June 17, 2019, 03:28:16 PM
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Topic: melting point range of mixture of cholesteryl benzoate and cholesterol??  (Read 4348 times)

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Cholesterol has melting point range of 147-150 C, and so does cholesteryl benzoate, but when I mixed those two and measured the melting point range in my teaching lab, the melting point range was much lower (120-125 C). I'm sure I used pure compounds, so how would I explain this?? ???

Offline nj_bartel

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When a compound is melted with an impurity, do you expect a lower or higher melting point for that substance?  A broader or tighter melting point range?

Offline gfunk

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Look into colligative properties.

Also, interesting to note is that those two compounds actually have two separate melting points.  They both have a transitional liquid-crystalline phase upon heating from solid to liquid.  For cholesteryl benzoate, it melts at 145*C (cloudy liquid) and 175*C (clear liquid) or so.
Grad Student - Organic Chemistry
University of Alberta

Offline typhoon2028

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Is it possible the two compounds are forming an eutectic mixture?

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