Irradiation reduction with ethanol

The quantum efficiency for the reaction described by Eq. 13 in 1 M acid with ethanol present is 50 times greater for U022+ (irradiated in the wavelength range 250-600 nm) than for Pu022+ (irradiated at wavelengths <350nm). Direct photochemical reduction of Pu(IV) also occurs in the same system ... 

Np(V) ultimately occurs, while in the latter, oxidation of Np(V) Np(VI) is observed (cf., Fig. 2 and Eq. 9). The difference is obviously due to the presence of photochemically produced NO2 which serves as the reductant for Np(VI). The quantum efficiencies for Np in Table II show that the reactions occur best when irradiated with 254 rather than 300 nm light in agreement with the increased QY for NO3 photo-reduction at shorter wavelengths (23) but in opposition to the difference in N0 light absorption as shown in Fig. 3. The Np(VI) reduction probably involves an excited state of Np, but the evidence in support of this is not conclusive. Although the quantum efficiency for Np(VI) reduction is not as great as that for the reduction of U0 + with ethanol or hydrazine, it is not so prohibitively low that it cannot be useful. 

Photoreduction. Irradiation of 3,17/i-cstradiol (1) with a Hanovia mercury vapor lamp in an aqueous ethanol solution containing sodium sulfite gives as the major product 3/J,17/3-dihydroxy-5a,10)3-estrane (2). Reduction in the presence of sodium borohydride gives (3) and (4) in low yield.1 Tt is suggested that the reduction with sodium sulfite may proceed through a sulfinate intermediate. This novel photoreduction method was first observed with kynurenic acid (5), which is reduced in this way to kynurenine yellow (6).2... 

Pyridone gives a small amount of piperidine, as well as some pyridine, but l-methyl-2-pyridone yields only a trace of methylpyridinium (picrate) Reduction of alkylpyridinium salts, electrolytically, with sodium amalgam or by x-ray irradiation in aqueous ethanol, can give l,r-dialkyl-l,r,4,4 -tetrahydro-4,4 -dipyridyls Electrolytic reduction of a mix-... 

The application of flavonoids for the treatment of various diseases associated with free radical overproduction is considered in Chapter 29. However, it seems useful to discuss here some studies describing the activity of flavonoids under certain pathophysiological conditions. Oral pretreatment with rutin of rats, in which gastric lesions were induced by the administration of 100% ethanol, resulted in the reduction of the area of gastric lesions [157]. Rutin was found to be an effective inhibitor of TBAR products in the gastric mucosa induced by 50%i ethanol [158]. Rutin and quercetin were active in the reduction of azoxymethanol-induced colonic neoplasma and focal area of dysplasia in the mice [159], Chemopreventive effects of quercetin and rutin were also shown in normal and azoxymethane-treated mouse colon [160]. Flavonoids exhibited radioprotective effect on 7-ray irradiated mice [161], which was correlated with their antioxidative activity. Dietary flavones and flavonols protected against the toxicity of the environmental contaminant dioxin [162], Rutin inhibited ovariectomy-induced osteopenia in rats [163],... 

Few examples of photochemical dehydrogenation reactions accompanied by cyclization are reported in the literature. 2,3,5-Triphenyl-tetrazolium chloride (CV), which is used biochemically as reduction indicator, on irradiation in ethanol with ultraviolet light, undergoes dehydrogenation accompanied by cyclization to yield 2,3 (2,2 -bi-phenylene)-5-phenyltetrazolium chloride (CVI).106 167 Light-induced cyclization of substituted derivatives of CV to the corresponding bi-phenylene derivatives has been reported recently. sl 33... 

Investigations of metals (Ag [28-30], Au [31, 33], Pt [18, 22, 30], Pd [11], Cu, Fig [41] etc.) photoreduction at surfaces of porous samples and colloidal particles of Ti02 shows, that in such systems metal is deposited on the semiconductor surface as separate particles of subnanometric - nanometric size. Such metal particles have ohmic contact with semiconductor surface [11, 24, 32] and developed electronic structure [24, 28-32], So, we concluded that photocatalytic nickel(II) reduction takes place at irradiation of suspensions, containing mesoporous Ti02, Ni2+ and ethanol, this process resulting in the... 

A cortisone synthesis using remote functionalization at an unactivated carbon centre has been achieved.97 Cortexolone (224) was converted into the 5a-H,3j3-OH derivative (formation of the bismethylenedioxy-compound followed by lithium-ammonia-ethanol reduction). Inversion98 of 3)8- to 3 -OH followed by esterification with m-iodobenzoic acid produced (225), which on irradiation in methylene chloride containing phenyl iodide dichloride gave the 9 a -chloro-derivative (not isolated). This was dehydrohalogenated and saponified by methanolic potash to yield (226) (75%) and thence, by further known steps, cortisone acetate. 

The photoreduction of N2 by irradiation of vanadium chloride in aqueous ethanol with u.v. light has been describedAn unstable dinitrogen divanadium complex has been proposed to be the key intermediate and the reaction products include NH3, N2H4, and H2. A model system for N2 reduction involves the photoreduction of acetylene and this can be achieved with a sacrificial bipysRu /Co " system. 

Irradiation of 1,4,8,11,15,18,22,25-octabutoxyphthalocyanine or its copper derivatives in degassed ethanol containing triethanolamine causes its reduction by a mechanism which involves a higher excited state of the substrate,and a plot of the log of the rate constants for the photoinduced intramolecular electron transfer in a supramolecular assembly of Zn and Au porphyrins bridged by diphenylphenanthroline has been found to decrease linearly with diminishing energy difference between the HOMO and LUMO of the participating orbitals. ... 

Nitrogen-13-labeled ammonia (ty2 = 10 min) is produced by reduction of 13N-labeled nitrates and nitrites that are produced by proton irradiation of water in a cyclotron. The reduction is carried out with titanium chloride in alkaline medium. 13N-NH3 is then distilled and finally trapped in acidic saline solution. Wester et al (1991) has used a pressurized target of aqueous ethanol, in which ethanol acts as a hydroxyl free radical scavenger to improve the... 

A less reactive bicyclo[3.2.0]hept-l(7)-ene substructure has been found in 164 (149). This compound was prepared from propellane 163 by photolysis and subsequent reduction. In contrast to 163, irradiation of the parent tricyclic ketone 165 in ethanol gives the saturated ketone 167. The formation of 167 is taken as evidence for the intermediate formation of the ketone 166. When 168 was treated with CsF in the presence of 1,3-diphenylisobenzofuran, an adduct was isolated, which was assigned the structure of the expected [2 + 4]cycloaddition product of 169 (150). 

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