Difference between revisions of "ESR Lab Activity"

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Line 3: Line 3:
  
 
[[File:Hydroquinones.png]]
 
[[File:Hydroquinones.png]]
−
 
−
:A=Hydroquinone (110.11 g/mol)
 
−
:B=methylhydroquinone (124.14 g/mol)
 
−
:C=2,3-dimethylhydroquinone (138.16 g/mol)
 
  
 
{| class="wikitable"
 
{| class="wikitable"
 
||Name
 
||Name
 +
||SDS
 
||Molar Mass
 
||Molar Mass
 
||Sigma Product Number
 
||Sigma Product Number
 
||Cost
 
||Cost
 
|-
 
|-
−
||Hydroquinone
+
||A = Hydroquinone (aka. 1,4-benzohydroquinone)
 +
||[[Media:Hydroquinone.pdf|SDS]]
 
||110.11 g/mol
 
||110.11 g/mol
 
||[http://www.sigmaaldrich.com/catalog/product/sial/h9003?lang=en&region=US H9003]
 
||[http://www.sigmaaldrich.com/catalog/product/sial/h9003?lang=en&region=US H9003]
 
||22.90 / 100g
 
||22.90 / 100g
 
|-
 
|-
−
||Methylhydroquinone
+
||B = Methylhydroquinone
 +
||[[Media:Methylhydroquinone.pdf|SDS]]
 
||124.14 g/mol
 
||124.14 g/mol
 
||[http://www.sigmaaldrich.com/catalog/product/aldrich/112968?lang=en&region=US 112968]
 
||[http://www.sigmaaldrich.com/catalog/product/aldrich/112968?lang=en&region=US 112968]
 
||59.20 / 250g
 
||59.20 / 250g
 
|-
 
|-
−
||2,3-dimethylhydroquinone
+
||C = 2,3-dimethylhydroquinone
 +
||[[Media:23Dimethylhydroquinone.pdf|SDS]]
 
||138.16 g/mol
 
||138.16 g/mol
 
||[http://www.sigmaaldrich.com/catalog/product/aldrich/300756?lang=en&region=US 300756]
 
||[http://www.sigmaaldrich.com/catalog/product/aldrich/300756?lang=en&region=US 300756]
Line 33: Line 33:
 
===Beaker Method===
 
===Beaker Method===
 
*Solution A: 1 M NaOH; 1 gram NaOH (39.997 g/mol) into 25 mL EtOH.
 
*Solution A: 1 M NaOH; 1 gram NaOH (39.997 g/mol) into 25 mL EtOH.
−
*Solution B: 1 M hydroquinone solution.
+
*Solution B: 1 M hydroquinone solution; 1.1 gram HQ in 10 mL EtOH.
 
*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.
 
*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.
  
Line 42: Line 42:
 
*Degas the syringe that contains solution B
 
*Degas the syringe that contains solution B
 
*Attach to double syringe drive
 
*Attach to double syringe drive
−
*Turn on double syringe drive
+
*Turn on double syringe drive that is attached to ESR
 
*Collect data
 
*Collect data
 +
[[File:Double syringe drive.jpg]]
 +
 +
Double Syringe Drive
  
 
==Results==
 
==Results==
 +
===1-electron Oxidation of Hydroquinone===
 +
 +
 +
[[File:14BZQ.jpg|500px]]
 +
 +
 +
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===
 +
 +
 +
[[File:EPR_MeH2Q.jpg|500px]]
 +
 +
 +
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==
 
==Analysis==
 +
===WinSim===
 +
====1-electron Oxidation of Hydroquinone====
 +
 +
[[File:hydrosemiquinone theoretical vs exp.png|500px]]
 +
 +
Hydrosemiquinone ESR spectrum (black) vs Winsim spectrum (red)
 +
 +
===Gaussian Calculations===
 +
 +
{|class="wikitable"
 +
||Atom
 +
||HF/3-21G
 +
||HF/6-31G
 +
||HF/6311G+(2p,d)
 +
||B3LYP/6-31G
 +
||B3LYP/3-21G
 +
||B3LYP/6311G+(2p,d)
 +
||HF/EPR-ii
 +
||B3LYP/EPR-II
 +
||
 +
|-
 +
||8
 +
||12.605
 +
||12.165
 +
||0.26898
 +
||1.10213
 +
||0.85863
 +
||0.52092
 +
||10.405
 +
||0.30942
 +
||
 +
|-
 +
||9
 +
||-14.289
 +
||-14.332
 +
||-0.18982
 +
||-2.73487
 +
||-2.67806
 +
||-2.55611
 +
||-12.281
 +
||-2.45135
 +
||
 +
|-
 +
||11
 +
||-14.289
 +
||-14.335
 +
||-0.19007
 +
||-4.10834
 +
||-2.68141
 +
||-2.55653
 +
||-12.281
 +
||-2.44583
 +
||
 +
|-
 +
||12
 +
||12.604
 +
||12.167
 +
||0.26907
 +
||1.27101
 +
||0.85927
 +
||0.52095
 +
||10.405
 +
||0.30859
 +
||
 +
|-
 +
||19
 +
||12.604
 +
||12.169
 +
||21.28576
 +
||1.27509
 +
||0.85858
 +
||0.52091
 +
||10.405
 +
||0.30943
 +
||
 +
|-
 +
||20
 +
||-14.289
 +
||-14.339
 +
||-24.52739
 +
||-4.09995
 +
||-2.67694
 +
||-2.55567
 +
||-12.281
 +
||-2.45143
 +
||
 +
|-
 +
||22
 +
||-14.289
 +
||-20.186
 +
||-24.72440
 +
||-2.74025
 +
||-2.68052
 +
||-2.55603
 +
||-12.281
 +
||-2.44580
 +
||
 +
|-
 +
||23
 +
||12.604
 +
||12.171
 +
||21.57883
 +
||1.10424
 +
||-0.58918
 +
||0.52091
 +
||10.405
 +
||0.30858
 +
||
 +
|-
 +
||24
 +
||0.661
 +
||0.796
 +
||17.77623
 +
||3.46774
 +
||-0.22807
 +
||-0.28092
 +
||0.786
 +
||-0.40397
 +
||
 +
|-
 +
||25
 +
||0.660
 +
||0.796
 +
||17.77641
 +
||3.27784
 +
||-0.22870
 +
||-0.28078
 +
||0.786
 +
||-0.40384
 +
||
 +
|}
 +
 +
[http://www.gaussian.com/g_tech/g_ur/m_basis_sets.htm Basis Sets]
  
 
==Conclusions==
 
==Conclusions==
 +
[[:File:ed066p263.pdf]]

Latest revision as of 22:42, 21 April 2022

Introduction

We are going to collect an ESR spectrum from a series of substituted hydroquinones.

Hydroquinones.png

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; 1.1 gram HQ in 10 mL EtOH.
  • 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.jpg

Double Syringe Drive

Results

1-electron Oxidation of Hydroquinone

14BZQ.jpg


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

EPR MeH2Q.jpg


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

1-electron Oxidation of Hydroquinone

Hydrosemiquinone theoretical vs exp.png

Hydrosemiquinone ESR spectrum (black) vs Winsim spectrum (red)

Gaussian Calculations

Atom HF/3-21G HF/6-31G HF/6311G+(2p,d) B3LYP/6-31G B3LYP/3-21G B3LYP/6311G+(2p,d) HF/EPR-ii B3LYP/EPR-II
8 12.605 12.165 0.26898 1.10213 0.85863 0.52092 10.405 0.30942
9 -14.289 -14.332 -0.18982 -2.73487 -2.67806 -2.55611 -12.281 -2.45135
11 -14.289 -14.335 -0.19007 -4.10834 -2.68141 -2.55653 -12.281 -2.44583
12 12.604 12.167 0.26907 1.27101 0.85927 0.52095 10.405 0.30859
19 12.604 12.169 21.28576 1.27509 0.85858 0.52091 10.405 0.30943
20 -14.289 -14.339 -24.52739 -4.09995 -2.67694 -2.55567 -12.281 -2.45143
22 -14.289 -20.186 -24.72440 -2.74025 -2.68052 -2.55603 -12.281 -2.44580
23 12.604 12.171 21.57883 1.10424 -0.58918 0.52091 10.405 0.30858
24 0.661 0.796 17.77623 3.46774 -0.22807 -0.28092 0.786 -0.40397
25 0.660 0.796 17.77641 3.27784 -0.22870 -0.28078 0.786 -0.40384

Basis Sets

Conclusions

File:ed066p263.pdf

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