CRSEXP032

=Researcher= Matthew McBride =Objective= To investigate the shift of [|acetone], [|ethanol], and [|methanol] in the NMR coaxial insert system with D20 and CDCl3 as the reference solvents. =Procedure= Prepared coaxial insert NMR tubes with acetone, ethanol, and methanol with D2O and CDCl3 in the outer NMR tube, and analyzed by 500MHz spectroscopy. Prepared coaxial insert NMR tubes with D2O and CDCl3 and acetone, ethanol, and methanol in the outer NMR tube and analyzed by 500MHz spectroscopy. =Results= [|HNMR Spectrum of CRSEXP32_normalNMR_acetoneinCDCl3]: Acetone mixed in CDCl3 in a standard NMR tube (not the coaxial system with the insert): 2.168 PPM (6H, s)

Reference solvent (CDCl3 or D2O) in the outer NMR tube and the sample (acetone, ethanol or methanol) in the coaxial insert: [|HNMR spectrum of CRSEXP32_insertacetone_outerCDCl3]: Acetone (insert) with CDCl3 as the reference solvent in the outer NMR tube: 3.083 PPM (6H, s) [|HNMR spectrum of CRSEXP32_insertacetone_outerD2O]: Acetone (insert) with D2O as the reference solvent in the outer NMR tube: 3.108 PPM (6H, s)

[|HNMR spectrum of CRSEXP32_insertethanol_outerCDCl3]: Ethanol (insert) in CDCl3 as the reference solvent in the outer NMR tube: 1.728 PPM (3H, t), 4.159 PPM (2H, m), 5.890 (1H, t) [|HNMR spectrum of CRSEXP32_insertethanol_outerD2O]: Ethanol (insert) in D2O as the reference solvent in the outer NMR tube: 1.753 PPM (3H, t), 4.184 PPM (2H, m), 5.913 PPM (1H, t)

[|HNMR spectrum of CRSEXP32_insertmethanol_outerCDCl3]: Methanol (insert) in CDCl3 as the reference solvent in the outer NMR tube: 4.100 PPM (3H, s), 5.660 PPM (1H, s). [|HNMR spectrum of CRSEXP32_insertmethanol_outerD2O]: Methanol (insert) in D2O as the reference solvent in the outer NMR tube: 4.127 PPM (3H, s), 5.684 PPM (1H, s).

Reference solvent (CDCl3 or D2O) in the coaxial insert and the sample (acetone, ethanol or methanol) in the outer NMR tube: [|HNMR spectrum of CRSEXP32_insertCDCl3_outeracetone]: Acetone (outer NMR tube) with CDCl3 as the reference solve in the coaxial insert: 3.074 PPM (6H, s) [|HNMR Spectrum of CRSEXP32_insertD2O_outeracetone]: Acetone (outer NMR tube) with D2O as the reference solvent in the coaxial insert: 3.095 PPM (6H, s)

[|HNMR spectrum of CRSEXP32_insertCDCl3_outerethanol]: Ethanol (outer NMR tube) with CDCl3 as the reference solvent in the coaxial insert: 1.726 PPM (3H, t), 4.156 (2H, m), 5.890 (1H, t) [|HNMR Spectrum of CRSEXP32_insertD2O_outerethanol]: Ethanol (outer NMR tube) with D2O as the reference solvent in the coaxial insert: 1.748 PPM (3H, t), 4.178 PPM (2H, m), 5.911 PPM (1H, t) =Discussion= In the traditional NMR tube sample preparation (with the sample mixed in with the reference solvent of CDCl3), the acetone peak was at 2.168 ppm. When the acetone sample was placed in the insert with the reference in the outer NMR tube, the acetone peak appeared at 3.083 ppm (CDCl3) and 3.108 ppm (D2O). When the acetone sample was placed in the outer tube and the reference was placed in the insert, the acetone peak appeared at 3.074 ppm (CDCl3) and 3.095 ppm (D2O) with decreased peak resolution. The [|manual for the coaxial inserts] instructs that the sample be placed in the outer NMR tube, but that had no effect on the location of the peaks and only caused the resolution of the spectra to decrease. Based on these findings, which are consistent with methanol and ethanol, the peak locations are not effected by whether the sample is in the insert or the outer tube. Additionally, the peak locations for the inserts are not effected by whether D2O or CDCl3 is used as the reference solvent with the coaxial inserts.

The peak locations are changed when the coaxial system is used. In the traditional NMR tube, the acetone peak was at 2.168 ppm, but was around 3.1 ppm in the coaxial system. For ethanol, the peaks are [|expected to appear] at 5.19 ppm, 3.56 ppm, and 1.11 ppm. However, when the coaxial insert is used, the ethanol peaks appear near 5.9 ppm, 4.2 ppm, and 1.7 ppm. Similarly, the methanol peaks are [|expected to appear] at 4.78 ppm and 3.31 ppm, but when the coaxial insert is used, the methanol peaks appear near 5.6 and 4.1 ppm. =Conclusion= The HNMR peak location is not altered by using D2O or CDCl3 as the reference solvent or whether the sample is in the insert or outer NMR tube of the coaxial system. The HNMR peak location is shifted downfield by using the coaxial insert system to obtain the HNMR spectra. =Log=

2012-10-22
13:00 Added acetone, ethanol, methanol and D2O to the inner coaxial insert of an NMR tube. Added D2O and CDCl3 to the outer NMR tube.

2012-10-23
10:00 Obtained the HNMR spectra of acetone, ethanol, and methanol each in the coaxial insert with D2O and CDCl3 as the solvent in the outer NMR tube. Obtained a sample of acetone in CDCl3 with the traditional NMR tube system (acetone dissolved in CDCl3). Obtained the HNMR spectra of acetone, ethanol, and methanol with the samples in the outer NMR tube and each D2O and CDCl3 in the coaxial insert as the locking solvent. The 500MHz NMR Spectrometer was used to obtain these spectra. The NMR spectra obtained are: CRSEXP32_normalNMR_acetoneinCDCl3, CRSEXP32_insertacetone_outerCDCl3, CRSEXP32_insertacetone_outerD2O, CRSEXP32_insertethanol_outerCDCl3, CRSEXP32_insertethanol_outerD2O, CRSEXP32_insertmethanol_outerCDCl3, CRSEXP32_insertmethanol_outerD2O, CRSEXP32_insertCDCl3_outeracetone, CRSEXP32_insertD2O_outeracetone, CRSEXP32_insertCDCl3_outerethanol and CRSEXP32_insertD2O_outerethanol.