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I am interested in ambient to 50 C. Several folks suggested stuff for low
(-30 or lower) that is not applicable for us. I believe a Neslab or FTS
will do a good job for us...
Heat Exchangers:
1. Cryocool cc-65 cold fingers to cool a
isopropanol bath
2. Home brew to use N2 on our Brukers. It is very stable, and works
over a broad range.
See
http://www/College/Facilities/nmr/apps/vt/vt.html . ##Address not
working##
for a description of the low temp Gozmo. I also wrote it up in TAMU a
few years ago
Parts (ex Dewar) are < $100.
3. M R Resources has in stock very reasonably priced Variable Temperature
controllers, dewars, transfer lines, and components
4. Neslab CC-65II Immersion Coolers with the immersion probes
housed in a 0.5 in id copper tube
5. FTS FC-20-84 with their P11-S copper tube-in-tube gas flow cooling coil.
currently offering only their XR-85 and XR-40
Comments::
- As for heat exchangers: we use Cryocool cc-65 cold fingers to cool a
isopropanol bath (in one case- sort of like you dry ice baths, but with
a refrigerated cold finger replacing the dry ice), or dry air running
over the cold finger directly (through a jacketed arrangement). The
isopropanol bath arrangement works pretty well- no attention is necessary
until the isopropanol fills with ice- usually about 3 months. The second
arrangement is simpler, but tends to freeze water out of our dry air, so
cannot be run for as long without thawing out.
-We found the Neslab sales force to be friendly, as well as interested in our
business and in the particular problems and concerns we had. They were
the ones that told us about the use of these units in Sykes' laboratory.
On the whole, my experiences working with Neslab were much better than
my experience trying to work with FTS.
-
We have tried to use a Neslab chiller, which has a long flexible tube
with a large (ca. 2 ft) cold finger at the end. We have tried both
putting the cold finger in an alcohol bath and using heat exchanger
coils, and also putting it in an insulated tube and blowing gas across
it directly. (My former associate had used the latter arrangement at
Purdue, and they apparently found it satisfactory.) In our hands,
neither has worked well. The direct gas gave lower temps, but it is
almost impossible to keep things tight; the heat exchanger method was
very slow and could not reach the temperatures it should. In both
cases we have had trouble keeping the chiller unit performing to
specs, and it seems to be too fragile for the kind of use it gets (or
would get if it worked).
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Here I was hoping to find a package that calculated C-13 shifts from
structures, I will be demoing several of these packages and will be happy
to let interested parties know how each package does.
Structure Prediction:
1. Softshell http://www.softshell.com (303) 242-7502
Chemwindow drawing package w/nmr module
2. Advanced Chemistry Development (800) 304-3988
Structure Drawing Package & C13 tool
H1 capabilities projected for Fall '96
3. Bio-Rad/Sadtler has some sort of C13-prediction program of the type...
4. 13C-NMR-Module V1.1b for Windows
by: H. Hnig; Copyright (C) May 1995
Address: http://fochsg02.tu-graz.ac.at/programs/nmr/
===================
Proton NMR Simulator
For Macintosh.
Available ($50) from JCE Software (Kersey Black, Proton NMR Spectrum
Simulator,
JCE Software, 1990 , Volume IIc, No. 1). Email: JCESOFT@MACC.WISC.EDU
By Kersey Black.
5. SpecTool
Comments::
- The softshell product has been in use here for ~1 year. Chem shifts
are +/- 5ppm. Output is nice because chem shifts are pasted directly
onto the structure.
The ACD package is more thorough and will permit calculations of
charged species (e.g. imidazole+ etc). The ACD package has spify
graphics and claims to have a more thorough computation of carbon
shieldings
- 13C-NMR-Module V1.1b for Windows
by: H. Hnig; Copyright (C) May 1995
Description
The module essentially consists of two main parts:
*13C-NMR-shift prediction of acyclics (C1-C6, all isomers; C8, alkenes, alkines)
and rings (C3-C8 isocyclics; aromatics like benzene, naphthalene, anthracene and
quinoline; and decalines).
*Data input, storage and retrieval for 13C-NMR data from own spectra or
literature values. Built in formula checks, retrieval of name segments or
empirical formulas, spectral display (including comparison of two spectra) and
printout. Presently roughly 700 spectra are contained in the beta-version.
Address: http://fochsg02.tu-graz.ac.at/programs/nmr/
===================
Proton NMR Simulator
A program for simulating proton NMR spectra on a Mac. Draw the structure on
screen and the spectrum will be displayed at 60-360 MHz. Clicking on a hydrogen
in the molecular structure indicates the multiplet generated by that hydrogen,
and clicking on any peak in the spectrum highlights the corresponding hydrogen
in the molecular structure drawing. Very easy to use.
-I recommend the Advanced Chemistry Development Inc (ACD) CNMR program for
calculating 13C NMR spectra; they have a demo program available by
calling 800-304-3988.