This procedure is called chloromethylation and will not only turn 1,3-benzodioxole into a methyl chloride but will work equally well in converting plain old benzene into benzyl chloride. Both are important stepping stones towards the production of X and meth. For example, benzyl chloride is a schedule I controlled substance because it will beget benzaldehyde and phenylacetonitrile (a precursor for phenylacetic acid).
The best method Strike found for this  does not use ZnCI which is usually included in this procedure as a facilitator to the addition of the chlo-romethyl group [37 p539, 136]. Strike does not feel that mistake of omission had occurred so Strike will proceed as such. 366g 1,3-benzodioxole, 99g paraformaldehyde and 500mL toluene are placed in the reaction -240-
flask of the apparatus shown in figure 16. This whole setup looks a little involved but it really isn't. The flask has all the components and HCI gas comes from either a gas cylinder or an HCI gas generator using H2S04 and HCI/NaCI which happens to be the exact same generator that the chemist is going to have anyway so that she can crystallize her freebase product (see crystallization section). Either sulfuric acid is dripped into the HCI/NaCI or the valve on the cannister is opened so that a gentle, steady little stream of HCI gas starts bubbling into the reaction fluid. The temperature needs to remain between 25-35°C as the bubbling continues for 3-4 hours. The solution is washed twice with cold water, twice with dilute sodium carbonate solution and once again with water. The solvent is dried through Na2S04 and distilled to give what is essentially called piperonyl chloride or benzyl chloride (yield= 70-90%). Now, if this procedure does not work as described then one should blame the Japanese, who said it would and then proceed to try it over again except this time one is going to add 30g of zinc chloride.
Continue reading here: Piperonal or Benzaldehyde From Chloromethyl Intermediate
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