Removing Solvent from NMR tubes

Step 1: Attach the J. Young’s NMR tube to the Schlenk line tubing using the tapered glass adapter supplied with the tubes and place under vacuum.

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J. Young’s NMR tube under vacuum.

Step 2: Submerge the NMR tube in a dewar of liquid nitrogen to freeze the solvent.

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Freezing the solution in liquid nitrogen.

Step 3: Once the solvent is frozen, open the teflon valve carefully by twisting it anti-clockwise, and evacuate the headspace for 20-30 seconds.

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Closed vs. open J. Young’s valve.

Step 4: Close the teflon valve and remove the NMR tube from the liquid nitrogen. Carefully thaw the solvent from the top down to the bottom by rubbing the tube between your thumb and fingers. This degasses the solvent which helps prevent bumping whilst under vacuum.

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Thawing the solution.

Step 5: Repeats steps 2 and 3. Remove the NMR tube from the liquid nitrogen and thaw the frozen solvent (from the top to the bottom) with the teflon valve open to begin evaporating off the solvent. Holding the NMR tube at an angle helps prevent bumping by increasing the surface area of the sample. If the sample does bump, it may be necessary to close the teflon valve and repeats steps 2-3 and then step 5 again until all visible of solvent has been removed.

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Thawing and evaporating the solvent under vacuum.

Step 6: Keep the NMR tube under vacuum for 5+ minutes to remove all traces of solvent and volatile material. Backfill the NMR tube with inert gas and then seal the teflon valve. The NMR tube is now ready to transferred into a glovebox or cycled back onto the Schlenk line for further manipulations.

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NMR tube after removal of solvent.