107-80-2Relevant articles and documents
Topological scheme for empirical estimation of13C NMR chemical shifts in polybromoalkanes
Dostavalova,Vasil'eva,Velichko
, p. 2494 - 2500 (1989)
1. For the first time, an empirical scheme has been proposed for estimating the chemical shift of carbon atoms in polybromoalkanes (including bromomethanes) with an error of ±1 ppm - a scheme based on the simplest topological indicators of a molecular graph and readily accessible algorithmization. 2. It has been shown that the plane graph model gives the best agreement between calculated and experimental values of the chemical shift of carbon atoms in the case of polysubstituted alkanes with a large number of equally probably conformations.
General Synthesis of Methyl- and Dimethyl-cyclobutanes from Simple 1,3-Diols by Phase Transfer Catalysis
Toeroek, Bela,Molnar, Arpad
, p. 801 - 804 (2007/10/02)
A general method is described for the preparation of methyl- and dimethyl-cyclobutanes from simple 1,3-diols.The key steps of the procedure are a phase transfer catalysed ring closure and the transformation of a carboxyl group to a methyl group.Phase transfer catalysis provides good yields in the synthesis of the cyclobutane skeleton.
Absolute Rate Constants for Bromine Abstraction from N-Bromoimides and Br2 by Alkyl Radicals
Tanko, James M.,Skell, Philip S.,Seshadri, Sri
, p. 3221 - 3225 (2007/10/02)
Imidyl radicals react with cyclopropanes solely via hydrogen abstraction.In the case of methylcyclopropane, the major product (cyclopropylcarbinyl bromide) is derived from abstraction of hydrogen from the methyl group.The resultant cyclopropylcarbinyl radical is partioned between two pathways: (1) abstraction of Br from N-bromoimide and (2) rearrangement to the allylcarbinyl radical (eventually yielding 4-bromo-1-butene).Since the absolute rate of the rearrangement is known, an absolute rate constant for the abstraction of Br from N-bromoimides by alkyl radicals can be derived (CH2Cl2 solvent, 15 deg C), k ca. (1.3-1.6)1xE10 M-1s-1.Reactions carried out in the presence of Br2 provide a third pathway for scavenging of the cyclopropylcarbinyl radical, providing kBr2=2.2x1E10 M-1s-1.Thus, trapping of primary R. by either N-bromoimides or Br2 occurs at rates that are diffusion-controlled.
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.
SELECTIVITIES OF pi - AND sigma -SUCCINIMIDYL RADICALS IN SUBSTITUTION AND ADDITION REACTIONS. APPENDIX: RESPONSE TO WALLING, EL-TALIAWI, AND ZHAO.
Skell,Tlumak,Seshadri
, p. 5125 - 5131 (2007/10/02)
A new method for studies of pi -succinimidyl (S// pi ) radicals is described, one that makes possible the study of reactions of this radical with a variety of substrates not accessible by the use of Br//2-NBS. NBS systems containing BrCCl//3 at mole fractions greater than 0. 3 show all the characteristics associated with S// pi behavior, and they function in the presence of olefins which serve as Br//2 scavengers. If CCl//4 is substituted for BrCCl//3, the system is clearly S// sigma . The S// pi behavior is contrasted with S// sigma and Br multiplied by (times) reactivities for H abstractions from a variety of substrates and for additions to tert-butylethylene, isobutylene, and 1,3-butadiene. In early-transition-state systems, for H transfer, the strength of the bond being broken and the strength of the bond being made are not the major factors in determining reactivities. The behavior in late-transition-state systems is influenced by both bond strengths. The S// pi radical shows intermediate behavior. These conclusions are supported by primary deuterium isotope effects for methylene chloride and chlororoform. The Appendix addresses a number of questions raised by the preliminary study of NBS reactions by Walling et al.
Alkyl Bromide Photobromination: Catalysis by Hydrogen Bromide and the Elimination-Readdition Pathway
Soumillion, Jean-Ph.,Ronneau, Claude,Dejaifve, Pierre
, p. 1907 - 1914 (2007/10/02)
In the photobromination of alkyl bromides, hydrogen bromide is shown to act as a catalyst and a kinetic study implies that two molecules of the acid are involved in catalysis.The catalysis is specific in two ways: only HBr is effective and it operates only with alkyl bromides having a β-hydrogen available for substitution.HBr favours the formation of 1,2-dibromides.This catalytic pathway is superimposed on the classical, uncatalysed mechanism.Isotopic labelling experiments show that an elimination-readdition pathway may also account for part of the reaction (maximum 20percent) but cannot explain the migration of bromine which is observed in the formation of β-dibromides.
