Spectroscopic Study of Photosensitized Oxidation of Polyisoprene

1977 ◽  
Vol 50 (4) ◽  
pp. 704-713 ◽  
Author(s):  
M. A. Golub ◽  
M. L. Rosenberg ◽  
R. V. Gemmer
Keyword(s):  
Zero Order ◽  
Double Bonds ◽  
Photosensitized Oxidation ◽  
The Third ◽  
Type Process ◽  
Zero Order Kinetics ◽  
Hydroperoxide Formation ◽  
Cis And Trans ◽  
In Cis ◽  
Suitable Measure

Abstract The microstructural changes which occur in cis- and trans-1,4-polyisoprenes and in squalene during photosensitized oxidation were investigated with the aid of infrared and proton and carbon-13 NMR spectroscopy. The singlet oxygenation of these isoprenic compounds resulted in allylic hydroperoxides with shifted double bonds, according to the expected “ene”-type process. In contrast to trans-1,4-polyisoprene and squalene, which displayed the three possible double bond shifts, cis-1,4-polyisoprene showed essentially two of the shifts (to di- and trisubstituted double bonds) and very little of the third (to exomethylene groups). A suitable measure of the extent of hydroperoxidation was afforded by the absorbance ratio, A3400/A1440≡A′. Similar correlations of A′ with oxygen uptake were obtained for the three isoprenic compounds, using chlorophyll or methylene blue as sensitizer. The use of rose bengal gave erratic results indicative of some autoxidation accompanying the hydroperoxide formation. The singlet oxygenation followed zero-order kinetics, the relative rates for cis- and trans-1,4-polyisoprenes being approximately 1.0:1.5.

scholarly journals Hydrogen Peroxide Oxidation of Coordinated Thiocyanate Ion in cis- and trans-[Coen2NH3NCS]2+: The Preparation and Properties of trans-[Coen2NH3CN]2+

1973 ◽  
Vol 51 (24) ◽  
pp. 4152-4158 ◽  
Author(s):  
Albert Richard Norris ◽  
James William Lennox Wilson
Keyword(s):  
Hydrogen Peroxide ◽  
Spectral Properties ◽  
Peroxide Oxidation ◽  
Reaction Conditions ◽  
Thiocyanate Ion ◽  
Hydrogen Peroxide Oxidation ◽  
Percent Conversion ◽  
Cis And Trans ◽  
In Cis

The hydrogen peroxide oxidation of thiocyanate ion in cis- and trans-[Coen2NH3NCS]2+ leads to the formation of the corresponding cis- and trans-cyanoammine- and diamminebis(ethylenediamine)cobalt-(III) complexes. The spectral properties of the previously unreported trans-[Coe2NH3CN]2+ are reported and compared to the spectral properties of the cis-isomer.Observations are made concerning the reaction conditions which favor a high percent conversion of trans-[Coen2NH3NCS]2+ to trans-[Coen2NH3CN]2+.

Structure and chemical bonding in cis- and trans-M(NO)2(O2CR)2 (M=Cr and Mo) complexes

Polyhedron ◽  
2000 ◽  
Vol 19 (26-27) ◽  
pp. 2565-2572 ◽  
Author(s):  
Ludmiła Szterenberg ◽  
Szczepan Roszak ◽  
Renata Matusiak ◽  
Antoni Keller
Keyword(s):  
Chemical Bonding ◽  
Cis And Trans ◽  
In Cis

Hydrogen bonding and conformation in cis- and trans-2-alkoxy-3-hydroxytetrahydrofurans

1968 ◽  
Vol 46 (1) ◽  
pp. 21-24 ◽  
Author(s):  
W. W. Zajac Jr. ◽  
F. Sweet ◽  
R. K. Brown
Keyword(s):  
Hydrogen Bonding ◽  
Infrared Spectra ◽  
Hydroxyl Absorption ◽  
Cis And Trans ◽  
In Cis ◽  
Infrared Data ◽  
Hydrogen Bonded

Infrared spectra show both free and hydrogen bonded hydroxyl absorption in several trans-2-alkoxy-3-hydroxytetrahydrofurans. The extent of non-bonded hydroxyl is greater than that of bonded hydroxyl. Suggestions are made of possible conformations which might account for the infrared data.

The Influence of Temperature and Concentration on Copper Deposition Kinetics in Supercritical Carbon Dioxide

2004 ◽  
Vol 812 ◽  
Author(s):  
Yinfeng Zong ◽  
James J. Watkins
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Supercritical Fluids ◽  
Zero Order ◽  
Copper Deposition ◽  
Deposition Kinetics ◽  
Zero Order Kinetics ◽  
Concentration Interval ◽  
Kinetics Of ◽  
Supercritical Carbon

AbstractThe kinetics of copper deposition by the hydrogen-assisted reduction of bis(2,2,7- trimethyloctane-3,5-dionato)copper in supercritical carbon dioxide was studied as a function of temperature and precursor concentration. The growth rate was found to be as high as 31.5 nm/min. Experiments between 220 °C and 270 °C indicated an apparent activation energy of 51.9 kJ/mol. The deposition kinetics were zero order with respect to precursor at 250 °C and 134 bar and precursor concentrations between 0.016 and 0.38 wt.% in CO2. Zero order kinetics over this large concentration interval likely contributes to the exceptional step coverage obtained from Cu depositions from supercritical fluids.

The catalytic decomposition of ethers on evaporated tungsten films

1968 ◽  
Vol 302 (1470) ◽  
pp. 385-398 ◽  
Keyword(s):  
High Activity ◽  
Water Vapour ◽  
Metal Surface ◽  
Initial Period ◽  
Catalytic Decomposition ◽  
Zero Order ◽  
Transitional Period ◽  
Zero Order Kinetics ◽  
Rate Of Reaction ◽  
Combined Action

The reactions of diethyl and di- n -propyl ethers have been studied in the presence of hydrogen on evaporated films of tungsten. In the temperature range from 200 to 260°C ethane and ethylene were formed from diethyl ether and small amounts of butenes were also produced. Each film had an initial high activity, especially for the formation of ethane, but the activity declined to a steady value during a transitional period. Subsequently, the decomposition of the ether occurred with zero order kinetics. A similar transitional period was observed during the decomposition of di- n -propyl ether but the change in the character of the reactions was more marked. Propane and propylene were formed initially, but very little further propane was produced after the initial period. If the surface of the tungsten was oxidized before exposure to ether, a high activity for the dehydration of the propyl ether was observed. Evidence from a number of experiments showed that irreversible changes were occurring to the catalyst during the transitional periods in which the metal surface was being converted to a different type of surface under the combined action of the ether and water vapour which was either added or formed by reaction. Most of the results could be interpreted on the assumption that two types of surface were formed—an oxidized surface of high activity for dehydration and an inactive surface covered by strongly adsorbed hydrocarbon residues. Subsidiary experiments were carried out with n -propanol on oxidized tungsten and evidence was found that the dehydration of the alcohol which was strongly adsorbed probably controlled the rate of reaction of the ether.

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