Results 291 to 300 of about 271,466 (344)
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σ‐Correlations and steric effects
Organic Magnetic Resonance, 1982AbstractCarbon‐1 shifts in 1‐dimethylimino‐3‐dimethylamino‐1‐(4‐substituted)phenylprop‐2‐ene perchlorates show high correlation and negative dependence v. a σ set having high f character, similar to α and carbonyl carbon shifts in 4‐substituted styrenes and N,N‐dimethylbezamides, respectively.
S. N. Balasubrahmanyam, I. M. Mallick
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Steric effects in carbene cycloadditions
Tetrahedron Letters, 1983Abstract Steric effects in cycloadditions with alkenes prevent the occurrence of a general linear free energy relationship between the reactivities of carbenes. Nevertheless, the isoselective temperature remains constant.
Bernd Giese, Woo Bung Lee, Carola Stiehl
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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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Fisher information and steric effect
Chemical Physics Letters, 2007Abstract A modified Fisher information, the sum of the one-electron Fisher information, is proposed. It is shown that the modified Fisher information is the original Fisher information plus a sum of differences of quantum and classical variances. A generalization of the Stam’s inequality is derived.
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Substituent effects on steric strain
Chemical Physics Letters, 2003Accurate quantum chemical calculations were performed on a series of mono-substituted tetrahedranes and [3]-prismanes by the high-level ab initio G3/B3LYP method. The relative stabilities of substituted tetrahedranes vs. their [3]-prismane analogues and the influence of substitution on steric strain are discussed.
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Conformational, Steric, and Stereoelectronic Effects
1984The total energy of a molecule is directly related to its geometry. Several aspects of molecular geometry can be recognized, and, to some extent, the energetic consequences can be dissected and attributed to specific structural features. Among the factors which contribute to total energy and have a recognizable connection with molecular geometry are ...
Francis A. Carey, Richard J. Sundberg
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Steric Effect of Methylene Groups. I
Journal of the American Chemical Society, 1945R T, ARNOLD, E, RONDESTVEDT
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