Re: ORGLIST: TLC help - monitoring a reaction

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From: will jones (willjones46$##$hotmail.com)
Date: Sat Feb 03 2007 - 14:17:17 EST


Ken,

As it is volatile, your best bet is GC. If you can't detect it, then you
need to change your column conditions. What I've done before in the past is
inject onto a column that is r.t and then ramp up the temperature to make
sure everything comes off. The methyl methacrylate will currently be coming
off with the solvent.

Depending on your resources, and what you are making as an end product, you
could monitor the reaction in an NMR vial. Assuming that you are reacting
the double bond, you could monitor the dissappearance of the vinylic
protons.

Personally, I'd go for the GC method. One thing you have to learn is that if
you cant see the reaction going on, you are flying blind and dont have a cat
in hell's chance of knowing how when the reaction is 'complete'.

Will

>From: "Ken Knott" <esprcorn$##$hotmail.com>
>To: everybody$##$orglist.net
>Subject: ORGLIST: TLC help - monitoring a reaction
>Date: Fri, 02 Feb 2007 00:16:09 -0500
>
>Ok, easy one again for ya guys...
>
>Again, I'm a 1st year grad student so I'm still struggling with some of the
>basics...
>
>I'm running a reaction where I'm supposed to monitor the disappearance of
>the starting material (methyl methacrylate) by TLC. I'm using a reaction
>scheme/protocol from another paper. But methy methacrylate appears to be
>very limitedly UV active and very volatile. So I can't really see the spot
>and even if I could it evaporates before it can elute. I think...
>
>Before realizing this I tried monitoring on GC in the lab, but I didn't get
>anything.. Again, likely due to the volatility of methyl methacrylate....
>
>Is there another way I can monitor the consumption of the methyl
>methacrylate? Or will I have to settle for monitoring the product
>possibly?
> Or just give it 24 hours and work it up crossing my fingers?
>
>In the paper where I got the reaction, their substrates are all UV active
>and non-volatile so this was not an issue for them.
>
>This is fun stuff... but I'm stumped...
>
>Thanks!!
>
>Ken
>
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