From: Jacob Zabicky (zabicky$##$bgumail.bgu.ac.il)
Date: Sun Dec 24 2000 - 05:02:57 EST
Hello Michael,
In you letter on heavy water enrichment you mention "careful electrolysis."
There is, of course, "careful distillation." Although equilibration with
deuterated water gives in the long run deuterated organics, these reactions
are slow and the position of the deuterioum atom is hard to control. Many
possibilities are open for introducing D at a particular site. Some
examples follow:
For ring deuteration of benzene, fast avenues could be the Griess reaction,
namely reduction of benzenediazonium salts in deuterated ethanol: (perhaps
better with higher alcohol homologs).
PhN3+ Cl- + R-OD -----> Ph-D + Ph-OR
Conditions may be chosen to favor deuteration, although a final
distillation may be required to separate the ether.
An alternative is desulfonation of aromatic sulfonic acids with hot
deuterium oxide:
Ph-SO3D + D2O -----> Ph-D + D2SO4
Both processes are applicable to aromatics other than benzene.
For deuteration at the alpha position of toluene, catalytic deuterolysis of
a benzyl ether can be effected:
PhCH2-OR + D2 ----> PhCH2-D + RO-D
Deuteration of alkylaromatics at farther removed positions may be carried
out via the Grignard reaction:
R-Br + Mg ----> R-MgBr
R-MgBr + D2O ------> R-D + DO-MgBr
All the best,
Jacob
At 9:15 20/12/0, Michael Fassbender wrote:
>Hi colleagues
>
>After some months of recess, I am back to Orglist again. I would like
>to draw the attention back to an interesting question raised by the
>Swedish colleague Jonas
>Nilsson (Hej Jonas! Haelsningar till Sverige, min Mormor aer svensk. ;-)) quite
>a while ago:
>
>On 28-Apr-2000 14:38:16 Jonas Nilsson wrote:
>> Dear Members
>>
>> My collegue an I was discussing over a cup of coffe about how
>> isotopically enriched materials are produced. Especially deuterated
>> solvents are of interest.
>> I just read on the internet about how "heavy water" was made during
>> world war two by careful electrolysis of large quantities of water
>> which
>> if I understand it right tends to make H2 leave easier than both HD
>00000000000000.> and
>> D2, thus enriching the remainder in deuterium.
>> 000000000000000000000000000000000000000000000000000000
>> Questions:
>> Is this still how it is made?
>
>The question was responded to by a reference to an Oak Ridge Lab Web page,
>outlining the principles of deuterium enrichment in water using H2S/NH3
>exchange
>equilibria. Now, since we have protic (i.e. acidic) molecules here, the
>issue is not
>that complicated.
>
>However, I would like to know how even non-protic, rather weakly acidic
>solvents are
>deuterated as for instance benzene, toluene or THF. What exchange mechanism is
>applicable in that cases?
>
>These are extremely weak acids, yet they are acids, so I can imagine that
>treating normal
>benzene or toluene with an excessive amount of solutions of e.g. NaOD
>(hydroxide) or even
>Na ND2 (amide) would give us -after boiling long enough- a certain
>D-enrichment in the organic phase.
>For more acidic molecules as acetone and acetonitrile these exchange rates
>are quite acceptable.
>
>But is there a more viable process for the technical deuteration of
>benzene and toluene? I'm looking
>forward to your input!
>
>Thanks
>
><><><><><><><><><><><><><><><><>
>Dr. Michael Fassbender
>Isotope and Nuclear Chemistry
>Chemistry Division, MS J514
>Los Alamos National Laboratory
>Los Alamos, NM 87545, U.S.A.
>Phone: +1-505- 665-7306
>Fax: +1-505- 665-4955
>Email: mifa$##$lanl.gov
><><><><><><><><><><><><><><><><>
>
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><META http-equiv=Content-Type content="text/html; charset=iso-8859-1">
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><STYLE></STYLE>
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><DIV><FONT face=Arial size=2>Hi colleagues</FONT></DIV>
><DIV><FONT face=Arial size=2></FONT> </DIV>
><DIV><FONT face=Arial size=2>After some months of recess, I am back to Orglist
>again. I would like</FONT></DIV>
><DIV><FONT face=Arial size=2>to draw the attention back to an interesting
>question raised by the Swedish colleague Jonas</FONT></DIV>
><DIV><FONT face=Arial size=2>Nilsson (Hej Jonas! Haelsningar till Sverige, min
>Mormor aer svensk. ;-)) quite</FONT></DIV>
><DIV><FONT face=Arial size=2>a while ago:</FONT></DIV>
><DIV><FONT face=Arial size=2><FONT size=3><FONT face=Arial
>size=2></FONT></FONT></FONT> </DIV>
><DIV><FONT face=Arial size=2><FONT size=3><FONT face="Times New Roman">On
>28-Apr-2000 14:38:16 Jonas Nilsson wrote:<BR><I>> Dear
>Members</I><BR><I>>
></I><BR><I>> My collegue an I was discussing over a cup of coffe about
>how</I><BR><I>> isotopically enriched materials are produced. Especially
>deuterated</I><BR><I>> solvents are of interest.</I><BR><I>> I just read
>on the internet about how "heavy water" was made during</I><BR><I>>
>world war
>two by careful electrolysis of large quantities of water</I><BR><I>>
>which</I><BR><I>> if I understand it right tends to make H2 leave
>easier than
>both HD</I><BR><I>> and</I><BR><I>> D2, thus enriching the remainder in
>deuterium.</I><BR><I>> </I><BR><I>> Questions:</I><BR><I>> Is this
>still how it is made?</I></FONT></FONT><BR></FONT></DIV>
><DIV><FONT face=Arial size=2>The question was responded to by a reference
>to an
>Oak Ridge Lab Web page, </FONT></DIV>
><DIV><FONT face=Arial size=2>outlining the principles of deuterium
>enrichment in
>water using H2S/NH3 exchange</FONT></DIV>
><DIV><FONT face=Arial size=2>equilibria. Now, since we have protic (i.e.
>acidic)
>molecules here, the issue is not</FONT></DIV>
><DIV><FONT face=Arial size=2>that complicated.</FONT></DIV>
><DIV><FONT face=Arial size=2></FONT> </DIV>
><DIV><FONT face=Arial size=2>However, I would like to know how even
>non-protic, rather weakly acidic solvents are</FONT></DIV>
><DIV><FONT face=Arial size=2>deuterated as </FONT><FONT face=Arial size=2>for
>instance benzene, toluene or THF. What exchange mechanism is</FONT></DIV>
><DIV><FONT face=Arial size=2>applicable in that cases? </FONT></DIV>
><DIV><FONT face=Arial size=2></FONT> </DIV>
><DIV><FONT face=Arial size=2>These are extremely weak acids, yet they are
>acids,
>so I can imagine that treating normal </FONT></DIV>
><DIV><FONT face=Arial size=2>benzene or toluene with </FONT><FONT face=Arial
>size=2>an excessive amount of solutions of e.g. NaOD (hydroxide) or even
></FONT></DIV>
><DIV><FONT face=Arial size=2>Na ND2 (amide) would </FONT><FONT face=Arial
>size=2>give us -after boiling long enough- </FONT><FONT face=Arial
>size=2>a
>certain D-enrichment in the organic phase. </FONT></DIV>
><DIV><FONT face=Arial size=2>For more acidic molecules as acetone </FONT><FONT
>face=Arial size=2>and acetonitrile these exchange rates are quite acceptable.
></FONT></DIV>
><DIV><FONT face=Arial size=2></FONT> </DIV>
><DIV><FONT face=Arial size=2>But is there </FONT><FONT face=Arial><FONT
>size=2>a
>more viable process for the technical deuteration of benzene and
>toluene? I'm looking</FONT></FONT></DIV>
><DIV><FONT face=Arial size=2>forward to your input!</FONT></DIV>
><DIV><FONT face=Arial></FONT> </DIV>
><DIV><FONT face=Arial><FONT size=2>Thanks</FONT></FONT></DIV>
><DIV><FONT face=Arial></FONT> </DIV>
><DIV><FONT face=Arial><FONT
>size=2><><><><><><><><><
>><><><><><><><><BR>Dr.
>Michael Fassbender<BR>Isotope and Nuclear Chemistry <BR>Chemistry Division, MS
>J514<BR>Los Alamos National Laboratory<BR>Los Alamos, NM 87545,
>U.S.A.<BR>Phone: +1-505- 665-7306<BR>Fax:
>+1-505- 665-4955<BR>Email: <A
>href="mailto:mifa$##$lanl.gov">mifa$##$lanl.gov</A><BR><><><>&l
>t;><><><><><><><><><&
>gt;<><><></FONT> </DIV></FONT></BODY></HTML>
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