TY - JOUR
T1 - Effects of alkyl chain structure on carbon-halogen bond dissociation and β-hydride elimination by alkyl halides on a Cu(100) surface
AU - Lin, Jong Liang
AU - Teplyakov, Andrew V.
AU - Bent, Brian E.
PY - 1996/6/20
Y1 - 1996/6/20
N2 - The effects of alkyl chain structure on the rate of carbon-halogen bond scission in alkyl chlorides, bromides, and iodides on a Cu(100) surface and on the rates of β-hydride elimination by the alkyl products of these carbon-halogen bond scission reactions have been studied under ultra-high-vacuum conditions. It is found that the carbon-halogen bond dissociation rates increase in the order: C-Cl < C-Br < C-I and C(1°)-X < C(2°)-X < C(3°)-X, where X denotes the halogen and 1°, 2°, 3° refer to the number of alkyl substituents at the halogen-substituted carbon. β-Hydride elimination by the corresponding alkyl groups shows the following trends: (1) alkyl chain length (greater than three carbons) does not significantly affect the rate of β-hydride elimination; (2) the rate increases with alkyl substitution at the α-carbon in the order primary alkyls < secondary alkyls, (3) the rate of increase is substantially larger than expected on the basis of the increase in the number of β-hydrogens, and (4) for C5 and C6 alkyls the rate of this reaction is faster for 3-alkyls than for 2-alkyls. Differences in rate of up to 3 orders of magnitude are observed as a function of alkyl chain structure, and possible correlations between thermodynamic and kinetic effects are discussed.
AB - The effects of alkyl chain structure on the rate of carbon-halogen bond scission in alkyl chlorides, bromides, and iodides on a Cu(100) surface and on the rates of β-hydride elimination by the alkyl products of these carbon-halogen bond scission reactions have been studied under ultra-high-vacuum conditions. It is found that the carbon-halogen bond dissociation rates increase in the order: C-Cl < C-Br < C-I and C(1°)-X < C(2°)-X < C(3°)-X, where X denotes the halogen and 1°, 2°, 3° refer to the number of alkyl substituents at the halogen-substituted carbon. β-Hydride elimination by the corresponding alkyl groups shows the following trends: (1) alkyl chain length (greater than three carbons) does not significantly affect the rate of β-hydride elimination; (2) the rate increases with alkyl substitution at the α-carbon in the order primary alkyls < secondary alkyls, (3) the rate of increase is substantially larger than expected on the basis of the increase in the number of β-hydrogens, and (4) for C5 and C6 alkyls the rate of this reaction is faster for 3-alkyls than for 2-alkyls. Differences in rate of up to 3 orders of magnitude are observed as a function of alkyl chain structure, and possible correlations between thermodynamic and kinetic effects are discussed.
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U2 - 10.1021/jp960538k
DO - 10.1021/jp960538k
M3 - Article
AN - SCOPUS:33748500215
SN - 0022-3654
VL - 100
SP - 10721
EP - 10731
JO - Journal of Physical Chemistry
JF - Journal of Physical Chemistry
IS - 25
ER -