Exp077_03-23-07.JPG

Objective

To combine piperonal and tertbutylamine and obtain almost complete conversion of the imine. Then add Boc-Gly-OH and see if the imine is reverted to the aldehyde.

Procedure

To remove water from starting solvent, added 3A molecular sieves to 10mL of CDCl3, stirring and then adding approx. 180mg of MgSO4. Made a solution of piperonal(159.1mg, 2mL, 1.06mmol, 0.53M, CDCl3) and a solution of tertbutylamine(105uL, 1mmol in 2 ml CDCl3, 0.5M) using the newly dired CDCl3 after filtering through cotton in a glass pipette. Combined the two solutions in the presence of X x 3A molecular sieves(Ymg) with stirring overnight. Took an NMR of the resulting solution. Made a solution of Boc-Gly-OH(178.8mg, 2mL, 1.02mmol, 0.51M, CDCl3) and resulting imine solution. After about 4 hours took HMR.

Results

Characterization of Starting materials in CDCl3

tertbutylamine
piperonal

Characterization of Imine

HMR 4hrs 077A
HMR 66hrs 077B

Characterization after addition of acid

HMR 2hr 077C
HMR 25hr 077D
Exp077 Excel

Discussion

  1. The imine (peak 8.2ppm) has a 73.04% conversion after almost 3 days. There is 3.75% difference in amine/aldehyde concentrations with an access of aldehyde (peak 9.82 ppm).
  2. After the addition of the acid, the imine decreases to about 9.68% of the total solution after two hours and then is used up after 25 hours. The percentage of aldehyde increases to 3.45% ocompared to the amine after 25 hours which suggests that there was reversal of the imine.
  3. This experiment did not utilize sieves during the imine process which was a mistake. Sieves and MgSO4 should be used in the starting components and imine solution over time.

Conclusion

The imine reverted to aldehyde.

Log

2007-03-23

10:10 Took and unknown amount of 3A molecular sieves and in a crucible, put over a Bunsen burner.
10:18 Took molecular sieves off Bunsen burner and put in a marked 13mL vial.
10:47 Took about 10mL of CDCl3 (nothing else) and added 66 x 3A molecular sieves. Put in stir bar and spun on stir plate.
11:12 Stopped spinning CDCl3. Decanted of CDCl3 and removed molecular sieves.
11:25 Prepared a solutions of piperonal (159.1mg, 2mL, 1mmol, 0.5M, CDCl3 approx numbers) and tertbutylamine (105uL, 2mL, 1mmol, 0.5M, CDCl3) Solutions were prepared by taking the CDCl3 that had been exposed to the sieves and adding approx 180mg of MgSO4. The CDCl3 was shaken and allowed to sit for about 3 minutes. The CDCl3 was then taken up by glass pipette and steadily passed through a cotton filter in a separate glass pipette which went directly into the volumetric 2mL flasks for the solutions.
11:38 Combined the aldehyde and amine solutions and started stirring in the presence of X x 3A molecular sieves.
12:15 Took NMR of starting materials in CDCl3 on 300MHz instrument.
14:48 Took a 0.5mL sample and added another 0.5mL CDCl3 to get an NMR.
15:35 Took HMR on 500MHz NMR instrument. First analysis showed that the reaction was only about half way through. Continued spinning solution.
18:00 Stopped spinning solution and allowing it to continue through the weekend.

2007-03-26

12:02 Took a 0.5mL sample and put directly into an NMR tube and added more CDCl3 to get a good NMR.
12:15 Took HMR of imine solution. Quick analysis shows that there is still aldehyde left.
12:50 Prepared a solution of Boc-Gly-OH(178.8mg, 2mL, 1mmol, 0.5M, CDCl3).
13:08 Added acid solution to imine solution.
15:15 Started stirring the acid/imine solution. Put imine solution that was used for HMR in a 13mL vial.
16:25 Took HMR of acid/imine. Quick analysis shows that there is a reversal of the imine.
17:20 Weighed out 508mg of fluffy MgSO4 and added it to the acid/imine solution in a centrifuge tube. Shook well and letting it sit allowing it to absorb water that is in the solution and any that is formed from the forward reaction.

2007-03-29

14:30 Took sample straight of acid/imine solution without dilution for HMR 77D
14:45 Took HMR

Tags

PiperonalInChI=1/C8H6O3/c9-4-6-1-2-7-8(3-6)11-5-10-7/h1-4H,5H2
tert-butylamine InChI=1/C4H11N/c1-4(2,3)5/h5H2,1-3H3
Boc-Gly-OHInChI=1/C7H13NO4/c1-7(2,3)12-6(11)8-4-5(9)10/h4H2,1-3H3,(H,8,11)(H,9,10)
imine: InChI=1/C12H15NO2/c1-12(2,3)13-7-9-4-5-10-11(6-9)15-8-14-10/h4-7H,8H2,1-3H3/b13-7-