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Ugi NMR Analysis
To remove water from imine solution by drying agents (3A molecular sieves and MgSO4) and all at once add a solution of Boc-Gly-OH and tert-butylisocyanide. Hypothesis is that the protonated imine formed does not last long and converts back to starting materials. If isocyanide is present, reversal may not occur or be reduced.
Prepared solutions of piperonal(155.2mg, 1.03mmol, 2mL CDCl3, 0.516M) and tertbutylamine(105uL, 1mmol, 2mL CDCl3, 0.5M) in 2mL volumetric flasks. Mixed solutions in the presence of 83(Xmg) 3A molecular sieves. Let imine form over 3 days. Added 446.8mg of MgSO4 to imine solution to remove water produced from reaction then filtered. repared a solution of Boc-Gly-OH(175.0mg, 1mmol, 2mL CDCl3, 0.5M) and tert-butylisocyanide(113uL, 1mmol, 2mL CDCl3, 0.5M) in 2mL volumetric flasks. Added the two solutions in a 5mL volumetric flask shook well and then added to imine solution.
Characterization of Starting Materials
HMR 1hr 080A
HMR 24hrs 080B
HMR 3days 080C
Addition of Acid and Isocyanide
HMR 2hrs 080D
There is 11.7% difference in concentration of the amine and aldehyde with an excess in aldehyde after 3 days. The reaction goes to completion after 24 hours as the tert-butyl peak around 1.15ppm moves completely to 1.28ppm. The imine is converted about 86.92% (peak 8.16 ppm)compared to the amine.
The imine peak at 8.16ppm decreases to 16.67% compared to the amine after the addition of the acid. No crystalline formed.
There was no initial NMR taken after the addition of the acid and isocyanide and only the one taken after two hours so no kinetics and not relative concentrations can be determined.
New peaks appear around the imine at 8.2, 8.24, and 8.04ppm. There is a multiplet at 7.36ppm. There is a doublet at 6.1ppm corresponding to the piperonal methyl group, and a peak at 5.9ppm common to Ugi products. The peak at 5.25ppm is from the acid. There is another doublet at 4.48ppm and a peak right next to it at 4.4ppm. There is a septet at 4.05ppm and a doublet at 3.85ppm. The imine is still present at 1.2ppm and the tert-butyl peaks overlap at 1.45ppm. There are small peaks scattered around this area at 1.51ppm, 1.41ppm, a doublet at 1.39ppm, and one peak at 1.34ppm.
Imine did not revert back to aldehyde. No crystalline Ugi was made but there is a strong likely hood that a Ugi product was made.
16:20 Prepared solutions of piperonal(155.2mg, 1.03mmol, 2mL CDCl3, 0.516M) and tertbutylamine(105uL, 1mmol, 2mL CDCl3, 0.5M) in 2mL volumetric flasks
17:15 Mixed aldehyde and amine solutions together in a 13mL vial in the presence of 83(Xmg) 3A molecular sieves.
17:52 Took 200uL of imine solution and added about 2mL of CDCl3 to take an initial HMR
18:30 Took HMR 1hr.
17:50 Took sample of imine solution and without diluting used for HMR
18:05 Took HMR 24.5hrs
11:00 Took HMR of imine solution
11:40 Added 446.8mg of MgSO4 to imine solution. Shook well and let sit for several minutes. Filtered solution into new 13mL vial.
12:00 Prepared a solution of Boc-Gly-OH(175.0mg, 1mmol, 2mL CDCl3, 0.5M) and tert-butylisocyanide(113uL, 1mmol, 2mL CDCl3, 0.5M) in 2mL volumetric flasks. Added the two solutions in a 5mL volumetric flask shook well and then added to imine solution.
14:15 Took HMR
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