Koch reaction, catalysts

By passing a mixture of carbon monoxide and hydrogen chloride into the aromatic hydrocarbon in the presence of a mixture of cuprous chloride and aluminium chloride which acts as a catalyst (Gattermann - Koch reaction). The mixture of gases probably reacts as the equivalent of the unisolated acid chloride of formic acid (formyl chloride) ... 

Koch Ro- ction. C-6-neoacids are readily available from amyl alcohols by the Koch reaction. Greater than 95% 2,2-dimethylbutyric acid [595-37-9] was obtained from 2-methyl-1-butene at 304 kPa (3 atm) CO and 35°C for 1 h with cupric oxide and sulfuric acid catalyst (31). Likewise,... 

Reduction of Acids. Patents claim catalysts for the hydrogenation of neoacids in the vapor-phase to the neoalcohols in good yields. For example, neopentyl alcohol has been prepared by passing pivaUc acid (obtained by the Koch reaction of isobutylene) over a Cu0/Zn0/Al202 catalyst at... 

Carbonylation, or the Koch reaction, can be represented by the same equation as for hydrocarboxylation. The catalyst is H2SO4. A mixture of C-19 dicarboxyhc acids results due to extensive isomerization of the double bond. Methyl-branched isomers are formed by rearrangement of the intermediate carbonium ions. Reaction of oleic acid with carbon monoxide at 4.6 MPa (45 atm) using 97% sulfuric acid gives an 83% yield of the C-19 dicarboxyhc acid (82). Further optimization of the reaction has been reported along with physical data of the various C-19 dibasic acids produced. The mixture of C-19 acids was found to contain approximately 25% secondary carboxyl and 75% tertiary carboxyl groups. As expected, the tertiary carboxyl was found to be very difficult to esterify (80,83). 

Another formylation reaction, which is named after Gattermann, is the Gatter-mann-Koch reaction. This is the reaction of an aromatic substrate with carbon monoxide and hydrogen chloride (gas) in the presence of a Lewis acid catalyst. Similar to the Gattermann reaction, the electrophilic agent 9 is generated, which then reacts with the aromatic substrate in an electrophilic aromatic substitution reaction to yield the formylated aromatic compound 10 ... 

The decarbonylation of aromatic aldehydes with sulfuric acid" is the reverse of the Gatterman-Koch reaction (11-16). It has been carried out with trialkyl- and trialkoxybenzaldehydes. The reaction takes place by the ordinary arenium ion mechanism the attacking species is H and the leaving group is HCO, which can lose a proton to give CO or combine with OH from the water solvent to give formic acid." Aromatic aldehydes have also been decarbonylated with basic catalysts." When basic catalysts are used, the mechanism is probably similar to the SeI process of 11-38. See also 14-39. 

By in situ MAS NMR spectroscopy, the Koch reaction was also observed upon co-adsorption of butyl alcohols (tert-butyl, isobutyl, and -butyl) and carbon monoxide or of olefins (Ao-butylene and 1-octene), carbon monoxide, and water on HZSM-5 (Ksi/ Ai — 49) under mild conditions (87,88). Under the same conditions, but in the absence of water (89), it was shown that ethylene, isobutylene, and 1-octene undergo the Friedel-Crafts acylation (90) to form unsaturated ketones and stable cyclic five-membered ring carboxonium ions instead of carboxylic acids. Carbonylation of benzene by the direct reaction of benzene and carbon monoxide on solid catalysts was reported by Clingenpeel et al. (91,92). By C MAS NMR spectroscopy, the formation of benzoic acid (178 ppm) and benzaldehyde (206 ppm) was observed on zeolite HY (91), AlC -doped HY (91), and sulfated zirconia (SZA) (92). 

The acid-catalyzed hydrocarboxylation of olefins (the Koch reaction) can be performed in a number of ways.565 In one method, the olefin is treated with carbon monoxide and water at 100 to 350°C and 500 to 1000 atm pressure with a mineral-acid catalyst. However, the reaction can also be performed under milder conditions. If the olefin is first treated with CO and catalyst and then water added, the reaction can be accomplished at 0 to 50°C and 1 to 100 atm. If formic acid is used as the source of both the CO and the water, the reaction can be carried out at room temperature and atmospheric pressure.566 The formic acid procedure is called the Koch-Haaf reaction (the Koch-Haaf reaction can also be applied to alcohols, see 0-103). Nearly all olefins can be hydrocarboxylated by one or more of these procedures. However, conjugated dienes are polymerized instead. 

Another commercial aldehyde synthesis is the catalytic dehydrogenation of primary alcohols at high temperature in the presence of a copper or a copper-chromite catalyst. Although there are several other synthetic processes employed, these tend to be smaller scale reactions. For example, acyl halides can be reduced to the aldehyde (Rosemnund reaction) using a palladium-on-barium sulfate catalyst. Formylation of aryl compounds, similar to hydrofomiylation, using HCN and HQ (Gatterman reaction) or carbon monoxide and HQ (Gatterman-Koch reaction) can be used to produce aromatic aldehydes. 

Koch Reacdon. C-6-neoacids are readily available from amji alcohols by the Koch reaction. Greater than 95% 2,2-dimethylbutyric acid [595-37-9] was obtained from 2-meth5i-1-butene at 304 kPa (3 atm) CO and 35°C for 1 h with cupric oxide and sulfuric acid catalyst (31). Likewise, 2,2-dimethylbutyric acid can be obtained in high yidd (75—80%) from 1- or 2-pentanol or neopentyl alcohol from the Koch-Haaf reaction (32,33). tert-Amy. alcohol gives a mixture of trimethyl acetic acid [75-98-9] (pivalic acid), 2,2-dimeth5ibutyric acid, C-7 acids, and C-11 acids under similar Koch-Haaf conditions (33). 

Thermodynamics can also be usefully employed in analyzing the role of a catalyst in organic synthesis. A typical example is the Gatterman-Koch reaction. 

A particularly misleading situation can occur when a reaction product forms a complex with the catalytic material. Thus the Gatterman-Koch reaction of benzene and carbon monoxide to produce benzaldehyde is thermodynamically unfavourable, but reaction proceeds under pressure in the presence of at least 1 mole AlCls/mole benzene. However, the benzaldehyde-AICI3 complex formed must be cleaved chemically, with water for example, to liberate the product. Surprisingly, the similar conversion of toluene to p-tolualdehyde (p-methylbenzaldehyde) is favourable, and separation from the catalyst system can be achieved by simple distillation workers with Mitsubishi in Japan have used BFa/HF. ... 

Other acid-catalysed addition reactions include reaction with nitriles (Ritter reaction), formaldehyde (Prins reaction) and carbon monoxide and water (Koch reaction). These reactions are normally catalysed by concentrated sulphuric acid. Extensive isomerization occurs and may even lead to quaternary compounds of the type RC(CH3)XR where X is the new functional group introduced into the molecule. Homogeneous catalysts have been developed which give simpler products without extensive isomerization. 

Koch reaction, which is promoted by AICI3 [210]. Activated aryl chlorides can also give the corresponding carbonylated products in low to moderate yields in ionic liquids using Pd-benzothiazole carbine as a catalyst under atmospheric pressure of CO at 140 °C [211]. 

Carboxylation of Alkanes and Alkenes. When alkenes react with carbon monoxide and water in the presence of strong mineral acids at elevated temperature and pressure, carboxylic acids are formed (87,88). The transformation is called the Koch reaction and may also be considered as hydrocarboxylation (eq. 61). Neocarboxylic acids with high selectivities are manufactured industrially with this process applying mixed Bronsted and Lewis acid catalysts (H2SO4, H3PO4, HF, and SbFg, BFg). 

Improvements in the Koch reaction were achieved by applying superacid systems as the acid catalyst (63). Triflic acid is especially useful because of its high acidity and the higher solubility of CO. Under superacidic conditions using HF-SbFs, alcohols, preferably secondary and tertiaiy alcohols, can be substituted for alkenes. Moreover, CO can react with monosubstituted methanes (methyl alcohol, dimethyl ether, methyl halides) to yield acetic acid or its derivatives. 

Carbonylation with Acid Catalysts Koch Reaction... 

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