| abstract |
The invention relates to a process for preparing trialkylgallium compounds of the general formula R 3 Ga. The process is based on the reaction of gallium trichloride (GaCh), optionally in a mixture with partially alkylated products, with an alkylaluminium compound of the type R a AICI b (where R = C 1 -C 5 -alkyl, a = 1, 2 or 3, b = 0, 1 or 2 and a + b = 3) in the presence of at least two alkali metal halides (e.g. NaCI and KCI) as auxiliary base. Preference is given to using alkylaluminium sesquichloride (R 3 AI 2 CI 3 ) or trialkylaluminium (R 3 AI). The reaction mixture is heated to a temperature in the range from 120°C to 250°C and the trialkylgallium compound formed is separated off via a separator which is operated at a temperature which is more than 30°C below the boiling point of the most volatile partially alkylated product. Complete alkylation is achieved here and partially alkylated products are recirculated to the reaction mixture. In a further step, the reaction mixture can be heated to a maximum of 350°C and the remaining fully alkylated and partially alkylated products can be separated off. The process provides a high yield of trialkylgallium compound and displays high gallium utilization; the products are used, e.g., as precursors for MOCVD processes. |