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Dehydration of Phenyl-1-propanol with any suitable catalyst like p-Toluenesulfonic Acid or Potassium Hydrogen Sulfate will eliminate water from the alcohol

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Reference:

https://www.thevespiary.org/rhodium/Rhodium/chemistry/p1pol.elimination.html#khso4

Now does that mean that it would work on MDP2POL that degraded to MDP1POL?

Yes, the same procedure would work for the conversion of MDP1Pol to Isosafrole.

Is is also used in Pihkal #94 for the synthesis of 1-(3,4-Methylenedioxyphenyl)-2-butene from 1-(3,4-methylenedioxyphenyl)-1-butanol.