scholarly journals Allenyl Azide Cycloaddition Chemistry. Photochemical Initiation and CuI Mediation Leads to Improved Regioselectivity

2008 ◽  
Vol 10 (8) ◽  
pp. 1665-1668 ◽  
Author(s):  
Ken S. Feldman ◽  
D. Keith Hester ◽  
Carlos Silva López ◽  
Olalla Nieto Faza
Keyword(s):  
Allenyl Azide ◽  
Photochemical Initiation

ChemInform Abstract: Allenyl Azide Cycloaddition Chemistry. Photochemical Initiation and CuI Mediation Leads to Improved Regioselectivity.

ChemInform ◽  
2008 ◽  
Vol 39 (35) ◽  
Author(s):  
Ken S. Feldman ◽  
D. Keith II Hester ◽  
Carlos Silva Lopez ◽  
Olalla Nieto Faza
Keyword(s):  
Allenyl Azide ◽  
Photochemical Initiation

Different radical initiation techniques of hydrosilylation reactions of multiple bonds in water: thermal and photochemical initiation

2010 ◽  
Vol 23 (10) ◽  
pp. 944-949 ◽  
Author(s):  
Julia Calandra ◽  
Al Postigo ◽  
Diana Russo ◽  
Norma Sbarbati Nudelman ◽  
Juan José Tereñas
Keyword(s):  
Multiple Bonds ◽  
Radical Initiation ◽  
Photochemical Initiation

Studies in polymerization. I. A method for determining the velocity constants in polymerization reactions and its application to styrene

1948 ◽  
Vol 192 (1030) ◽  
pp. 309-328 ◽  
Keyword(s):  
Kinetic Scheme ◽  
Frequency Factor ◽  
Thermal Polymerization ◽  
Kinetic Chain ◽  
Rate Of Increase ◽  
Initiation Reaction ◽  
After Effect ◽  
Photochemical Initiation ◽  
First Time ◽  
General Method

A general method for determining the velocity constants of initiation, propagation, transfer and termination in polymerization reactions is described. The method depends essentially on the measurement of the rate of increase of viscosity for various rates of chain initiation. In the case of radical polymerizations photochemical initiation is most convenient. Measurement of the photochemical after-effect then gives four independent relations between the four velocity constants. The method has been tested by a detailed study of the thermal and photochemical polymerization of styrene. Velocity constants have been determined at 0 and 25° C, and the activation energies and frequency factors calculated. Results are given in tables 5 and 6. It is shown for the first time that chain transfer is important in the thermal polymerization of pure styrene, occurring 11 times per kinetic chain at 25° C. This result invalidates conclusions which previous workers have reached. Other rather unexpected results are that the initiation reaction has a much higher activation energy than has been generally supposed, and a normal frequency factor, while termination is activated. A detailed kinetic scheme is proposed which removes certain unjustifiable assumptions present in earlier ones. This is shown to be consistent with all the available evidence.

Photochemical initiation of gaseous detonations

1978 ◽  
Vol 5 (11-12) ◽  
pp. 971-982 ◽  
Author(s):  
J.H. Lee ◽  
R. Knystautas ◽  
N. Yoshikawa
Keyword(s):  
Gaseous Detonations ◽  
Photochemical Initiation

Photochemical Initiation of Free Radicals in Cotton Cellulose

1966 ◽  
Vol 36 (9) ◽  
pp. 822-827 ◽  
Author(s):  
Glyn O. Phillips ◽  
Oscar Hinojosa ◽  
Jett C. Arthur ◽  
Trinidad Mares
Keyword(s):  
Free Radicals ◽  
Cotton Cellulose ◽  
Photochemical Initiation

The kinetics of polysulphone formation - I. The formation of 1-butene polysulphone at 25° C

1952 ◽  
Vol 212 (1108) ◽  
pp. 96-112 ◽  
Keyword(s):  
Sulphur Dioxide ◽  
Primary Process ◽  
Propagation Process ◽  
A Value ◽  
Absorption Of Light ◽  
Rate Of Reaction ◽  
Liquid Sulphur ◽  
Rate Of Absorption ◽  
Photochemical Initiation ◽  
Kinetics Of

The formation of 1-butene polysulphone from mixtures of liquid sulphur dioxide and 1-butene has been investigated dilatometrically at 25° C. Photochemical and silver nitrate initiation have been used, most of the work being carried out in mixtures containing an excess of sulphur dioxide. There is a discrepancy, in the case of photochemical initiation, between the molecular weight as estimated from the intrinsic viscosity of the polymer, and that deter­mined from the rate of reaction and rate of absorption of light. This discrepancy is ascribed to an inefficient primary process. The variation of rate with initiator, monomer and retarder concentrations has been investigated. The initiator exponent has a value intermediate between 0.5 and 1.0, indicating the occurrence of at least two termination processes. Kinetic expressions have been deduced for various possible termination mechanisms, and. in order to obtain agreement with experiment it is necessary to assume that the propagation process involves the addition to the growing chain of a 1:1 molecular complex of 1-butene and sulphur dioxide.

Sign in / Sign up

Export Citation Format

Share Document