Octanal, oxidation

Base-induced rearrangement of bicyclo[2.2.2]octane oxide 67 gives predominantly bicyclo[2.2.2]octanone 68 (Scheme 5.15), which once again indicates that close proximity between the carbenoid center and the C-H bond into which it may insert is important if such an insertion is to occur [30]. In comparison, the sense of product distribution is reversed for the related substrate bicyclo[2.2.2]octadiene oxide 70 on treatment with LDA [15, 22], alcohol 72 being the favored product. 

Tetrahalosulphones, reactions of 417 Tetrakis(alkylsulphinylmethyl)methanes 575 Thiacyclohexanes, reactions of 599 Thiacyclo[3.3.0]octane oxides, synthesis of 607... 

The activity data confirm that an IR absorption band at 960 cm" is a necessary condition for titanium silicates to be active for the selective oxidation of hydrocarbons with aqueous H2O2 as suggested by Huybrechts et al. (9). However, this band is not a sufficient condition for predicting the activity of the TS-1 catalyst. Although TS-l(B) and TS-l(C) show intensities for the 960 cm- band similar to TS-1 (A), their activities are different First of all, the reaction data reveal that TS-1 (A) is much more active than TS-l(B) for phenol hydroxylation, while both samples show similar activity for n-octane oxidation and 1-hexene epoxidation. Therefore, the presence of the IR band at 960 cm-i in TS-1 catalysts may correlate with the activities for the oxidation of n-octane and the epoxidation of 1-hexene but not for phenol hydroxylation. However, note that the amorphous Ti02-Si02 also has an IR absorption band at 960 cm- and it does not activate either substrate. 

Effect of sodium and aluminum on TS-1. The catalytic activities of aluminum and/or sodium containing TS-1 are depicted in Table IV. The data show that the addition of aluminum during the synthesis of TS-1 yields a material (TAS-1(D)) that has a lower conversion of n-octane oxidation and a smaller IR peak ratio. The existence of the acid sites due to the incorporation of aluminum into the framework of TS-1 may accelerate the decomposition of H2O2 to water and oxygen during the reaction. However, reducing the number of acid sites by exchanging with sodium ions only increases the conversion by 1% (Na/TAS-1(D)). Therefore, the addition of aluminum into the synthesis mixture most likely reduce the amount of titanium present in the sample. 

Table IV. n-Octane oxidation on aluminum and/or sodium containing TS-1...

The addition of sodium during the synthesis of TS-1 completely eliminates the activity for n-octane oxidation and also the IR band at 960 cm- (this IR band is present in the amorphous precursor, Ti02-Si02). It has been shown (12) that the presence of sodium in itie synthesis gel prevents the incorporation of titanium into the zeolite framework. However, the addition of sodium ter the zeolite crystallizes does not... 

The addition of aluminum during the synthesis of TS-1 reduces its activity for n-octane oxidation. The presence of sodium in the synthesis gel of TS-1 completely eliminates the catalytic activity for alkane oxidation. However, the presence of sodium in preformed TS-1 does not have a significant effect on its catalytic activity. 

G.M. Come, V. Warth, P.A. Glaude, R. Foumet, F. Battin-Leclerc, and G. Scacchi. Computer-Aided Design of Gas-Phase Oxidation Mechanisms—Application to the Modeling of n-Heptane and Iso-Octane Oxidation. Proc. Combust. Inst., 26 755-762,1996. 

H.J. Curran, P. Gaffuri, W.J. Pitz, and C.K. Westbrook. A Comprehensive Modeling Study of Iso-Octane Oxidation. Combust. Flame, 129 253-280,2002. 

Direct evidence for the existence of a negative temperature coefficient of reaction rate, and the distinctions between alkanes of different structure were demonstrated in recent studies of -heptane and 2,2,4-trimethylpen-tane (f-octane) oxidation in a well-stirred flow reactor (Figs 6.1 and 6.2). The experiments were performed by Dagaut et al. [30] at 1 MPa and a mean residence time of Is over the temperature range 550-1150K. The fuel at the reactor inlet was set at a fixed mole fraction, 10 , and the [RH] [O2] ratio was chosen in the proportions 1 36,1 22, 1 11 and 1 7.5. These correspond to the stoichiometric proportions 4> = 0.3, 0.5, 1.0 and 1.5 respectively. The reactants were diluted with an excess of N2 in order to maintain isothermal conditions in the reactor. 

Typical molecular products of n-heptane and i-octane oxidation over the temperature range 550-1200 K at 1.0 MPa in a jet-stirred flow reactor. The components are listed according to their maximum mole fractions of products below, above or in the vicinity of 850 K [31]... 

The production of 2,2,4,4-tetramethyltetrahydrofuran as a major product of /-octane oxidation points to the predominance of the alkylperoxy radical isomerization R02 Q(1,6)00H involving either,... 

Figure 4. Selectivity of alkane oxidation with Fe/Pd/A zeolite and H2/O2. a) substrate selectivity between n-octane and cyclohexane and b) regioselectivity of n-octane oxidation.

The oxidation of various hydrocarbons such as n-octane, cyclohexane, toluene, xylenes and trimethyl benzenes over two vanadium silicate molecular sieves, one a medium pore VS-2 and the other, a novei, iarge pore V-NCL-1, in presence of aqueous HjOj has been studied. These reactions were carried out in batch reactors at 358-373 K using acetonitrile as the solvent. The activation of the primary carbon atoms in addition to the preferred secondary ones in n-octane oxidation and oxidation of the methyl substituents in addition to aromatic hydroxyiation of alkyl aromatics distinguish vanadium silicates from titanium silicates. The vanadium silicates are also very active in the secondary oxidation of alcohols to the respective carbonyl compounds. V-NCL-1 is active in the oxidation of bulkier hydrocarbons wherein the medium pore VS-2 shows negligible activity. Thus, vanadium silicate molecular sieves offer the advantage of catalysing selective oxidation reactions in a shape selective manner. 

Scheme 1.6 Cyclo-octane oxidation catalyzed by FeNPs in reverse microemulsions or RuNPs in biphasic water-organic media (Ref. [49b], Roucoux-Patin group).

C6ME G.M., WARTH V., GLAUDE P.A., FOURNET R., BATTIN-LECLERC F., SCACCHI G., Computer-aided design of gas-phase oxidation mechanisms. Application to the modeling of n-heptane and iso-octane oxidation 26 Symp. (Int.) on Combustion, 755 (1996). 

Computer Aided Design of Gas Phase Oxidation Mechanisms - Application to the Modelling of n-Heptane and Iso-octane Oxidation, Proceedings of the Combustion Institute, Vol. 26, pp. 755-762. 

Curran HJ, Gaffuri P, Pitz WJ, Westbrook CK. A comprehensive modeling study of iso-octane oxidation. Combust Flame 2002 129 253-80. 

Ranzi, E., Faravelli, T., Gaffuri, P., Sogaro, A., D Anna, A., Ciajolo, A. A wide-range modeling study of iso-octane oxidation. Combust. Flame 108, 24—42 (1997)... 

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