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Reaction Attempts
ChemSpider Links: Acetone, Piperidine, Mesityl oxide, and Diacetone alcohol

Researcher

Matthew McBride

Objective

To observe the possible products of mixing together acetone and piperidine at standard temperature and pressure by HNMR spectroscopy. D2O was used as the external reference in the outer coaxial NMR tube (the coaxial system has been shown to shift peaks).

Procedure

Five screw cap vials were prepared containing approximately 300┬ÁL of total volume of:
1. Acetone
2. Piperidine
3. Approximately equal amounts of acetone and piperidine by volume
4. Piperidine with one drop of acetone
5. Acetone with one drop of piperidine
These solutions were analyzed by HNMR spectroscopy at time 0 hours (shortly after preparing the solutions) and time 24 hours using the coaxial insert system. The samples were placed in the inner coaxial NMR tube with D2O as the reference (4.8 ppm) in the outer coaxial NMR tube.

Results

Time: 0 Hours
HNMR Spectrum of CRS027_Vial1_0hours: Acetone: Acetone peak at 3.11 ppm (s, 6H) (with impurity present at 4.00 ppm).
HNMR Spectrum of CRS027_Vial2_0hours: Piperidine: Piperidine peaks at 3.10 ppm (t, 4H), 2.31 ppm (s, 1H), and 1.86 ppm (m, 6H).
HNMR Spectrum of CRS027_Vial3_0hours: Approximately equal amounts of acetone and piperidine (by volume): Acetone peak at 2.83 ppm (s, 6H). Piperidine peaks at 3.45 ppm (t, 4H), 2.95 ppm (s, 1H), and 2.21 ppm (m, 6H). Diacetone alcohol peaks at 1.667 ppm (6H, s), 2.518 ppm (3H, s), and 4.402 ppm (2H, s).
Mole Fraction Spreadsheet
HNMR Spectrum of CRS027_Vial4_0hours: One drop of acetone and an excess of piperidine: Acetone peak at 2.48 ppm (s, 6H). Piperidine peaks at 3.11 ppm (t, 4H), 2.34 ppm (s, 1H), and 1.88 ppm (m, 6H).
Mole Fraction: 0.03 acetone/0.97 piperidine.
HNMR Spectrum of CRS027_Vial5_0hours: One drop of piperidine and an excess of acetone: Acetone peak at 3.09 ppm (s, 6H) with impurity at 3.91 ppm. Piperidine peaks at 3.71 ppm (t, 4H), 2.96 ppm (s, 1H), and 2.48 ppm (m, 6H).
Mole Fraction Spreadsheet: 0.98 acetone/0.02 piperidine.

Time: 24 Hours
HNMR Spectrum of CRS027_Vial1_24hours: Acetone: Acetone peak at 3.11 ppm (s, 6H) (with impurity present at 4.00 ppm).
HNMR Spectrum of CRS027_Vial2_24hours: Piperidine: Piperidine peaks at 3.10 ppm (t, 4H), 2.34 ppm (s, 1H), and 1.86 ppm (m, 6H).
HNMR Spectrum of CRS027_Vial3_24hours: Approximately equal amounts of acetone and piperidine (by volume): Acetone peak at 2.81 ppm (s, 6H). Piperidine peaks at 3.43 ppm (t distorted, 4H), 2.97 ppm (s, 1H), and 2.20 ppm (m, 6H). Diacetone alcohol peaks at 1.650 ppm (6H, s), 2.502 ppm (3H, s), and 4.404 ppm (2H, s).
Mole Fraction Spreadsheet
HNMR Spectrum of CRS027_Vial4_24hours: One drop of acetone and an excess of piperidine: Acetone peak at 2.48 ppm (s, 6H). Piperidine peaks at 3.11 ppm (t, 4H), 2.35 ppm (s, 1H), and 1.88 ppm (m, 6H).
Mole Fraction Spreadsheet
HNMR Spectrum of CRS027_Vial5_24hours: One drop of piperidine and an excess of acetone: Acetone peak at 3.09 ppm (s, 6H) with impurity at 3.91 ppm. Piperidine peaks at 3.71 ppm (t, 4H), 2.96 ppm (s, 1H), and 2.48 ppm (m, 6H).
Mole Fraction Spreadsheet

Discussion

Due to the presence of singlets around 1.6 (6H), 2.5 (3H) and 4.4 (2H) ppm, which have integration of 6:3:2 corresponding to the expected singlets of diacetone alcohol, it can be determined that diacetone alcohol was formed. At 0 hours, the mole fraction of diacetone alcohol was 0.0002, the mole fraction of acetone was 0.6219 and the mole fraction of piperidine was 0.3779. At 24 hours, the mole fractions acetone and piperidine were 0.6202 and 0.3746, respectively. The mole fraction of diacetone alcohol had increased to 0.0052. At 0 hours, the ratio of acetone to diacetone alcohol was 3202:1, but at 24 hours, this ratio was 119:1. The formation of the diacetone alcohol was only observed in the approximately 50/50 by volume mixture (Vial 3), which had a mole fraction of 0.62 acetone/0.38 piperidine. In the mixtures with mole fractions of 0.03 acetone/0.97 piperidine and 0.98 acetone/0.02 piperidine, no formation of diacetone alcohol was observed. No formation of Mesityl oxide, which would have consisted of four singlet peaks, was observed.

The acetone peak shifts upfield in the presence of piperidine. Without piperidine present, the acetone peak is at 3.11 ppm. In an approximately 50/50 mixture by volume, the acetone peak is 2.81 ppm. One drop of acetone in an excess of piperidine has an acetone peak at 2.48 ppm. Acetone with one drop of piperidine has the peak at 3.09 ppm. Typically, the peak for acetone is observed at 2.05 ppm. The use of the coaxial insert is shifting the acetone peak downfield.

Similarly, the piperidine peak appeared to slightly shift upfield in the presence of acetone. The piperidine peak at 3.10 ppm shifted to 3.43 ppm (50/50 mixture), 3.11 ppm (excess), and 3.71 ppm (drop). The piperidine peak at 2.34 ppm shifted to 2.97 ppm (50/50), 2.35 ppm (excess), and 2.96 ppm (drop). The piperidine peak at 1.86 ppm shifted to 2.20 ppm (50/50), 1.88 ppm (excess), and 2.48 ppm (drop). However, the coaxial insert system does interfere with the shift, so it would need to be determined whether this change in shift is due to the coaxial system.

Conclusion

Acetone underwent a self-condensation in the presence of piperidine to form diacetone alcohol. After 24 hours at room temperature and pressure, the ratio of acetone to diacetone alcohol was 119:1. The coaxial insert system with D2O as the reference solvent caused the acetone peak to shift upfield to 3.11 ppm from the typical location of 2.05 ppm.

Log

2013-09-30

12:39 Added reagent grade acetone to a screw cap vial (Vial #1), piperidine to a vial (Vial #2), approximately equal amounts of acetone and piperidine to a vial (Vial #3), one drop of acetone and an excess of piperidine to a vial (Vial #4), and one drop of piperidine and an excess of acetone to a vial (Vial #5).
13:22 The HNMR spectrum of Vials #1 and #2 were obtained using the 500 MHz HNMR with the sample in the inner coaxial NMR tube and D2O in the outer NMR tube. These are samples CRS027_Vial1_0hours and CRS027_Vial2_0hours.
14:06 The HNMR spectrum of Vials #3 and #4 were obtained using the 500 MHz HNMR with the sample in the inner coaxial NMR tube and D2O in the outer NMR tube. These are samples CRS027_Vial3_0hours and CRS027_Vial4_0hours.
14:26 The HNMR spectrum of Vials #5 was obtained using the 500 MHz HNMR with the sample in the inner coaxial NMR tube and D2O in the outer NMR tube. This is sample CRS027_Vial5_0hours.

2013-10-01

13:31 The HNMR spectrum of Vials #1, #2, #3, #4 and #5 were obtained using the 500 MHz HNMR with the sample in the inner coaxial NMR tube and D2O in the outer NMR tube. These are samples CRS027_Vial1-5_24hours.