[nate]

When studying SN2 and SN1 reactions, I was asked about iodomethane.  The question was posed as "Iodomethane appear like a harmless molecule, but is really dangerous.  Why"

I have looked all though the textbook and can find no direct answer.  Can someone help me please?

Thanks

[Albert]

In my opinion, CH3I is dangerous because I- is an excellent group, when it comes to SN2 and SN1 reactions: this gives you the opportunity to do many SN-reactions. i.e. :

CH₃I +  CH₃COO- -> CH_COOCCH₃  + I-


SN-reactions result extremely fast (depending on the reagent), uncontrollable and exotermic.

[Donaldson Tan]

iodine is a good leaving group. it makes the carbon atom of iodomethane very susceptible to nucleophillic attack.

[nate]

Thanks to both of you.  That is the line of thinking that I was taking, but couldn't find anything to support it in my textbook.  I knew that Iodide was a great leaving group and just thought that it would result in fast and uncontrollable reactions.

Thanks

[movies]

In my opinion, CH3I is dangerous because I- is an excellent group, when it comes to SN2 and SN1 reactions: this gives you the opportunity to do many SN-reactions.

MeI is very good for S_N2 reactions but very poor for S_N1 reactions!  Think about the intermediate: methyl cation is very unstable.

[alphahydroxy]

Just a further point to add:

Many things will undergo rapid reactions, and therefore be inherently dangerous, but methyl iodide is toxic and carcinogenic.

The reason for this stems directly from its susceptiblity to SN2 attack by nucleophiles, and is the same reason for a large number of potent electrophiles also being toxic and carcinogenic, namely the fact that it will readily alkylate your DNA causing mutations and all sorts of nasty things in your body.

Something to bear in mind when using it....