Catalytic deuterium exchange reactions with organics. XXXVI. The labelling of ( - )-inositol on self-activated platinum oxide with and without radiation

1967 ◽  
Vol 20 (12) ◽  
pp. 2647 ◽  
Author(s):  
SJ Angyal ◽  
CM Fernandez ◽  
JL Garnett
Keyword(s):  
Tritiated Water ◽  
Platinum Oxide ◽  
Deuterium Exchange ◽  
Exchange Reactions ◽  
Catalytic Method ◽  
Experimental Conditions ◽  
Extensive Degradation

Exchange of (-)-inositol with curie levels of tritiated water on self- activated platinum oxide leads to incorporation of tritium of which 92.5% is found at C l and C 6, 3.7% at C 2 and C 5, and 3.8% at C 3 and C 4. Isotope scavenging indicates that inversion occurs only at C1 yielding labelled myoinositol. Exchange is accelerated in the presence of u.v. light without extensive degradation. A comparison has been made between the Wilzbach gas irradiation technique and the catalytic method for labelling (-)-inositol. Possible mechanisms for tritium incorporation in (-)-inositol are discussed for the various experimental conditions used.

Catalytic deuterium exchange reactions with organics. XII. Further studies in platinum catalyst preparation-the process of self-activation

1965 ◽  
Vol 18 (7) ◽  
pp. 993 ◽  
Author(s):  
JL Garnett ◽  
WA Sollich
Keyword(s):  
Active Sites ◽  
Catalyst Deactivation ◽  
Platinum Catalyst ◽  
Platinum Oxide ◽  
Deuterium Exchange ◽  
Hydrogen Gas ◽  
Distribution Data ◽  
Exchange Reactions ◽  
Π Complex ◽  
Distribution Studies

A new process for the activation of platinum oxide, termed self-activation, is described. This procedure involves the reduction of platinic oxide with an organic compound such as benzene, naphthalene, or n-octane. The potential of the resulting catalyst in deuterium exchange reactions has been evaluated with three characteristic organic compounds, n-octane, naphthalene, and benzene. A comparison has been made in the properties of prereduced catalysts prepared by a self-activation procedure and catalysts activated conventionally with hydrogen gas. For high-temperature exchange reactions ( >90�), the former catalysts are to be preferred since higher final activities of up to 300% may be achieved. The kinetics of self-activation suggest that catalyst deactivation by reagents may be due to modification of active sites. With aromatic compounds, it is proposed that this deactivation occurs through a π-complex interaction. Isotope distribution studies in the labelled benzenes indicate that self-activated, prereduced catalysts, by comparison with hydrogen-activated catalysts, exhibit relatively low M values in relation to their activities. Distribution data are consistent with the explanation that catalyst deactivation by benzene is a process involving the generation of new types of active sites which are more numerous but of lower activity than the original sites. Attempts to stabilize prereduced catalysts by chemical methods were unsuccessful.

Catalytic deuterium exchange reactions with organics. XXIV. Electron spin resonance studies of adsorption on platinum oxide

1966 ◽  
Vol 19 (4) ◽  
pp. 529 ◽  
Author(s):  
IT Ernst ◽  
JL Garnett ◽  
WA Sollich-Baumgartner
Keyword(s):  
Transition Metal Oxides ◽  
Hydrogen Exchange ◽  
Platinum Oxide ◽  
Active Species ◽  
Paramagnetic Species ◽  
Charge Transfer Complexes ◽  
Severe Reaction ◽  
Exchange Reactions ◽  
Spin Resonance ◽  
Solid Liquid

The formation of paramagnetic species on catalyst surfaces at room temperature through the interaction of polynuclear aromatics in solid, liquid, or solute form with hydrated platinum oxide (PtO2,2H2O) is reported. The results are attributed to the formation of charge-transfer complexes, where the transferred electrons couple weakly, forming essentially a "diradicaloid" complex with a low-lying, thermally populated, triplet state. The effect of solvent, particle size, oxygen, water of crystallization, and temperature on the generation and stability of these e.s.r. active species has been investigated. The possible importance of these paramagnetic species in catalytic self-activation and hydrogen exchange reactions has been discussed. The following Group VIII transition metal oxides gave no e.s.r. spectra under relatively severe reaction conditions such as 1 hr at 120�: PdO; Ru02,2H20; RuO2; Rh2O3; IrO2,2H2O; ReO2; and NiO.

Radical cation formation during the adsorption of polycyclic aromatic hydrocarbons on platinum oxide

1973 ◽  
Vol 26 (1) ◽  
pp. 221 ◽  
Author(s):  
JL Garnett ◽  
KJ Nicol ◽  
A Rainis
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Radical Cation ◽  
Aromatic Hydrocarbons ◽  
Hyperfine Splitting ◽  
Radical Cations ◽  
Platinum Oxide ◽  
Adsorbed Species ◽  
Experimental Conditions ◽  
Polycyclic Aromatic

Experimental conditions are reported for resolving the hyperfine splitting of e.p.r. spectra obtained from the interaction of polycyclic aromatic hydrocarbons with platinum oxide. By contrast with earlier interpretations where only a singlet was obtained even with perylene, the present results indicate that the adsorbed species are radical cations.

Hydrogen-deuterium-exchange reactions of methoxide-methanol clusters

1990 ◽  
Vol 112 (19) ◽  
pp. 6832-6838 ◽  
Author(s):  
S. E. Barlow ◽  
Dang Thuy Thanh ◽  
Veronica M. Bierbaum
Keyword(s):  
Deuterium Exchange ◽  
Hydrogen Deuterium Exchange ◽  
Exchange Reactions ◽  
Hydrogen Deuterium

Acetate-catalyzed Bromination and Exchange Reactions of 2-Butanone

1972 ◽  
Vol 50 (19) ◽  
pp. 3229-3232 ◽  
Author(s):  
J. W. Thorpe ◽  
J. Warkentin
Keyword(s):  
Deuterium Exchange ◽  
Acetate Buffer ◽  
Direct Reaction ◽  
Exchange Reactions ◽  
Good Agreement

Products from bromination of 2-butanone in an aqueous acetate buffer were studied in order to compare the regiochemistry of monobromination with that of deuterium exchange. The good agreement found suggests that direct reaction of Br2 with unenolized ketone, for which there have been claims in the literature recently, is unimportant or absent under the conditions of the experiments.

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