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| Dirk Bruere at NeoPax... |
 Posted: Fri Oct 23, 2009 8:18 am |
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Anonymous wrote:
[quote]Thank you all for the helpful responses, notwithstanding
the "crap quality" of my question (note from my earlier
post that I had this question doing legal research for a
client, and that I am not a chemist).
If I am to understand fully - chemists will often use a
stream of nitrogen as a "blanket" on top of chemical reactions
in order to displace oxygen in the ambient air. The goal
is to avoid an oxygen reaction on top of whatever is boiling,
1. It is always a stream but can be a static layer (blanket).
(Fill a balloon and connect it to the system.)
2. Modern commercial lab nitrogen is 99.999% pure and is also
very dry. Sometimes the N2 is used to keep moisture (from normal
humid air) out of the reaction.
3. Likewise, trace atmospheric CO2, should that be a problem.
4. It has already been noted by Dirk that N2 is not inert but
only "almost inert". Yep. You need to know your chemistry
to decide if N2 is 'inert enough' under those conditions.
5. Many of you realize that this lawyer guy is probably
charging his client $400-$700 per hour (in 6 minute increments)
to surf the web and pick our brains for an answer while many
of those who KNOW the answers are unemployed or underemployed
and earning squat.
[/quote]
In which case send my $100 to paypal and I'll tell you all the really
secret stuff.
[quote]1) Is the real goal here to prevent contaminating the finished
product with whatever would result from boiling in an oxidized
environment?
Not necessarily. Air (oxygen) or water (humidity) might simply
be destroying a catalyst: the reaction stops, party over,
but no contamination. It could be prematurely stopping
the propagation step in a polymerization reaction. Etc.
What's the reaction? What's the patent number? We'll tear it
apart for you.
[/quote]
--
Dirk
http://www.transcendence.me.uk/ - Transcendence UK
http://www.theconsensus.org/ - A UK political party
http://www.blogtalkradio.com/onetribe - Occult Talk Show |
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| Dirk Bruere at NeoPax... |
| Posted: Fri Oct 23, 2009 8:19 am |
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Guest
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George Orwell wrote:
[quote]Oops. Typos.
1. It is always a stream but can be a static layer (blanket).
(Fill a balloon and connect it to the system.)
It is NOT always a stream but can be a static layer ...
What's the reaction?
"Diphenylphosphine (29.4 g, 158 mmol, 1 eq) was added
instantly giving a red coloration. ..."
Although Wikipedia doesn't say so, other sources say that
Ph2PH is pyrophoric = ignites spontaneously in air (due
to the oxygen O2 + Ph2PH ----> Ph2POOH) and I would always
handle Ph2PH under N2 for safety as well as to make sure
it did what it was supposed to do in the reaction and not
just form Ph2POOH.
[/quote]
I bet it's really poisonous as well.
That "phosphine" bit in its name is a real giveaway.
--
Dirk
http://www.transcendence.me.uk/ - Transcendence UK
http://www.theconsensus.org/ - A UK political party
http://www.blogtalkradio.com/onetribe - Occult Talk Show |
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| Matt... |
| Posted: Fri Oct 23, 2009 12:35 pm |
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Guest
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[quote]
2. Modern commercial lab nitrogen is 99.999% pure and is also
very dry. Sometimes the N2 is used to keep moisture (from normal
humid air) out of the reaction.
3. Likewise, trace atmospheric CO2, should that be a problem.
4. It has already been noted by Dirk that N2 is not inert but
only "almost inert". Yep. You need to know your chemistry
to decide if N2 is 'inert enough' under those conditions.
[/quote]
So, some variables that implicate the need to heat a reaction to
reflux under nitrogen include moisture, the possibility (however
remote) that something will react with the shield gas, which are
generally inert, and the effect of an oxidized atmosphere on a
catalyst?
[quote]
5. Many of you realize that this lawyer guy is probably
charging his client $400-$700 per hour (in 6 minute increments)
to surf the web and pick our brains for an answer while many
of those who KNOW the answers are unemployed or underemployed
and earning squat.
[/quote]
Come now, my billables fall during a recession too. Plus, the
alternative would be to bill the same amount seeking the same answer
to a basic chemistry question from an overpriced expert.
[quote]What's the reaction? What's the patent number? We'll tear it
apart for you.
[/quote]
The dispute involves a spinoff from an American chemical engineering
firm. Spinoffs involve division of property, so this research is to
get a feel for patents that will be affected by the transaction. If
for no other reason, I'm looking for basic familiarity with the terms
in the documents I work with. Unfortunately spinoffs also involve a
lot of litigation and private contracts, so much of it is privileged
work product. However, when we submit motions to the court I will post
a link to them and you can tear them to your heart's desire.
Thank you again. |
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| Bolaleman... |
| Posted: Mon Oct 26, 2009 10:23 am |
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Guest
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On Oct 22, 3:04 pm, Matt <matt.m... at (no spam) gmail.com> wrote:
[quote]Chemistry folks (I am not a chemist),
In doing legal research, I have discovered US patents that describe a
certain procedure to be done "under nitrogen." For example,
"Diphenylphosphine (29.4 g, 158 mmol, 1 eq) was added instantly giving
a red coloration. The solution was heated at reflux under nitrogen for
17 hours."
What is involved in boiling something "under nitrogen" that is
different from simply boiling it?
Thank you,
[/quote]
this means that you need to work in an inert nitrogen atmosphere in
the absence of air (or oxygen). This requires a constant flushing with
dried nitrogen gas. Examples are shown in the following images (as an
image tells more than 1000 words...):
http://www.ilpi.com/inorganic/glassware/gifs/schlenkline.gif
(check out
http://images.google.com/imgres?imgurl=http://www.ilpi.com/inorganic/glassware/gifs/schlenkline.gif&imgrefurl=http://www.ilpi.com/inorganic/glassware/vacline.html&usg=__n9adsTPo_56XvlTwlviewfJQIE0=&h=267&w=400&sz=76&hl=en&start=20&sig2=6KVyO4GEXUaeLZKVIAd0dw&um=1&tbnid=M4AVAnUkDB9euM:&tbnh=83&tbnw=124&prev=/images%3Fq%3Dreaction%2Bunder%2Bnitrogen%2Batmosphere%26hl%3Den%26rlz%3D1R2GGLL_en%26sa%3DN%26um%3D1&ei=UQPmSrGrI5WyNu7y1Z4D
to learn about the glassware you'll need).
Everything of course depends on the type of reaction you want to
perform and the quantity you want to produce (lab scale, pilot scale,
etc.).
Bolaleman
http://bit.ly/XbBjW |
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| Bolaleman... |
| Posted: Mon Oct 26, 2009 10:26 am |
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Guest
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On Oct 22, 3:04 pm, Matt <matt.m... at (no spam) gmail.com> wrote:
[quote]Chemistry folks (I am not a chemist),
In doing legal research, I have discovered US patents that describe a
certain procedure to be done "under nitrogen." For example,
"Diphenylphosphine (29.4 g, 158 mmol, 1 eq) was added instantly giving
a red coloration. The solution was heated at reflux under nitrogen for
17 hours."
What is involved in boiling something "under nitrogen" that is
different from simply boiling it?
Thank you,
[/quote]
I found a website where a reflux under nitrogen is described:
http://www.chem.ubc.ca/faculty/wassell/CHEM310/Experiment_1/Experiment1.htm
hope that helps a little bit more!
Bolaleman
http://bit.ly/XbBjW (chemist jobs database) |
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