Carbonylation of benzene to benzaldehyde

Carbonylation of benzene to benzaldehyde has been achieved with IrBr(CO) (dppe) (dppe-Ph PCH CH PPh ),... 

Carbonylation of benzene to benzaldehyde has been studied in different acidic ionic liquids of the type [C4mim]X—AICI3 (X = Cl or Br), resulting in high selectivities (96%) towards... 

Carbonylation of benzene to benzaldehyde is also catalyzed by Rh(Ir)Cl(CO)(PPh2)2, RhH(CO)(PPh2)3 as well as IrH3(CO)(dppe) or IrH(CO)2dppe [66]. In each case the formation of a square planar 16 VE intermediate M(X)LL 2, as the active catalytic species was proved or made probable. 

Activation of benzene occurs in THF solution when [RhCl(CO)(PMe3)2] is photolysed at 233K. The two cis- hydridophenyl products eliminate benzene at room temperature and the kinetics of this step have been investigated. In a related study the same intermediates were also observed in the photochemical carbonylation of benzene to benzaldehyde catalysed by [RhCl(CO)(PMe3)2]. ... 

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). 

Several examples of transition metal-catalyzed insertions of carbon monoxide and isocyanide into the C-H bond are known. The carbonylation of a C-H bond to an aldehyde requires photoirradiation conditions. Eisenberg et al. have found iridium-[45,46] or rhodium-catalyzed [47] photocarbonylation of benzene affording benzaldehyde, albeit with low efficiency [45-47]. They have also reported the photochemical carbonylation of benzene catalyzed by ruthenium(O) complexes [48]. 

After the initial spate of discoveries of C-H oxidative addition of (het-ero)arenes, attempts were made to extend the methodology to catalytic carbonylation of (hetero)arenes and alkanes. Pioneering work by Eisenberg for the first time allowed the photochemical carbonylation of benzene 6 to be performed using [IrH3(dppe)(CO)] 54 complex (Scheme 13). C-H bond activation of benzene 6 followed by insertion of CO led to the formation of benzaldehyde 55. 

Complexes of rhodium, iridium and ruthenium have also been used as homogeneous catalysts in the photochemical carbonylation of benzene and other reactions that involve C-H bond cleavage in hydrocarbons. It has been found that long-term continuous photolysis of benzene solutions containing CO and one of the rhodium or iridium complexes RhCl(CO)(PPh3)2, RhH(CO)(PPh3)3, or IrCl(CO)(PPh3)2 leads to the formation of benzaldehyde ... 

Acidic ILs promote the benzaldehyde formation by direct carbonylation of benzene [106]. Up to 91% yield with 96% benzaldehyde selectivity was obtained with BMI-Br/AlCl3 IL. Under similar reaction conditions, using AICI3 alone as Lewis acid catalyst, benzaldehyde is formed in much lower yields (Table 6.4). 

The carbonyl group reactivities in thiophenes and benzenes are very similar, as shown by the similar rates of alkaline hydrolysis of esters and by the great similarity of the thiophenealdehydes to benzaldehyde in numerous carbonyl group reactions. This has been ascribed to the counteracting —I- -M effects of the thienyl group in this kind of reactions. ... 

Mediated by Tin. In 1983, Nokami et al. observed an acceleration of the reaction rate during the allylation of carbonyl compounds with diallyltin dibromide in ether through the addition of water to the reaction mixture.74 In one case, by the use of a 1 1 mixture of ether/water as solvent, benzaldehyde was allylated in 75% yield in 1.5 h, while the same reaction gave only less than 50% yield in a variety of other organic solvents such as ether, benzene, or ethyl acetate, even after a reaction time of 10 h. The reaction was equally successful with a combination of allyl bromide, tin metal, and a catalytic amount of hydrobromic acid. In the latter case, the addition of metallic aluminum powder or foil to the reaction mixture dramatically improved the yield of the product. The use of allyl chloride for such a reaction,... 

In the present paper we have studied four acid catalyzed reaotions involving carbonyl compounds alkylation of benzene with formaldehyde, esterification of phenylacetic acid, Friedel-Crafts acylation by phenylpropanoyl chloride, and the cross aldolic condensation of acetophenone with benzaldehyde in the presence of three Hp zeolites with different framework Si-to-Al... 

Initial studies of solvent effects, on the reactions of triarylarsonium benzoylylides with p-nitrobenzaldehyde in N, A-dimethylformamide, dimethyl sulphoxide or methanol, indicated little solvent effect in these cases" ", but later studies of the more finely balanced reactions of semi-stabilized ylides have provided examples of strong influences due to the effect of different base and solvent when the ylide is generated in the presence of a carbonyl compound ". Thus, when benzyltriphenylarsonium bromide or p-chloroben-zyltriphenylarsonium bromide were treated with sodium hydride in benzene in the presence of a variety of p-substituted benzaldehydes the products were alkenes, but if sodium ethoxide in ethanol was used the isolated products were epoxides ". Likewise, when triphenylarsonium benzylylide was generated by phenyllithium in the presence of either benzaldehyde or acetaldehyde, the preponderant product was the epoxide whereas use of sodium amide as base provided mostly the alkene . Similar results were obtained when an allyltriphenylarsonium salt was deprotonated using different hexamethyldisilaz-... 

This azide, prepared by adding a solution of n-butyl bromide to a slurry of of sodium azide in water, cleaves ketones of the type ArCOCHjR in benzene or nitrobenzene at 70-90° in the presence of a catalytic amount of sulfuric acid to two carbonyl components. Acetophenone gives benzaldehyde (80%) and formaldehyde (83%) propiophenone gives benzaldehyde and acetaldehyde. The reaction is interpreted as involving combination of the azide with the coiyugate acid of the ketone, release of nitrogen from the diazonium cation with elimination of water, hydration, and cleavage. 

Carbon-13 shifts, measured by the double-resonance technique, of the carbonyl group of weto-substituted benzaldehydes correlate with Hammetts parameter. In the case of the para-substituted benzaldehydes, there was no correlation between the chemical shift and a, presumably because, in contrast to substituted benzenes, resonance contributions for both electron-attracting and releasing groups will not significantly affect the electron density at the carbonyl carbon. 

It has also been shown that H-Y or AlCls-doped H-Y zeolite can be used for benzene carbonylation to produce either benzoic acid or benzaldehyde (99). No quantitative data on selectivity and conversion of benzene in carbonylation products are given. 

The carbonylation of methane is catalyzed by RhCl(P(CH3)3)3 under irradiation to yield acetaldehyde (eq. (49)) (11). The utilization of dense CO2 as a stable and CH4-miscible reaction medium is the key to accomplish the reaction. The reaction presumably proceeds via the oxidative addition of the C—H bond to the rhodium center. The C—H oxidative addition product obtained from RhCl(P(CH3)3)3 and benzene was successfully isolated, and the structure was unambiguously determined by X-ray analysis (compound B, eq. (50) (76). The resulting complex is a (phenyl)(hydrido)rhodium complex, as expected and gave benzene and benzaldehyde upon treating with CO. 

Similar trinuclear carbonyl hydride cluster, Os3(CO)xq (m-H)2 (compound 1.4), catalyzes the oxidation of cyclooctane to cyclooctyl hydroperoxide by hydrogen peroxide in acetonitrile solution [12]. Selectivity parameters obtained in oxidations of various linear and branched alkanes as well as kinetic features of the reaction indicated that the alkane oxidation occurs with the participation of hydroxyl radicals. A similar mechanism operates in the transformation of benzene into phenol and styrene into benzaldehyde. The system also oxidizes 1-phenylethanol to acetophenone. The kinetic study... 

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