Magnesium organometallics at -78°C react with alkanoyl halides to form ketones. It is necessary to work at a low temperature to avoid adding a second equivalent of organometallic, in which case the product obtained would be an alcohol.
![reaction-alkanoyl-organometallic-halides reaccion-haluros-alcanoilo-organometalicos](/images/stories/organica-ii/haluros-alcanoilo/organometalicos/reaccion-haluros-alcanoilo-organometalicos-01.png)
The mechanism occurs in two stages:
Stage 1. Addition of the organometallic to the halide
![reaction-alkanoyl-organometallic-halides reaccion-haluros-alcanoilo-organometalicos](/images/stories/organica-ii/haluros-alcanoilo/organometalicos/reaccion-haluros-alcanoilo-organometalicos-02.png)
Stage 2. Elimination
![reaction-alkanoyl-organometallic-halides reaccion-haluros-alcanoilo-organometalicos](/images/stories/organica-ii/haluros-alcanoilo/organometalicos/reaccion-haluros-alcanoilo-organometalicos-03.png)
Cuprates also react with alkanoyl halides to form a ketone. Its lower reactivity allows it to work at room temperature.
![reaction-alkanoyl-organometallic-halides reaccion-haluros-alcanoilo-organometalicos](/images/stories/organica-ii/haluros-alcanoilo/organometalicos/reaccion-haluros-alcanoilo-organometalicos-04.png)