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    NMR Spectrum of Caffeine and Vapor Pressure of Sublimation

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    A. How many peaks would you expect to fin in the NMR spectrum of caffeine?

    B. What characteristic absorptions of bands would you expect to find in the infrared spectrum of caffeine?And show the infrared spectrum

    C. the vapor pressure of 1,2-dipheneylethane, p-dichlorobenzene, and 1,3,5-trichlorobenzene are 0.06, 11.2, and 1.4 torr, respectively, at their melting point (52-54 degrees C). Which compound is likely to be sublimed most rapidly at a reduced pressure of 15 torr and a tempreature of 40 degrees C?

    d. To color spots of TLC plates for easier visualiztion after elution with solvent, the plates can be "developed" in a sealed chamber containing solid iodine. Explain how the solid-vapor equilibrium operates in this instance.

    e. Caffeine is soluble is ethyl acetate. Do you think that the purity of your product could be checked by TLC using ethyl acetate as an elution solvent? Explain.

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    Solution Summary

    The NMR and IR spectrum of caffeine is discussed. TLC visualization techniques and sublimation are also discussed.