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Magpie
lab constructor
Posts: 5939
Registered: 1-11-2003
Location: USA
Member Is Offline
Mood: Chemistry: the subtle science.
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Leonid Lerner in his book shows that there is an equilibrium between PCl5 and PCl3, ie
PCl5 <---> PCl3 + Cl2
K = 0.042 @ 190°C
When I pulled a vacuum on the PCl5 I first noticed the residual chloroform released from the PCl5 condensing/evaporating on the walls of the RBF.
Then PCl5 sublimate formed on the walls along with a clear liquid film. I'm thinking now that this liquid was likely PCl3. With the oil bath at
110°C the PCl3 was likely being evaporated and then condensed in the condenser. From there it would mix with the chloroform in the receiving flask.
So this is another possible source of loss of PCl5.
The single most important condition for a successful synthesis is good mixing - Nicodem
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Magpie
lab constructor
Posts: 5939
Registered: 1-11-2003
Location: USA
Member Is Offline
Mood: Chemistry: the subtle science.
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I used 5g of my PCl5 to convert benzophenone oxime to benzanilide using a Beckmann rearrangement. Yield was 64%.
The single most important condition for a successful synthesis is good mixing - Nicodem
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