Toluene oxidation route

The cumene oxidation route is the lea ding commercial process of synthetic phenol production, accounting for more than 95% of phenol produced in the world. The remainder of synthetic phenol is produced by the toluene oxidation route via benzoic acid. Other processes including benzene via cyclohexane, benzene sulfonation, benzene chlorination, and benzene oxychl orin ation have also been used in the manufacture of phenol. A Hst of U.S. phenol production plants and their estimated capacities in 1994 are shown in Table 2, and worldwide plants and capacities are shown in Table 3. 

Of the two commercially operated technologies, the toluene oxidation route affords not only phenol but also the specialty chemicals benzaldehyde and benzoic acid (Equation 13.1) ... 

Ring and aryl methyl group oxidation were the initial toluene-degradation routes speculated on for the nitrate-reducing enrichment obtained by Kuhn etal. (1988) and the metabolically diverse iron-reducing bacterium Geobacter metallireducens (Lovley Lonergan, 1990). The speculation was consistent with the fact that both of these cultures could metabolize the appropriate suite of putative intermediates. However, conclusive evidence as to which pathway was actually involved was not obtained. 

Figure 8. Sehematic of MCMvS.l peroxide bieyelie route for toluene oxidation and postulated OH regeneration pathway.

Phenol production route Benzene sulfonation Benzene chlorination Benzene oxychlorinotion Cumene Alkylation me 1 hod Oxidation Toluene oxidation... 

Suvorov, Rafikov, and Anuchina (111) came to the conclusion that the first step of toluene oxidation over vanadium oxides yields hydroperoxide which may decompose by various routes. The formation of high-conversion products does not occur in parallel. 

All routes have every reaction stage producing one target bond. At the global metrics level, routes 6 and 9 have the least -kernel, routes 8 and 9 have the least E -excess, and routes 6-10 have the least -auxiliaries. Overall, routes 8 and 9 have the least -total. On balance, routes 6 (Wacker-Raschig process) and 9 (Wacker-toluene oxidation process) appear to have the most positive counts based on all metrics parameters. 

Here it has been established by us for the first time that, as well as in the case of ethylbenzene oxidation, in toluene oxidation in the presence of system Ni(II)(acac)2+MP the route of formation major toluene... 

In nickel catalyzed toluene oxidation the route of formation major oxidation products, benzaldehyde (BAL), benzyl alcohol (BZA) and benzoic acid (BA) is changed from successive (catalysis by coordinated unsaturated complexes Ni(II)(acac)2 MP on parallel (catalysis by complexes Ni2(OAc)3(acac)-MP ( A ). 

As in the case of other hydrocarbons, the oxidation of aromatic compounds is induced by OH radicals. Figure 5 illustrates prominent oxidation pathways for toluene. Two routes may be distinguished. One is abstraction of a hydrogen atom from the methyl group, which leads to benzaldehyde as the main product. The other pathway is the addition of OH to the aromatic ring to form... 

Arylsulfonyl chlorides are typically employed as the cyclization agents in the oxidative route to dioxazines. In the manufacture of Pigment Violet 23 crude the most commonly employed agents are benzene- or p-toluene-sulfonyl chloride. Some literature articles describing the synthesis of dioxazines refer to the sulfonyl chlorides... 

Obviously, there is a definite need for cleaner, more efficient routes to adipic acid. The question which immediately arises is, naturally, what does the Amoco system do in cyclohexane oxidation In this context it is interesting to compare the relative oxidizabilities of toluene, cyclohexane, cyclohexanol and cyclohexanone (Table 2). 

Ester (9) can easily be made from acid (H)- You might consider two approaches to this a one-carbon electrophile addition via chloromethylation (Table T 2.2) and oxidation or FGl (Table 2,3) back to p-chlorotoluene (12). The latter is easier on a large scale. The p-chlorotoluene (12) can be made either by direct chlorination of toluene or by the diazotisation route (p T 12) again from toluene. 

Thiotraamidophosphoric acids (35) are isoelectronic with phosphoric acids and were initially reported from the reaction of phosphorus pentasulfide with primary amines at high temperatures.62 Subsequently, an improved synthesis for 35 with increased yields and milder conditions has been reported involving the room temperature reaction of thiophosphoryl chloride and primary amines (Equation 50).63 The most convenient route to the analogous selenium derivatives SeP(NHPh)3 is from the oxidation of P(NHPh)3 with elemental selenium (Equation 51).63 Also isoelectronic with phosphoric acids are dithio wamido-phosphoric acids (36), which can be prepared from the reaction of phosphorus pentasulfide with an excess of primary amine at 30°C in toluene (Equation 52).62 The selenium derivatives of 36 can be prepared in a similar reaction from phosphorus (V) selenide, although due to their increased acidity... 

Other routes. Alternate process technologies for making phenol avoid the cumene route. A few plants have used toluene as a feed, oxidizing it over a cobalt catalyst to give benzoic acid. That is followed by a reduction (removal of oxygen atom) to give phenol and carbon dioxide. 

A minor route, which now accounts for 2% of phenol, takes advantage of the usual surplus of toluene from petroleum refining. Oxidation with a number of reagents gives benzoic acid. Further oxidation to p-hydroxybenzoic acid and decarboxylation yields phenol. Here phenol competes with benzene manufacture, also made from toluene when the surplus is large. The last 2% of phenol comes from distillation of petroleum and coal gasification. 

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