Alcohol oxidation reaction

In the Absence of Oxygen Methanol, Ethanol, 2-Propanol, and t-Butyl Alcohol Alcohols such as methanol, ethanol, and 2-propanol are converted with Pt/Ti02 to the corresponding dehydrogenation products such as formaldehyde, acetaldehyde, and acetone, respectively, with the formation of equimolar H2. t-Butyl alcohol is converted into 2,5-dimethyl-2,5-hexanediol with the formation of H2 through intermolecular dimerization since t-butyl alcohol has no alpha-hydrogen. In these oxidative reactions, alcohols are oxidized by photoformed holes, while photoexcited electrons reduce water (or H" ) to form H2 [4]. 

Typical nucleophiles known to react with coordinated alkenes are water, alcohols, carboxylic acids, ammonia, amines, enamines, and active methylene compounds 11.12]. The intramolecular version is particularly useful for syntheses of various heterocyclic compounds[l 3,14]. CO and aromatics also react with alkenes. The oxidation reactions of alkenes can be classified further based on these attacking species. Under certain conditions, especially in the presence of bases, the rr-alkene complex 4 is converted into the 7r-allylic complex 5. Various stoichiometric reactions of alkenes via 7r-allylic complex 5 are treated in Section 4. 

Section 15 11 Oxidation of alcohols to aldehydes and ketones is a common biological reaction Most require a coenzyme such as the oxidized form of nicotin amide adenine dmucleotide (NAD" )... 

Aldehydes are more easily oxidized than alcohols which is why special reagents such as PCC and PDC (Section 15 10) have been developed for oxidizing primary alco hols to aldehydes and no further PCC and PDC are effective because they are sources of Cr(VI) but are used m nonaqueous media (dichloromethane) By keeping water out of the reaction mixture the aldehyde is not converted to its hydrate which is the nec essary intermediate that leads to the carboxylic acid... 

The radicals are then involved in oxidations such as formation of ketones (qv) from alcohols. Similar reactions are finding value in treatment of waste streams to reduce total oxidizable carbon and thus its chemical oxygen demand. These reactions normally are conducted in aqueous acid medium at pH 1—4 to minimize the catalytic decomposition of the hydrogen peroxide. More information on metal and metal oxide-catalyzed oxidation reactions (Milas oxidations) is available (4-7) (see also Photochemical technology, photocatalysis). 

Oxidation of LLDPE starts at temperatures above 150°C. This reaction produces hydroxyl and carboxyl groups in polymer molecules as well as low molecular weight compounds such as water, aldehydes, ketones, and alcohols. Oxidation reactions can occur during LLDPE pelletization and processing to protect molten resins from oxygen attack during these operations, antioxidants (radical inhibitors) must be used. These antioxidants (qv) are added to LLDPE resins in concentrations of 0.1—0.5 wt %, and maybe naphthyl amines or phenylenediamines, substituted phenols, quinones, and alkyl phosphites (4), although inhibitors based on hindered phenols are preferred. 

Petoxycatboxyhc acids have been obtained from the hydrolysis of stable o2onides with catboxyhc acids, pethydtolysis of acyhinida2ohdes, reaction of ketenes with hydrogen peroxide, electrochemical oxidation of alcohols and catboxyhc acids, and oxidation of catboxyhc acids with oxygen in the presence of o2one (181). 

This ladical-geneiating reaction has been used in synthetic apphcations, eg, aioyloxylation of olefins and aromatics, oxidation of alcohols to aldehydes, etc (52,187). Only alkyl radicals, R-, are produced from aliphatic diacyl peroxides, since decarboxylation occurs during or very shortiy after oxygen—oxygen bond scission in the transition state (187,188,199). For example, diacetyl peroxide is well known as a source of methyl radicals (206). 

A typical phenol plant based on the cumene hydroperoxide process can be divided into two principal areas. In the reaction area, cumene, formed by alkylation of benzene and propylene, is oxidized to form cumene hydroperoxide (CHP). The cumene hydroperoxide is concentrated and cleaved to produce phenol and acetone. By-products of the oxidation reaction are acetophenone and dimethyl benzyl alcohol (DMBA). DMBA is dehydrated in the cleavage reaction to produce alpha-methylstyrene (AMS). 

Oxidation of cumene to cumene hydroperoxide is usually achieved in three to four oxidizers in series, where the fractional conversion is about the same for each reactor. Fresh cumene and recycled cumene are fed to the first reactor. Air is bubbled in at the bottom of the reactor and leaves at the top of each reactor. The oxidizers are operated at low to moderate pressure. Due to the exothermic nature of the oxidation reaction, heat is generated and must be removed by external cooling. A portion of cumene reacts to form dimethylbenzyl alcohol and acetophenone. Methanol is formed in the acetophenone reaction and is further oxidized to formaldehyde and formic acid. A small amount of water is also formed by the various reactions. The selectivity of the oxidation reaction is a function of oxidation conditions temperature, conversion level, residence time, and oxygen partial pressure. Typical commercial yield of cumene hydroperoxide is about 95 mol % in the oxidizers. The reaction effluent is stripped off unreacted cumene which is then recycled as feedstock. Spent air from the oxidizers is treated to recover 99.99% of the cumene and other volatile organic compounds. 

AHyl alcohol can be easily oxidized to yield acrolein [107-02-8] and acryhc acid [79-10-7]. In an aqueous potassium hydroxide solution of RuQ., aHyl alcohol is oxidized by a persulfate such as K2S20g at room temperature, yielding acryhc acid in 45% yield (29). There are also examples of gas-phase oxidation reactions of ahyl alcohol, such as that with Pd—Cu or Pd—Ag as the catalyst at 150—200°C, in which ahyl alcohol is converted by 80% and acrolein and acryhc acid are selectively produced in 83% yield (30). 

Although saturated alcohols are sufftcientiy stable toward quinones to be used as solvents for these oxidation reactions, hen2ylic (43) and aHyUc alcohols are often readily converted to the corresponding carbonyl compounds (44), as shown in equation 2 for ben2ene systems (33). For the substituents indicated, yields are as follows ... 

Rhenium oxides have been studied as catalyst materials in oxidation reactions of sulfur dioxide to sulfur trioxide, sulfite to sulfate, and nitrite to nitrate. There has been no commercial development in this area. These compounds have also been used as catalysts for reductions, but appear not to have exceptional properties. Rhenium sulfide catalysts have been used for hydrogenations of organic compounds, including benzene and styrene, and for dehydrogenation of alcohols to give aldehydes (qv) and ketones (qv). The significant property of these catalyst systems is that they are not poisoned by sulfur compounds. 

The initiating step in these reactions is the attachment of a group to the sulfoxide oxygen to produce an activated intermediate (5). Suitable groups are proton, acyl, alkyl, or almost any of the groups that also initiate the oxidations of alcohols with DMSO (40,48). In a reaction, eg, the one between DMSO and acetic anhydride, the second step is removal of a proton from an a-carbon to give an yUde (6). Release of an acetate ion generates the sulfur-stabilized carbonium ion (7), and the addition of acetate ion to the carbonium ion (7) results in the product (eq. 15) ... 

In plasticizer manufacture, eg, of phthalates or sebacates, uskig sulfuric or/ -toluenesulfonic acid catalysts, the temperature (140—150°C) requked for rapid reaction and high conversion may dehydrate or oxidize the alcohol and may yield a dark or foul-smelling product. Neutral titanates do not cause such side reactions. Although a temperature of 200°C is requked, esterifications can easily be forced to over 99% conversion without the formation of odors or... 

From Boric Oxide and Alcohol. To avoid removing water, boric oxide, B2O3, can be used in place of boric acid. The water of reaction (eq. 4) is consumed by the oxide (eq. 5). Because boric acid reacts with borates at high temperatures, it is necessary to filter the reaction mixture prior to distillation of the product. Only 50% of the boron can be converted to ester by this method. In cases where this loss can be tolerated, the boric oxide method is convenient. This is particularly tme for methyl borate and ethyl borate preparation because formation of the undesirable azeotrope is avoided. 

Health and Safety Factors (Toxicology). Manufacture of cyanamide and calcium cyanamide does not present any serious health hazard. Ingestion of alcohoHc beverages by workmen within several hours of leaving work sometimes results in a vasomotor reaction known as cyanamide flush. Cyanamide interferes with the oxidation of alcohol and accumulation of acetaldehyde probably accounts for this temporary phenomenon. Although extremely unpleasant, it has not been known to result in serious illness or to have any permanent effect. 

The oxidation of alcohols with lead tetraacetate was the first reaction used for oxygenation of an angular methyl group in steroids. It is a simple and efficient method and produces tetrahydrofuran derivatives directly from alcohols. 

Oxidative reactions frequently represent a convenient preparative route to synthetic intermediates and end products This chapter includes oxidations of alkanes and cycloalkanes, alkenes and cycloalkenes, dienes, aromatic fluorocarbons, alcohols, phenols, ethers, aldehydes and ketones, carboxylic acids, nitrogen compounds, and organophosphorus, -sulfur, -selenium, -iodine, and -boron compounds... 

Zinc-tartrate complexes were applied for reactions of both nitrones and nitrile oxides with allyl alcohol and for both reaction types selectivities of more than 90% ee were obtained. Whereas the reactions of nitrones required a stoichiometric amount of the catalyst the nitrile oxide reactions could be performed in the presence of 20 mol% of the catalyst. This is the only example on a metal-catalyzed asymmetric 1,3-dipolar cycloaddition of nitrile oxides. It should however be no-... 

Oxidation of C12-C14 n-paraffms using boron trioxide catalysts was extensively studied for the production of fatty alcohols.Typical reaction conditions are 120-130°C at atmospheric pressure. ter-Butyl hydroperoxide (0.5 %) was used to initiate the reaction. The yield of the alcohols was 76.2 wt% at 30.5% conversion. Fatty acids (8.9 wt%) were also obtained. Product alcohols were essentially secondary with the same number of carbons and the same structure per molecule as the parent paraffin hydrocarbon. This shows that no cracking has occurred under the conditions used. The oxidation reaction could be represented as ... 

The mechanism of the oxidation reaction, resulting from treatment of an alcohol with dicyclohexylcarbodiimide and methyl sulfoxide in the presence of a proton source, was elucidated by isotope experiments (24). These confirmed that the reaction proceeded by formation of a... 

Alcohols undergo an oxidation reaction to yield carbonyl compounds on treatment with CrO. Forexample, 2-ftvt-butylcyclohexanol gives 2-terT-butylcyclo-hexanone. If axial -OH groups are generally more reactive than their equatorial isomers, which do you think would react faster, the cis isomer of 2-ferf-butylcyclohexanol or the trans isomer Explain. 

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