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Banana asked in 科學及數學化學 · 1 decade ago

heat and reflux

I would like to know the difference of the meaning of heat and reflux in organic chemistry. As all organic substances are volatile, why some of the reaction need to use heat but not reflux?

2 Answers

Rating
  • 1 decade ago
    Favorite Answer

    some reactant such as amine is very sensitive to heat. if u overheat them, they will decompose. if u just continuously heat up a solution that requires not so much energy, u might just ruin the reaction as u will not synthesize the desired product. another bad example of heating is when one of ur active reactants is glucose. if u overheat glucose, it is like combusting them and they simply go brown and lose their reactivity. refluxing tends to be heating the solution at a fixed temperature. although it will be hard trying to maintain at a fixed temperature, a range is usually given. for example, if the amine decompose at 170*C, and u want to input as much activation energy as possible, u might try to maintin your sand bath at around 155*C - 165*C.

  • choy
    Lv 5
    1 decade ago

    Reflux is employed to prevent the volatile substances from escaping since:

    1. the quantity of the volatile substances left after heating is important for the experiment, e.g. for chemical calculation.

    AND/OR

    2. the escape of the volatile substance causes hazard such as poisoning or explosion.

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