Phenol Hock process

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). 

Phenol is the starting material for numerous intermediates and finished products. About 90% of the worldwide production of phenol is by Hock process (cumene oxidation process) and the rest by toluene oxidation process. Both the commercial processes for phenol production are multi step processes and thereby inherently unclean [1]. Therefore, there is need for a cleaner production method for phenol, which is economically and environmentally viable. There is great interest amongst researchers to develop a new method for the synthesis of phenol in a one step process [2]. Activated carbon materials, which have large surface areas, have been used as adsorbents, catalysts and catalyst supports [3,4], Activated carbons also have favorable hydrophobicity/ hydrophilicity, which make them suitable for the benzene hydroxylation. Transition metals have been widely used as catalytically active materials for the oxidation/hydroxylation of various aromatic compounds. 

The only investigation so far refers to the second reaction of a two-step industrial process, the Hock process, which is used for phenol production world-wide [64]. 

The Hock process includes the oxidation of cumene by air to hydroperoxides using large bubble columns and the cleavage of the hydroperoxide via acid catalysis, which is reaction [OS 82]. This process is used for the majority of world-wide phenol production and, as a secondary product, also produces large quantities of acetone [64]. Phenol is used, e.g., for large-scale polymer production when reacted in a polycondensation with formaldehyde. 

Cumox [Cumene oxidation] A process for making acetone and phenol by oxidizing cumene, based on the Hock process. This version was further developed and licensed by UOR Three plants were operating in 1986. UOP now licenses the Allied-UOP Phenol process, which combines the best features of Cumox and a related process developed by the Allied Chemical Corporation. 

Oxidation of hydrocarbons with dioxygen is more facile when the C-H bond is activated through aromatic or vinylic groups adjacent to it. The homolytic C-H bond dissociation energy decreases from ca. 100 kcal mol-1 (alkyl C-H) to ca. 85 kcal mol-1 (allylic and benzylic C-H), which makes a number of autoxidation processes feasible. The relative oxidizability is further increased by the presence of alkyl substituents on the benzylic carbon (see Table 4.6). The autoxidation of isopropylbenzene (Hock process, Fig. 4.49) accounts for the majority of the world production of phenol [131] ... 

Alkylation of benzene with propene to isopropylbenzene (cumene), oxidation of cumene to the corresponding tert-hydroperoxide and cleavage to phenol and acetone (Hock process). 

Among these processes, only the Hock process and the toluene oxidation are important industrially. The other processes were discarded for economic reasons. In the Hock process acetone is formed as a by-product. This has not, however, hindered the expansion of this process, because there is a market for acetone. New plants predominantly use the cumene process. More than 95% of the 4,691,000 my (m = metric tonnes) consumed is produced by the cumene peroxidation process. Phenol s consumption growth rate of 3% is primarily based on its use in engineering plastics such as polycarbonates, polyetherimide and poly(phenylene oxide), and epoxy resins for the electronic industry. The Mitsui Company is, for instance, the world s second largest producer of phenol. Japan s production... 

The cumene process, sometimes referred to as the Hock process, was made possible by the discovery of cumyl hydroperoxide and of its cleavage to phenol and acetone [1]. Shortly after World War II the reaction was developed into an industrial process by the Distillers Co. (BP Chemicals) in the United Kingdom and Hercules in the USA. The first commercial plant was started in Montreal, Canada, in 1952 by M.W Kellogg. 

The autoxidation of alkylbenzenes constitutes the industrial route for the production of the corresponding hydroperoxides. The two well-known examples are the production of 1-phenylethyl hydroperoxide in the Shell and ARCO processes for the co-production of styrene and propene oxide, and the production of cumene hydroperoxide for the production of phenol via the Hock process (1,2) A disadvantage of the Hock-process is the co-production of acetone. One possible alternative involves the use of cyclohexylbenzene (CHB) in Scheme 1. 

In the Hock process, cumene [C6H5CH(CH3)2] is first oxidized to produce cumene hydroperoxide [C6HsC(CH3)2C00H], which is then reduced to produce acetone and phenol (C6H50H) or... 

The cleavage of CHP into phenol and acetone was first reported by Hock and Lang [2]. Hence, the cumene oxidation process for the production of phenol and acetone is known as the Hock process. As claimed by Zakoshansky [3], the reaction route was supposedly discovered in parallel in the former USSR. 

Oxidative esterification of arenes with carboxylic acids produces aryl esters, which can be used as precursors to valuable phenol derivatives (Scheme 8.6). Commercial production of phenol involves the aerobic oxidation of cumene to cumene hydroperoxide, followed by conversion to acetone and phenol under acidic conditions (Hock process) [49]. Aerobic acetoxylation of benzene to phenyl acetate provides a potential alternative route to phenol, and Pd-catalyzed methods for this transformation have been the focus of considerable effort. None ofthese methods are yet commercially viable, however. 

Aerobic selective oxidation of alkylaromatics, including cumene (CU), ethylbenzene (EtB), and cyclohexylbenzene (CyB), to the corresponding hydroperoxides (CHPs) represents a key step for several large-scale productions, including the Hock process for the synthesis of phenol (see Chapter 2) [15] and the Shell styrene monomer/propylene oxide (SM/PO) process for the production of propylene oxide (PO) and styrene monomer (SM) [16]. 

Cumene [98-82-8] is the principal constituent of heavy naphtha which is the feedstock for phenol and acetone synthesis by the Hock process. It is also a byproduct in the production of sulfite pulp. 

Moreover, the Hock process offers the opportunity for the synthesis of raw materials that are necessary for the preparation of other phenolics, such as 4,4 -( 1 -methylethylidene)bisphenol. This substance can be synthesized by the reaction of phenol and propanone in the presenee of acids [29], as shown by equation 5. The 4,4 -(l-methylethylidene)bisphenol is an essential reactant for the manu cture of other polymers such as polycarbonates, epoxides and polysulfones. 

Sumitomo Chemical has developed a new process for the manufacture of phloroglucinol which is used in relatively small amounts as a pharmaceutical intermediate. It is based on the oxidative cleavage of 1,3,5-triisopropylbenzene, in a method similar to the Hock process for the production of phenol. 

Hock-process Phenol 6 90-100 - Cumene/ O2 (air) Most important phenol synthesis... 

Phenol production is typically carried out by add induced conversion of cumene hydroperoxide to phenol and acetone (Hock process). Cumene hydroperoxide is obtained by oxidation of cumene. The cumene feedstock for the latter reaction is provided by Friedel-Crafts alkylation of benzene with propene. Alternative routes (chlorobenzene hydrolysis, cydohexanol dehydrogenation, oxidative decarboxylation of benzoic acid) exist but are of much lower industrial relevance. 

The most important source of acetone is the Hock process for phenol production. In this process acetone is obtained as stoichiometric coupling product. If acetone needs to be produced deliberately, it can be obtained by oxidative dehydrogenation or dehydrogenation of isopropanol. Oxidative dehydrogenation proceeds at 400-600 °C at silver or copper contacts, direct dehydrogenation is carried out at 300-400 °C using zinc contacts. Alternatively, acetone can also be obtained by a Wacker-Hoechst oxidation of propylene. Acetone is used industrially as solvent. Moreover, the aldol condensate products of acetone (diacetone alcohol) are used as solvents. Acetone is also converted in an add catalyzed reaction with two moles of phenol for the synthesis of bisphenol A. Bisphenol A is an important feedstock for the production of epoxy resins and polycarbonates. 

Hock process A process used to produce phenol and acetone from cumene (isopropyl benzene). The process first involves using air in the oxidation of cumene liquid to form cumene hydroperoxide ... 

The most common precursor to phenolic resins is phenol. More than 95% of phenol is produced via the cumene process developed by Hock and Lang (Fig. 7.1). Cumene is obtained from the reaction of propylene and benzene through acid-catalyzed alkylation. Oxidation of cumene in air gives rise to cumene hydroperoxide, which decomposes rapidly at elevated temperatures under acidic conditions to form phenol and acetone. A small amount of phenol is also derived from coal. 

Hock Also known as the Hock Lang process, and the cumene peroxidation process. A process for converting isopropyl benzene (cumene) to a mixture of phenol and acetone m-di-isopropyl benzene likewise yields resorcinol, and p-di-isopropyl benzene yields hydro-quinone. The basis of the process is the liquid-phase air oxidation of cumene to cumene hydroperoxide ... 

Invented in Germany during World War II by H. Hock and S. Lang in the course of developing cumene hydroperoxide for initiating the polymerization of butadiene-styrene mixtures. After the war the process was developed by the Distillers Company in England and Allied Chemical Corporation in the United States. Since 1954 this has been the main commercial process for the production of phenol and acetone. By 1987, 97 percent of the phenol made in the United States was produced via this route. In 1990, both resorcinol and hydro-quinone were produced commercially by this route as well. See also Cumox. 

The known reaction product of the oxidation of cyclohexene was assigned as the hydroperoxide 27 by Criegee in 1936. The oxidation of cumene to the hydroperoxide 28 proceeds by a chain mechanism (equations 35, 36), and the conversion of the hydroperoxide by acid to phenol and acetone, in what has become a commercially important process, was reported by Hock and Lang in 1944. 2s... 

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