Isopropyl alcohol electron transfer

Electron transfer to acetophenone from the isopropyl radical ion, an a-hydroxy radical, has been discussed above and is responsible for the ketyl spectrum in N20-saturated solutions of isopropyl alcohol. Hence, transfer from the tert-butyl radical ion, a /3-hydroxy radical, either does not take place or is too slow to be observed under the given experimental conditions. 

The trapped electrons were formed simply by depositing alkali metal atoms on ice or solid alcohols at 77°K. Studies were made of the reactions between sodium or potassium atoms and ice (HgO or D2O), methanol, ethanol, isopropyl alcohol, t-butyl alcohol or dodecanol. The reactions of caesium, rubidium and lithium with ice were also investigated. The deposits were highly coloured and the optical and e.s.r. spectra showed that the electron was no longer associated with the alkali metal ion but had been transferred completely to the solid matrix. 

Photoreduction (253.7 nm) of pyridinium ions in isopropyl alcohol is used to generate pyridinyl radicals for EPR measurements . The mechanism of the reaction probably involves formation of the Si state of the pyridinium ion followed by electron transfer from the solvent. Dimer formation from the radical is observed in a number of cases (Eq. 3). ... 

Table V. Electron Transfer Rate Constants for Aromatic Molecules in Isopropyl Alcohol at 25°C.a...

The simple alkenes have negative electron affinities and therefore will not capture electrons. At the pressure of water vapor used, Reaction 2 is fast enough to preclude other reactions of H20+ (22). Charge or proton transfer to propylene may also be excluded on energetic grounds. The effect of propylene on G( H2) w from water vapor containing small amounts of isopropyl alcohol will therefore be owing to the capture of H atoms in competition with their abstraction reaction from isopropyl alcohol... 

Since much of the methane yield appears to be produced via methyl radicals, the yield should be affected by propylene concentration. We found little effect below 1 mole % propylene but the yield fell by 20% as the propylene concentration increased to 10 mole %, both in the presence and absence of SFe. These results, however, do not indicate how much methane is formed from CH3 precursors and how much by molecular processes. The effect of propylene is being studied further in an attempt to obtain this information. The electron scavengers appear to increase the methane yield slightly. Since they do not decrease the yield, this probably means that electron-positive ion neutralization does not produce methane. The reason for the increase in G(CH4) is not clear but it could occur if ion-ion neutralization produced methane, or if some physical interaction caused a transfer of energy from the additives to isopropyl alcohol. The slight increase in CH4 yield with SF concentration tends to favor the latter assumption. 

A series of nondissociative electron transfer reactions involving aromatic radical ions produced by electron attachment in isopropyl alcohol solutions, have been studied by pulse radiolysis by Dorfman and co-workers (9). Donor radical anions were derived from diphenyl,... 

Absolute confirmation that electron transfer from N20 to acetophenone does not take place was provided by the following experiments. In an aqueous, alkaline solution of acetophenone containing a large concentration of isopropyl alcohol and saturated with N20, the spectrum of ketyl is observed. However, when the experiment is repeated using a high concentration of tert-butyl alcohol instead of isopropyl alcohol, no ketyl spectrum is observed. If, therefore, in the former experiment the ketyl spectrum arises by electron transfer from N20" to acetophenone, the presence of the alcohol would be irrelevant since isopropyl alcohol is a poor electron scavenger and thus a similar result should have been observed for tert-butyl alcohol. 

In the steady-state radiolysis of aqueous isopropyl alcohol containing N20, electron transfer from the isopropyl alcohol radical ion to N20 has been suggested (38). Since electron transfer from this radical ion to benzophenone is efficient even in N20-saturated solution, transfer to N20, if it occurs, must be slow and unimportant under the conditions of the above pulse experiments. 

Model four-stage electron transfer chains have been observed (8) using either isopropyl alcohol radicals (or ethyl alcohol), aceto and benzophenone, and, in addition, a very low concentration of ferricyanide ion. One alkaline N20-saturated solution contained 0.5M isopropyl alcohol, 2.5 X 10"8M acetophenone, 10"4M benzophenone, and 8 pM ferricyanide ion. Electron transfer from the alcohol radical ion to acetophenone, followed by transfer to benzophenone, was observed, as expected. However, the benzophenone anion spectrum decayed exponentially. The transmission of the solution, over the spectral region of the ferricyanide absorption (4100 A. maximum) increased, indicating the consumption of this solute. The kinetics of ferricyanide decay were similar to those for decay of the benzophenone ketyl absorption. The... 

Much of the kinetic work has been concerned with the oxidation of isopropyl alcohol to acetone in aqueous sulphuric or acetic acids. The rate-determining step definitely involves the breaking of a carbon-hydrogen bond, as isopropyl alcohol is oxidised 6-7 times faster than its 2-deutero derivative . At all acidities, the rate of oxidation shows a first-order dependence on both the concentration of HCr04 and the alcohol, but the dejiendence on [H] varies. In dilute acidic solution the rate is proportional to [H] , to [H] in more concentrated solution and to Ho in 20-60% aqueous sulphuric acid . These observations are consistent with two mechanisms (i) a bimolecular electron transfer process (218) ,... 

The affect of variations in chemical structure of amines on the photo-initiating ability of 4- -propoxythio-xanthone was also investigated in photopolymerizations of n-butyl methacrylate and a commercial triacrylate resin in isopropyl alcohol solution. The conclusion from that study is that the activity is highly dependent on the ionization potential of the particular amine, the formation of a triplet exciplex and an electron transfer process. Analyses of chloroform extracts of the cured resin confirmed that the alkylamino radical is the initiating radical. ... 

The oxidation of alcohols in iron(n)-hydrogen peroxide systems has been re-examined, and the effects of copper(ii) ions described. A new kinetic analysis has been developed, and the nature of the interactions of the radicals produced on reaction of the peroxide with the metal ion indicates that, in the reaction with isopropyl alcohol, )S-hydroxyalkyl radicals are not oxidized by iron(m) but dimerize, whereas in the presence of copper(n) they are oxidized to glycols. It is suggested that oxidation of radicals by iron(m) involves an electron-transfer process, which may in some cases be reversible,... 

The reaction of a mixture of oxalic acid and isopropyl alcohol with chromium(vi) occurs at a rate much greater than that for either of the two substrates alone,both substrates undergoing oxidation. In the presence of free-radical scavengers, the products are a 1 1 ratio of acetone and CO2, indicating a two-electron oxidation of the alcohol and a one-electron transfer for the oxalic acid. In the absence of acrylonitrile, however, the yields of these products are not compatible with a simple mechanism. The suggested mechanism is considered to involve a one-step, three-electron oxidation with the change in the chromium reactant from CrVi->-Crin over a wide concentration range, the rate may be described by the rate law... 

While [Pt2(pop)4 ] is a strong reductant, it is not sufficiently reducing to transfer one electron to an alcohol (27). Extraction of a hydrogen in a primary photoprocess would produce an isopropyl radical that could undergo disproportionation to yield acetone (28) ... 

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