OF AROMATIC ETHERS

FIELD OF THE INVENTION

The present invention relates to the process tor the preparation of halogenated derivatives of aromatic ethers Formula I.

BACKGROUND OF THE INVENTION

The haiogenated derivatives of aromatic ethers of Formula i play an important role as precursors for the preparation of medicaments and crop protection agents.

wherein R and R' together are an oxygen atom, and X represents a hydrogen, fluorine, chlorine, bromine or iodine.

The U,S Patent No. 7, 148,365 describes a process for the preparation of 5-bromo- 2,2-difluorobe.nzo-l ,3-dioxoies by reaction of 2,2-dif!uorobenzo- 1.3-dioxoles with bromine in the presence of at. least two Friedel-Crafts catalysts of which one is hydrogen fluoride

The US Patent No. 4,895,871 describes a process of preparation of 5-bromo-2,2- ciifluorofoenzo-i, 3-dioxoles by reaction of 2,2-di iluorobeiizo- 1 ,3-d toxolcs with bromine in the presence of carbon tetrachloride and iron powder.

The processes disclosed in the listed prior art employ either toxic solvents and/or lewis acids, however, the yield, of mono bromo derivatives obtained from such processes is substantially low. Thus, there is a need in the art to provide simple, cost-effective and industrially scalable process for the preparation of compounds of Formula I.

SUMMARY OF THE INVENTION The present invention provides a process for the preparation of compounds of Formula I, comprising; a) reacting compound of Formula II with the source of bromine in the presence of hydrogen peroxide, and

wherein R and R' together are an oxygen atom, and X represents a hydrogen, fluorine, chlorine, bromine or iodine; b) isolating compound of Formula I.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a process for the preparation of compounds of Formula L comprising; a) reacting compound of Formula II with the source of bromine in the presence of hydrogen peroxide, and

wherein R and R' together are an oxygen atom, and X represents a hydrogen, fluorine, chlorine, bromine or iodine; b) isolating compound of Formula L

The compound of Formula II may be prepared by any method known in the art, for example, method known in U.S Patent No. 4,895,871. The bromine source may be any alkali metal bromide with mineral acid orhydrogen bromide. The alkali metal bromide may be selected from sodium bromide, potassium bromide and caesium bromide.The step a) may take place in the presence of mineral acid The mineral acid may be selected from hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, hydrofluoric acid,fiuorosulfonic acid,chlorosulfonic acid or mixture thereof.The step a) may be carried out in the presence or absence of organic solvent. The step a) may be carried at a temperature of about -15°C to about 100°C, for example, at about 5°C to about 80°C. The step a) may be aided by stirring the contents. The step a) may take place for about 5 minutes to about 24 hours, for example, 10 minutes to about 60 hours, for example, 30 hours to about 50 hours.

The process for preparation of compound of Formula I may be carried in a continuous mode.

The compound of Formula 1 is isolated from step a) reaction mixture. The compound of Formula I may be isolated by filtration, layer separation, decantation, evaporation, concentration, crystallization and distillation or mixture thereof.

While the present invention has been described in terms of its specific embodiments, certain modifications and equivalents will be apparent to those skilled in the art and are intended to be included within the scope of the present invention. EXAMPLE

Example 1

Process of preparation of 5-bromo-2,2-difluoro-1,3-benzodioxole:

A mixture of 2,2-difluoro-l ,3-benzodioxote (560 g) and Hydrogen bromide(l 100 g, Assay 47%) were taken in a reaction vessel fitted with cold condenser. The reaction mixture was cooled to 10°C and 30 % Hydrogen Peroxide solution (806 g) was added slowly in lot wise. Upon completion of addition, the temperature of the reaction mixture was cautiously raised to 70°C. The organic layer was separated and washed with 20 % of sodium metabisulfite and then washed with 20% of potassium bicarbonate solution. The organic layer was dried over magnesium sulfate and filtered. The filtrate was distilled under high vacuum to obtain the title compound.

Yield: 538 g