Alcohol, oxidation over

Biirgi T. Combined in situ attenuated total reflection infrared and UY-vis spectroscopic study of alcohol oxidation over Pd/Al2C>3. J Catal. 2005 229 55. 

Effect of Base on O-Ally/ Alcohol Oxidation over... 

Alcohol oxidation over the loose powder catalysts were conducted in a fixed bed reactor at 230 °C and atmospheric pressure. The details of the reactor system was previously described elsewhere [8]. The catalysts were pretreated in a flow of Oj/He for 15 min prior to oxidation reaction. A reactant stream of CHjOH/Oj/He = 6/13/81 with a total flow rate of 100 ml/min was used for methanol oxidation. For ethanol and 2-butanol oxidation, a gaseous mixture of Oj/He (13/81 ml/min) containing saturated ethanol or 2-butanol vapor at ambient temperature was introduced into the reactor. Analyses of reactants and products were carried out by an on-line Hewlett Packard 5890B GC. The spent catalysts were also characterized by Raman spectrometer. 

This Equation does not differ from the usual Mars-Van Krevelen redox equation. The rate constants of the separate steps of oxidation and reduction from Equation (11) are listed in Table 3. They are-compared in the same Table with the rate constants determined separately from the experiments on reduction and reoxidation. The coincidence between the calculated and experimental rate constants confirms the proposed redox mechanism of allyl alcohol oxidation over the rhombic phase of V-MoOg catalyst. 

Water is usually considered the most environmentally benign solvent however, the poor solubility of bulkier alcohols and molecular oxygen under ambient conditions has limited its application (in the absence of surfactants [25]). Pt nanoparticles supported on a water-soluble anion exchange resin exhibit excellent E-factors (12.8kilo waste per kilo product) in addition to very good activity and selectivity for alcohol oxidation [136]. Similarly, water has been used as solvent for, for example, benzyUc and primary alcohol oxidations over supported or stabilized Pd [137], Pt [138], and Au [139] clusters. 

Kinetic studies of competitive alcohol oxidation over Au/TiOj have postulated a unique ensemble in which a carbocation can be stabilized adjacent to a neighboring gold-oxo center [163]. This work proposed that benzylic alcohols oxidize via C-H cleavage at the benzylic position. Electronic effects in PVP-stabilized gold nanoparticles for p-hydroxy benzyl alcohol selox have also been reported [164] XANES, XPS, and FT-IR suggest that anionic 1.5 nm Au clusters are the most catalytically active, with electron donation from the polymer stabilizer creating Au-superoxo species (Figure 2.11). 

Grunwaldt, J., Caravati, M. and Baiker, A. (2006). In situ extended X-ray absorption fine structure study during selective alcohol oxidation over Pd/Al203 in supercritical carbon dioxide, J. Phys. Chem. B, 110, pp. 9916-9922. 

By passing the alcohol vapour over a copper - chromium oxide catalyst deposit on pumice and heated to 330°, for example ... 

Isobutyl alcohol [78-83-1] forms a substantial fraction of the butanols produced by higher alcohol synthesis over modified copper—zinc oxide-based catalysts. Conceivably, separation of this alcohol and dehydration affords an alternative route to isobutjiene [115-11 -7] for methyl /-butyl ether [1624-04-4] (MTBE) production. MTBE is a rapidly growing constituent of reformulated gasoline, but its growth is likely to be limited by available suppHes of isobutylene. Thus higher alcohol synthesis provides a process capable of supplying all of the raw materials required for manufacture of this key fuel oxygenate (24) (see Ethers). 

In the three-step process acetone first undergoes a Uquid-phase alkah-cataly2ed condensation to form diacetone alcohol. Many alkaU metal oxides, metal hydroxides (eg, sodium, barium, potassium, magnesium, and lanthanium), and anion-exchange resins are described in the Uterature as suitable catalysts. The selectivity to diacetone alcohol is typicaUy 90—95 wt % (64). In the second step diacetone alcohol is dehydrated to mesityl oxide over an acid catalyst such as phosphoric or sulfuric acid. The reaction takes place at 95—130°C and selectivity to mesityl oxide is 80—85 wt % (64). A one-step conversion of acetone to mesityl oxide is also possible. 

By selection of conditions and catalyst, the intermediate hydroxyimine (11) can be directed to either (he hydroxy ketone (10) or amino alcohol (12), Over platinum oxide in methanol-acetic acid-water the amino alcohol forms, whereas over alkali-free Ra-Ni in methanol-water or over 10% Pd-on-C in methanol-water containing boric acid, the hydroxy ketones form in excellent yield. Nitrile oxide cycloadditions have been applied to five-membered ring syntheses (.50). 

A biomimetic oxidation with perfluorinated porphyrin complexes [(F20TPP) FeCl] showed high catalytic activity with secondary alcohols with over 97% yield in all cases [144]. Furthermore, this catalyst is able to oxidize a broad range of alcohols under mild conditions with wCPBA as terminal oxidant. Here, an a-hydroxyalkyl radical species is proposed as central intermediate. 

A 1/1,2/1 mixture of 2-methoxyethanol/polyacrylamide + hydrogen per-oxide/toluene respectively volatilised slowly and intermittently by heating over a period of four weeks. The detonation was explained by the ether-alcohol oxidation by the peroxide. 

Oxidation reactions occur on several sites of the acid and alcohol moieties, depending on the chemical structures. For example, the trans methyl of the isobutenyl group in chrysanthemates is preferentially oxidized over the cis methyl group in rats, and the 4 -position of the phenoxy ring is oxidized to a larger extent as compared with other positions [8] (Fig. 1). 

Di-isopropyl phosphorofluoridate. Phosphorus oxydichlorofluoride (50 g.) is dissolved in dry ether (100 c.c.), isopropyl alcohol (dried over calcium oxide 50 g., 15 per cent excess) in dry ether (100 c.c.) is added slowly with cooling, and the mixture kept for 1 hr. Dry ammonia is then passed through the liquid, with cooling. The liquid... 

Figure 9.(A) Reaction scheme for the selective benzyl alcohol oxidation without any over-oxidation to benzoic acid. (B) Plot of % of conversion over the reaction time for the benzyl alcohol oxidation reaction catalyzed by NPyc at various recyclic conditions with 30%H2O2. (C) The reaction step up picture.

---