High pressure carbonylation

High-pressure carbonylation of CpMo(CO)jR yields the very unstable acyls. The acetyl was detected by infrared spectroscopy but not isolated (70), whereas the propionyl decomposes readily to [CpMo(CO)3]2 (172). 

Very recently, Bercaw and co-workers have reported a high yield preparation of 33 via the high pressure carbonylation of (Tj-C5Mes)HfH2 in toluene (72). 

The high-pressure carbonylation of dimeric palladium derivatives 183 (R = Me or cyclopropyl) in ethanol or methanol/ chloroform leads in moderate yields to fused isoindoles 184 as mixtures with their alkoxy derivatives 185, easily separated by flash chromatography (Equation (25) a991JOM371)). 

Since, in many cases the metal esters may be prepared from the metal carbonylate anion and a chloroformate, this reaction scheme enables cationic metal carbonyl compounds to be prepared from a neutral carbonyl compound, without recourse to high-pressure carbonylation, as required in Section A,2. Such a synthetic route is indicated as follows ... 

Complexes containing from one to six carbonyl groups are known and all obey the 18-electron rule. The colorless salt [Tc(CO)6]A1C14 is formed by the reaction of [Tc(CO)5C1] with A1C13 under 300 atm CO pressure and is soluble in THF, acetone, and methanol and stable in aqueous solution (65). The carbonyl halides [Tc(CO)5X] (X = Cl, Br, I) may be prepared by the reaction of the halogen with [Tc2(CO)10]. Reaction with chlorine and bromine occurs readily at room temperature but reaction with iodine is extremely slow. The iodide has been prepared by the high-pressure carbonylation of [Tc(CO)4I]2 (45). An alternative... 

The reaction of [Tc2(CO)io] in CCI4 solution with I2 is extremely slow. Direct action of F on Tc2(CO)io]° at 100 °C in sealed ampules yielded the dimer [Tc2(CO)4lj2 which was converted to Tc(CO)5l]" by high-pressure carbonylation. Ihe diamagnetic, colorless compound absorbs in the IR at 2000, 2024, 2055, and 2146 cm" again in agreement with C4V symmetry [622], lire temperature dependence of the [Tc(CO)5ll vapor pressure was determined [627],... 

Murry first prepared Cp2Ti(CO)2 via the high-pressure carbonylation of Cp2Ti(jjCC5H5)2 (equation 44). The reduction and carbonylation of Cp2TiCl2 to give Cp2Ti(CO)2... 

Analogous high-pressure carbonylations of terminal as well as internal alkynes in the presence of PtH(SnCl3) (PPh3)2 have been describedi. Treatment of phenylacetylene with carbon monoxide in the presence of cobalt(II) chloride, potassium cyanide and nickel(II) cyanide under phase-transfer conditions gave a mixture of the acids 257 and 258, in which... 

Palladium-carbonyl complexes are typically formed from PdX2 (X = Cl, Br, or I) and CO. For example, Pd2(CO)2Cl4 is obtained by high-pressure carbonylation of PdCl2. Similarly, the anionic M[Pd(CO)X3] are obtained from carbonylation of PdX2 or M2(Pd2X6). While the iodide is relatively unstable, the chloride and bromide could be characterized by X-ray crystallography. 

The production of acetic acid by a fermentation process is far too slow and thus too expensive. The first industrial process for synthetic production of acetic acid was based on the liquid-phase oxidation of acetaldehyde. In the 1950s, as the petrochemical industry developed rapidly, the direct liquid phase oxidation of butane and naphtha became the preferred route to acetic acid. Significant amounts of by-products are formed, and complex purification units were needed. Today, the industrially preferred process is the conversion of methanol with CO (catalytic carbonylation). The reaction is exothermic and shows a volume decrease, and thus the equilibrium is favored by low temperatures and high pressures. There are two general technologies for methanol carbonylation, high-pressure carbonylation at 700 bar (BASF) or low-pressure carbonylation at 30 bar (Monsanto, BP). 

Vanadium, Niobium, and Tantalum.—High-pressure carbonylation of [CpNbCy in the presence of Na-Cu-Al affords high yields ca. 90%) of [CpNb(CO)4], and the preparation can be carried out on a large scale ca. 35 g) irradiation of this product in solution in THF affords [CpNb(CO)3(THF)], which is a useful intermediate for the preparation of complexes of the type [CpNb(CO)3L] e.g., reactions with CO and to afford a labelled tetracarbonyl. A study of... 

High-pressure carbonylation of [CpTaCU] in the presence of Na-PhH, followed by treatment of the product with mesityl oxide affords the unusual product (1) whose crystal structure has been determined. Hydrogenation of [Cp Ta( -propene)Cl2] affords [ Cp Ta(H)Cl2 2], which adds CO giving the stabilized formyl complex (2) further reaction with PMcs gives the product (3). ... 

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