Cyclohexanol reaction with acetic acid

A powerful oxidizer. Explosive reaction with acetaldehyde, acetic acid + heat, acetic anhydride + heat, benzaldehyde, benzene, benzylthylaniUne, butyraldehyde, 1,3-dimethylhexahydropyrimidone, diethyl ether, ethylacetate, isopropylacetate, methyl dioxane, pelargonic acid, pentyl acetate, phosphoms + heat, propionaldehyde, and other organic materials or solvents. Forms a friction- and heat-sensitive explosive mixture with potassium hexacyanoferrate. Ignites on contact with alcohols, acetic anhydride + tetrahydronaphthalene, acetone, butanol, chromium(II) sulfide, cyclohexanol, dimethyl formamide, ethanol, ethylene glycol, methanol, 2-propanol, pyridine. Violent reaction with acetic anhydride + 3-methylphenol (above 75°C), acetylene, bromine pentafluoride, glycerol, hexamethylphosphoramide, peroxyformic acid, selenium, sodium amide. Incandescent reaction with alkali metals (e.g., sodium, potassium), ammonia, arsenic, butyric acid (above 100°C), chlorine trifluoride, hydrogen sulfide + heat, sodium + heat, and sulfur. Incompatible with N,N-dimethylformamide. 

The selective oxidation of saturated hydrocarbons is a reaction of high industrial importance. Besides a variety of other oxidants, hydrogen peroxide as a very clean oxidant has also been used for these purposes . As an example, in 1989 Moiseev and coworkers reported on the vanadium(V)-catalyzed oxidation of cyclohexane with hydrogen peroxide (Scheme 146) . When the reaction was carried out in acetic acid cyclohexanol and cyclohexanone were formed, bnt conversions were very poor and did not exceed 13%. Employing CF3COOH as solvent, complete conversions could be obtained within 5 min-ntes. Here, cyclohexyl trifluoroacetate was the main product (85% of the products formed) resulting from the reaction of cyclohexanol (the primary product of the oxidation) with CF3COOH. 

The oxidation of a secondary alcohol to a ketone is usually accomplished with a solution of the alcohol and aqueous acidic chromic acid in either acetone or acetic acid, with a solution of sodium dichromate in acetic acid, or by reaction of the alcohol with aqueous acidic chromic acid as a heterogeneous system. An example is the oxidation of the substituted cyclohexanol below (Reaction XXXV) with sodium dichromate in sulfuric acid (55). 

Catalytic reactions were performed in CH2C12 under an 02 atmosphere Zn was used as an electron source and acetic acid as a proton donor (14). Under these reaction conditions ([2] [substrate] = 1 125), the production of adamantan-l-ol (248%), adamantan-2-ol (50%), and adamantan-2-one (108%) was observed. With cyclohexene as substrate, a mixture of cyclohexanol (54%), cyclohexanone (73%), and cyclohexene oxide (20%) was generated. In a similar experiment with cyclohexane, cyclohexanol (99%), and cyclohexanone (84%) were obtained. The product distribution is inconsistent with a free radical process for ada-mantane, the 3°/2° carbon reactivity ratio is 2.2. Control experiments demonstrated that both Zn dust and acetic acid were necessary, whereas larger quantities of acetic acid quenched the reaction (Table II). This may be due to the acidolysis of the n-oxo bond. Simple monomeric complexes such as FeClTPP (TPP is tetraphenylporphin), Fe(acac)3 (acac is acetylacetonate), and [Fe(HBpz3)2]+, 3, were inactive as catalysts under identical conditions. Furthermore, [Fe3+(Salen)]20, 1, did not show any reactivity. 

Hypochlorites are very good oxidizers of alcohols and are frequently selective enough to oxidize secondary alcohols in preference to primary alcohols see equations 288-291). Solutions of sodium hypochlorite in acetic acid react exothermically with secondary alcohols within minutes [693]. Calcium hypochlorite in the presence of an ion exchanger (IRA 900) oxidizes secondary alcohols at room temperature in yields of 60-98% [76 5]. Tetrabutylammonium hypochlorite, prepared in situ from 10% aqueous sodium hypochlorite and a 5% dichloromethane solution of tetrabutylammonium bisulfate, oxidizes 9-fluorenol to fluorenone in 92% yield and benzhydrol to benzophenone in 82% yield at room temperature in 35 and 150 min, respectively [692]. Cyclohexanol is oxidized to cyclohexanone by teit-butyl hypochlorite in carbon tetrachloride in the presence of pyridine. The exothermic reaction must be carried out with due precautions [709]. 

When l-(buten-3-yl)cyclohexanol and l-(penten-4-yl)cyclohexanol are treated with chromium trioxide in acetic acid and acetic anhydride, oxidation at the double bonds results in the formation of carbi xylic acids, which cyclize to form 7- and 8-lactones, respectively [5(55], The same reaction occurs with the cycloheptanol analogues in better yields (equation 282) [56S]. 

In the presence of dioxygen, the carbon radical R- produced by reactions (201) and (202) ar transformed into alkylperoxy radicals ROO, reacts with Co or Mn species to regenerate th Co " or Mn " oxidants, and produce primary oxygenated products (alcohol, carbonyl compounds which can be further oxidized to carboxylic acids. This constitutes the basis of several Industrie processes such as the manganese-catalyzed oxidation of n-alkenes to fatty acids, and the cobal catalyzed oxidation of butane (or naphtha) to acetic acid, cyclohexane to cyclohexanol-on mixture, and methyl aromatic compounds (toluene, xylene) to the corresponding aromatic monc or di-carboxylic acids. ... 

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 best result reported in the open literature is of 73% conversion with 73% selectivity to AA, obtained at normal O2 pressure, in acetic acid with 1 mol% Mn (acac)2, the by-products being glutaric acid (9%), succinic acid (6%), cyclohexyl acetate (2%) and cyclohexanol (1%) [30bj. The generation of the PINO from NHPI (Scheme 7.7) with oxygen is assisted by the Co(II) species therefore, the addition of a small amount of Co (O Ac) 2 enhances the oxidation process. In contrast, if the reaction is performed in an acetonitrile solvent, with a Co(OAc)2 catalyst at 75 °C, the main product is cyclohexanone (78% selectivity at 13% cyclohexane conversion). 

The well-known oxidations of primary and secondary alcohols with Cr species proceed through chromate esters. The definitive mechanistic expeii-ments " demonstrating that previously observed chromate esters were indeed on the reaction pathway showed that either formation or decomposition of the ester could be rate-determining. The rates of oxidation of cyclohexanol and the secondary hydroxyl group of a very steiically hindered steroid in aqueous acetic acid were measured as a function of the solvent composition. The former increased radically as the acetic add concentration increased whereas the latter remained invariant. The former exhibited a primary deuterium kinetic isotope effect of 5, whereas there was no KIE on the oxidation of the crowded steroid. Therefore, the rate-determining step in the oxidation of the cyclohexanol was decomposition of the chromate ester and in the oxidation of the steroid it was its formation, with the ester an obligate intermediate in both reactions. 

Most of the catalysts employed in the chemical technologies are heterogeneous. The chemical reaction takes place on surfaces, and the reactants are introduced as gases or liquids. Homogeneous catalysts, which are frequently metalloorganic molecules or clusters of molecules, also find wide and important applications in the chemical technologies [24]. Some of the important homogeneously catalyzed processes are listed in Table 7.44. Carbonylation, which involves the addition of CO and H2 to a C olefin to produce a + 1 acid, aldehyde, or alcohol, uses rhodium and cobalt complexes. Cobalt, copper, and palladium ions are used for the oxidation of ethylene to acetaldehyde and to acetic acid. Cobalt(II) acetate is used mostly for alkane oxidation to acids, especially butane. The air oxidation of cyclohexane to cyclohexanone and cyclohexanol is also carried out mostly with cobalt salts. Further oxidation to adipic acid uses copper(II) and vanadium(V) salts as catalysts. The... 

Bubble columns, in which the liquid is the continuous phase, are used for slow reactions. Drawbacks with respect to packed columns are the higher pressure drop and the important degree of axial and radial mixing of both the gas and the liquid, which may be detrimental for the selectivity in complex reactions. On the other hand they may be used when the fluids carry solid impurities that would plug packed columns. In fact, many bubble column processes involve a finely divided solid catalyst that is kept in suspension, like the Rheinpreussen Fischer-Tropsch synthesis, described by Kolbel [1], or the former I. G. Farben coal hydrogen process, or vegetable oil hardening processes. Several oxidations are carried out in bubble columns the production of acetaldehyde from ethylene, of acetic acid from C4 fractions, of vinylchloride from ethylene by oxychlorina-tion, and of cyclohexanone from cyclohexanol. 

We tried to accumulate oxidation reactions using copper chloride under these conditions (Fig. 6) but observed that the system had already started to deactivate after the first reaction. Furthermore, the system began to produce cyclohexanol in the accumulation reactions, which was not observed before. After 4 accumulations we obtained a 0.120 M solution of one + ol (8.3 1) with 100% selectivity but only 18% efficiency with respect to hydrogen peroxide. Using copper perchlorate in the absence of acetic acid, we were also able to accumulate one + ol to a concentration of 0.120 M (one ol = 5.9 1), but observed that the reaction was less efficient at the beginning (Fig. 7). Interestingly, the... 

These researchers have indicated that the overall order of this reaction is 3, that the order in acetic acid is 2, and that the order in cyclohexanol is 1. Recognizing that in dioxane solution at 40°C, acetic acid exists primarily as a dimer, propose a set of mechanistic equations that are consistent with the indicated rate expression. 

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