Halcon process

This process is one of the three commercially practiced processes for the production of acetic anhydride. The other two are the oxidation of acetaldehyde [75-07-0] and the carbonylation of methyl acetate [79-20-9] in the presence of a rhodium catalyst (coal gasification technology, Halcon process) (77). The latter process was put into operation by Tennessee Eastman in 1983. In the United States the total acetic anhydride production has been reported to be in the order of 1000 metric tons. 

Sales demand for acetophenone is largely satisfied through distikative by-product recovery from residues produced in the Hock process for phenol (qv) manufacture. Acetophenone is produced in the Hock process by decomposition of cumene hydroperoxide. A more selective synthesis of acetophenone, by cleavage of cumene hydroperoxide over a cupric catalyst, has been patented (341). Acetophenone can also be produced by oxidizing the methylphenylcarbinol intermediate which is formed in styrene (qv) production processes using ethylbenzene oxidation, such as the ARCO and Halcon process and older technologies (342,343). 

A key feature of the Halcon process is the use of low pressure distillation (less than 80 kPa = 12 psi) to break the pbenol—aniline a2eotrope and allow economical separation of aniline from phenol (67). 

The production of styrene and propylene epoxide from ethylbenzene (Halcon process) that includes the following three technological stages [234],... 

The second manufacturing method for propylene oxide is via peroxidation of propylene, called the Halcon process after the company that invented it. Oxygen is first used to oxidize isobutane to r-butyl hydroperoxide (BHP) over a molybdenum naphthenate catalyst at 90°C and 450 psi. This oxidation occurs at the preferred tertiary carbon because a tertiary alkyl radical intermediate can be formed easily. 

One molybdenum-catalyzed epoxidation, which is of indnstrial importance, needs special mention the Halcon process , which is the molybdennm-catalyzed epoxidation of propylene with TBHP or 1-phenylethyl hydroperoxide on a large scale (Scheme 74), and has been developed and patented by researchers from Halcon and Atlantic Richfield . 

Halcon Process, t-butyl hydroperoxide, 428 Half-fractional factorial design, analytical methods, 624... 

The main emphasis has been on the homologation of methanol to ethanol (O. Homologation of substrates other than methanol has up till now been less widely studied. However, there is an increasing interest in the hydrocarbonylation of esters, as is evidenced by e.g. the development of the Halcon process (2 ) for the production of ethyli-dene diacetate as a precursor for vinyl acetate. 

Propionic Acid. The Reppe reaction is used to transform ethylene, carbon monoxide, and water to propionic acid.82 [Ni(CO)4] is formed in situ from nickel salts under reaction conditions (270-320°C, 200-240 atm). The addition of halogens and phosphine ligands allows milder reaction conditions (Halcon process, 170-225°C, 10-35 atm). Propionic acid yields are around 95%. 

Inserting oxygen into the C-H bond of an alkane initially leads to hydroperoxides. When this reaction is performed with atmospheric oxygen it is also called autooxidation. It usually leads to a multitude of products, because of further spontaneous reactions, so this reaction is of limited synthetic use. An exception is oxidation of isobutane with oxygen, which leads to 70 % yield of tert-butyl hydroperoxide at a conversion of 80% (Table 1, entry 7). Hydrogen bromide is used, among other compounds, as an initiator [15]. tert-Butyl hydroperoxide is used as an oxidant in propylene oxide production by the Halcon process. In the formation of phenol by the cumene process cumene is oxidized into the corresponding hydroperoxide in a similar way. 

Molybdenum complexes are the most effective catalysts known for the selective epoxidation of olefins with alkyl hydroperoxides (210-212). Commonly known is the Arco or Halcon process for the large-scale manufacture of propylene oxide from propylene. This process uses t-BuOOH or ethyl benzene hydroperoxide (EBHP) as an oxidant and Mo(CO)6, for example, as a source of Mo. The Mo(CO)6 acts as a catalyst precursor, which is converted into a soluble active form by complexation with diols (3). Chemists have designed several supported versions of the catalysts for this epoxidation chemistry. A clear classification can be made on the basis of the nature of the support. 

Isobutene is present in refinery streams. Especially C4 fractions from catalytic cracking are used. Such streams consist mainly of n-butenes, isobutene and butadiene, and generally the butadiene is first removed by extraction. For the purpose of MTBE manufacture the amount of C4 (and C3) olefins in catalytic cracking can be enhanced by adding a few percent of the shape-selective, medium-pore zeolite ZSM-5 to the FCC catalyst (see Fig. 2.23), which is based on zeolite Y (large pore). Two routes lead from n-butane to isobutene (see Fig. 2.24) the isomerization/dehydrogenation pathway (upper route) is industrially practised. Finally, isobutene is also industrially obtained by dehydration of f-butyl alcohol, formed in the Halcon process (isobutane/propene to f-butyl alcohol/ propene oxide). The latter process has been mentioned as an alternative for the SMPO process (see Section 2.7). 

Thermodynamically, the carbonylation of methyl acetate (AG298 -10 kJ/mol) is considerably less favourable than that of methanol (AG298 -74 kJ/mol). This means that the reaction does not reach completion but attains an equilibrium which is dependent on the temperature and the CO pressure. Two variants are currently practised commercially that developed by Tennessee Eastman, based on a Halcon process, and a BP process in which acetic acid and the anhydride are co-produced in proportions which can be varied according to demand. Syngas for the Eastman process is made from coal which is mined close to the plant in Tennessee and the acetic anhydride produced is used to make cellulose acetate for film production. The BP process uses syngas generated from North Sea gas which is piped directly to the BP plant in EIull. [Acetic anhydride manufacture M. J. Eloward, M. D. Jones, M. S. Roberts, S. A. Taylor, Catalysis Today, 1993, 18, 325]. 

Aniline can also be prepared by the amination of phenols under a pressure of 15 to 16 atm at a temperature of 380 to 385°C in the presence of a silica- alumina catalyst (Halcon process). 

Unsaturated fatty compounds are the preferred educts in industrial epoxidation. Numerous methods are available to transform then to the corresponding epoxides. Epoxidation with molecular oxygen [3], dioxiranes [4], hydrogen peroxide with methyltrioxorhenium as catalyst [5, 6], the Halcon process [7], or enzymatic reactions [8] are the most important industrial processes (cf. Section 2.4.3). 

In the Halcon process, the amination of 7 takes place in the vapor phase with a silica-alumina catalyst (Scheme 3). Amination of phenol has the advantage of reduced capital costs, long catalyst life and high quality product. Excess ammonia favors high conversion of the mildly exothermic (AH = —544 kcal ruol 1) and reversible reaction, and also minimizes formation of byproducts. Generally, however, the price of phenol makes this process more expensive than the nitrobenzene routes. The last plant in the US to produce aniline from phenol by amination was operated by Sunoco Chemicals. It produced 140 million lbs./year-1, with diphenylamine, or DPA (8) as a coproduct, at Haverhill, Ohio, and ceased production in 200213,14. Aristech Chemical Corporation at one time operated a phenol-to-aniline process in the US. 

Epoxidation with hydroperoxides is the basis for the large-scale indirect production of propylene oxide by a process that has been called the Oxirane or Halcon processes. Early work was reported by Smith in a patent issued in 1956 [457], which described soluble heteropoly acids containing transition metals such as chromium, molybdenum, and tungsten that could be employed as homogeneous catalysts for the reaction of olefins with organic hydroperoxides and hydrogen peroxide. 

Alkene epoxidation is a very useful reaction in industry and organic s)mthesis. The resultant epoxides are essential precursors in the s)mthesis of various important substances like plasticizers, perfumes, and epoxy resins [1]. For example, over 5,000,000 and 70,000 metric tonnes of propylene and butene oxides, respectively, are produced per year [2]. Current commercial production of propylene oxide (PO) usually employs the chlorohydrin process or the Halcon process, which gives rise to disposal problem for the resultant salts or large amounts of coproducts. As a result of increasing stringent enviromnent legislation, there is currently much interest in the research and development of environmentally friendly methods for preparation of PO without any coproduct. 

The Halcon process performs chemical dimerization in two steps. In the first, acrylonitrile is dimerized to methylene glutaronitrile (branched dimer) ... 

The other benzene oxidation processes are usually distinguished from the Halcon process by the technique employed to recover and purify maleic anhydride. This applies... 

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