3-Nitroacetophenone preparation

That's a good answer.  But you should also investigate other reasons.  Consider, could it get so hot that the reagent evaporates?  You get no yield from reactant in the air of the hood, instead of the flask.  Could excess heat drive the reaction backwards?  You might want to investigate that.  That is, prove it before you start to claim that.

The reaction is highly egzotermic and produces lots of heat, i dont know if it may start a fire, the chemical is instable in big temperature, i dont know if its explosive?

Thank You!!

Also look at this thread, a forum regular has asked much the same question over here: http://www.chemicalforums.com/index.php?topic=79245.0

You must show you have attempted the question, this is a Forum Rule.

What will happen to the temperature if the reaction is not cooled?
Why might this cause a problem?