The alkyl iodide produced depends on the nature of the groups. If one group is

Me and the other a primary or secondary alkyl group, it is methyl iodide which is produced. This can be explained on the assumption that the mechanism is , and because of the steric effect of the larger group, attacks the smaller methyl group. When the substrate is a methyl ‐alkyl ether, the products are t ‐ RI and MeOH. This can be explained by an mechanism, the carbonium ion produced being the since tertiary carbonium ion is more stable than a primary or secondary carbonium ion.