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    Improvements in the production of carboxylic acid esters
    28.
    发明专利
    Improvements in the production of carboxylic acid esters 未知

    公开(公告)号：GB828876A

    公开(公告)日：1960-02-24

    申请号：GB1612258

    申请日：1958-05-20

    Applicant: BASF AG

    Inventor： KROEPER HUGO ,  WIRTH FRIEDRICH ,  HUCHLER OTTO

    IPC: C07C51/10

    Abstract: The invention comprises a process for the preparation of m-phthalic acid and terephthalic acid esters by reacting a dihalogen benzene, a mono halogenated benzoic acid or a mono-halogenated benzoic acid ester with an alkali alcoholate, in an anhydrous medium in the presence of carbon monoxide at elevated temperature and increased pressure. Starting materials specified are m- and p-dibrombenzene, m- and p-dichlorobenzene and m- and p-chlorobenzoic acid or its esters. The alcoholates of sodium or potassium are preferably employed, especially those derived from e.g. methanol, ethanol, or propanol. The reactants may be present in stoichiometrical proportions, or either of the two reactants may be present in slight excess, e.g. up to 0.1 mol. Solvents such as benzene, gasoline or the alcohol corresponding to the alcoholate, may be used, provided that they are anhydrous. A catalyst such as metal carbonyls, e.g. the carbonyls of nickel, cobalt, iron, molybdenum, chromium, or metal carbonyl hydrides, e.g. cobalt carbonyl hydride or complex metal carbonyl compounds such as Fe(CO)4Br2, R3P2N1(CO)2 or R3PN1(CO3), where R represents a hydrocarbon radical, e.g. alkyl or aryl. The metal carbonyl compounds may be added as such or formed from their components during the reaction, e.g. by adding the carbonyl forming metals in a fine dispersion to the reaction mixture. It is preferable to use those compounds of carbonyl-forming metals which are soluble in the reaction medium, e.g. the acetates, formates, acetylacetonates, acetylacetates of nickel. The metals may be added to the initial materials in amounts of 0.1 to 3% by weight, with reference to the content of carbonyl-forming metal. The reaction may be carried out at 100-400 DEG C. at 5-700 atmospheres of carbon monoxide, and may be batchwise or continuous. If the necessary pressure for the reaction cannot be set up by heat alone in a closed vessel, further carbon monoxide or an inert gas such as nitrogen may be forced into the apparatus. Examples are given of the preparation of dimethyl terephthalate, together with some free terephthalic acid as a by-product, from p-dichlorbenzene and sodium methylate.

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