Results 181 to 190 of about 142,813 (213)

Steric hindrance in acetamidomesitylene

Journal of Applied Chemistry, 1951
AbstractThe acetyl group of acetamidomesitylene is not split off either by acids or by alkalis under analytical conditions. A laboratory preparation of acetamidomesitylene is described.
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Steric Hindrance in Vinyl-Mesitylene

Nature, 1948
A NUMBER of workers have observed various anomalous properties in nuclear-substituted derivatives of mesitylene, such anomalies usually being ascribed to restricted rotation about the bond connecting the substituent to the benzene ring caused by the two ortho-methyl - groups.
G. T. Kennedy, F. R. Buck, E. M. Tanner, F. Morton   +3 more
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Origin of steric hindrance in ethane

International Journal of Quantum Chemistry, 1994
AbstractSteric hindrance has been regarded as a result of nonbonding atomic repulsion and measured in terms of empirically obtained van der Waals radii. The authors sought the cause of steric hindrance using the partial derivatives of the energy‐components with respect to a nuclear coordinate.
Hiroaki Tokiwa, Hiroshi Ichikawa
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Steric hindrance in butadiene and ethylene

Tetrahedron, 1970
Abstract The structure of ethylene, trans - and cis -butadiene was determined theoretically, based on self consistent steric analysis. The calculated structures agree with the known experimental data. The energy path of the cis-trans isomerization of butadiene was calculated both for the ground state and the first excited state.
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Steric hindrance in substituted dibenzofurans

Journal of the Chemical Society, Perkin Transactions 2, 1977
Ten alkyl-substituted dibenzofurans (3) have been synthesized by irridiation of the corresponding diphenyl ethers (4). 13C Chemical shift analysis indicates that some of the highly substituted compounds (3d, g–i) are probably twisted out of the molecular plane due to steric interaction of the substituents in the 1 and 9 positions.
Stefan Berger, Klaus-Peter Zeller
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Quantum Mechanical Size and Steric Hindrance

The Journal of Physical Chemistry A, 2006
A quantum mechanical definition of molecular size and shape is formulated from the electronic second moment of the Hartree-Fock wave function. The shape tensor is defined to be invariant with respect to the origin. The geometric average of the eigenvalues of the tensor correlates very well with van der Waals and Bragg-Slater radii.
Raymond A. Poirier, Joshua W. Hollett, Aaron Kelly   +2 more
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Steric hindrance in macromolecular solutions

Journal of Polymer Science, 1947
AbstractThe same point in the space cannot be occupied simultaneously by two molecules. In a solution of rigid rodlike macromolecules, each molecule prevents its neighbors from occupying certain positions, the whole of which form the forbidden angle. Calculation shows that in the case of rigid, filiform molecules, this angle is large even at very low ...
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ChemInform Abstract: STERIC HINDRANCE IN AROMATIC HYDROGEN EXCHANGE

Chemischer Informationsdienst, 1973
Acid-catalysed hydrogen exchange at the ortho position of tetraphenylmethane is sterically hindered, and is only the second known example of hindrance in the reaction.
Roger Taylor, Herbert V. Ansell
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Domain growth kinetics and steric hindrance

Phase Transitions, 1991
Abstract We propose a simple model on which the effects of steric hindrance on domain growth after deep quenches can be studied. The work is motivated by recent experiments on cyanoadamantane. We observe extremely slow domain growth which is unusual for systems with non-conserved order parameter and non-diffusive (Glauber) dynamics.
Willart, J.-F., Naudts, Jan, Descamps, M.   +2 more
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The origin of steric hindrance in cyclohexane derivatives

Experientia, 1953
Aus der Veresterungsgeschwindigkeit der stereoisomeren Menthole mitp-Nitrobenzoylchlorid lasst sich schliessen, dass diese Molekule in derjenigen Konstellation reagieren, in welcher die Oxygruppe eine aquatoriale Stellung einnimmt. In starren Molekulen (wie dietrans-Dekalole), bei denen die Verschiebung einer Oxyoder Estergruppe von der polaren in die ...
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