Apr 9, 2013 - Reaction of dimethylsulfoxonium methylide with azomethines, azines, hydrazones, and nitriles. Chemische Berichte. .... Another project currently undergoing experimentation is an aqueous anionic oxy- cope rearrangement.
University of Illinois Springfield
University of Illinois Springfield
Greening the Wittig and other Reactions for the Undergraduate Organic Teaching Laboratory
Department of Chemistry
Department of Chemistry
Dyllan Tiburzi, Leanne Deak, and Layne A. Morsch* Department of Chemistry, University of Illinois Springfield, One University Plaza, MS HSB 314 Springfield, IL 62703-5407 Abstract
Data and Results Analysis (cont’d)
Data and Results
We were interested in applying green chemistry techniques and processes to the Wittig reaction, an important way to make alkenes from aldehydes. The traditional Wittig reaction involved solvents and components that are dangerous to both the experimenter and the environment. The new techniques that were applied to the Wittig reaction were done to make the reaction both safe and efficient for Undergraduate Organic Chemistry labs. Various changes were made to the traditional procedure that included elimination of reaction solvent, replacing recrystallization solvent with natural chemicals, lowering stir times, eliminating chromatographic purification and removing heating from the process. The reactions were successful with a wide variety of aromatic aldehyde starting materials, The products were analyzed via 1H Nuclear Magnetic Resonance Spectroscopy (1H NMR), Thin Layer Chromatography (TLC), Gas Chromatography Mass Spectrometry (GCMS), Infrared Spectroscopy (IR), and melting point determination. Most products gave sufficient yields to be acceptable for both analysis and identification in an Undergraduate Organic Chemistry lab setting.
MS Data Review Active Chromatogram and Spectrum Plots - 8/30/2013 2:01 PM File: c:\users\lmorsc1\documents\research\uis\gcms data\johnson\tmck w2f 4-23-2013 3-01-28 pm.sms Sample: TMCK W2F Operator: SRJ Scan Range: 1 - 1584 Time Range: 0.00 - 24.98 min. Date: 4/23/2013 4:01 PM kCounts Ionization Off
1A
60:500
TMCK W2F 4-23-2013 3-01-28 PM.SMS TIC
2 4 .7 6 2 m in
TMCK W2 4-23-2013 2-30-41 PM.SMS TIC
20
5
2 4 .0 7 5 m in
1 6 .8 9 5 m in
20
7 .2 8 8 m in
10
+ 2 4 .2 2 8 m in
30
15
10
0 5
10
15
Spectrum 1A BP: 194.2 (5298=100%), tmck w2 4-23-2013 2-30-41 pm.sms
20
0
minutes 5
14.730 min, Scan: 927, 60:500, Ion: 6770 us, RIC: 26508, BC
10
15
Spectrum 1A BP: 194.2 (7820=100%), tmck w2f 4-23-2013 3-01-28 pm.sms
194.2 5298
100%
20
minutes
16.805 min, Scan: 1060, 60:500, Ion: 4922 us, RIC: 36951, BC 194.2 7820
100%
179.3 4707 179.3 6447
75%
75%
178.3 3275
178.3 4613
50%
50%
25% 63.1 714 62.2 385
77.1 484
115.3 750
89.2 613
152.3 424
165.3 474
180.3 573
25%
193.3 1191 195.2 809
193.3 1537 63.1 981 62.2 407
77.1 596
115.3 881
89.2 868
152.3 466
165.3 623
180.3 970
0%
0%
100
50
100
150
200
250
Fig 3. GC-MS spectrum for crude product of p-tolualdehyde. The GC shows the 64:36 Z to E ratio, while the MS shows the Z isomer of the product.
150
200
250
m/z
300 m/z
Fig 4. GC of the recrystallized product from a reaction with p-tolualdehyde. The MS represents the data of the pure E-isomer recovered from recrystallization.
These chromatograms are representative of the data that was received for each of the tested aldehydes. Both the E- and Z-isomers were observed via TLC and then further analysis was conducted using GC-MS. Relative abundance in the recrystallized product was determined based on the peak areas in the chromatograms.
Introduction Green chemistry revolves around 12 principles acting as a guideline for assessing environmental/user friendliness of various chemical reactions. Prevention, less hazardous chemical synthesis, utilizing safer solvents, and design for energy efficiency are just a few to name2. Standard organic reactions typically use energy consuming techniques and solvents that are volatile organic compounds (VOCs), which are harmful due to their high vapor pressure and low boiling point.3 To reduce the usage of VOCs and energy intensive techniques while still retaining efficiency of a process, a reaction can be performed under aqueous or solvent-free conditions at room temperature, safe enough for an Undergraduate Organic Chemistry Lab. A common reaction studied is the Wittig reaction. A Wittig reaction is an organic reaction between a phosphonium ylide and an aldehyde or a ketone that produces an alkene.1 Using this reaction in the undergraduate teaching curriculum gives a great chance to address the methodology in planning greener reactions.
1A
60:500
+ 2 4 .2 4 6 m in
Ionization Off 25
1 6 .8 0 9 m in
kCounts
+ 2 4 .8 0 3 m in
File: c:\users\lmorsc1\documents\research\uis\gcms data\johnson\tmck w2 4-23-2013 2-30-41 pm.sms Sample: TMCK W2 Operator: SRJ Scan Range: 1 - 1584 Time Range: 0.00 - 24.98 min. Date: 4/23/2013 3:30 PM
1 4 .7 2 4 m in
MS Data Review Active Chromatogram and Spectrum Plots - 8/30/2013 1:58 PM
Conclusion Analysis of the crude and recrystallized products by 1H NMR, GCMS, TLC and IR show successful reactions for each of the starting aldehydes. The waste for each reaction was small compared to traditional reactions. The experiment helped students to apply their spectroscopic skills through applied NMR and MS. The crude product analysis was useful in helping students identify E and Z isomers. Considering the results of experimentation, it is possible to say that the Wittig products can be synthesized from an array of compounds. Also, with respect to less harmful reagents and techniques, the hazardous aspects of the reaction were minimized, making the reaction a good example to learn about green chemistry.
Data and Results Analysis 1H
NMR of anisaldehyde
Tuesday, April 09, 2013 2:23 PM
O
O
H
Fig 1.1H-NMR spectrum of panisaldehyde starting material. The spectrum shows the indicative aldehyde peak, present in all of the starting materials used during experimentation. This spectrum also shows the typical doublet of doublets from a para substituted benzene.
Traditional Wittig Reaction4 vs. “Green” Wittig Reaction Traditional Method • Involves an aldehyde or ketone and a triphenyl phosphonium ylide • Produces an alkene and triphenylphosphine oxide • n-butyllithium used as base
Further Research • Another project currently undergoing experimentation is an aqueous anionic oxycope rearrangement. Preliminary analysis looks promising, though greening the reaction has been complicated since there is no solid product to recrystallize.
• DMF or ether as solvent • Stir for 4 hours at RT
References
• Reflux over night
1. 1H
• Extracted with ether • Dissolve & Recrystallize with 1-Propanol
“Green” Method • • • • •
Sodium hydroxide replaced n-butyllithium as the base Solvent-free Stirring reduced to 30 minutes Reflux process removed from reaction Dissolve & Recrystallize with Ethanol
1.10 equivalent of benzyltriphenylphosphonium chloride and 1.0 equivalent starting aldehyde/ketone were combined with 5 mL 10 N sodium hydroxide. The reaction mixture was stirred for 30 minutes. Product was filtered via vacuum filtration. Recrystallized product from Ethanol. Crystalline product was filtered and massed. TLC, melting point determination, and NMR were conducted to analyze products.
NMR of Wittig product from anisaldehyde
Tuesday, April 09, 2013 2:20 PM
Fig 2.1H-NMR spectrum of panisaldehyde product. The spectrum clearly shows peaks for the conjugated alkenes in the structure. Unlike figure 1, the spectrum lacks the aldehyde peaks, suggesting product formation and consumption of the starting material. The product still contains the –CH3 methoxy peak at 3.8 ppm ensuring that the original molecule did not experience side reactions at this group. Pre Med Advising Page 1
O
2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15.
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Acknowledgments • University of Illinois Springfield, Department of Chemistry • University of Illinois Springfield Undergraduate Student Research Grant Program • University of Illinois Springfield Scholarly Presentation Support Program
