1. moleculeoftheday
  2. Methyl Iodide (Makin' methyls)

Methyl Iodide (Makin' methyls)

By moleculeoftheday on October 31, 2006.

Methyl iodide is another simple organoiodide:

Methyl Iodide: InChI=1/CH3I/c1-2/h1H3

Probably the most common lab use is tacking a methyl group onto something; MeI is a great substrate for the SN2 reaction.

Despite its ubiquity, methyl iodide isn't nearly the best alkylating agent. It's cheap and simple, so it sees a lot of use, but there are many things that are better, such as dimethyl sulfate (used a lot industrially, from what I've read), methyl triflate (PDF) (toxic and great), trimethyloxonium salts (my favorite), and the so-called "magic methyl," methyl fluorosulfonate, which has a pretty good vapor pressure (being volatile and such a good methylating agent, magic methyl methylates you,). The latter has been banned in a lot of universities (which is saying a lot, considering how the toxic stuff gets a by in academia).

Tags
Synthesis

More like this

Trimethyloxonium salts (When it absolutely, positively, must be methylated)
When you take organic chemistry, you learn about methyl iodide for putting on a methyl group. Eventually, though, if you stick with chemistry, you need an alkylating agent for grown-ups. There's a lot of good ones, including dimethyl sulfate, methyl triflate (PDF), and the ever-so-toxic "magic…
EPA approves methyl iodide use. No surprise.
Fumigating the soil before planting pretty much kills any pests that might be in it. Unfortunately the fumigant tends to seep up through the soil and expose workers and others nearby. When the highly toxic fumigant methyl bromide was banned under the Montreal protocol as a greenhouse gas an ozone…
Naturopaths: Able to turn even Epsom salt potentially deadly
Naturopathy and naturopaths are a fairly frequent topic on this blog—and for very good reason. If there is an example of a pseudomedical "discipline" that has been gaining undeserved "respectability," it's naturopathy. It's licensed in all too many states, and physicians who have fallen under the…
What Do You Need to Make Cold Atoms? Part 3: Test and Measurement
The third category in our look at lab apparatus, after vacuum hardware and lasers and optics is the huge collection of electronic gear that we use to control the experiments. I'll borrow the sales term "test and measurement" as a catch-all description, though this is really broader than what you'll…

MeI as Molecule of the Day? Feh. At least mention the tuft of copper Brillo in the bottle.

There's icilin, [1.1.1]propellane, helicenes, twistane and its ridiculously large optical rotation absent any chromophores, boromycin, bullvalene and its two-step synthesis, superphane, triquinacene and its non-olefinic properties, tetracyclones plus diaryl acetylenes [4+2] into chicken wire (when was the last time you did a condensed phase reaction at near red heat?), cruise missile fuel, Phil Eaton's momma in the hospital setting up the synthesis of cubane... and you did methyl iodide? Feh.