Oxidation cyclohexanol to cyclohexanone

A notable exception is catalytic oxidation wherein a pyridodipyrimidine is used as a shuttle in the oxidation of alcohols by molecular oxygen. Pyridodipyrimidine (92) oxidizes cyclohexanol to cyclohexanone and the dihydro form (93) is oxidized in situ back to (92) by oxygen (equation 41). The yield of cyclohexanone is >22 000% based on (92). ... 

High yields of ketones result from the gentle oxidation of alcohols with compounds of ruthenium. Ruthenium tetroxide oxidizes cyclohexanol to cyclohexanone in carbon tetrachloride at room temperature in 93% yield [940], Instead of the rather expensive ruthenium tetroxide, which is required in stoichiometric amounts, catalytic amounts of ruthenium trichloride may be used in the presence of sodium hypochlorite as a reoxidant with the same results [701]. Sodium ruthenate [937] and potassium ruth-enate [196], which are prepared from ruthenium dioxide and sodium periodate in sodium hydroxide and from ruthenium trichloride and potassium persulfate, respectively, also effect oxidations to ketones at room temperature. 

The catalytic oxidation of cyclohexanol to cyclohexanone was carried out over both neat and intercalated complexes (Fig.6). Both neat complex and intercalated complexes selectively oxidized cyclohexanol to cyclohexanone (100% selectivity). It is clear from the figure that the intercalated complex (here MgAl-3) was twice as active (in terms of conversion) compared to the neat complex. However, the conversion tend to level off upon complete consumption of H2O2 in the reaction mixture. The reaction was presumed to... 

The 0-atom donor, lutidine-AT-oxide, has been used with Ru(TMP)(0)2 to catalyze the room temperature oxidation of alcohols to the corresponding aldehydes or ketones in -80% . Thus, under Ar, allyl alcohols were oxidized selectively to a,P-unsaturated aldehydes selectively, and PI1CH2OH to PhCHO Ph(CH2)20H was not oxidized. Cyclohexanol and adamantanol gave the corresponding ketones. The related 2,6-Cl2pyNO system, mentioned in the previous section, catalytically oxidizes cyclohexanol to cyclohexanone. ... 

Another recent patent (22) and related patent application (31) cover incorporation and use of many active metals into Si-TUD-1. Some active materials were incorporated simultaneously (e.g., NiW, NiMo, and Ga/Zn/Sn). The various catalysts have been used for many organic reactions [TUD-1 variants are shown in brackets] Alkylation of naphthalene with 1-hexadecene [Al-Si] Friedel-Crafts benzylation of benzene [Fe-Si, Ga-Si, Sn-Si and Ti-Si, see apphcation 2 above] oligomerization of 1-decene [Al-Si] selective oxidation of ethylbenzene to acetophenone [Cr-Si, Mo-Si] and selective oxidation of cyclohexanol to cyclohexanone [Mo-Si], A dehydrogenation process (32) has been described using an immobilized pincer catalyst on a TUD-1 substrate. Previously these catalysts were homogeneous, which often caused problems in separation and recycle. Several other reactions were described, including acylation, hydrogenation, and ammoxidation. 

Other mediators which have been used in combination with diaphorase for the regeneration of NAD+ are riboflavin and Vitamin K3, which is 2,3-dimethyl-1,4-naphthoquinone. However, especially riboflavin is not stable enough for synthetic applications [40]. Better stability is exhibited by phenanthrolindiones as mediators. In combination with diaphorase, Ohshiro [41] showed the indirect electrochemical oxidation of cyclohexanol to cyclohexanone using the NAD+ dependent HLADH with a turnover frequency of two per hour. For an effective enzymatic synthesis, this turnover frequency, however, would be too small. In our own studies, we were able to accelerate the NAD(P)+ regeneration considerably by lowering the electron density within the... 

We then coupled the regeneration system 1 to the horse liver alcohol dehydrogenase (HLADH) catalyzed oxidation of cyclohexanol to cyclohexanone as a model system (Fig. 9). 

Allylic P-unsaturated,alcohols (geraniol, 3-phenyl-2-propenol) were efficiently oxidised to the aldehydes by fran.y-Ru(0)2(TMP)/(lutidine-iV-oxide)/CgHg [586]. As fran.y-Ru(0)2(TMP)/(Cl2pyN0)/CgHy24h it oxidised cyclohexanol to cyclohexanone [587]. 

Most of the work reported with these complexes has been concerned with kinetic measurements and suggestions of possible mechanisms. The [Ru(HjO)(EDTA)] / aq. HjOj/ascorbate/dioxane system was used for the oxidation of cyclohexanol to cw-l,3-cyclohexanediol and regarded as a model for peroxidase systems kinetic data and rate laws were derived [773], Kinetic data were recorded for the following systems [Ru(Hj0)(EDTA)]702/aq. ascorbate/dioxane/30°C (an analogue of the Udenfriend system cyclohexanol oxidation) [731] [Ru(H20)(EDTA)]70j/water (alkanes and epoxidation of cyclic alkenes - [Ru (0)(EDTA)] may be involved) [774] [Ru(HjO)(EDTA)]702/water-dioxane (epoxidation of styrenes - a metallo-oxetane intermediate was postulated) [775] [Ru(HjO)(EDTA)]7aq. H O /dioxane (ascorbic acid to dehydroascorbic acid and of cyclohexanol to cyclohexanone)... 

Exercise 15-30 How many moles of permanganate would be required to oxidize (a) one mole of cyclohexanol to cyclohexanone and (b) one mole of phenylmethanol (benzyl alcohol) to benzenecarboxylic acid in basic solution (Review Section 11-1... 

The oxidation of cyclohexanol to cyclohexanone with fluorine and aqueous acetonitrile was performed in a single-channel microreactor operated under annular flow at room temperature. A conversion of 84% and a selectivity of 74% were observed [313], In a similar way, diols such as 1,2-cyclohexanediol were partly or fully oxidized. A 53% selectivity to the monooxidation product was obtained at a conversion of 87% the dioxidation product was obtained with 30% yield. 

Gelbard has used peroxotungstates supported on polypyridine polymers in the epoxidation of cyclohexene with hydrogen peroxide.66 Polypyridine polymers were also used to support heteropolyperoxometallates for use in the oxidation of alcohols with hydrogen peroxide.67 The tetranuclear complex [cetylpyridinium chloride][P04 WO(02)2 4] supported on polypyridine was found to be an effective catalyst for the oxidation of cyclohexanol to cyclohexanone, also with hydrogen peroxide. 

The reaction starts with the oxidation of cyclohexanol to cyclohexanone by nitric acid several paths are then available for cyclohexanone transformation into adipic acid. The main one involves cyclohexanone nitrosation to 2-nitrosocyclohexanone which further reacts with nitric acid to afford 2-nitro-2-nitrosocyclohexanone (Figure 9). The latter gives, upon hydrolysis, 6-nitro-6-hydroximinohexanoic acid which eventually breaks down to adipic acid and nitrous oxide (N2O). 

Oxidation of alcohols. Grob and Schmid used /-butyl hypochlorite in carbon tetrachloride or ether in the presence of pyridine for oxidation of cyclohexanol to cyclohexanone and of /i-butanol to //-butyl butyrate. Ginsburg et aU oxidized 3-hydroxysteroids by dropwise addition of /-butyl hypochlorite in CCli to a solution of the steroid in CCl, at room temperature. When the ketone was to be chlorinated as formed, the reaction was done in acetic acid at followed by heating on the steam bath. Levin et al. obtained 3-ketosteroids in high yield by oxidation of the 3-atcohols with /-butyl hypochloride in dry /-butanol. 

The commercial process for the production of nylon 6 starts with the oxidation of cyclohexane with oxygen at 160°C to a mixture of cyclohexanol and cyclohexanone with a cobalt(II) catalyst. The reaction is taken to only 4% conversion to obtain 85% selectivity. Barton and co-workers have called this the least efficient major industrial chemical process.240 They have oxidized cyclohexane to the same products using tort bu(ylhydroperoxide with an iron(III) catalyst under air (70°C for 24 h) with 89% efficiency based on the hydroperoxide. The oxidation of cyclohexanol to cyclohexanone was carried out in the same way with 99% efficiency. A cobalt catalyst in MCM-41 zeolite gave 38% conversion with 95% selectivity in 4 days at 70 C.241 These produce ferf-butyl alcohol as a coproduct. It can be dehydrated to isobutene, which can be hydro-... 

The oxidation of cyclohexanol to cyclohexanone with CBT proceeds by an analogous mechanism (87M583). 

The activity of the catalysts for cyclohexane oxidation are shown in Table 3. Similar trends analogous to cyclohexanol oxidation is observed in this case also. It can be observed that the conversion for cyclohexane oxidation of Mo-MCM-41 is higher than that reported for TS-1 [16]. This is apparently because of the larger pore size of Mo-MCM-41 permitting a bulky molecule like cyclohexane into the pores in comparison to TS-1. Ulf Schuchardt et al. [16] have reported that the turn over numbers are in the range of 1-100 for cyclohexane oxidation on TS-1 under comparable experimental conditions. The selectivity ratio of cyclohexanol to cyclohexanone is around 1 for TS-1 [14] whereas it is of the order of 0.15 for Mo-MCM-41 and is of the order of 0.40 for the impregnated samples. It is seen that Mo-MCM-41 is more selective to the production of cyclohexanone. 

Anionic copper(II)phthalocyanine monosulphonate (CuPcMs) and copper(II) phthalocyanine tetrasulphonate (CuPcTs) complexes have been successfully intercalated into the intergallery of Mg-Al layered double hydroxides through direct synthesis method. XRD results indicated an inclined orientation of the anion in the interlamellar space. A better thermal stability was noticed for the macrocycle ligand upon intercalation. The visible spectra showed a hyspochromic shift upon intercalation indicating disturbance of the macrocycle ligand pltmarity. An enhanced activity for the selective oxidation of cyclohexanol to cyclohexanone was observed for the intercalated complex in comparison with neat complex. 

Heyns et al,427 have worked out a method for oxidation of cyclic alcohols to ketones (bicyclic systems composed of two fused five-membered rings, only endo-hydroxyl groups are attacked.460... 

The search for mild oxidizing reagents that convert alcohols to aldehydes or ketones under neutral or near neutral conditions has produced a new type of reagent that contains a hypervalent iodine. Dess and Martin showed that 2-iodobenzoic acid (75) reacted with KBrOs in sulfuric acid to give a 93% yield of 76. Subsequent heating (100°C) with acetic anhydride and acetic acid produced 77 in 93% yield, the so-called Dess-Martin periodinane. This reagent converted alcohols to ketones or aldehydes, illustrated by the transformation of cyclohexanol to cyclohexanone in 90% yield, in dichloromethane at 25°C. In this particular... 

Selective oxidation of ethylbenzene to acetophenone [Cr-Si, Mo-Si] Selective oxidation of cyclohexanol to cyclohexanone [Mo-Si]... 

Direct fluorination of toluene using elemental fluorine is not feasible since the heat release cannot be controlled with conventional reactors. So the process is deliberately slowed down. Hence, the direct fluorination needs hours in a laboratory bubble column. It can be completed within seconds or even milliseconds when using a miniature bubble column, operating close to the kinetic limit. The Bayer-Villiger oxidation of cyclohexanol to cyclohexanone with fluorine and aqueous formic acid (5% water) is done in miniature bubble column reactors at 60% conversion at 88% selectivity. 

The authors demonstrated the catalytic properties of the resulting composite materials. Thus, rho-TMGP with encapsulated Mn porphyrin was found to be active for cyclohexane oxidation using tcrt-butyl hydroperoxide as the oxidant, cyclohexanol and cyclohexanone being the only products detected (91.5% total yield after 24 h at 65°C and with 3.8% catalysts loading). The solid was found to retain its crystallinity, no leaching of the metalloporphyrin was detected, and it was reused for 11 catalytic cycles without significant lose of activity [68]. 

Scheme 8.2. A representation of a pathway for the oxidation of cyclohexanol to cyclohexanone by chromic anhydride.

The second item in Thble 8.5 shows the oxidation of cyclohexanol to cyclohexanone with chromic anhydride (chromate, chromium(VI)). A wide variety of subtly different methods, largely substrate dependent, utilize the reduction of yellow orange chromium(VI) to green chromium(III) to affect oxidation. Among these is the Jones oxidation, which involves the treatment of alcohol substrate with a sto-chiometric quantity of chromic anhydride (CrOs, chromium(VI)) in aqueous sulfuric acid (H2SO4). A potential pathway for the conversion is shown in Scheme 8.2. The disproportionation of Cr+ to Cr+ and Cr+ follows much the same pattern as that for manganese (Mn+ to Mn and Mn+ ) as shown in Scheme 8.1. 

The catalytic dehydrogenation of cyclohexanol to cyclohexanone is performed on a zinc oxide catalyst at temperatures of 570-650 K /40/. Fig. 17 shows the intrinsic rate equation together with the corresponding rate parameters determined using a laboratory microintegral reactor, operated isothermally and filled with catalyst of 0.3 mm particle diameter. 

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