Objective
Monitor the formation of an aromatic imine by HMR and CMR in CDCl3
Steps
- Make up separate 1 mL of 1M solutions of piperonal and
5-methylfurfurylamine in CDCl3.
- Take HMRs and CMRs of the aldehyde and amine. Use 5 sec relaxation
time and acquire for about 15 mins for the CMR. This should be good enough
based on James' results at 1M in
methanol.
- Combine the two solutions into a 1 dram vial and shake vigorously
then transfer to an NMR tube.
- Take HMR at 5, 10 and 20 minutes after mixing.
- Take CMR at 25 min after mixing.
- Take HMR at 40 min after mixing.
- Take CMR at 45 min after mixing.
- Take HMR at 80 mins after mixing.
- Take CMR at 85 mins after mixing.
- Continue to take NMRs after interval doubling until no more change
is observed.
Variations
- Use methanol-d4 instead of CDCl3.
- Use phenylacetaldehyde instead of piperonal to see the difference
with an aliphatic aldehyde. We expect the aromatic aldehyde to be slower.
- Use 30 and 60 sec relaxation times to approach quantitative peak
heights in CMR.