Hock reaction

Because the protonation of ozone removes its dipolar nature, the electrophilic chemistry of HOs, a very efficient oxygenating electrophile, has no relevance to conventional ozone chemistry. The superacid-catalyzed reaction of isobutane with ozone giving acetone and methyl alcohol, the aliphatic equivalent of the industrially significant Hock-reaction of cumene, is illustrative. 

Whereas TiCU interacts with the peroxide bridge yielding ethers, SnCl4 promotes a selective displacement of the alkoxide to form peroxides. Heterolysis of an 0-0 bond (Hock reaction) furnishes oxycarbenium ion intermediates via 1,2-shifts (path a), whereas acid-catalyzed C-O ionization affords carbenium ions (path b, Scheme 13). 

Extensive studies have been carried out by Giggins and Pettit and by Vasantasree and Hocking on a range of nickel chromium alloys with up to 50% alloying addition. Generally the principles outlined above can be used to interpret the experimental observations, where the thermodynamics of the reaction are a major factor determining the rate of attack, depending upon whether oxide or sulphide is the stable phase. 

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. 

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. 

Urea-formaldehyde resins can be cured with isopropylbenzene production wastes containing 200 to 300 g/liter of AICI3 as an acid hardener [189]. Isopropylbenzene is formed as an intermediate in the Hock process by a Friedel-Crafts reaction from propene and benzene. The mixture hardens in 45 to 90 minutes and develops an adhesion to rock and metal of 0.19 to 0.28 MPa for 0.2% AICI3 and 0.01 to 0.07 MPa for 0.4% AICI3, respectively. A particular advantage is the increased pot life of the formulation. 

After-reactions such as Hock-Cleavage or dehydration may become predominant at room or higher temperatures. While, for example, hydroperoxide 278 is cleaved to two molecules of cyclohexanone (280) only in the presence of acid,206 photosensitized oxygenation of allo-ocimene (281),220 homoverbenene (286),198 sorbic acid methyl ester... 

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... 

The black trinuclear iron complex Fe3(CO)8(Ph2C2)2> one of two isomers obtained by the reaction of excess tolane with dodecacarbonyl iron, contains not only a heterocyclic iron atom similar to that first observed by Hock and Mills (36) but also has two iron atoms lying symmetrically on either side of the heterocyclic ring (42) in a manner similar to that suggested by the author on theoretical grounds (20) (Fig. 9). 

Kopinke, F.-D., Georgi, A., Mackenzie, K., and Kumke, M. U. (2000). Sorption and chemical reactions of polycyclic aromatic hydrocarbons with dissolved refractory organic subtances and related model compounds. In Refractory Organic Substances (ROS) in the Environment, Frimmel, F. H., Abbt-Braun, G., Heumann, K. G., Hock, B., Ludemann, H.-D., and Spiteller, M., eds., Wiley-VCH, Weinheim, pp. 475-515. 

Following the autoxidation of cyclohexa-1,3-diene and cyclopenta-diene at 15 to 20°, Hock and Depke147 isolated small yields of the cyclic peroxides 147 and 148, respectively. 147 can be obtained in better yields by photosensitized oxidation of cyclohexa-1,3-diene (see Section IV, B) and by the action of hydrogen peroxide and sodium hypochlorite on cyclohexa-1,3-diene154. In the last reaction, oxygen... 

The lability of the carbon-tellurium double bond has frequently thwarted attempts to study both telluraldehydes and telluroketones. Tel-lurocarbonyl compounds stabilized by coordination to transition metals have been known since 1980 [80CC635 83AG(E)314 88JOM161]. However, free telluraldehydes were unknown until 1989 when two different synthetic routes were reported. Erker and Hock trapped tellurobenzalde-hyde (92, R = Ph) generated by reaction of ylide (91) with tellurium powder adduct 93 was obtained in low yield [89AG(E)179]. 

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. 

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