CATALYTIC ACTIVATION OF MOLECULAR HYDROGEN BY RUTHENIUM (III) CHLORIDE COMPLEXES

1961 ◽  
Vol 39 (6) ◽  
pp. 1372-1376 ◽  
Author(s):  
J. F. Harrod ◽  
Stefania Ciccone ◽  
J. Halpern
Keyword(s):  
Molecular Hydrogen ◽  
Present System ◽  
Chloride Complexes ◽  
Rate Law ◽  
Catalytic Activation ◽  
Catalyzed Reactions ◽  
Kinetics Of ◽  
Hcl Solution

Ruthenium(III) chloride, in aqueous HCl solution, was found to activate H2 homogeneously and to catalyze the reduction by H2 of Ru(IV)and Fe(III). The kinetics of these reactions were examined and, in each case, the rate law was found to be −d[H2]/dt = k1[H2][RuIII] where k1 = 4.0 × 1014 exp [−23,800/RT] M−1 sec−1. The mechanisms of these reactions are discussed and compared to those of other homogeneously catalyzed reactions of hydrogen. A special feature of the present system is the resistance of the catalytic species itself (i.e. RuIII) to reduction by H2.

CATALYTIC ACTIVATION OF HYDROGEN IN AQUEOUS SOLUTION BY THE CHLOROPALLADATE(II) ION

1959 ◽  
Vol 37 (9) ◽  
pp. 1446-1450 ◽  
Author(s):  
J. Halpern ◽  
J. F. Harrod ◽  
P. E. Potter
Keyword(s):  
Aqueous Solution ◽  
Ferric Chloride ◽  
Molecular Hydrogen ◽  
Homogeneous Catalyst ◽  
Rate Law ◽  
Catalytic Activation ◽  
Kinetics Of ◽  
Mechanism Of The Reaction

The kinetics of the reduction of ferric chloride by molecular hydrogen in aqueous solution, in the presence of chloropalladate(II), were examined. The latter acts as a homogeneous catalyst for the reaction. The rate-law was found to be,[Formula: see text]where[Formula: see text]The mechanism of the reaction is discussed.

Kinetic modelling of reactions for the synthesis of 2-methyl-5-ethyl pyridine

2021 ◽  
Author(s):  
Emanuele Moioli ◽  
Leo Schmid ◽  
Peter Wasserscheid ◽  
Hannsjoerg Freund
Keyword(s):  
Kinetic Modelling ◽  
Acid Catalyst ◽  
Acid Catalyzed ◽  
Catalyzed Reactions ◽  
Kinetics Of

The kinetics of the acid catalyzed reactions of acetaldehyde ammonia trimer (AAT) and paraldehyde (para) to 2-methyl-5-ethyl pyridine (MEP) in the presence of an acid catalyst were investigated systematically. A...

Ferricyanide Oxidation of Butanol Homogeneously Catalysed by Chlororuthenium Complexes

1979 ◽  
Vol 32 (9) ◽  
pp. 1905 ◽  
Author(s):  
AF Godfrey ◽  
JK Beattie
Keyword(s):  
Aqueous Solution ◽  
Complex Formation ◽  
Linear Dependence ◽  
Rate Constants ◽  
Homogeneous Catalyst ◽  
Basic Solution ◽  
Rate Law ◽  
Kinetics Of ◽  
Solution Estimates ◽  
Butanol Concentration

The oxidation of butan-1-ol by ferricyanide ion in alkaline aqueous solution is catalysed by solutions of ruthenium trichloride hydrate. The kinetics of the reaction has been reinvestigated and the data are consistent with the rate law -d[FeIII]/dt = [Ru](2k1k2 [BuOH] [FeIII])/(2k1 [BuOH]+k2 [FeIII]) This rate law is interpreted by a mechanism involving oxidation of butanol by the catalyst (k1) followed by reoxidation of the catalyst by ferricyanide (k2). The non-linear dependence of the rate on the butanol concentration is ascribed to the rate-determining, butanol-independent reoxidation of the catalyst, rather than to the saturation of complex formation between butanol and the catalyst as previously claimed. Absolute values of the rate constants could not be determined, because some of the ruthenium precipitates from basic solution. With K3RuCl6 as the source of a homogeneous catalyst solution, estimates were obtained at 30�0�C of k1 = 191. mol-1 s-1 and k2 = 1�4 × 103 l. mol-1 s-1.

Spatiotemporal control over the co-conformational switching in pH-responsive flavylium-based multistate pseudorotaxanes

2015 ◽  
Vol 185 ◽  
pp. 361-379 ◽  
Author(s):  
Ana Marta Diniz ◽  
Nuno Basílio ◽  
Hugo Cruz ◽  
Fernando Pina ◽  
A. Jorge Parola
Keyword(s):  
Molecular Organization ◽  
Present System ◽  
Spectroscopic Techniques ◽  
Ph Responsive ◽  
Conformational Switching ◽  
Ph Values ◽  
Stable Species ◽  
Ph Dependent ◽  
Spatiotemporal Control ◽  
Kinetics Of

A multistate molecular dyad containing flavylium and viologen units was synthesized and the pH dependent thermodynamics of the network completely characterized by a variety of spectroscopic techniques such as NMR, UV-vis and stopped-flow. The flavylium cation is only stable at acidic pH values. Above pH ≈ 5 the hydration of the flavylium leads to the formation of the hemiketal followed by ring-opening tautomerization to give the cis-chalcone. Finally, this last species isomerizes to give the trans-chalcone. For the present system only the flavylium cation and the trans-chalcone species could be detected as being thermodynamically stable. The hemiketal and the cis-chalcone are kinetic intermediates with negligible concentrations at the equilibrium. All stable species of the network were found to form 1 : 1 and 2 : 1 host : guest complexes with cucurbit[7]uril (CB7) with association constants in the ranges 105–108 M−1 and 103–104 M−1, respectively. The 1 : 1 complexes were particularly interesting to devise pH responsive bistable pseudorotaxanes: at basic pH values (≈12) the flavylium cation interconverts into the deprotonated trans-chalcone in a few minutes and under these conditions the CB7 wheel was found to be located around the viologen unit. A decrease in pH to values around 1 regenerates the flavylium cation in seconds and the macrocycle is translocated to the middle of the axle. On the other hand, if the pH is decreased to 6, the deprotonated trans-chalcone is neutralized to give a metastable species that evolves to the thermodynamically stable flavylium cation in ca. 20 hours. By taking advantage of the pH-dependent kinetics of the trans-chalcone/flavylium interconversion, spatiotemporal control of the molecular organization in pseudorotaxane systems can be achieved.

Sign in / Sign up

Export Citation Format

Share Document