Hock synthesis

Nowadays, synthetic vanUlm is obtained predominantly from petrochemical sources. For vanillin, the key compound is guaiacol (o-methoxyphenol). This is obtained initially from wood tar, coal tar, wood distillate or lignite distillate. Targeted syntheses start from benzene via dichlorobenzene, catechol may be obtained, which is further monomethylated. The second route begins with the oxidation of cumene (the so called Hock synthesis ) to give phenol, and continues with nitration, methylation, reduction, diazotisation and heating of the diazonium salt solution. [142]... 

With the availability of relatively inexpensive phenol from the Hock synthesis by cumene oxidation, it has also become economical to produce aniline by gas-phase ammonolysis (400 °C, 200 bar) of phenol. 

Zooker-process Bisphenol A atmos. 50-90 HCl Phenol/ acetone Both reaction components can be produced by Hock synthesis... 

American Cyanamid operated a plant with a capacity of 14,000 tpa 2-naphthol, for some years prior to 1982 for the oxidation of 2-isopropylnaphthalene. 2-Iso-propylnaphthalene can be obtained from propylene and naphthalene at 150 to 240 °C and 10 bar with a phosphoric acid catalyst using a large excess of naphthalene, followed by isomerization to a mixture of 1- and 2-isopropylnaphthalenes (5 95). The introduction of air (oxygen) at 110 °C produces the a-hydroperoxide of the 2-isomer. The hydroperoxide is cleaved with sulfuric acid, in a manner analogous to the Hock synthesis of phenol the 2-naphthol yield is around 95%. 

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. 

Acetophenone can be hydrogenated catalytically to 1-phenylethanol. It is obtained as a byproduct in the Hock phenol synthesis and is purified from the high-boiling residue by distillation. The quantitites obtained from this source satisfy the present demand. 

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]. 

A brief screen of potential radical mediators revealed that most oxidants facilitated the tosyl group elimination (Table 4). However, two lead reagents were identified, azobisisobutyronitrile (AIBN) and cumene hydroperoxide (CHP), both of which delivered the product in >80% solution yield, while minimizing over-oxidation. Ultimately, CHP was selected due to its commercial availability and ease of handling—CHP is used in the commercial synthesis of acetone and phenol (via the Hock rearrangement)." ... 

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. 

T. Fey, M. Holscher, H. Keul, H. Hocke, Alternating poly(ester am-ide)s from succinic anhydride and a, co-amino alcohols synthesis and thermal characterization, Polym. Int. 52 (2003) 1625-1632. 

One of the important processes in the petrochemical industry is the production of phenol. Phenol is an important raw material for the synthesis of petrochemicals, agrochemicals, and plastics. Examples of employment of phenol as an intermediate are production of bisphenol A, phenolic resins, caprolactam, alkyl phenols, aniline, and other useful chemicals. Current worldwide capacity for phenol production is nearly 7 milUon metric tons per year. More than the 95% of phenol is produced by the common industrial process known as Hock or cumene process involving three successive reaction steps ... 

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. 

Cumene gained particular technical importance following the discovery of the phenol synthesis via the oxidation of cumene by Heinrich Hock and Shon Lang in Clausthal/Germany in 1944. Cumene had already been obtained by Cornelius Radziewanowski in 1895, by reaction of benzene and isopropyl chloride in the presence of aluminum filings and dry hydrogen chloride. A 66 % yield was... 

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

Cumene hydroperoxide is produced in the second step of the Hock method in the form of 35 weight % solution. The necessary concentration of the CHP solution to 80 weight % is a potentially hazardous operation as generally is the production and handling of peroxides. Therefore, a better solution is starting the process of the BPA production directly from the synthesis of CHP from cumene, followed by direct use of so obtained CHP for the reaction with phenol [70]. Thus, a one pot synthesis of BPA from CHP and phenol, carried out at 100 C, in the presence of 20 weight % of dodecatungstenophosphoric acid supported on acidic montmoril-lonite clay (K-10), and without the CHP separation, was successfully tested. 

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. 

Weare WW, Schrock RR, Hock AS, Muller P. Synthesis of molybdenum complexes that contain hybrid triamidoamine ligands, [(hexaisopropylterphenyl-NCH2CH2)2 NCH2CH2N-aryl], and studies relevant to catalytic reduction of dinitrogen. Inorg Chem. 2006 45 9185-9196. 

Phenol is one of the most important intermediates of the chemical industry. The global capacity for its production was around 10 Mt/y in 2008, with an actual production around 8.7 Mt. About 40% of the produced phenol is used for the synthesis of bisphenol A, a monomer for polycarbonates. Another 30% is consumed in the production of phenolic resins. The most important route for the industrial production of phenol is, by far, the cumene process, which accounts for 98% of the installed capacity. The cumene process is based upon the researches of Heinrich Hock on the... 

Two carbonyl fragments could also be formed on acid-catalyzed hydrolysis of the aUyhc hydroperoxides that mostly proceeds through Hock-type fragmentation. AUyHc alcohols obtained by reduction of the corresponding allylic hydroperoxides are versatile building blocks with diverse synthetic utility they could also be either regioselectively dehydrated to l,3-dienes or oxidized to a,P-unsaturated ketones. The ene-reaction was also utilized in the synthesis of some natural products and diastereoselective allene derivatives. ... 

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