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Steric effects in alkylpyrimidines
Recueil des Travaux Chimiques des Pays-Bas, 1978AbstractTreatment of solutions of 4,6‐dimethylpyrimidine and 4,6‐di‐t‐butylpyrimidine in acid with aliphatic acids (RCO2H) in the presence of silver nitrate and ammonium peroxydisulfate gave the 2‐R‐4,6‐dimethyl‐ and 2‐R‐4,6‐di‐t‐butylpyrimidines (R = C2H5, i‐C3H7, t‐C4H9). Ths pKa values of these compounds were measured.
van der Plas, H.C., Koudijs, A.
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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 ...
Jacques-Emile Dubois +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 ...
Jacques-Emile Dubois +2 more
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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
Alan J. Welch +4 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.
J. E. Eilers, A. Greenberg, A. Liberles
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Attractive steric effects cause some organic structures to be more stable when bulky side-groups are closer together.
J. E. Eilers, A. Greenberg, A. Liberles
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Steric effect on fluorescence quenching
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2005In this communication we have reported the steric effect on the fluorescence quenching rate constants of the electron transfer (ET) process. We have done a comparative study using donor (D)-acceptor (A) systems with different exergonicity (-deltaG(f)). Different carbazole derivatives (CZ): 1,4-dicyanobenzene (DCB) systems (-deltaG(f) = 0.7-0.8 eV) were
Nandita Ghosh +3 more
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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.
A.J.S. Williams, S.H. Graham
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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.
A.J.S. Williams, S.H. Graham
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σ‐Correlations and steric effects [PDF]
Organic Magnetic Resonance, 1982 AbstractCarbon‐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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Conformational, Steric, and Stereoelectronic Effects [PDF]
, 1984 The 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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Conformational and Other Steric Effects [PDF]
, 1977 The 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. The features that are of greatest significance in organic chemistry are nonbonded interactions, both repulsive and ...
Francis A. Carey, Richard J. Sundberg
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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.
Stephen L. Craig +2 more
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