Trans-9-Anthracene Analysis

The literature value for the melting point range for Trans-9-(2-phenylethenyl)anthracene is 130-133 oC. The obtained range was lower than that at 120.3 to 123.8 oC. Because it is lower than the known value, this means the obtain product is not completely pure. Impurities in the compound can result in a decrease in the compounds melting point, which is observed here. The impurities could be 1-propanol due to an insufficient drying. If the experiment was performed again, the product would need to be dried completely by properly running the suction filtration for a sufficient amount of time. The percent yield was 75.69%. This is somewhat low, and when comparing this with the determined melting point value, it can be concluded that some impurities were left over in the final product. In other words, these impurities would contribute to the final mass of the product, therefore,
lowering the actual yield of the pure product alone without the impurities contributing to the final weight. The possible reasons for the loss of product can be attributed to many different errors. For example, when adding the 9-athraldehyde to the round bottom flask, not all of the reactant was transferred to the flask due to it sticking to the watch glass. Also during the decanting stage after drying the solution with calcium chloride, not all of the solution was removed due to the precaution taken to not transfer the calcium chloride. The IR spectrum of the obtained product from the reaction was taken and compared to an IR spectrum for the starting material, 9-anthraldehyde.
For the 9-anthraldheyde spectrum, the peaks at just over 3000 cm-1 indicates the presence of sp2 carbon hydrogen bonds. The peaks at 2858.3 and 2772.1 cm-1 shows the presence of an aldehyde. The peak at 1664.0 cm-1 indicates the presence of a carbon oxygen double bond, more specifically conjugated with a phenyl group. The two peaks at ~1600 and ~1550 cm-1 along with the overtones located around 1900 cm-1 indicates the presence of a benzene ring. For the product, the peaks located just over 3000 cm-1 indicate carbon hydrogen bonds. The weak carbon-carbon double bond peak located at 1621 cm-1 indicates the presence of a trans alkene. This is also supported by the peak located at 964.93 cm-1, the trans isomer peak. The two peaks at 1621.31 and 1516.29 cm-1 along with the overtones located around 1900 cm-1 indicates the presence of a benzene ring. Based on this data, it can be concluded that a successful Wittig Reaction occurred to produce the trans
alkene.