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On the origin of the steric effect
Physical Chemistry Chemical Physics, 2012A quantitative analysis of the steric effect of aliphatic groups was carried out from first principles. An intuitive framework is proposed that allows the separation and straightforward interpretation of two contributors to the steric effect: steric strain and steric shielding (hindrance). When a sterically demanding group is introduced near a reactive
Pintér, Balasz +4 more
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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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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
Suchandra, Chatterjee +3 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, 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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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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