CH2I?

[Sina Rahmani 4A]

why is CH2I called Iodomethyl? I thought CH3I would be Iodomethyl. Thanks!

[Chem_Mod]

CH3I is iodomethane, but CH2I invokes that it is a substituent, so it would be an iodomethyl group just like like the difference between methane (CH4) and methyl as a substituent (CH3).

[Jasmeet Dhaliwal 3E]

CH2I is called iodomethyl because the whole molecule is a substituent, but within this molecule, iodine is also acting as a substituent; it's a case of a substituent within a substituent. If we were to consider CH3I, carbon already forms four bonds. It would not be able to bond to another atom, and thus it could not be a substituent. CH3I is called iodomethane for this reason.