Angular Dependence of Dipolar Substituent Effects

2007 ◽  
pp. 183-224 ◽  
Author(s):  
Keith Bowden ◽  
Edward J. Grubbs
Keyword(s):  
Angular Dependence ◽  
Substituent Effects

ChemInform Abstract: Angular Dependence of Dipolar Substituent Effects.

ChemInform ◽  
2010 ◽  
Vol 25 (50) ◽  
pp. no-no
Author(s):  
K. BOWDEN ◽  
E. J. GRUBBS
Keyword(s):  
Angular Dependence ◽  
Substituent Effects

Transoid Homoallylic Proton-Proton Coupling Constants

1989 ◽  
Vol 42 (5) ◽  
pp. 659 ◽  
Author(s):  
M Barfield ◽  
RJ Spear ◽  
S Sternhell
Keyword(s):  
Angular Dependence ◽  
Substituent Effects ◽  
Coupling Constants ◽  
Mo Calculations ◽  
Proton Proton ◽  
Proton Coupling ◽  
Tentative Assignment ◽  
Single Compound ◽  
Derivatives Of

Transoid homoallylic coupling constants (5JH,H) for six compounds (5,10-dihydroindeno[2,1-alindene and confertifolin derivatives) of fixed stereochemistry were determined and compared with calculated values. Magnetic equivalence limited discrete determination of 5Jtrans and 5Jcis to three of these compounds. The single compound where unequivocal assignment could be made revealed 5Jtrans > 5Jcis; this was supported in two other compounds by tentative assignment. Changes in the magnitude of the couplings suggested that substantial substituent effects may be operative. INDO-MO calculations correctly predicted the angular dependence but incorrectly predicted 5Jcis > 5Jtrans.

Substituent effects and solvents

1992 ◽  
Vol 89 ◽  
pp. 1567-1571
Author(s):  
O Pytela ◽  
M Ludwig
Keyword(s):  
Substituent Effects

Substituent Effects on the Thermal Decomposition of Phosphate Esters on Ferrous Surfaces

2019 ◽  
Author(s):  
James Ewen ◽  
Carlos Ayestaran Latorre ◽  
Arash Khajeh ◽  
Joshua Moore ◽  
Joseph Remias ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Film Formation ◽  
Substituent Effects ◽  
Vapour Phase ◽  
Industrial Applications ◽  
Phosphate Esters ◽  
Antiwear Additives ◽  
Formation Mechanisms ◽  
Phosphate Ester ◽  
Wide Range

<p>Phosphate esters have a wide range of industrial applications, for example in tribology where they are used as vapour phase lubricants and antiwear additives. To rationally design phosphate esters with improved tribological performance, an atomic-level understanding of their film formation mechanisms is required. One important aspect is the thermal decomposition of phosphate esters on steel surfaces, since this initiates film formation. In this study, ReaxFF molecular dynamics simulations are used to study the thermal decomposition of phosphate esters with different substituents on several ferrous surfaces. On Fe<sub>3</sub>O<sub>4</sub>(001) and α-Fe(110), chemisorption interactions between the phosphate esters and the surfaces occur even at room temperature, and the number of molecule-surface bonds increases as the temperature is increased from 300 to 1000 K. Conversely, on hydroxylated, amorphous Fe<sub>3</sub>O<sub>4</sub>, most of the molecules are physisorbed, even at high temperature. Thermal decomposition rates were much higher on Fe<sub>3</sub>O<sub>4</sub>(001) and particularly α-Fe(110) compared to hydroxylated, amorphous Fe<sub>3</sub>O<sub>4</sub>. This suggests that water passivates ferrous surfaces and inhibits phosphate ester chemisorption, decomposition, and ultimately film formation. On Fe<sub>3</sub>O<sub>4</sub>(001), thermal decomposition proceeds mainly through C-O cleavage (to form surface alkyl and aryl groups) and C-H cleavage (to form surface hydroxyls). The onset temperature for C-O cleavage on Fe<sub>3</sub>O<sub>4</sub>(001) increases in the order: tertiary alkyl < secondary alkyl < primary linear alkyl ≈ primary branched alkyl < aryl. This order is in agreement with experimental observations for the thermal stability of antiwear additives with similar substituents. The results highlight surface and substituent effects on the thermal decomposition of phosphate esters which should be helpful for the design of new molecules with improved performance.</p>

Calculating Sputter Rate Angular Dependence Using Optical Profilometry (Preprint)

2007 ◽  
Author(s):  
Alexander C. Barrie ◽  
Bryan S. Taylor ◽  
Jared M. Ekholm ◽  
Jr Hargus ◽  
William A.
Keyword(s):  
Angular Dependence ◽  
Optical Profilometry
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