Problem with phenol
myagi at u.washington.edu
Tue Jun 20 11:58:12 EST 1995
You REALLY DON'T want to do this at home. The best thing to do would be
an old organic chemist to show you how. S/he is probably also the only
person around who would have the glassware and equipment you need.
Basically you need :a heating mantle, a round-bottom distilling flask with
at least 2 necks (one for the thermometer and another for the condenser),
a condenser (at least that's what we called it: a glass tube inside
another glass tube that had inlet and outlet nipples for cooling air),
and a bunch of bottles for collecting your distilled stuff.
Keep in mind that some of the crud that's in crummy phenol is EXPLOSIVE.
So work in a good chemical hood and BE CAREFUL. Melt your crystalline
phenol in a hot water bath with some water and put it into the
roundbottom flask. Put the flask in the heating mantle (set fairly low)
and heat gently. Fit a thermometer into the top neck (if it's part of
the distillation set it should fit firmly), and the condenser into the
side neck, and watch. The water will distill off at 100o; dump it. Now
watch more carefully. The temperature should go steadily up to 160o. If
anything else distills off before you get there, collect it and discard
in organic chemical waste. The pure phenol will start coming off when
you reach 160o. Collect this stuff into bottles (we used to sit the
bottles in ice to speed the crystallization). We used to then spritz the
bottles with nitrogen gas to slow down the oxidation, cap tightly, and
store at -20o, wrapped in foil. All the phenol comes off around 160o. If
you see the temperature start to go up (and the volume of stuff boiling
off slow down), stop collecting. We used to let everything cool off and
clean the glassware by acid washing.
All in all, you really don't want to do this. It takes all day, you're
handling very hot, very corrosive liquids, and you often don't end up
with very much, unless you have a huge distillation apparatus.
If money is a problem, one thing you could try is to just buy the cheap
liquid phenol. As long as it's clear (not pink or yellow) when you open
the bottle, it's useable for molecular biology. If it is discolored when
you open the bottle, you can complain to the distributor because the
stuff is oxidized and therefore not pure. We did this for years. If it
is clear, then just equilibrate it with Tris and handle like the
expensive stuff. It does tend to go bad faster than the expensive stuff.
Good luck, hope this helps.
On 19 Jun 1995, minghoi wu wrote:
> : Hiranya Roychowdhury (hroychow at NMSU.EDU) wrote:
> : : On Fri, 16 Jun 1995, Ramachandran wrote:
> : : The type of phenol that one uses in the lab is very much dictated by
> : : economics. If the lab has ample money, you could simply buy the purest
> : : form of re-distilled compound from one of the major suppliers. If not,
> : : then you could buy the not-so-pure chemical and distill it yourself in
> : : the lab. We did it once a year in my PhD lab. It was not fun.
> Can you tell me the steps to redistill phenol coz the only phenol
> I have is that "not so pure" one from Sigma (crystal form). I called
> Sigma theother day, all they said was it has to be heated up to 160
> degree but they don't have the exact procedure on their computer.
> Either the protocol or literature would be helpful. Thanks!
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