Verfahren zur Herstellung von ª‡-Naphthylessigsaeure und deren Estern

a -Naphthylacetic acid is manufactured by heating monochloroacetic acid or the anhydride or an ester thereof with naphthalene in the presence of a metallic chloride catalyst, preferably ferric chloride or a body capable of liberating ferric chloride under the reaction conditions. The reactants may be refluxed until the calculated amount of hydrochloric acid is liberated from the reaction mixture. Elevated pressure and higher temperature enable the duration of the reaction to be reduced or the vaporous reaction mixture may be passed over the catalyst. The catalyst may be supported on silica gel, active carbon, pumice stone or similar carriers and should be finely powdered when operating in solution or crushed in vapour phase operation. a -Naphthylacetic acid is obtained from the reaction product by extraction of the solution obtained, tarry impurities being precipitated by suitable adjustment of the pH before the a -naphthyl acetic acid. In an example monochloroacetic acid, naphthalene and anhydrous ferric chloride are refluxed. The reaction products are extracted with dilute caustic soda solution and the resulting solution is acidified in two stages with hydrochloric acid, the second precipitate being the desired product.