Difference between revisions of "ESR Lab Activity"
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Revision as of 20:21, 28 April 2016
Introduction
We are going to collect an ESR spectrum from a series of substituted hydroquinones.
| Name | SDS | Molar Mass | Sigma Product Number | Cost |
| A = Hydroquinone (aka. 1,4-benzohydroquinone) | SDS | 110.11 g/mol | H9003 | 22.90 / 100g |
| B = Methylhydroquinone | SDS | 124.14 g/mol | 112968 | 59.20 / 250g |
| C = 2,3-dimethylhydroquinone | SDS | 138.16 g/mol | 300756 | 118.00 / 5g |
Experimental
Beaker Method
- Solution A: 1 M NaOH; 1 gram NaOH (39.997 g/mol) into 25 mL EtOH.
- Solution B: 1 M hydroquinone solution.
- Procedure: To 2 ml of 1 M hydroquinone solution add 2-3 drops of solution A. A color change will indicate the reaction has occurred. Quickly transfer colored sample to ESR sample tube, place in ESR spectrometer, tune, and collected data.
Flow Method
- Solution A: 0.05 M NaOH; 0.05 grams NaOH (39.997 g/mol) into 25 ml EtOH.
- Solution B: 1 M hydroquinone solution.
- Procedure: Prepare two 60 ml syringes, 1 with solution A and 1 with solution B.
- Degas the syringe that contains solution B
- Attach to double syringe drive
- Turn on double syringe drive that is attached to ESR
- Collect data
Double Syringe Drive
Results
1-electron Oxidation of Hydroquinone=
This is the EPR spectrum of the "hydro-semiquinone" (aka. 1,4-benzosemiquinone)
EPR Parameters: 9.4 GHz, 3360 G Center field, 15 G sweep width. [Above data needs the x-axis changed over to magnetic field in G]
1-electron Oxidation of Methylhydroquinone
This is the EPR spectrum of the "methyl-hydro-semiquinone" (aka. methyl-semiquinone)
EPR Parameters: 9.4 GHz, 3360 G Center field, 15 G sweep width. [Above data needs the x-axis changed over to magnetic field in G]
Analysis
WinSim
Gaussian Calculations
| Atom | HF/3-21G | HF/6-31G | HF/6311G+(2p,d) | B3LYP/6-31G | |||||
| 8 | 12.605 | ||||||||
| 9 | -14.289 | ||||||||
| 11 | -14.289 | ||||||||
| 12 | 12.604 | ||||||||
| 19 | 12.604 | ||||||||
| 20 | -14.289 | ||||||||
| 22 | -14.289 | ||||||||
| 23 | 12.604 | ||||||||
| 24 | 0.661 | ||||||||
| 25 | 0.660 |