In the wacker, Pd+2 is reduced to Pd(0) while at the same time, safrole is oxidized to MDP-2-P. In order to avoid using ~1g PdCl2 per gram safrole, the Pd(0) must be reoxidized to Pd+2. This can be done in many ways. In one method, benzoquinone is reduced to hydroquinone while oxidizing the palladium. In another method, CuCl2 is reduced to CuCl while oxidizing the palladium. Benzoquinone can be used in stoichiometric quantities, but CuCl2 cannot because the chloride ions inhibit the reaction. Therefore, the CuCl is reoxidized to CuCl2 using oxygen or an alkyl nitrite. Three methods evolve from these three oxidation steps:
1) The benzo wacker
2) The O2 wacker
3) The alkyl nitrite wacker
Although I have never done it, the benzo wacker seems the easiest for newbees. The other two have several bugs in them that I am trying to work out right now.
There are two simultaneous reactions that the safrole undergoes in the wacker. One of them is the oxidation to MDP-2-P. The other is the isomerization to isosafrole. Both of these are catalyzed by palladium. The benzo and O2 wackers produce isosafrole as a byproduct. The alkyl nitrite wacker does not, b/c alkyl nitrite inhibits the isomerization.
Also, if you pull safrole at 170C, your ketone will come over at about 215-220C, right in the polymerizaton range. There is approximately a 45C range b/t the two boiling points. The 25C difference talk is bullshit. I strongly recommend getting a new vacuum pump, as you need a very powerful hotplate to distill something over 200C.