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 methyl," methyl fluorosulfonate.

Part of being a grown-up, though, is settling down with an alkylating agent, and aside from the odd dirty weekend with some of the more exotic compounds, it's trialkyloxonium salts for me:

i-9bc6b8f3355bc7f3ac7b2af023bff6e5-trimethyloxonium.png

We used to have coffee together in the morning, but the methanol got to me...

Tags

More like this

Methyl iodide is another simple organoiodide: 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…
In my earlier post, I described the feeling I had as I started my graduate training in chemistry that there was a huge pile of knowledge I would need to acquire to make the transition from science student to grown-up scientist. I should make it clear (in response to JSinger's comment that I seemed…
One of the interesting developments within the tribe of science is the way that blogs, email lists, and things of that ilk have made public (or at least, more public) conversations within a field that used to happen only in private. The discussions of Aetogate on the VRTPALEO list are just one…
It's time for Dr. Free-Ride to have a chat with the grown-ups. If you're a kid and you're reading this, think how much the adults in your life would appreciate it if you got up from the computer and put away your stuff that needs putting away (or played with your brother or sister nicely, or…

You know, given the hazards inherent in methylating agents, I do believe you missed a chance at a primo Tarantino reference -- "when you absolutely, positively have to methylate every mofo in the room."

there is a lovely method for making triethyloxonium tetrafluoroborate in Org Syn. You just mix together BF3 etherate, dry ether and epichlorohydrin. The stuff crashes out. I did it on a 50g scale.

You get trimethyl oxonium from triethyloxhonium just by blowing dimethylether gas stream over it. The alkyls exchange, bitches...

What? No methyl lithium?