Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: Chaste on November 09, 2010, 10:40:47 AM
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It is a conventional simple reflux set up for the synthesis of ligand bpm(bis(pyrazolyl)methane).
I'm guessing it acts as a lubricant? to reduce friction but what is its significance?
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It is a conventional simple reflux set up for the synthesis of ligand bpm(bis(pyrazolyl)methane).
I'm guessing it acts as a lubricant? to reduce friction but what is its significance?
It is used to stop the ground glass joints freezing together. Just don't use too much or it will end up in your product.
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It is a conventional simple reflux set up for the synthesis of ligand bpm(bis(pyrazolyl)methane).
I'm guessing it acts as a lubricant? to reduce friction but what is its significance?
why don't we use it always?
It is used to stop the ground glass joints freezing together. Just don't use too much or it will end up in your product.
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By "the cone" I'm assuming you mean the glass joint where it fits into the flask.
The reason is the joint between condenser and flask isn't airtight. So once you get your solvent boiling it can escape through that joint and then your flask will dry out if you leave it for long enough. Greasing the joint makes it airtight and prevents the solvent from evaporating out (also prevents air and moisture from getting in if you need to be concerned about that).
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By "the cone" I'm assuming you mean the glass joint where it fits into the flask.
The reason is the joint between condenser and flask isn't airtight. So once you get your solvent boiling it can escape through that joint and then your flask will dry out if you leave it for long enough. Greasing the joint makes it airtight and prevents the solvent from evaporating out (also prevents air and moisture from getting in if you need to be concerned about that).
I get it now. Thanks for the explanation!
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By "the cone" I'm assuming you mean the glass joint where it fits into the flask.
The reason is the joint between condenser and flask isn't airtight. So once you get your solvent boiling it can escape through that joint and then your flask will dry out if you leave it for long enough. Greasing the joint makes it airtight and prevents the solvent from evaporating out (also prevents air and moisture from getting in if you need to be concerned about that).
Even without greasing I have never had solvent loss through the joint, but without greasing I've had plenty of frozen joints. I guess it fulfills both functions.
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sorry, I don't understand what's frozen? does it mean the condenser and the flask becomes stuck and difficult to separate from each other at the end of the refluxing?
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sorry, I don't understand what's frozen? does it mean the condenser and the flask becomes stuck and difficult to separate from each other at the end of the refluxing?
Exactly that!
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I haven't ever lost product through that joint either; however J-bone is right, for some reactions, such as the formation of a Grignard reagent, where water will prevent product formation, it is imperative for the air tight seal, unless you're conducting the reaction in the Sahara, then by all means, use no grease!