Octahedral metal carbonyls: reactions and bonding. VII. Kinetics of the substitution reactions of 2,5-dithiahexane complexes of chromium hexacarbonyl and molybdenum hexacarbonyl

1968 ◽  
Vol 7 (3) ◽  
pp. 584-588 ◽  
Author(s):  
Gary C. Faber ◽  
Gerard R. Dobson
Keyword(s):  
Molybdenum Hexacarbonyl ◽  
Metal Carbonyls ◽  
Substitution Reactions ◽  
Chromium Hexacarbonyl ◽  
Kinetics Of

Evidence for general base catalysis by protic solvents in a kinetic study of alcoholyses and hydrolyses of 1-(phenoxycarbonyl)pyridinium ions under both solvolytic and non-solvolytic conditions

2009 ◽  
Vol 74 (1) ◽  
pp. 43-55 ◽  
Author(s):  
Dennis N. Kevill ◽  
Byoung-Chun Park ◽  
Jin Burm Kyong
Keyword(s):  
Second Order ◽  
Base Catalysis ◽  
Substitution Reactions ◽  
Third Order ◽  
Methoxy Derivative ◽  
First Order ◽  
General Base ◽  
Protic Solvents ◽  
Kinetics Of ◽  
Pyridinium Ions

The kinetics of nucleophilic substitution reactions of 1-(phenoxycarbonyl)pyridinium ions, prepared with the essentially non-nucleophilic/non-basic fluoroborate as the counterion, have been studied using up to 1.60 M methanol in acetonitrile as solvent and under solvolytic conditions in 2,2,2-trifluoroethan-1-ol (TFE) and its mixtures with water. Under the non- solvolytic conditions, the parent and three pyridine-ring-substituted derivatives were studied. Both second-order (first-order in methanol) and third-order (second-order in methanol) kinetic contributions were observed. In the solvolysis studies, since solvent ionizing power values were almost constant over the range of aqueous TFE studied, a Grunwald–Winstein equation treatment of the specific rates of solvolysis for the parent and the 4-methoxy derivative could be carried out in terms of variations in solvent nucleophilicity, and an appreciable sensitivity to changes in solvent nucleophilicity was found.

Studies in polymerization. XIII. The activated initiation of vinyl polymerization by metal carbonyls

1962 ◽  
Vol 268 (1335) ◽  
pp. 553-566 ◽  
Keyword(s):  
Kinetic Mechanism ◽  
Molybdenum Hexacarbonyl ◽  
Metal Carbonyls ◽  
Group Vi ◽  
Radical Intermediates ◽  
Vinyl Polymerization ◽  
Organic Halogen ◽  
Halogen Compounds ◽  
Iodine Compounds ◽  
Reaction Proceeds

It has been found that the hexaearbonyls of group VI metals in the presence of some organic halogen compounds are active initiators of vinyl polymerization. Molybdenum hexacarbonyl is the most active, and halogen compounds containing —CC1 3 , —CBr 3 are generally more effective than those with fewer halogen atoms joined to a single carbon. Fluorine and iodine compounds are inactive. A study has been made of the initiation of the polymerization of methyl methacrylate by the Cr(CO) 6 + CCl 4 system. The polymerization is markedly retarded by carbon monoxide. It is shown that the reaction proceeds through free-radical intermediates, and a kinetic mechanism for initiation is derived (equation (4)) leading to the expression (5) for the rate of chain starting. This quantity may be calculated from (5) with the aid of the numerical values in table 3. Kinetic observations are in satisfactory agreement with this mechanism. The nature of the participating reactions is discussed.

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