| 摘要 |
Carboxylic acids, halides, anhydrides or esters thereof are prepared by reacting an olefin, optionally substituted by halogen, alkoxy or ester groups, with carbon monoxide in a substantially non-aqueous liquid medium and in the presence of a halide or p -complex of palladium, rhodium or ruthenium, said p -complex being derived from the halide of the metal and the olefin reactant, and optionally hydrolysing the resultant halide, anhydride or ester to the corresponding acid. Numerous olefin starting materials are specified, a preferred class being those containing allyl groups. In general, the reaction yields acid halides and anhydrides, but if the olefin reactant contains an ether linkage the initial product is an ester. The reaction product may contain halogen substituents orginating from the metal halide catalyst. The p -complex may be formed in situ from the metal halide and olefin reactant. The catalyst can be used to stoichiometric or greater quantities, but may also be employed in small amounts in combination with an oxidizing agent, e.g. HCl, O2, combined with a redox system, e.g. copper chloride, in order to regenerate any precious metal which is reduced. The reaction rate may be enhanced by the addition of other metal compounds, e.g. the carboxylates of alkali and alkaline earth metals, Cu, Fe, Al, Ba, Zn and Cd. Also alkali and/or alkaline earth metal halides may be used to increase the polarity of the reaction medium. A large number of substances are specified as suitable reaction media. The reaction may be effected within wide ranges of temperature and pressure, e.g. -80 DEG to 800 DEG C., 0.1 to 250 atmos. The carbon monoxide may be diluted with an inert gas, e.g. N2, CH4. Examples describe the preparation of acrylic acid, b -chloropropionic acid, 4,4,4-trichlorobutyric, b -chlorobutyric acid, b -dichloropropionic acid, b -chloroacrylic acid, vinylacetic acid, isopropenyl acetic acid, 3-pentenic acid, acetic anhydride, vinylacetic anhydride, 3-cyclohexene carboxylic acid and 3-cyclooctene carboxylic acid chloride. The p -complexes of Pd, Rh and Ru may be prepared in situ by reaction between the Pd, Rh or Ru chlorides and the olefin reactant. Alternatively, the complexes may be made in a separate step by reaction of the olefinic compound and a compound of the precious metal or the activated metal itself. Specified complexes are bis-(p -allylpalladium chloride), bis - (p - allylpalladium bromide), acetylacetonato - (allyl) palladium, bis - (p - isobutenylpalladium chloride), bis-(p -crotylpalladium chloride), bis - (p - crotylpalladium bromide), bis - (p - cyclohexenylpalladium chloride), bis - (p - 4 - chlorocrotylpalladium chloride), bis - (p - 2 - methyl - 4 - chlorocrotylpalladium chloride), p - allylcarbonylpalladium chloride, p - isobutenylcarbonylpalladium chloride, ethylenepalladium chloride and ethylenerhodium chloride. |
