Check out Safety Emporium for your N95, N99, and face shield needs.
Date: Sat, 9 Oct 2010 18:35:40 -0500
Reply-To: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
Sender: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
From: "Koster, Sandra" <koster.sand**At_Symbol_Here**UWLAX.EDU>
Subject: Re: Science Education & Safety
In-Reply-To: <62CF6C9F10C1D44DA44CCC3EE395B53F01E42CDF42**At_Symbol_Here**N5AA20.okcu.edu>
Although ethyl acetate has more water solubility than methylene chloride, i
t
will certainly form a separate layer with water so it will work in the
students' hands the same way ether does. It is not that much more water
soluble than ether. Our science majors organic lab has used it as an
extraction solvent in a different reaction. It would take more drying agen
t
before evaporating and its bp is 77C instead of the 40C for methylene
chloride. The solubility of caffeine in ethyl acetate is reported to be
only about 1/4 its solubility in methylene chloride and it is not as easy t
o
do a series of extractions with ethyl acetate as with methylene chloride
since the ethyl acetate will be the top layer instead of the bottom one. An
MSDS from Fisher lists caffeine as being soluble in ethyl acetate but only
slightly soluble in ether so that explains its poor results. If I have tim
e
though I might try ethyl acetate as a replacement myself and see how it goe
s
if for no other reason than the residues of ethyl acetate the student have
with their tea water would be less of a problem to dispose of than methylen
e
chloride.
Sandra Koster
Senior Lecturer
University of Wisconsin-La Crosse
On Sat, Oct 9, 2010 at 11:06 AM, Nail, John wrote:
> I need to take exception with the statement =91benzene =85 is a solvent
that
> simply should not be used under any circumstances=92. Research involving
very
> reactive organometallic molecules uses hexadeuterated benzene (C6D6) as a
> solvent for NMR samples. The alternatives solvents either react with the
> sample molecule (example: CDCl3) or are prohibitively expensive (example:
> D12-cyclohexane).
>
>
>
> In regards to the original question about using dichloromethane as an
> extraction solvent - the sad reality is that the alternative solvents d
on=92t
> work as well as does dichloromethane for this experiment. A few weeks ago
,
> we performed the extraction of caffeine from tea using diethyl ether -
the
> results were very disappointing. Ethyl acetate and 2-propanol have also b
een
> proposed for this experiment - both of these are water-soluble. Pedagog
ical
> reasons prevent me from using water-soluble solvents for this experiment.
> Students find the concept of solvent-solvent extraction sufficiently
> confusing before we make it more complex by using even moderately
> water-soluble solvents as the =91water insoluble phase=92.
>
>
>
> This discussion reminds me of why there often is an adversarial
> relationship between faculty and EHS staff.
>
>
>
> Dr. John Nail
>
> Professor of Chemistry
>
> Oklahoma City University
>
>
> ------------------------------
>
> *From:* DCHAS-L Discussion List [mailto:DCHAS-L**At_Symbol_Here**LIST.UVM.EDU] *On Behalf
> Of *Norwood, Brad
> *Sent:* Saturday, October 09, 2010 7:01 AM
>
> *To:* DCHAS-L**At_Symbol_Here**LIST.UVM.EDU
> *Subject:* Re: [DCHAS-L] Science Education & Safety
>
>
>
> While I agree (mainly) in principle with Ernest, there are some things th
at
> really should come off of the list. An obvious example (and I=92m being
> extreme here, not intending to imply Ernest wouldn=92t agree) is benzene.
I=92m
> sure we=92d all agree that this is a solvent that simply should not be us
ed
> under any circumstances.
>
>
>
> But Ernest=92s point is *spot-on*. If all we do is =91dumb down=92 the c
ontent
> of labs and remove all possible hint of danger, we exacerbate the problem
of
> a society full of chemophobic individuals who simply do not know how to
> handle *any* chemical, much less make a rational decision as to whether a
> given situation is really a problem or not. Heck, if this is going to be
> our response (i.e. let=92s remove all danger from the lab), we might as w
ell
> discontinue =91real=92 labs and just do the whole thing as an online & vi
rtual
> experience. Take a video of the experiment and let the kiddies watch it.
>
>
>
> I think we do our students (and, ultimately, society itself) a disservice
> when we immediately presume that we must be the nanny-protector from all
> harm. The real world does not operate this way (ambulance-chasing, TV
> ad-trolling trial lawyers notwithstanding). Far better to teach them wha
t
> the real issues are and how to think critically through a situation to
> assess it, and to actually perform, hands-on, real chemical reactions wit
h
> real chemicals and reagents - some of which can harm them - to demons
trate
> that, with proper handling, care and understanding, chemicals can and do
> perform wonderful things for us.
>
>
>
> I=92ll get off my soapbox now.
>
>
>
> Brad
>
>
>
>
>
>
>
> Dr. Bradley K. Norwood
>
> Laboratory Director
>
> Arista Laboratories
>
> 1941 Reymet Road
>
> Richmond, VA 23237
>
> (804) 271-5572 ext. 307
>
> (804) 641-4641 (cell)
>
> brad.norwood**At_Symbol_Here**aristalabs.com
>
>
>
>
>
> ************** D i s c l a i m e r ***************
> This e-mail message is confidential and may contain legally privileged
> information. If you are not the intended recipient you should not read,
> copy, distribute, disclose or otherwise use the information in this e-mai
l.
> Please also telephone us (804-271-5572), or fax us (804-271-5594),
> immediately and delete the message from your system. E-mail may be
> susceptible to data corruption, interception and unauthorized amendment,
and
> we do not accept liability to such corruption, interception or amendment
or
> the consequences thereof.
>
>
>
>
>
>
>
>
>
>
>
> *From:* DCHAS-L Discussion List [mailto:DCHAS-L**At_Symbol_Here**list.uvm.edu] *On Behalf
> Of *Ernest Lippert
> *Sent:* Friday, October 08, 2010 11:51 PM
> *To:* DCHAS-L**At_Symbol_Here**LIST.UVM.EDU
> *Subject:* Re: [DCHAS-L] Science Education & Safety
>
>
>
> I guess I am "Old School" but it is hardly possible to teach (or practice
)
> chemistry without some exposure to more or less dangerous chemicals. What
> needs to be taught is how to handle chemicals safely, not how to handle o
nly
> safe chemicals. We must be careful not to occupationally regulate ourselv
es
> out of existence.
>
> Regards,
>
> Ernest Lippert
>
> On Fri, Oct 8, 2010 at 3:51 PM, Russell Vernon
> wrote:
>
> I found out today that one of our teaching labs is conducted an extractio
n
> experiment with dichloromethane (caffeine from coffee)
>
> I would like to provide them a reasonable alternative extraction experime
nt
> with an occupationally regulated carcinogen=85
>
>
>
> If you have a recommendation to look at, would you please contact me?
>
> Thanks,
>
> -Russ
>
>
>
> *Russell Vernon, Ph.D.*
>
> Research Safety
>
> Environmental Health & Safety
>
> University of California, Riverside
>
> 900 University Ave
>
> Riverside, CA 92521
>
> www.ehs.ucr.edu
>
> russell.vernon**At_Symbol_Here**ucr.edu
>
>
>
> Direct (951) 827-5119
>
> Admin (951) 827-5528
>
> Fax (951) 827-5122
>
>
>
>
>
Although ethyl acetate has more water solubility than methylene chloride, i
t will certainly form a separate layer with water so it will work in the st
udents' hands the same way ether does.=A0 It is not that much more wate
r soluble than ether.=A0 Our science majors organic lab has used it as an e
xtraction solvent in a different reaction.=A0 It would take more drying age
nt before evaporating and its bp is 77C instead of the 40C for methylene ch
loride.=A0 The solubility of caffeine in ethyl acetate is reported to be on
ly about 1/4 its solubility in methylene chloride and it is not as easy to
do a series of extractions with ethyl acetate as with methylene chloride si
nce the ethyl acetate will be the top layer instead of the bottom one. An M
SDS from Fisher lists caffeine as being soluble in ethyl acetate but only s
lightly soluble in ether so that explains its poor results.=A0 If I have ti
me though I might try ethyl acetate as a replacement myself and see how it
goes if for no other reason than the residues of ethyl acetate the student
have with their tea water would be less of a problem to dispose of than met
hylene chloride.
Sandra Koster
Senior Lecturer
University of Wisconsin-La Crosse
=A0
On Sat, Oct 9, 2010 at 11:06 AM, Nai
l, John
<jnail**At_Symbol_Here**okcu.
edu> wrote:
I need to take
exception with the
statement =91benzene =85 is a solvent that simply should not be used
under any circumstances=92. Research involving very reactive organometallic
molecules uses hexadeuterated benzene (C6D6) as a solvent for NMR samples.
The
alternatives solvents either react with the sample molecule (example: CDCl3
) or
are prohibitively expensive (example: D12-cyclohexane).
=A0
In regards to
the original question about
using dichloromethane as an extraction solvent - the sad reality is that
the alternative solvents don=92t work as well as does dichloromethane for
this experiment. A few weeks ago, we performed the extraction of caffeine f
rom
tea using diethyl ether - the results were very disappointing. Ethyl
acetate and 2-propanol have also been proposed for this experiment - both
of these are water-soluble. Pedagogical reasons prevent me from using
water-soluble solvents for this experiment. Students find the concept of
solvent-solvent extraction sufficiently confusing before we make it more
complex by using even moderately water-soluble solvents as the =91water
insoluble phase=92.
=A0
This discussio
n reminds me of why there
often is an adversarial relationship between faculty and EHS staff.<
/font>
=A0
Dr. John Nail<
/span>
Professor of C
hemistry
Oklahoma City<
/span> University
=A0
=A0
While I agree
(mainly) in principle with Ernest, there are some things that really should
come off of the list.=A0 An obvious example (and I=92m being extreme
here, not intending to imply Ernest wouldn=92t agree) is benzene.=A0
I=92m sure we=92d all agree that this is a solvent that simply should
not be used under any circumstances.
=A0
But Ernest=92s
point is spot-on.=A0 If al
l we
do is =91dumb down=92 the content of labs and remove all possible hint
of danger, we exacerbate the problem of a society full of chemophobic
individuals who simply do not know how to handle any chemical, much less make a rational decision as
to whether
a given situation is really a problem or not.=A0 Heck, if this is going to
be our response (i.e. let=92s remove all danger from the lab), we might as
well discontinue =91real=92 labs and just do the whole thing as an
online & virtual experience.=A0 Take a video of the experiment and let
the kiddies watch it.
=A0
I think we do our
students (and, ultimately, society itself) a disservice when we immediately
presume that we must be the nanny-protector from all harm.=A0 The real worl
d
does not operate this way (ambulance-chasing, TV ad-trolling trial lawyers
notwithstanding).=A0 Far better to teach them what the real issues are and
how to think critically through a situation to assess it, and to actually
perform, hands-on, real chemical reactions with real chemicals and reagents
- some of which can harm them - to demonstrate that, with proper
handling, care and understanding, chemicals can and do perform wonderful th
ings
for us.
=A0
I=92ll get off
my soapbox now.
=A0
Brad
=A0
=A0
=A0
Dr. Bradley K.
Norwood
Laboratory Director
Arista Laboratories
1941 Reymet Road
Richmond,
VA=A0 23237
(804) 271-5572 ext.
307
(804) 641-4641 (cell)
brad.
norwood**At_Symbol_Here**aristalabs.com
=A0
=A0
*************
* D i s c l a i m e r ***************
This e-mail message is
confidential and may
contain legally privileged information. If you are not the intended recipie
nt
you should not read, copy, distribute, disclose or otherwise use the
information in this e-mail. Please also telephone us (804-271-5572), or fax
us
(804-271-5594), immediately and delete the message from your system. E-mail
may
be susceptible to data corruption, interception and unauthorized amendment,
and
we do not accept liability to such corruption, interception or amendment or
the
consequences thereof.
=A0
=A0
=A0
=A0
=A0
=A0
I guess I am "Old School" but it is hardly
possible to teach
(or practice) chemistry without some exposure to more or less dangerous
chemicals. What needs to be taught is how to handle chemicals safely, not
how=A0to handle=A0only safe chemicals. We must be careful not to
occupationally regulate ourselves out of existence.
On Fri, Oct 8, 2010 at 3:51 PM, Russell Vernon <<
a href="mailto:russell.vernon**At_Symbol_Here**ucr.edu" target="_blank">russell.vernon**At_Symbol_Here**u
cr.edu> wrote:
I found out today
that one of our teaching labs is conducted an extraction experiment with
dichloromethane (caffeine from coffee)
I would like to
provide them a reasonable alternative extraction experiment with an
occupationally regulated carcinogen=85
=A0
If you have a
recommendation to look at, would you please contact me?
Thanks,
-Russ
=A0
Russell Vernon, Ph.D.
Research
Safety
Environme
ntal Health & Safety
Universit
y of California,
Riverside
900
University Ave
Riverside
, CA
92521
www.ehs.ucr.edu
russell.vernon**At_Symbol_Here**ucr.edu
=A0
Direct (9
51) 827-5119
Admin (95
1) 827-5528
Fax (951)
827-5122
=A0
=A0
Previous post | Top of Page | Next post