Process for preparing a 4-hydroxy-benzodioxol
AssigneeFisons Limited
InventorHarold George Haynes
Life of this patent
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Abstract
4-Hydroxy-benzodioxoles of formula ##STR1## in which R.sup.1 and R.sup.2 are alkyl of 1 to 4 carbon atoms or together represent an alkylene chain of 5 to 7 carbon atoms, which can be converted to pesticides, e.g. by reaction with methyl isocyanate, are prepared by reacting pyrogallol with a ketal of formula ##STR2## in which R.sup.3 and R.sup.4 are alkyl of 1 to 4 carbon atoms, at at least 90.degree. C.
Claims14
Process for preparing a 4-hydroxy-benzodioxole of the formula ##STR17## in which R.sup.1 and R.sup.2 are the same or different and each represents alkyl of 1 to 4 carbon atoms or together represent alkylene of 5 to 7 carbon atoms,
- which process comprises the step of reacting pyrogallol with a ketal of the formula ##STR18## in which R.sup.1 and R.sup.2 are as defined above and R.sup.3 and R.sup.4 are the same or different and each represents alkyl of 1 to 4 carbon atoms, at a temperature of at least 90.degree. C in the absence of any material which is not pyrogallol, the ketal, a reaction product of the process claimed herein or an inert diluent.
Process for preparing 2,2-dimethyl-4-hydroxybenzodioxole which comprises the step of reacting pyrogallol with 2,2-dimethoxypropane at a temperature of at least 90.degree. C in the presence of an inert solvent for the reactants and in the absence of any material which is not pyrogallol, 2,2-dimethoxypropane, a reaction product or an inert diluent, while distilling off the solvent and methanol from the reaction mixture and adding to the reaction mixture additional 2,2-dimethoxypropane during the distillation.
Dependencies are inferred from the claim text.