[2938-72-9] · C2H6AlI · Dimethylaluminum Iodide · (MW 183.96)
(methylating agent; catalyst)
Alternate Name: dimethyliodoaluminum.
Physical Data: bp 111 °C/50 mmHg.1
Solubility: sol toluene, benzene.
Form Supplied in: must be prepared.2
Handling, Storage, and Precautions: although little is reported in general compilations of safety, normal precautions should prevail. Assume that this reagent behaves like Diethylaluminum Iodide: moisture-sensitive and pyrophoric. Reacts with water to form an explosive and flammable gas. Extremely harmful if vapors are inhaled. The reagent is absorbed through skin. Wear gloves. Corrosive. Air-sensitive; must be stored under inert atmosphere. Use in a fume hood.
When Me2AlI is used to deliver a methyl group to a carbonyl, there appears to be a powerful solvent effect that directs attack on cyclohexanones (eq 1).2 Although the reaction specificity is notable, the reaction is of minimal value because most starting material is recovered, often in the range of 90%.
A preference was also noted for 1,4-attack over 1,2-attack (eq 2). As comparison, reaction with Trimethylaluminum gave exclusive 1,2-attack.
Bradford P. Mundy
Colby College, Waterville, ME, USA