Liquid-phase co-oxidations

Comparatively few values have been measured for liquid-phase co-oxidations of hydrocarbon mixtures. With the exception of the cumene-Tetralin system, the reported values are all surprisingly low even for other systems giving tertiary and secondary (or primary) peroxy radicals. For example, at 60°C. values of 0.7 (36) and 1.3 (4) have been reported for the co-oxidation of cumene and ethylbenzene kt = 2.0 X 107 at 30°C. (14)], and a value of 1.4 (2) has been reported for the co-oxidation of cumene and 1-hexene [which gives mainly primary peroxy radicals with kt probably 1.3 X 108 at 30°C. (15)]. The confirmation that the present work provides for a relatively large value in the cumene-Tetralin system suggests that the other > systems deserve a close and careful reinvestigation. 

Liquid-Phase Co-Oxidations at Institut Francais du Petrole (IFP). 

Vreugdenhil AD, Reit H. Liquid-phase co-oxidation of aldehydes and olefins— radical versus non-radical epoxidation. Rec Trav Chim 1972 91 237-245. 

Let us consider the situation, when more than one final reaction proceeds in the system, for example, liquid-phase co-oxidization of two hydrocarbons R H and R2H ... 

Let us consider as an example the process of a liquid-phase co-oxidization of the hydrocarbons upon the final reactions (2.36) and (2.37) a set of the elementary reactions of a chain propagation is represented in (2.38) and a graph G = S, X) is shown in Figure 2.4. A route of this directed graph is given in (2.39). Let us introduce the notifications... 

Liquid-phase air oxidation of mesitylene with Co, Mn, and Bt catalysis produces 1,3,5-benzenetricarboxyhc acid [554-95-0] (trimesic acid) (10) (37) as does the oxidation with dilute nitric acid (qv). Amoco has oxidized mesitylene to trimesic acid on a small scale (see Phthalic acid and other BENZENECARBOXYLIC acids). Less vigorous stepwise oxidation of mesitylene can yield 3,5-dimethylbenzoic acid [499-06-9] (11) and 5-methyhsophthahc acid... 

The literature on liquid-phase olefin oxidation has been well reviewed (1, 2, 3, 5, 6, 8,12,14,15, 16,17, 18,19,20). Recent attention has been focused on the effects of structure and reaction conditions on the proportions of alkenyl hydroperoxy radical reaction by the abstraction and addition mechanisms at lower temperatures and conversions. The lower molecular weight cyclic and acyclic olefins have been extensively studied by Van Sickle and co-workers (17, 18, 19, 20). These studies have recently been extended to include higher molecular weight alkenes (16). 

Co saturated hydrocarbons are used extensively in the United States, whereas the acetylene process was used almost exclusively in Europe until recently. These processes were extended by the late 1950 s and early 1960 s by a new approach called the Wacker process or the Wacker-Hoechst process, consisting of the liquid phase catalytic oxidation of ethylene to acetaldehyde, as outlined in Table II. 

Langhendries et al [5.74] analyzed the liquid phase catalytic oxidation of cyclohexane in a PBMR, using a simple tank-in-series approximate model for the PBMR. In their -reactor the liquid hydrocarbon was fed in the tubeside, where a packed bed of a zeolite supported iron-pthalocyanine catalysts was placed. The oxidant (aqueous butyl-hydroperoxide) was fed in the shellside from were it was extracted continuously to the tubeside by a microporous membrane. The simulation results show that the PBMR is more efficient than a co-feed PBR in terms of conversion but only at low space times (shorter reactors). A significant enhancement of the organic peroxide efficiency, defined as the amount of oxidant used for the conversion of cyclohexane to the total oxidant converted, was also observed for the PBMR. It was explained to be the result of the controlled addition of the peroxide, which gives low and nearly uniform concentration along the reactor length. 

One of the most important industrial achievements in the field of liquid-phase selective oxidation has been the discovery of titanium silicalite-1 (TS-1) at Eni in the late 1970s, by Taramasso and co-workers. Thanks to the unique reactivity properties of TS-1, several innovative processes that use hydrogen peroxide are now industrial processes, and others are under advanced development. 

Kishore, D. and Rodrigues, A. (2008). Liquid Phase Catalytic Oxidation of Isophorone with terf.-butylhydroperoxide over Cu/Co/Fe-MgAl Ternary Hydrotalcites, Appl. Catal. A Gen., 345, pp. 104-111. 

A novel method for the synthesis of gold nanoparticles with different particle size (3-15 nm) and shape, supported on both the inner and outer surfaces of poly(o-phenylenediamine) (PoPD) hollow microspheres was developed by Guo and co-workers. The supported gold nanoparticles were active in the liquid-phase aerobic oxidation of alcohols using water as a solvent and K2CO3, under very mild conditions (room temperature) with yields of 91-95%. 

Liquid-phase oxidation of lower hydrocarbons has for many years been an important route to acetic acid [64-19-7]. In the United States, butane has been the preferred feedstock, whereas ia Europe naphtha has been used. Formic acid is a coproduct of such processes. Between 0.05 and 0.25 tons of formic acid are produced for every ton of acetic acid. The reaction product is a highly complex mixture, and a number of distillation steps are required to isolate the products and to recycle the iatermediates. The purification of the formic acid requires the use of a2eotropiag agents (24). Siace the early 1980s hydrocarbon oxidation routes to acetic acid have decliaed somewhat ia importance owiag to the development of the rhodium-cataly2ed route from CO and methanol (see Acetic acid). 

Liquid-Phase Oxidation. In the early 1960s, both Cams Chemical Co. (La SaEe, Illinois) and a plant in the Soviet Union started to operate modernized Hquid-phase oxidation processes. 

Manufacture and Processing. PytomeUitic acid and its dianhydtide can be synthesized by oxidizing dutene [95-93-2] (1,2,4,5-tettamethylbenzene). Liquid-phase oxidation using strong oxidants such as nittic acid, chromic acid, or potassium permanganate produces the acid which can be dehydrated to the dianhydtide in a separate step. This technology is practiced by AUco Chemical Co., a part of International Specialty Chemicals. 

Over the years, Pourbaix and his co-workers in the CEBELCOR Institute, founded under his direction, extended these diagrams by including lines for metastable compounds. Figure 7.66 illustrates such a presentation for the Fe-O system over the temperature range 830-2200 K. Pourbaix used these diagrams as a basis for a discussion of the stability of metallic iron (solid, liquid and vapour phases), the oxides of iron as a function of oxygen pressure and temperature from which he explained the protection of iron at high temperature by immunity and passivation. He also pointed out the... 

The chemistry of vinyl acetate synthesis from the gas-phase oxidative coupling of acetic acid with ethylene has been shown to be facilitated by many co-catalysts. Since the inception of the ethylene-based homogeneous liquid-phase process by Moiseev et al. (1960), the active c ytic species in both the liquid and gas-phase process has always been seen to be some form of palladium acetate [Nakamura et al, 1971 Augustine and Blitz, 1993]. Many co-catalysts which help to enhance the productivity or selectivity of the catalyst have appeared in the literature over the years. The most notable promoters being gold (Au) [Sennewald et al., 1971 Bissot, 1977], cadmium acetate (Cd(OAc)j) [Hoechst, 1967], and potassium acetate (KOAc) [Sennewald et al., 1971 Bissot, 1977]. 

A recent stndy (13,27) describes the use of Co-Si-TUD-1 for the liquid-phase oxidation of cyclohexane. Several other metals were tested as well. TBHP (tert-butyl hydroperoxide) was used as an oxidant and the reactions were carried out at 70°C. Oxidation of cyclohexane was carried out using 20 ml of a mixture of cyclohexane, 35mol% TBHP and 1 g of chlorobenzene as internal standard, in combination with the catalyst (0.1 mmol of active metal pretreated overnight at 180°C). Identification of the products was carried out using GC-MS. The concentration of carboxylic side products was determined by GC analysis from separate samples after conversion into the respective methyl esters. Evolution and consumption of molecular oxygen was monitored volumetrically with an attached gas burette. All mass balances were 92% or better. 

The chain mechanism is complicated when two hydrocarbons are oxidized simultaneously. Russell and Williamson [1,2] performed the first experiments on the co-oxidation of hydrocarbons with ethers. The theory of these reactions is close to that for the reaction of free radical copolymerization [3] and was developed by several researchers [4-9], When one hydrocarbon R H is oxidized in the liquid phase at a sufficiently high dioxygen pressure chain propagation is limited only by one reaction, namely, R OO + R H. For the co-oxidation of two hydrocarbons R1 and R2H, four propagation reactions are important, viz,... 

RY Kucher, IA Opeida. Co-oxidation of Organic Compounds in Liquid Phase. Kiev Naukova Dumka, 1989 [in Russian],... 

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