[CH2:1]([Br:3])[Br:2].[OH-].[Na+].[CH3:6][C:7]1[CH:13]=[CH:12][CH:11]=[C:9]([OH:10])[C:8]=1[OH:14]>[Br-].C([N+](CCCC)(CCCC)CCCC)CCC.O>[CH2:1]([Br:3])[Br:2].[CH3:6][C:7]1[C:8]2[O:14][CH2:1][O:10][C:9]=2[CH:11]=[CH:12][CH:13]=1400 g of methylene bromide and 50 g of tetrabutylammonium bromide are taken under reflux in a stirred apparatus and a solution of 400 ml of water, 130 g of sodium hydroxide and 200 g of 3-methylpyrocatechol are added dropwise in the course of 5 hours. At the end of the addition, the mixture is subsequently stirred for a further 2 hours, cooled and extracted with methylene chloride. The organic phase is dried and distilled on a column. After first runnings of unreacted methylene bromide, 175 g of 4-methyl-1,3-benzodioxole are obtained.
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