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The Synthesis of trans-9-(2-phenylethenyl)anthracene
Aaron Chung, Sarah Joiner
[email protected], Department of Chemistry, University of New Hampshire, Durham, NH
12/9/16
Introduction
Chemiluminescence is one of the major tools in modern chemistry,
biology, and medicine as it permits quantitative determination of
various compounds at low concentrations1. By Wittig reaction, trans9-(2-phenylethenyl)anthracene can be synthesized, which can used in
a wide variety of chemiluminescent experiments due to its blue
fluorescence2. Proper preparation of the ylide and aldehyde will
ideally yield an efficient synthesis while also exploring procedural
improvements.
Results and Discussion
Synthesis towards the desired product could be achieved more efficiently by
oxidizing the starting material in an alternative manner. A Pyridinium
Chlorochromate oxidation could produce the intermediate product, 9anthraldehyde, in better yields and purity4. Synthesis could be attempted
once more with TLC to monitor the reaction/purity. If the product was
properly synthesized, future chemiluminescent experiments could have been
performed.
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B
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Experimental
A multistep synthesis was performed, starting with 9anthracenemethanol to yield trans-9-(2-phenylethenyl)anthracene.
The starting material was oxidized by performing a classic Swern
oxidation to yield the intermediate product, 9-anthraldehyde3.
Future Work
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Figure 1. 1H NMR of Crude 9-anthraldehyde
Conclusion
Synthesis of the starting materials was completed, however, the
target product requires further studies. Trans-9-(2phenylethenyl)anthracene was not successfully synthesized,
suggesting alternative routes be utilized.
Scheme 1. Oxidation of 9-anthracenemethanol
Acknowledgements
A phosphonium ylide was prepared by an overnight reflux with
triphenylphosphine and benzyl chloride in toluene, yielding
benzyltriphenylphosphonium chloride. The aldehyde was treated with
the ylide in a Wittig reaction to yield the desired product, trans-9-(2phenylethenyl)anthracene.
I would like to thank the UNH Department of Chemistry, David
Danico, Graham Beaton, William Butler and Sarah Joiner.
Figure 2. 1H NMR of Contaminated Product
Scheme 2. Wittig Reaction of 9-anthraldehyde
Each product was analyzed by 1H NMR and
melting point, when applicable, to determine purity.
The 1H NMR of 9-anthraldehyde, Figure.1, exhibits a small aldehyde peak at 11.8ppm,
which suggests that the Swern oxidation resulted in crude product. Due to time
constraints, the crude product was not purified any further.
The Wittig reaction resulted in contaminated product, as starting material is still
illustrated within the spectrum. Furthermore, the melting point of the final product,
(110-117)°C, did not match literature values.
References
1. W.R.G. Baeyens, S.G. Schulman, Y. Zhao; Chemiluminescence-Based Detection: Principles
and Analytical Applications in Flowing Streams and in Immunoassays. Journal of
Pharmaceutical and Biomedical Analysis. 1998, 17(6-7), (941-953)
2. Jaworek. Christine, Lacobucci. Sarah; Wittig Reaction: The Synthesis of trans-9-(2phenylethenyl)anthracene Revisited. Journal of Chemical Education. 2002,79,(111)
3. Yusuke.O; Hikaru.S; Shigefumi.K; Total Synthesis of Amphirionin-4. Organic Letters. 2016, 18,
(2399-2402)
4. Luzzio A. Fredrick; Fitch W. Richard; Moore J. William; Mudd J. Kelli; A Facile Oxidation of
Alcohols Using Pryidinium Chlorochromate/Silica Gel. Journal of Chemistry Education. 1999,
76(9), (974-975)