Relation entre structure et réactivité dans les réactions d'addition nucléophile sur les dérivés carbonylés: influence de la tension angulaire sur la réactivité de cyclanones et cyclanols angulairement contraints

1982 ◽  
Vol 60 (3) ◽  
pp. 239-242 ◽  
Author(s):  
Bernard Boyer ◽  
Gérard Lamaty ◽  
Claude Moreau ◽  
Patrick Geneste
Keyword(s):  
Rate Constants ◽  
Reaction Pathway ◽  
Acid Oxidation ◽  
Initial State ◽  
Torsion Angles ◽  
Chromic Acid Oxidation ◽  
Late Transition ◽  
Almost All ◽  
Rate Constants For Addition

The rate constants for addition of sodium borohydride on the angularly constrained cyclic ketones, tricyclo[3.3.1.1.3,7]-2-decanone (1), bicyclo[3.3.1]-9-nonanone (2), bicyclo[3.2.1.])-8-octanone (3), and bicyclo[2.2.1.]-7-heptanone (4), have been determined in water/dioxane (50:50 v/v) at 25 °C. These values demonstrate the energy differences caused by the changes in torsion angles on passing from the initial state to the transition state. The activation energies determined, representing almost all of the energy associated with the angular torsion, are indicative of a late transition state.Comparison of rate constants for the reduction of these ketones where the reaction site carbon changes from sp2 to sp3 hybridization with the rates for chromic acid oxidation of the corresponding alcohols (opposite change of hybridization) demonstrates that the effects of the angular variations can also act as criteria for the determination of the position of transition states along the reaction pathway. [Journal Translation]

Relation entre structure et réactivité dans les réactions d'addition nucléophile sur les dérivés carbonylés: influence des interactions diaxiales-1,3 sur la réactivité de cyclanones et cyclanols stériquement encombrés

1979 ◽  
Vol 57 (21) ◽  
pp. 2848-2852 ◽  
Author(s):  
Bernard Boyer ◽  
Gérard Lamaty ◽  
Claude Moreau ◽  
Patrick Geneste
Keyword(s):  
Carbon Atom ◽  
Transition State ◽  
Sodium Borohydride ◽  
Rate Constants ◽  
Chromic Acid ◽  
Acid Oxidation ◽  
Cyclic Ketones ◽  
Chromic Acid Oxidation ◽  
Opposite Change ◽  
Late Transition

The rate constants for the addition of sodium borohydride to the sterically hindered cyclic ketones, 3,3,5-trimethylcyclohexanone (2), 3,3,5,5-tetramethylcyclohexanone (3), bicyclo[3,2,1]-3-octanone (4), tricyclo[5,2,1,03,8]-3-decanone (5), tricyclo[5,3,1,03,8]-5-undecanone (6) and bicyclo[3,3,1]-3-nonanone (7) have been determined at 25 °C in a 50/50 by volume mixture of water and dioxane. The values demonstrate energies due to 1,3-diaxial interactions that arise on passing from the initial to the transition states. The measured energies of activation represent almost the total conformational energy corresponding to these interactions, suggesting a late transition state.Comparison of the rates of reduction of these ketones where the carbon atom at the site of attack passes from sp2 to sp3 hybridisation, with the rates of chromic acid oxidation of the corresponding alcohols showing therefore the opposite change in hybridisation, indicates that the magnitude of the 1,3-diaxial interactions can serve to determine the position of the transition state along the reaction coordinate.The observed differences in reactivity can also contribute to the elucidation of conformational problems. [Journal translation]

A Direct Determination of Rubber Hydrocarbon. Chromic Acid Oxidation Method

1943 ◽  
Vol 16 (3) ◽  
pp. 660-667 ◽  
Author(s):  
V. L. Burger ◽  
W. E. Donaldson ◽  
J. A. Baty
Keyword(s):  
Acetic Acid ◽  
Chromic Acid ◽  
Direct Determination ◽  
Acid Oxidation ◽  
Laboratory Procedure ◽  
Oxidation Method ◽  
Chromic Acid Oxidation

Abstract A method for the direct determination of rubber is reported. This method utilizes the property of rubber hydrocarbon when oxidized by chromic acid to form definite and reproducible amounts of acetic acid. This determination has been reduced to a comparatively simple laboratory procedure, whose accuracy (in the absence of interferences) is 1 to 2 per cent.

Determination of Methyl Groups in Alkylbenzenes by Chromic Acid Oxidation

1961 ◽  
Vol 33 (3) ◽  
pp. 453-455 ◽  
Author(s):  
S. G. Brandenberger ◽  
L. W. Mass ◽  
Isaac. Dvoretzky
Keyword(s):  
Chromic Acid ◽  
Acid Oxidation ◽  
Methyl Groups ◽  
Chromic Acid Oxidation

EPR spectroscopy determination of the rate constants for addition of [O 4 S] •– radical anion to double bonds

2018 ◽  
Vol 28 (2) ◽  
pp. 190-191
Author(s):  
Rashid G. Gasanov ◽  
Marina V. Tsikalova ◽  
Olga E. Zaborina ◽  
Vladimir I. Lozinsky
Keyword(s):  
Epr Spectroscopy ◽  
Rate Constants ◽  
Radical Anion ◽  
Double Bonds ◽  
Rate Constants For Addition

Basic set of experiments for determination of mechanical properties of sand

2014 ◽  
Vol 62 (1) ◽  
pp. 129-137
Author(s):  
A. Sawicki ◽  
J. Mierczyński
Keyword(s):  
Mechanical Properties ◽  
Soil Mechanics ◽  
Physical And Mechanical Properties ◽  
Local Strain ◽  
Initial State ◽  
Laboratory Equipment ◽  
Additional Information ◽  
Basic Set ◽  
Initial Anisotropy

Abstract A basic set of experiments for the determination of mechanical properties of sands is described. This includes the determination of basic physical and mechanical properties, as conventionally applied in soil mechanics, as well as some additional experiments, which provide further information on mechanical properties of granular soils. These additional experiments allow for determination of steady state and instability lines, stress-strain relations for isotropic loading and pure shearing, and simple cyclic shearing tests. Unconventional oedometric experiments are also presented. Necessary laboratory equipment is described, which includes a triaxial apparatus equipped with local strain gauges, an oedometer capable of measuring lateral stresses and a simple cyclic shearing apparatus. The above experiments provide additional information on soil’s properties, which is useful in studying the following phenomena: pre-failure deformations of sand including cyclic loading compaction, pore-pressure generation and liquefaction, both static and caused by cyclic loadings, the effect of sand initial anisotropy and various instabilities. An important feature of the experiments described is that they make it possible to determine the initial state of sand, defined as either contractive or dilative. Experimental results for the “Gdynia” model sand are shown.

Population Change, Modernization and Welfare. By Joseph Spengler. Prentice-Hall Inc., Englewood Cliffs, N.J. 1974.

1977 ◽  
Vol 16 (2) ◽  
pp. 220-222
Author(s):  
Zeba A. Sathar
Keyword(s):  
Population Growth ◽  
Population Change ◽  
Population Control ◽  
Stable Condition ◽  
Developed Countries ◽  
Wide Field ◽  
Wide Scale ◽  
Socio Economic Variables ◽  
Almost All

The book covers a wide field, touching on almost all aspects of popula¬tion change on a world-wide scale. It discusses, using world and country data, the relationships between demographic and socio-economic variables, and elaborates on" their relative importance in the determination of population problems which confront the world as a whole and nations individually. Policies designed to alleviate these problems are discussed with an emphasis on those related to population control. The first chapter is entitled "Population Growth: Past and Prospective" and reviews the various parameters associated with population change in the past and in the future. It touches upon the concept of a stable population in order to show the elements which cause a population to change (i.e. remove it from its stable condition). The main elements of change, population growth, migration, mortality and natality are discussed individually. The chapter is concluded by a description of the main differences in these elements and other socio-economic conditions as they exist in the less-developed and developed countries.

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