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Tip
of the Month - Using
DMSO, DMF, NMP, DMAC?
This is one of our best "automatic PTC triggers." If you are using
DMSO, DMF, NMP or DMAC for nucleophilic substitutions, there is a very high
probability that you can replace these solvents with phase-transfer catalysis
and water-immiscible solvents (or no solvent!) to greatly improve workup which
will result in higher isolated yield, less waste and much better solvent
recovery. There is no doubt that these high boiling polar aprotic solvents
provide excellent reactivity in nucleophilic substitutions, however, they are
usually hard to recover, keep dry and avoid entraining product during workup.
Wouldn't you much rather use PTC and toluene (for example), separate the phases
at the end of the reaction and proceed with easy workup, product isolation and
solvent recovery?*
Contact Marc Halpern at tel
(+1) 856-222-1146 or by E-mail [1]
if you would like us to send you a table comparing DMSO to PTC/toluene,
or [2] if you have a potential opportunity to replace DMSO, DMF, NMP or DMAC
with PTC, or [3] if you disagree with the statement that PTC can usually
advantageously replace these solvents.
Please
forward the PTC Tip of the Month to your colleagues
PTC 2-Day Course - Deadline
extended to April 7
Last chance to register
for the 2-day course "Practical Phase-Transfer Catalysis" to be held
in New Jersey on May 6-7, 2003. Click here
for the agenda. Alternatively, train your whole department on-site, in a private
in-house course. Since 1996, 480 process development chemists,
synthesis chemists and process engineers from 87 companies have greatly
benefited from 28 public and private in-house PTC courses in the US and Europe.
This is the only public PTC course in the US in 2003 (Japan planned for October
2003).
A veteran pharmaceutical process chemist wrote (Apr 2002 course): "Best training in my 18
years in industry." He also reported scaling up a new PTC process
within 6 months. Registration Deadline: April 7, 2003.
PTC Reaction of the Month
Here is a report of a very challenging nucleophilic substitution in which DMSO
doesn't work and PTC gives 98% isolated yield. To quote from the article:
"Several attempts to make an alpha-azido ester by reaction of an alpha-chloro
boronic ester with an alkali metal azide in DMSO have been unsuccessful."
Eventually, the authors achieved the results shown below by using PTC and
restricting the temperature with a very long reaction time. The authors note
very importantly that using azide with dichloromethane can form an extremely
explosive byproduct and hence they use other solvents.* Singh, R.; Matteson, D.;
J. Org. Chem., 2000, 65, 6650.
PTC Breakthrough Process Screening
PTC Organics offers PTC
Breakthrough Process Screening for rapid and highly effective evaluation of breakthrough
phase-transfer catalysis processes. As the world leader in industrial
phase-transfer catalysis, PTC Organics develops
breakthrough high-performance low-cost PTC processes. Contact Marc
Halpern at PTC Organics by E-mail,
website, telephone (+1
856-222-1146) or fax (+1 856-222-1124).
Meet
PTC Organics at Chemspec
Learn how PTC Organics can help you improve process
performance and process R&D effectiveness using Phase-Transfer Catalysis by
scheduling a meeting with Marc Halpern at Chemspec to be held in
Manchester, UK on June 4-5, 2003. The meetings will be held in the SOCMA lounge
area (PTC Organics is a SOCMA member). Contact Marc
Halpern at PTC Organics by E-mail,
website, telephone (+1
856-222-1146) or fax (+1 856-222-1124).
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*
Before
performing any PTC reactions read this important message
Organic chemical reactions are inherently dangerous. Moreover, phase-transfer
catalysis may provide rate and other enhancements which can intensify associated
hazards. Under no circumstances should anyone perform any procedure on any scale
based in whole or in part on any of the contents of this E-mail before
thoroughly establishing safe operating procedures and performing a full and
competent hazardous operations analysis with the participation of qualified
technical personal trained in chemical, engineering, safety, industrial hygiene
and environmental disciplines and sciences.
The list of PTC Tip of the Month subscribers
will not be sold and will be used only by PTC
Communications, Inc. and PTC Organics, Inc. to provide information related to
Phase-Transfer Catalysis. PTC Communications, Inc. reserves the right to
distribute the PTC Tip of the Month to selected industrial chemists, engineers and
managers.
PTC Tip of the Month #7
Copyright 2003 PTC Communications, Inc.