In organic chemistry lab it is important to give students hands-on experiences to help them further their understanding of important chemistry topics. Binary phase diagrams incorporate many of these topics into a single graph. Differential Scanning Calorimetry (DSC) has been shown to produce data to make binary phase diagrams for alloys; however, it is more difficult to produce these diagrams using non-metal organic compounds. The purpose of this experiment was to determine if the DSC could be used to give students a challenging, yet doable experiment to prepare a binary phase diagram and determine the eutectic composition for the mixture of cis/trans-1,2-dibenzoylethylene. The conclusions from this work are: (i) The eutectic composition for cis/trans-1,2-dibenzoylethylene is at the weight percent of 30% cis and 70% trans which corresponds to an onset melting temperature of 93.5 °C; (ii) as the cis increased from a weight percent of 30% the melt temperature also increased; (iii) as the trans increased from a weight percent of 70% the melt temperature also increased; (iii) the DSC produced sufficient data necessary to develop a binary phase diagram of peak melt temperatures vs the weight percent of the cis isomer; (iv) the DSC could be incorporated into an organic chemistry lab to enhance student’s knowledge of important topics while giving them an experience working with advanced laboratory thermal instruments.

Application of differential scanning calorimetry in an organic chemistry laboratory course: Development of a binary phase diagram of cis/trans 1, 2-dibenzoylethylene

254th National Meeting (2017)

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