Fractional distillation is part of the essential experimental techniques taught to first-year chemistry students, especially during practical organic chemistry work. The characterization of the distillate generally involves measuring the boiling temperature, the refractive index or the infrared spectrum. In this paper, an unknown mixture composed of two organic solvents is given to the students in order to be separated by fractional distillation and characterized. To perform this task, the benchtop 1 H NMR spectroscopy was introduced to complement other analytical methods and to familiarize students with this technique while implementing their reasoning abilities.
4-Methoxy-ortho-phthalaldehyde and 4-hydroxy-ortho-phthalaldehyde are potentially useful molecules for fluorimetric analysis of a variety of amines and for the elaboration of complex molecular architectures. Nevertheless, literature generally describes their synthesis in very low yield (below 5%), mainly due to the inefficiency of the last oxidation step. In this paper, we report a reliable synthesis of 4-substituted-ortho-phthalaldehyde analogues in 51% overall yield owing to the addition of a protecting step of the unstable key intermediate 4,5-dihydroisobenzofuran-5-ol. Oxidation and deprotection steps were also studied in order to provide an effective availability of these two dialdehyde compounds that may increase their future applications.
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