Cyclohexane, oxidation photochemical

This formation was linear as a function of time and cyclohexanol was only detected as a very minor product. Cyclooctane was similarly oxidized with the formation of cyclooctanone as a major product. Other iron(III)porphyrins involving different axial ligands, like Fe(TDCPP)Q and Fe(TPP)Cl, were much less efficient and less selective. Irradiation of Fe(TDCPP)OH in the presence of 02 and cis-stilbene failed to give any formation of stilbene epoxide, and cyclohexene was mainly oxidized on its allylic position with formation of cyclohex-2-enol and cyclohex-2-enone under such conditions. Finally, the intermediate formation of OH radicals was detected by spin trapping experiments during cyclohexane oxidation by 02 with photochemically-activated Fe(TDCPP)OH. 

Toray. The photonitrosation of cyclohexane or PNC process results in the direct conversion of cyclohexane to cyclohexanone oxime hydrochloride by reaction with nitrosyl chloride in the presence of uv light (15) (see Photochemical technology). Beckmann rearrangement of the cyclohexanone oxime hydrochloride in oleum results in the evolution of HCl, which is recycled to form NOCl by reaction with nitrosylsulfuric acid. The latter is produced by conventional absorption of NO from ammonia oxidation in oleum. Neutralization of the rearrangement mass with ammonia yields 1.7 kg ammonium sulfate per kilogram of caprolactam. Purification is by vacuum distillation. The novel chemistry is as follows ... 

Carless HAJ, Billinge JR, Oak OZ (1989) Photochemical routes from arenes to inositol intermediates the photo-oxidation of substituted cw-cyclohexane-3,5-diene-l,2-diols. Tetrahedron Lett 30 3113-3116. 

Several, oxidatively coupled xanthates (64-66), compounds (also called xanthides) containing the photochemically reactive, sulfur-sulfur bond, have been studied.130 Homolytic cleavage of this reactive bond is the primary reaction for these compounds, although this process is normally masked by recombination of the radicals produced. This primary, light-initiated process becomes apparent when a mixture of the xanthide 64 and ethyl xanthide (67) is irradiated in cyclohexane, because an equilibrium between 64, 67, and the mixed xanthide 68 is rapidly established. 

Fornal E, Giannotti C. Photocatalyzed oxidation of cyclohexane with heterogenized decatungstate../ Photochem. Photobiol A Chem 2007 188 279-86. 

Hoyano JK, Graham WAG. Oxidative addition of the carbon-hydrogen bonds of neopentane and cyclohexane to a photochemically generated iridium(I) complex. J Am Chem Soc 1982 104(13) 3723-3725. 

J. K. Hoyano, and W. A. G. Graham, Oxidative Addition of the Carbon-Hydrogen Bonds of Neopentane and Cyclohexane to a Photochemically Generated Iridium(I) Complex, J. Am. Chem. Soc. 104, 3723-3725 (1982). 

On the other hand, it is interesting to use the supercritical C02 as an alternative solvent for various photochemical reactions, particularly for photo-initiated oxidation reactions, due to the non-ignitability of C02. Thus we are studying photo-induced oxidation reactions of ternary mixtures of hydrocarbon/02/C02. Partially oxidized products have been found to be produced in the case of C Hg, ethylene (C2H4) and cyclohexane (C6H,2) which have been studied so far. The present paper mainly reports the case of C Ii, in order to understand the behavior of typical olefinic hydrocarbons which are expected to trap some active species during the reaction. 

Since a-alkylthio carbocations are formed from a-stannyl sulfides by the oxidation with metallic reagents, we first studied the photochemical reaction of a-stannyl sulfides and conjugated enones. A methanol solution of (phenylthiomethyl)tributylstannane (61A) and 2-cyclohexen-l-one (14d) was irradiated through a UV cut filter hu > 300 nm). As expected, 3-(phenylthiomethyl)cyclohexan-l-one (62), and l-phenylthiomethyl-2-cyclohexen-l-ol (63) were obtained in 53% total yield as a 48 5 mixture. The corresponding silyl derivatives... 

Photochemical decomposition of quinoxaline 1-oxide in water affords quinoxalin-2(l//)-one, and irradiation of quinoxaline 1-oxide in cyclohexane gives quinoxalin-2(lFf)-one and 2 -isocyanoformanilide. ... 

A better synthesis (89% yield) of Fe(CO)3(PPh3)2 is reported from [PPN]2[Fe4(CO)i3], where PPN+ = bis(triphenylphosphine)iminium. The C0X2 (X = Cl, Br, I) catalyzed substitution of CO in Fe(CO)j is reported to yield Fe(CO)4L species in 15 to 99% yield and Fe(CO)3(PPh3)2 was prepared (net 62% yield) from Fe(CO)s in a two-step procedure that requires a chromatographic separation. Strohmeier and Muller report that irradiation of Fe(CO)s in the presence of several phosphines produces Fe(CO)3L2 and Fe(CO)4L complexes in yields that range from 13% for the synthesis of Fe(CO)3[P(/i-Bu)3]2 to 35% for Fe(CO)3[P(c-C6Hn)3]2. For some of the compounds synthesized, vacuum sublimation is necessary to separate the Fe(CO)3L2 species from Fe(CO)4L. The one-step photochemical procedure we report here employs cyclohexane as a solvent. That enables unreacted phosphine, Fe(CO)s, and Fe(CO)4L to remain in solution while pure Fe(CO)3L2 precipitates. It is essential that the phosphines used in these reactions be free of phosphine oxides, which labilize CO and yield products other than Fe(CO)3(PR3)2 complexes. 

A patent has been lodged covering the sulfochlorination of gaseous alkanes. " Photochemical bromination using N-bromosuccinimide of the arenes (136) has been examined under a nitrogen atmosphere. The remote functionalization of the alcohol (137) has been carried out using DIB/Ii/cyclohexane. The product obtained from this, after oxidation, is the iodoketone (138, 84%). ... 

Photochemical reactions of materials enclosed in zeolites can lead to different proportions of products, or in some cases, to different products than those run in solutions.207 The distribution can vary with the zeolite. The enhanced selectivity in the oxidation of hydrocarbons with oxygen208 was mentioned in Chap. 4. The oxidation of cyclohexane in NaY zeolite with oxygen and visible light to yield cyclohexane hydroperoxide with complete selectivity at more than 40% conversion may have considerable industrial potential. Heating the hydroperoxide yields only cyclohexanone which can be oxidized to adipic acid for use in making nylon 6,6.209... 

Poly(ethylene-co-1,4-cyclohexane dimethylene terephthalate) The thermal and photochemical oxidation processes of a polyester based on poly(ethylene-co-l,4-cyclohexanedimethylene terephthalate) (PECT) with approximately 30% of 1,4-cyclohexanedimethanol have been studied by means of chemiluminescence [88], Also, the stabilization activity of some commercial antioxidants has been evaluated, and it has been related to hydroperoxide levels in the polymer. 

Radiolysis. The photochemical experiments suggest that in the radiolysis a reaction of nitrous oxide with excited molecules would be expected in cyclohexane but should be less important in 2,2,4-trimethylpentane. The radiolysis results (Figure 3 and Table III) show that at nitrous concentrations less than 10 mM, where reactions of excited molecules are unimportant, G(N2) is the same for cyclohexane and 2,2,4-trimethylpentane solutions. At concentrations of nitrous oxide from 20 to 160 mM, G(No) from cyclohexane solutions is greater than G(N2) from 2,2,4-trimethylpentane solutions, and the excess yield increases with the concentration of nitrous oxide. [The nitrogen yields reported here for the concentration range 5-200 mM are in good agreement with those reported by Sherman (20)] Nitrous oxide reduces G(H2) from cyclohexane (16, 17, 18, 20, and Table III), but it has little effect on G(H2) and G(CH4) from 2,2,4-trimethylpentane. 

The photochemical oxidation of heptaldehyde has been studied in two extensive kinetic investigations [28,29] under slightly different conditions from the standpoint of temperature and solvents. (McNesby and Davis [28] solvent, cyclohexane oxygen pressure, 100—600 torr temperature, 20—35° C. Lemaire [29] solvent, decane oxygen pressure, 50—720 torr temperature, 0—17°C.)... 

The rates of oxidative addition of EtsSiH, Et2MeSiH, EtMe2SiH, and Et2SiH2 to photochemically generated Cp Mn(CO)2, where Cp = Cp, CpMe, and Cp, have been determined in both neat silane and a 50/50 mixture of silane and methyl cyclohexane. ... 

Recently, for the photochemical oxidation of indan, tetralin, 2-ethyl-naphthalene and cyclohexane by nitropyridinium salts, the mechanism has been proposed [39d], which also involves the stages of electron and hydrogen atom transfer (Scheme 11.3). 

In the GiflV reaction of cyclohexane in the presence of P(OMe)3, ketone and a new product were formed instead of the expected alcohol. This new product was identified as cyclohexyl dimethyl phosphate l, 49 jf a carbon-centered cyclohexyl radical was an intermediate, one would expect the catalytic conversion of trimethyl phosphite into trimethyl phosphate in the presence of dioxygen. The latter reaction was indeed observed when genuine cyclohexyl radicals were photochemically generated under similar conditions to those employed in the Gif reaction l. So, once again this demonstrates that Gif-oxidation does not produce free alkyl radicals. 

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