Novel process for preparation of 3-bromoanisole and 3-bromonitrobenzene

A technology of bromonitrobenzene and bromoanisole, which is applied in the new field of preparing 3-bromoanisole and 3-bromonitrobenzene, can solve the problems of expensive and difficult to use, and achieve high yield and high purity Effect

Inactive Publication Date: 2001-05-23
BROMINE COMPOUNDS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The main disadvantage of this method is the relatively expensive and technically difficult to use alkali metal bromate

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0054] Preparation of BNB by bromination of nitrobenzene in oleum

[0055] Introduce 1.24 g of iodine and 427 g of H into a 1 liter flask equipped with a mechanical stirrer, condenser, thermometer and dropping funnel at room temperature 2 SO 4 (97%), with stirring and cooling, add 316 g of oleum (65% free SO 3 ). 246 g (2 mol) of nitrobenzene are added dropwise within 1 hour at a temperature of 10-12° C., followed by 128 g (0.8 mol) of bromine at 20° C. within 2.5 hours. Stirring was continued for an additional 2.5 hours at 30°C. Samples were taken during bromination and analyzed by GC to check reaction conversion. After the reaction was finished, the reaction mixture was carefully added to 540 g of water at 70-80° C. within 0.5 hours. Phase separation at 60°C gave 350 g of crude BNB and distillation at a pressure of about 20 mmHg and 100-130°C gave 230 g of BNB with a purity of 98-99% (GC area). About 75 g of the initial fraction of nitrobenzene was used in the followin...

Embodiment 17

[0067] Preparation of MBA using prepared solid sodium methoxide

[0068] To a 1 liter reactor equipped with a mechanical stirrer and a reflux condenser was added 60 ml of toluene, BNB (60.6 g, 0.3 mol), sodium methoxide powder (19.4 g, 0.36 mol), solid KOH powder (33.6 g, 0.51 mol) and tetrabutylammonium bromide (18.2 g, 0.056 mol). Air is forced into the reaction solution during the reaction to quench unwanted free radical reactions. The homogeneous mixture was stirred vigorously at 50°C for 1-2 hours (GC analysis showed >99% conversion of BNB). The mixture was then cooled and inorganic compounds were removed with water, followed by phase separation. The organic phase was washed with aqueous hydrochloric acid to remove PTC and its residual decomposition products after washing with water. Gas chromatography of the organic phase obtained after separation showed an MBA content of 97% (area %); less than 0.2% of reduced products were formed.

[0069] Alternatively, instead of...

Embodiment 18

[0071] The method was as described in Example 17 except that solid potassium methylate was used instead of sodium methylate. After 1 hour, the reaction mixture was analyzed by gas chromatography. Analysis showed an MBA content of 95% (area %).

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PUM

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Abstract

Process for the preparation of 3-bromoanisole comprising methoxydenitrating 3-bromonitrobenzene in the presence of a phase-transfer catalyst (PTC), and the preparation of 3-bromonirtobenzene by the bromination of nitrobenzene with bromine in oleum. The methoxydenitration reagent in an alkali metal methoxide, which is selected from sodium methoxide and potassium methoxide. The amount of methoxide used is 1-1.5 mol per mol of 3-bromonitrobenzene. The alkali methoxide can be a pre-prepared solid or it can be prepared in situ, by the reaction of the corresponding alkali hydroxide and methanol. In the case when pre-prepared solid methoxide is used, the effective amount of alkali hydroxide is between 1.2-1.7 mol per mol of 3-bromonitrobenzebe. The reaction temperatures are between about 40 to 80° C., with preference to reaction temperatures of 50 to 55° C. In the case in which methoxide is prepared in situ, the effective amount of alkali hydroxide is between 2.2-2.4 mol per mol of 3-bromonitrobenzene. The reaction temperatures are between about 50 to 80° C. with preference to reaction temperatures of 55 to 65° C.

Description

field of invention [0001] The present invention relates to a process for the preparation of 3-bromoanisole by denitration and methoxylation of 3-bromonitrobenzene in the presence of a phase transfer catalyst. Background of the invention [0002] 3-Bromoanisole (hereinafter also denoted as MBA) is an intermediate in the pharmaceutical field. It is especially used in the production of the painkiller Tramadol. [0003] Among the several known methods for preparing MBA, the most commonly used is the methylation reaction based on m-bromophenol. See eg Hewett, J. Chem. Soc. 50 (1936) and Natelson, Gottfried, J. Amer. Chem. Soc. 61, 1001 (1939). M-bromophenol itself is prepared from m-bromoaniline or m-aminophenol through diazotization reaction. Berti et al reported a method for preparing MBA from m-aminoanisole by diazotization reaction in Ann. Chim 49, 1237, 1248 (1959). [0004] A major disadvantage of these known methods for the industrial production of MBA is that they use...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C41/01C07C43/225C07C201/12C07C205/12
CPCC07C205/12C07C41/01C07C201/12C07C43/225
Inventor M·格尔蒙特J·兹尔博曼
Owner BROMINE COMPOUNDS
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