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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
Future Work
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, trans-9-(2phenylethenyl)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
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Experimental
A multistep synthesis was performed, starting with 9anthracenemethanol to yield trans-9-(2phenylethenyl)anthracene. The starting material was
oxidized by performing a classic Swern oxidation to yield
the intermediate product, 9-anthraldehyde3.
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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, 9-anthraldehyde, 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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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-(2-phenylethenyl)anthracene was not successfully
synthesized, suggesting alternative routes be utilized.
Scheme 1. Oxidation of 9-anthracenemethanol
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.
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Acknowledgements
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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
1H
Scheme 2. Wittig Reaction of 9-anthraldehyde
Each product was analyzed by 1H NMR and
melting point, when applicable, to determine
purity.
The 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)