is formed, which is characterized by a statistical distribution of the H atom over the three positions of the five-membered ring.To distinguish between the two possible mechanisms of the isomerization (opening of the cyclopropane ring C-C bond dissociation/ 1,3-diyl formation and 1,2-C,H retro-insertion/ethylcarbene formation), the D distribution in 1 and 3 was carefully determined by 1H-NMR spectroscopy.The results show that the isomerization is initiated by generation of a 1,3-diradical. - Keywords: Isotopic labeling/ Isomerization/ Phenylcyclopropane/ Pyrolysis
- Kopinke, Frank-Dieter,Zimmermann, Gerhard,Aust, Janette,Scherzer, Klaus
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p. 721 - 726
(2007/10/02)
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- Efficient Conversion of Alkyl Chlorides into Bromides
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The convenient and selective catalytic conversion of secondary and tertiary alkyl chlorides into bromides with hydrogen bromide in the presence of small amounts of anhydrous iron(III) bromide is described.
- Yoon, K. B.,Kochi, J. K.
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p. 1013 - 1014
(2007/10/02)
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- REAGENTS AND SYNTHETIC METHODS 52. SILANE REDUCTION OF CARBONYL COMPOUNDS IN THE PRESENCE OF IODINE.
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Synthetic utility of 1,1,3,3,-tetramethyldisiloxane (TMDS) reagent under the influence of iodine is described.TMDS reagent in combination with iodine produces alkyl iodides from carbonyl compounds and oxiranes in good to excellent yields.Reduction of quinones into hydroquinones is also described.The mentioned transformations are explained from mechanistic points of view.
- Lecea, B.,Aizpurua, J. M.,Palomo, C.
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p. 4657 - 4666
(2007/10/02)
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- Thermocatalytic Reactions of Bromochloropropanes
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The thermodynamic characteristics of the disproportionation and dehydrohalogenation reactions of halogenopropanes (1,2- and 2,2-isomers) have been calculated and tested experimentally.The legitimacy of using the incremental method for the calculation of the thermodynamic functions of bromochloropropanes has been demonstrated.An increase of the length of the hydrocarbon group and the geminal positions of the halogen atoms in the molecule greatly reduce the probability of disproportionation reactions.
- Levanova, S. V.,Rodova, R. M.,Tereshkina, T. P.,Zabrodina, T. I.
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p. 1142 - 1146
(2007/10/02)
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- Direct and Regioselective Transformation of α-Chloro Carbonyl Compounds into Alkenes and Deuterioalkenes
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The successive treatment ethyl chloroacetate or chloroacetyl chloride with Grignard reagents and lithium powder leads to symmetrical terminal olefins in a regioselective manner.The best results are obtained with acid chlorides.The influence of the temperature and the reaction time on overall yield of the process are studied; in general, yields are increased by working at low temperature (-60 deg C).Internally substituted olefins are obtained from α-chloro acid chlorides through a similar process.The treatment of α-chloro aldehydes, ketones and carboxylic acid derivatives (esters or acid chlorides) with lithium aluminium hydride or lithium aluminium hydride/aluminium chloride and lithium powder at low temperature (-60 deg C) leads in a regioselective manner to olefins with the same carbon skeleton as the starting carbonyl compound.Reactions with lithium aluminium deuteride lead to incorporation of deuterium at predetermined positions in the alkene.
- Barluenga, Jose,Yus, Miguel,Concellon, Jose M.,Bernad, Pablo
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p. 2721 - 2726
(2007/10/02)
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- REARRANGEMENT OF 1,3-BROMOCHLOROPROPANE ON ACTIVATED ALUMINA
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The rearrangement of 1,3-bromochloropropane (BCP) on activated alumina was carried out at 160-280 deg C.This reaction proceeded as follows.Br(CH2)3ClBr(CH2)3Br + Cl(CH2)3Cl It was suggested that the acidic sites of alumina played an important role in the rearrangement of halogen atom.
- Shinoda, Kiyonori,Yasuda, Kensei
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p. 1243 - 1244
(2007/10/02)
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- The Reaction of Propene with Iodine Bromide
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Iodobromination of propene gives a mixture (c. 60:40) of 2-bromo-1-iodopropane and 1-bromo-2-iodopropane.This mixture of kinetic control converts into an equilibrium (c. 70:30) mixture with heat.The addition to the double bond is postulated to occur through a bridged iodonium ion rather than through a simple carbocation, and hence Markownikoff's rule need not apply to this system
- Alberts, Vincent,Carman, Raymond M.
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p. 455 - 459
(2007/10/02)
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