5408-86-6Relevant articles and documents
Vibrational spectra of cis and trans but-2-enes: assignments, isolated CH stretching frequencies and CH bond lengtsh
McKean, D. C.,MacKenzie, M. W.,Morrisson, A. R.,Lavalley,J. C.,Janin, A.,et al.
, p. 435 - 450 (1985)
Infrared and Raman spectra have been obtained from 11 isotopomers of cis and trans but-2-enes in various phases (c- and t-CH3CHCHCH3, CH3CHCDCH3, CD3CHCHCD3, CD3CHCDCD3, CD3CDCDCD3; c-CH3CDCDCH3).Nearly all the fundamentals are securely assigned.Isolated CH stretching frequencies νisCH are observed or deduced from the spectra and used to predict CH bond lenghts and dissociation energies.The olefinic CH and methyl CHs bonds are stronger in the cis compound than those in the trans, in keeping with substituent effects previously observed in propene, and with molecular mechanics predictions.Comparison of νisCH values with local mode fifth overtone spectra for cis-CH3-CH=CH-CH3 indicates that the part of the latter associated with the CHa bond cannot be readily interpreted.
Electron-Transfer Reactions and Associated Conformational Changes. Electrochemical Reduction of Some Vicinal Dibromides
O'Connell, Kathleen M.,Evans, Dennis H.
, p. 1473 - 1481 (1983)
The effect of molecular conformation on the electrochemical reduction of derivatives of trans-1,2-dibromocyclohexane (1-4) and substituted 1,2-dibromoethanes (5-8) has been investigated by low-temperature cyclic voltammetry.Reduction via conformations with antiperiplanar bromine atoms is preffered and conformational interconversion prior to electron transfer was observed in trans-1,2-dibromocyclohexane (1), 1,1-dimethyl-trans-3,4-dibromocyclohexane (2), meso- and dl-1,2-dibromo-1,2-diphenylethane (meso-5 and dl-5), and 2,3-dibromo-2,3-dimethylbutane (8).Digital simulation of the low-temperature voltammetric data has provided thermodynamic and kinetic information on the conformational interconversion in 1, 2, 5, and 8.The energy barriers to conformational interconversion in meso- and dl-2,3-dibromobutane (meso-6 and dl-6) are quite small, and conformational effects in the electrochemical reduction of 6 could not be detected at temperatures as low as -135 deg C. 1-Methyl-cis-3,trans-4-dibromocyclohexane (3), 1-methyl-trans-3,cis-4-dibromocyclohexane (4), and meso- and dl-3,4-dibromo-2,5-dimethylhexane (meso-7 and dl-7) exist almost entirely in a single conformation.Voltammetric peak potentials of 3,4,meso-7, and dl-7 reflect the geometry of their principal conformation.
Induced Fitting and Polarization of a Bromine Molecule in an Electrophilic Inorganic Molecular Cavity and Its Bromination Reactivity
Hayashi, Yoshihito,Inada, Yasuhiro,Katayama, Misaki,Kikukawa, Yuji,Kitajima, Hiromasa,Seto, Kensuke,Watanabe, Daiki,Yamashita, Shohei
supporting information, p. 14399 - 14403 (2020/07/13)
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.
Stereochemistry of Polymethylated β,β'-Dibromoethers Formed by Bromination of Alkene-Epoxide Mixtures
Neill, David,Thomas, Susan E.
, p. 2620 - 2622 (2007/10/02)
Examination of β,β'-dibromoethers formed when bromine is added to alkene-epoxide mixtures in pentane at -78 deg C revealed that opening of the bromonium ion and the epoxide occurs under high stereochemical control, whilst approach of the epoxide and the bromomonium ion is subject to lower or no stereochemical control.
Efficient Conversion of Alkyl Chlorides into Bromides
Yoon, K. B.,Kochi, J. K.
, p. 1013 - 1014 (2007/10/02)
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.
A reinvestigation of the vapor phase bromination of 2-bromobutane
Tanner, Dennis D.,Ruo, Tomoki C. S.,Kosugi, Yoshio,Potter, Alan
, p. 2310 - 2316 (2007/10/02)
The soltuion phase photobromination of 2-bromobutane yields 2,2-dibromobutane, meso-2,3-dibromobutane, dl-2,3-dibromo-dibromobutane, small amounts of 1,2-dibromobutane, and 2,2,3-tribromobutane.However, in the corresponding vapor phase bromination these products appear along with other polybrominated products.The yield of these polybromides increases with temperature.The increase in yield of the polyhalogenated materials is rationalized by considering the thermal instabilty of the β-bromoalkyl radical, which eliminates a bromine atom to form the corresponding alkene.It is demonstrated that in the vapor phase allylic bromination competes succesfully with bromine addition.Reaction schemes are suggested to explain the formation of polybromides.An explanation is also offered for the dicrepancy between these results and those of previously reported vapor phase work.
