Results 211 to 220 of about 127,504 (265)
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Tetrahedron, 1980
The steric effect of alkyl groups as characterized by the revised Taft E's parameter is analysed using an approach based on the DARC topological system and its PELCO correlation method. This approach involves an analysis of the systemativ variation of E's in a topological dequencing of alkyl groups and shows the existence of three regions of distinct ...
Annick Panaye +2 more
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The steric effect of alkyl groups as characterized by the revised Taft E's parameter is analysed using an approach based on the DARC topological system and its PELCO correlation method. This approach involves an analysis of the systemativ variation of E's in a topological dequencing of alkyl groups and shows the existence of three regions of distinct ...
Annick Panaye +2 more
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Journal of Chemical Education, 1973
Attractive steric effects cause some organic structures to be more stable when bulky side-groups are closer together.
A. Liberles, A. Greenberg, J. E. Eilers
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Attractive steric effects cause some organic structures to be more stable when bulky side-groups are closer together.
A. Liberles, A. Greenberg, J. E. Eilers
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Tetrahedron, 1965
Increasing size of the group R leads to the formation of a higher proportion of ketone in the methylation of amines of the type, Ph·CH(NH2)·R, and of a higher proportion of secondary amine in the aluminohydride reduction of oximes of the type, Ph·C(:NOH)·R.
S.H. Graham, A.J.S. Williams
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Increasing size of the group R leads to the formation of a higher proportion of ketone in the methylation of amines of the type, Ph·CH(NH2)·R, and of a higher proportion of secondary amine in the aluminohydride reduction of oximes of the type, Ph·C(:NOH)·R.
S.H. Graham, A.J.S. Williams
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Steric effects in heteroboranes
Journal of Organometallic Chemistry, 1994Abstract In (Ph 3 PCu) 2 Ph 2 C 2 B 9 H 9 ( Ia ) and {( o -tol) 3 PCu} 2 Ph 2 C 2 B 9 H 9 ( Ic ) one copper atom occupies a polyhedral vertex position but is slipped away from the cage carbon atoms (the latter the more so) to relieve phosphine ṫ C cage -phenyl crowding. The second copper atom is exo -facially bonded to the B(8)B(9)B(12) triangular
Kerry J. Adams +4 more
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Steric Effects and Solvent Effects in Ionic Reactions
Science, 2002Rates of S N 2 reactions of chloride ion with methyl- and tert -butyl–substituted chloroacetonitrile were measured by using Fourier transform–ion cyclotron resonance spectrometry to follow the isotopic exchange reaction.
Colleen K, Regan +2 more
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Is the Hammett’s Constant Free of Steric Effects?
The Journal of Physical Chemistry A, 2012In this work, we have explored the validity of the hypotheses on which rest the Hammett's approach to quantify the substituent effect on a reaction center, by applying two DFT energy decomposition schemes. This is performed by studying the change in the total electronic energy, ΔΔE, associated with a proton transfer isodesmic equilibrium.
Luis, Rincón, Rafael, Almeida
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Steric effects in dispersion forces interactions
Physical Review E, 2008Classically, there have been two different ways to obtain mean-field theories for liquid crystals. One is based on short-range repulsive steric forces and the other on long-range attractive dispersion forces. In the former approach, it is the anisotropic shape of the molecules that leads to the anisotropic interaction, and in the latter it is the ...
Sonnet, A.M., Virga, E.G.
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Sterically crowded aryloxide compounds of aluminum: electronic and steric effects
Organometallics, 1991The mononuclear, four-coordinate aluminum compounds AlR 2 (BHT)L and AlR(BHT) 2 L [R=Me, Et; BHT=2,6-di-tert-butyl-4-methylphenoxide; L=2-Mepy, 4-Mepy, 2,6-Me 2 py, CH 3 CN, N(C 2 H 4 ) 3 CH, HNEt 2 , HN i Bu 2 , H 2 N t Bu,H 2 N n Bu, NH 3 , py•O] are obtained when AlR 3 is treated with the correct molar equivalent of BHT-H and the appropriate Lewis ...
Matthew D. Healy +2 more
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Remote Control by Steric Effects
Science, 2014A rhodium-catalyzed reaction places a silicon substituent on the site farthest away from the largest group present on an aromatic ring. [Also see Research Article by Cheng and Hartwig ]
Mamoru Tobisu, Naoto Chatani
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Steric effects in molecular adsorption
The Journal of Chemical Physics, 1988The results of a molecular beam surface scattering experiment with preferentially orientated NO on Ag[111] are given. In adsorption molecules oriented with the O end towards the surface have a larger trapping probability.
M. G. Tenner +3 more
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