Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C315/00—Preparation of sulfones; Preparation of sulfoxides
  • C07C315/04—Preparation of sulfones; Preparation of sulfoxides by reactions not involving the formation of sulfone or sulfoxide groups
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C317/00—Sulfones; Sulfoxides
  • C07C317/44—Sulfones; Sulfoxides having sulfone or sulfoxide groups and carboxyl groups bound to the same carbon skeleton

Definitions

• the invention relates to a process for the preparation of 3-bromomethylbenzoic acids by bromination of the corresponding 3-methylbenzoic acids. It also relates to certain 3-bromomethylbenzoic acids.
• Bromomethyl aromatics can in principle be prepared from the corresponding methyl aromatics by side chain bromination, cf. Houben-Weyl, Vol. 5, page 331 ff. (1960).
• electron-negative substituents such as carboxyl, alkylcarbonyl, cyano and nitro significantly hinder the reaction, so that only poor yields can be achieved.
• WO 99/06339 discloses a process for the preparation of substituted benzyl bromides by bromination of the corresponding methyl aromatics in the presence of azocarboxylic acid esters or nitriles and in the presence of an oxidizing agent.
• EP-A 0 292 944 describes the preparation of 3-bromomethyl-2-chloro-4-methylsulfonyl-benzoic acid methyl ester by free-radical initiating bromination of 2-chloro-3-methyl-4-methylsulfonyl-benzoic acid methyl ester in carbon tetrachloride. The free acid 3 ⁇ bromomethyl-2-chloro or 4-methylsulfonylbenzoic acid is then prepared from this last-mentioned compound by saponification.
• the present invention thus relates to a process for the preparation of 3-bromomethylbenzoic acids of the general formula II
• R 1 for fluorine, chlorine or bromine
• R 2 represents (CC 4 ) alkyl.
• Suitable radical initiators for the bromination according to variant A) are commercially available radical initiators known to those skilled in the art, such as diaroyl peroxides, azocarboxylic acid esters and azocarboxylic acid nitriles. For example, azoisobutyronitrile and Called dibenzoyl peroxide. Irradiation with light according to variant B) takes place with commercially available photo lamps and is basically known to the person skilled in the art.
• solvents which have been found to be inert to the bromination conditions have proven suitable. These include, for example, halogenated hydrocarbons such as methylene chloride, chloroform, carbon tetrachloride, 1, 2-dichloroethane and chlorobenzene and compounds such as acetonitrile.
• halogenated hydrocarbons such as methylene chloride, chloroform, carbon tetrachloride, 1, 2-dichloroethane and chlorobenzene and compounds such as acetonitrile.
• the solvents chlorobenzene and acetonitrile have been found to be advantageous for process variant A) and the solvents chlorobenzene, methylene chloride and 1,2-dichloroethane for process variant B). Mixtures of these solvents can of course also be used.
• the reaction is generally carried out at a temperature of 40 to 100 ° C., preferably 70 to 100 ° C.
• the process is preferably carried out under reflux.
• NBS N-bromosuccinimide
• free-radical initiator is advantageously introduced in solvent and then slowly warmed up. If necessary, the reaction can be accelerated by adding a little bromine. NBS is preferably used in excess.
• a compound of the formula I is advantageously initially introduced in solvent and then bromine is added dropwise after heating with irradiation with a photolamp. Bromine is preferably used in excess.
• the reaction mixture is allowed to cool. If the bromination was carried out according to process variant A), it is expedient to first add sodium bisulfite solution and optionally solvent. Further processing then depends on the solubility and purity of the product. In the case of process variant B), the reaction product can generally be suctioned off directly after cooling. In both cases, the reaction product is washed and, if necessary, further purified by recrystallization, for example from ethyl acetate or butyl acetate.
• R 1 for fluorine, chlorine or bromine
• R 2 stands for (-CC 4 ) -alkyl, and the compound 3-bromomethyl-2-chloro-4-methylsulfonyl-benzoic acid should be excluded.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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• 2002
  • 2002-08-29 JP JP2003526877A patent/JP2005502701A/ja active Pending
  • 2002-08-29 KR KR10-2004-7003499A patent/KR20040034718A/ko not_active Application Discontinuation
  • 2002-08-29 HU HU0401197A patent/HUP0401197A3/hu unknown
  • 2002-08-29 WO PCT/EP2002/009630 patent/WO2003022800A1/de not_active Application Discontinuation
  • 2002-08-29 MX MXPA04002291A patent/MXPA04002291A/es unknown
  • 2002-08-29 BR BR0212422-0A patent/BR0212422A/pt not_active IP Right Cessation
  • 2002-08-29 EP EP02772228A patent/EP1427700A1/de not_active Withdrawn
  • 2002-08-29 IL IL16081802A patent/IL160818A0/xx unknown
  • 2002-08-29 US US10/489,142 patent/US20040236146A1/en not_active Abandoned
  • 2002-08-29 CN CNA028177045A patent/CN1553891A/zh active Pending

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