At present, it is not possible to do NMR at higher temperature. Maybe, it is very interesting to design a heat insulated magnetic tube to perform your experiment.

Better to get info from the manufacture.

You need to maintain the temperature to keep the lock phase and swimming through out the acquisition.  Never try to heat the tube out of the magnet

NMR analysis with different temperature i.e., those higher or lower than the ambient probe temperature, if you are not careful it will potential to cause serious damage to the instrument. So better discuss with manufacturer and perform the analysis. 

Contrary to what above said you can use your Bruker spectrometer between the temperature range of approximately -100 C to +120 C (unless an inappropriate probe is installed allowing no temperature control at all .). If the probe is right, don't worry measuring at 60 C, it is very common in the practice of NMR and it is relatively close to ambient conditions. (You need to shim as usual.) As Clemens advices, it is very important to know the boiling points of the components, especially when you use common glass tubes, which meant to be used under atmospheric pressure. Exceeding the boiling point of one of the component, the contents may contaminate or damage the expensive probe-head after spilling out from the tube by loosening the plastic cap or by breaking (exploding) the glass.

Yes you can use the Bruker at higher temperature. You can increase the probe temperature from NMR setting. I have used Bruker at 80 C for isoquinoline lakaloids. I have studied the confirmations of natural products at various temperature using various solvents. By using DMSO you can done your experiment at higher temperature.

Thank you all for the answers and suggestions.

I’ve consulted an engineer from Bruker. The engineer told me that I can set the temperature to even above 100 C, just as Imre said. And, we can preheat samples out of the magnet to save time. He also reminded me to change air to N2 accordingly.

Then I told the engineer that there is no heating probe for my NMR spectrometer. He suggested me not to heat the sample out of the NMR spectrometer because samples will cool down quickly if the probe is not capable of heating samples. It is necessary to maintain the temperature to keep the lock phase, just as Li Fu said.

To sum up, you can analyze samples under high temperature, only when your NMR spectrometer is equipped with heating probes.

I never tried with heating conditions. Now, It is really interesting to know the heating techniques in NMR. In future, It would be really useful for me too. Thank you guys. 

If your instrument has a Variable Temperature controler, as Dr Tóth said you can run the NMR spectrum from -100 ºC to 100 ºC. We have an old Bruker AMX-300 an we usually run spectra at 80-95 ºC. You have to take care to heat it up with a ramp  of about 5 ºC/min and maintain at the temperature you like for 10 min. Then you have to shim the spectrometer and run the spectrum.

I would expect that most instruments of the Avance II series are equipped with variable temperature. Type "edte" in Topspin and see what happens. There should be a connector on the probe for the heater and one for the thermocouple. Please send me the system order number and I should be able to determine if you can do VT work. If your instrument is equipped with  BBO probe you can go to 150C maximum. But beware of boiling pointrs of solvents or components in your solution.

I think if you have difficulty of using your NMR machine for raising up the measuring temperature (due to lack of temperature regulator) 

Why don't you use another tool rather than NMR..!!?

If your sample contains a UV visible moiety ... you may use electronic circular dichroism (ECD) with collaboration with other institutes if you do not have it. 

If your sample does not contain a UV visible moiety, you may use vibrational circular dichroism (VCD) spectroscopy that measure the samples under IR condition.

See the attached reference that may help you

Best regards

I doubt that you can catch conformational isomerism of unprotected carbohydrates with UV.  NMR clearly is the way to go here. (cf EXCSY and or coalescence points). It is less common to have a cooling unit but It would very much surprise me if you did not have a at least a heater/VTU. 

>>>>Clearly Clemens can help you with this.

60 deg C should not be a problem for a modern AVANCE II era standard 5mm probe unless you have a cryoprobe. 

Heating up the sample and putting it in the NMR is a bad idea. This will cause horrible shimming (and tuning issues) and by the time you can actually measure anything the sample is at RT again anyway.  In addition to boiling solvents which should not be a problem for DMSO at that temperature also consider this. If you have a large sample volume you may end up with convection (at higher temps) because of the temperature gradient at the bottom of the sample and the top. … This also happens with the CHCl3 line shape sample (solvent Acetone) at high temp + there you may also have condensation depending on the temp. 

Dr. Markus 

For sure you are professinal of NMR but other methods are exist.

please see the attached paper which talks about exciton chirality using VCD ... just a protection with acetyl will lead to determination of the conformation ..

I hope it may give benefit.

Most NMR spectrometeres (but not necessarily all) are equipped with VT (variable temperature) NMR accessories. Additionally, there are NMR probes that may be operated only in a limited temperature range. So, before you start your experiments you should consult someone that is familiar with and experienced in you specific NMR spectrometer and related hardware, otherwise you may damage something. See the answer by Clemens Anklin.

In general, recording NMR spectra at different temperatures (under heating or cooling) is an established technique for decades...

As suggested earlier for another question, when you need to work at temperatures higher than the boiling point of your solvent (or very close to it), you can use high-pressure NMR tubes. Naturally, this requires special preparations and precautions for safety. 

What type of probe do you have? My broadband probe does have heating?

Clemens, I did not get the system order number. Our technician, who is responsible for the operation and maintenance of the NMR spectrometer, told me that there is no thermocouple or heating control line for the spectrometer. I’ve send my sample to Xiamen University and they can analyze my sample under high temperature.

Again, thank you all for your suggestions and answers. I’ve learned a lot during the discussion. I love this place. :)

Theoretically it should be possible. Now the molecules have higher energies so spectra should not be identical to ambient temperature spectra. Initial calibrations will have to be done, for the comparison purpose, I suppose.

Hi,

I have been working with a Bruker 400MHz, at a sample temperature of 90 degrees on specific carbohydrate and I have observed that conformational isomer ratios are not the same when the sample is heated externally and analysed. The conformational ratios are significantly different when heating and analysis is simultaneous. In my case I used 10%D2O +90%H2O solvent. An engineer at your laboratory can help you setup or manipulate the sample temperatures initially, after which you can be autonomous with it.

So, to answer your question, yes, it is possible to heat the sample and try immediate analysis but the results may not be represenatitve of the temperature effect. This is my observation gathered from my experimental results.

Your question is very old now, but if you have had some interesting results from external heating method, please let me know.

Thanks.

Yes you can, but keep the temperature 5-10 degrees below the boiling temperature of the used solvents

Every Bruker spectrometer has a possibility to make spectra at various temperatures. Especially Avance 400 model has a possibility to work between -100 to +120 C.

Yes we can do NMR on high temperature but I think d6 DMSO will be the good NMR solvent for recording NMR at High temp.