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ChemWiki: The Dynamic Chemistry E-textbook > Reference > Lab Techniques > Reflux

Reflux

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So, you need to drive a chemical reaction by heating it at reflux. You will need to heat the reaction at the boiling point of your solvent(s) and fit a reflux condenser to the RBF. The condenser has cold water flowing through it; the solvent which has evaporated from the reaction will condense on the surface of the condenser and drip back down into the reaction, thus preventing your reaction from drying out.

  1. Make sure all of your glassware is clean.  Rinse with water and acetone at the very least; even small amounts of impurities can act as catalysts that can drive other reactions different from your desired reaction and lower your yield. 
  2. Clamp your round-bottom flask on your heating pad and stirrer.  Make sure your stir bar is in the round-bottom before you add liquid.  If you are not using a stir bar, add boiling stones. You may also use a teflon sleave at the junction of the RBF and the condenser to prevent the ground glass joints from fusing together.
  3. Set the reflux condenser in the round bottom.
  4. Start heating your reaction. Gradually increase the temperature until the solvent boils. Some heating mantles take quite a while to heat up.

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Last Modified
10:05, 2 Oct 2013

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