Alkylbenzenes, oxidation using

Alkylbenzene oxidation is usually carried out at 90-100 and 0.2-1 bar oxygen pressure in acetic acid [41]. Cobalt(III) acetate is added in relatively high concentrations (ca. 0.1 M). To avoid long induction periods, methyl ethyl ketone or ozone are used as activators to promote reoxidation of cobalt(II) to the active cobalt(III) [42]. The following reaction mechanism is generally accepted [3,43-48] ... 

In one of the pioneering studies in this field it was reported that commercial FeBTC (Aldrich, Basolite F 300) is a suitable catalyst for the oxidation of benzylic hydrocarbons by ieri-butyl hydroperoxide (TBHP). Xanthene, fluorene, and alkylbenzenes (Scheme 2.10) were found to be suitable substrates for these oxidations using FeBTC as catalyst. FeBTC was more active catalyst than Cu3(BTC)2 and AIOH(BTC) was inactive for the process. 

Using dicyclohexyl-18-crown-6 it is possible to dissolve potassium hydroxide in benzene at a concentration which exceeds 0.15 mol dm-3 (Pedersen, 1967). The free OH- has been shown to be an excellent reagent for ester hydrolysis under such conditions. The related solubilization of potassium permanganate in benzene, to yield purple benzene , enables oxidations to be performed in this solvent (Hiraoka, 1982). Thus, it is possible to oxidize a range of alkenes, alcohols, aldehydes, and alkylbenzenes under mild conditions using this solubilized reagent. For example, purple benzene will oxidize many alkenes or alcohols virtually instantaneously at room temperature to yield the corresponding carboxylic acids in near-quantitative yields (Sam Simmons, 1972). 

They used this new oxidizing reagent for a rapid and selective oxidation of primary and secondary benzylic alcohols to the corresponding aldehydes and ketones in good to excellent yields. BTPCP was later used for oxidation of various alkylbenzenes under neutral conditions in aqueous CH3CN to the corresponding carbonyl compounds in good yields (equation 34) °. ... 

A new reagent, AMiydroxyphthalimide combined with Co(acac)n (n = 2,3), transforms alkylbenzenes to ketones, whereas methylbenzenes give the corresponding carboxylic acids.1121 Phthalimide N-oxyl was found to be the key intermediate. Novel oxoperoxo Mo(VI) complexes mediate the cost-effective and environmentally benign oxidation of methylbenzenes to carboxylic acids.1384 Similar green oxidation of p-xylene to terephthalic acid was reported by using a Ru-substituted heteropolyanion.1385... 

Benzenol and the 2-, 3-, and 4-methylbenzenols (cresols) can be isolated from coal tar (Section 22-11). Benzenol itself is used commercially in such large quantities that alternate methods of preparation are necessary and most of these start with benzene or alkylbenzenes. Direct oxidation of benzene is not satisfactory because benzenol is oxidized more readily than is benzene. 

Lead tetraalkyl derivatives are used in catalytic systems to polymerise olefines, as catalysts of re-etherification and polycondensation, to speed up the alkylation of lateral chains of alkylbenzenes with ethylene and its derivatives. An addition of lead tetraalkyl derivatives (0.05-2% of alkylben-zene quantity) to catalysts of the liquid-phase oxidation of alkylbenzenes speeds up the oxidation. Tetraethyllead proved to be a good initiator for Diels-Alder reactions to join polymers with alkenylsiloxy chains and can be used as an additive to reduce the attrition and wear of rubbing metal parts. Tetrabutyllead is an active cross-linking agent for polyethylene and modifying agent for plastics. 

The oldest surfactant is soap, which may be traced back to the ancient Egyptians and beyond. Synthetic surfactants had been produced in the first half of the 20th century but it was only after World War II, with the development of the modern petrochemical industry, that alternative feedstocks to oleochemicals became readily available. Hence chloroparaf-fins and/or alphaolefins and benzene were used to produce alkylbenzene (or alkylate ), processes were developed to produce a range of synthetic fatty alcohols and alkylene oxide chemistry resulted in ethylene oxide and propylene oxide building blocks becoming readily available. 

Side chains of alkylbenzenes are oxidized to benzoic acid derivatives by treatment with hot potassium permanganate or hot chromic acid. Because this oxidation requires severe conditions, it is useful only for making benzoic acid derivatives with no oxidizable functional groups. Oxidation-resistant functional groups such as —Cl, —NO2, —SO3H, and —COOH may be present (Section 17-15A). 

Previously, the most widely used method for preparation of 4-alkyl-benzoyl chlorides on a laboratory scale has been from the benzoic acids obtained by oxidation of aromatic ketones, usually 4-alkylacetophe-nones. 14 The latter are usually prepared by acylating alkylbenzenes. Although this sequence gives high yields, it is lengthy (three completely separate steps) and the scale is restricted in the second step because of the large volumes required. The submitters state that they were unable to repeat the reported alkylation of toluic acid.15 Methods that lead to formation of ortho and para isomeric intermediates are inconvenient since they require that the isomers be separated.16"19... 

The alkenylation reaction proceeds at 100° or below. Yields of 80-91 of mcmobutenylated alkylbenzene were obtained from toluene, o- and p-xylene, and ethylbenzene using sodium deposited cxi calcium oxide (23). 

Most aromatic compounds, whether of high or low reactivity, can be nitrated, because a wide variety of nitrating agents is available. For benzene, the simple alkylbenzenes, and less reactive compounds, the most common reagent is a mixture of concentrated nitric and sulfuric acids,but for active substrates, the reaction can be carried out with nitric acid alone, or in water, acetic acid, acetic anhydride, or chloroform.Nitric acid in acetic anhydride/trifluoroacetic anhydride on zeolite H-(3 was used to convert toluene to 2,4-dinitrotoluene, and AcONOi on clay converted ethylbenzene to ortho-para nitro ethylbenzene. " In fact, these milder conditions are necessary for active compounds, such as amines, phenols, and pyrroles, since reaction with mixed nitric and sulfuric acids would oxidize these substrates. With active substrates, such as amines and phenols, nitration can be accomplished by nitrosation under oxidizing conditions with a mixture of dilute nitrous and nitric acids.A mixture of N02/02/Fe(acac)3 can be used for active compounds, as can NaN02 with trichloroisocyanuric acid on wet silica gel, or N2O4 and silica acetate. Trimethoxybenzenes were nitrated easily with ceric ammonium nitrate on silica gel, and mesitylene was nitrated in an... 

---