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Author: Subject: question melting point cinnamic acid/urea
hello
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[*] posted on 17-9-2005 at 21:55
question melting point cinnamic acid/urea


What are the mixed melting points of cinnemic acid/urea at 25:75, 50:50 and75:25? I'm not sure that I did it right.
Thanks
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Nicodem
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[*] posted on 18-9-2005 at 01:58


Hello,
you surely don't expect any of us to go and measure that for you?:(
Besides you can't measure the melting point of such a mixture unless it is homogenous and monophasic.

Why would you need such a useless information? (it is actually the curiosity that made me post this:P)




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The_Davster
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[*] posted on 18-9-2005 at 08:49


It sounds like hello is in some sort of beginning level college or uni organic chem course, and he/she thinks they messed up the first lab of the course. Melting point labs are always the first lab in an organic chem course.

Am I right?;)




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chemoleo
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[*] posted on 18-9-2005 at 12:14


Or it is to do with forming some phenylethylamine derivative.

I can even see where a melting point might come in.

[Edited on 18-9-2005 by chemoleo]




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[*] posted on 18-9-2005 at 14:19


Quote:
Originally posted by Nicodem
Besides you can't measure the melting point of such a mixture unless it is homogenous and monophasic.


So what's an eutectic? :P

Even if it shows a "mushy state", you have solidus (freezing point, below which all is solid) and liquidus (melting point, above which all is liquid) points, so it's not an impossible question.

Tim




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Nicodem
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[*] posted on 18-9-2005 at 14:23


Chemoleo, I also had the same thought but for a Hoffman rearangement you need a satuarated amide and not a cinnamic acid amide. Besides, you need not to know the m.p. of such a mixture to make the amide since the temperature needed is above the melting point of urea. This information is of no use whatsoever.

edit: Tim, I agree. What I wanted to say is that I don't feel like we are here to do a whole phasic transition diagram for others. Each do his own homework.

[Edited on 18-9-2005 by Nicodem]




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[*] posted on 18-9-2005 at 14:34


Tim: http://en.wikipedia.org/wiki/Eutectic



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