Variable Temperature NMR Experiments 变温NMR实验资料

仪器资料 · 发表于 2018-7-30 15:08:33

Why Low temperature NMR?
􀂃 Chemical instability
􀂃 Following a low temperature reaction
􀂃 Following exchange processes/conformational changes.
Why high temperature NMR?
􀂃 Solubility issues
􀂃 Broad peaks
􀂃 Following an elevated temperature reaction
􀂃 Following exchange processes/conformational changes
Initial Considerations:
􀂃 Solvent melting/boiling point.
􀂃 Solubility (solubility can be reduced at lower temps)
􀂃 Do you need to know exact temperature? If so, calibration is necessary.
􀂃 Experiment time: Allow ~ 10 minutes between each change of
10 degrees, both cooling down, and coming back to room temperature.
􀂃 If you want to start at -78°C, you need to have a blank nmr tube with your solvent in the NMR as it cools down…shim on the blank, then exchange with your sample (which you already have cooled to -°78C externally) when the blank has reached the desired temperature.