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Topic: melting point range of mixture of cholesteryl benzoate and cholesterol??  (Read 6129 times)

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yg7s7

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melting point range of mixture of cholesteryl benzoate and cholesterol??
« on: March 31, 2009, 11:19:10 PM »
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?? ???
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Offline nj_bartel

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Re: melting point range of mixture of cholesteryl benzoate and cholesterol??
« Reply #1 on: April 01, 2009, 12:51:43 AM »
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?
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Offline gfunk

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Re: melting point range of mixture of cholesteryl benzoate and cholesterol??
« Reply #2 on: April 01, 2009, 09:17:37 AM »
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.
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Grad Student - Organic Chemistry
University of Alberta

Offline typhoon2028

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Re: melting point range of mixture of cholesteryl benzoate and cholesterol??
« Reply #3 on: April 01, 2009, 10:44:26 AM »
Is it possible the two compounds are forming an eutectic mixture?
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