The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 03, 1992
Filed:
Mar. 20, 1989
Philip J Turner, Widnes, GB;
Martin Jeff, Houston, TX (US);
Interox Chemicals Limited, London, GB;
Abstract
Selective bromination of alkylarenes to the alpha monobrominated derivative is desirable as a precursor for the selective production of, for example, the corresponding alcohols. The product can be obtained by a photolytic reaction between the substrate, hydrogen peroxide and hydrogen bromide in approximately equimolar ratios in an organic solvent, but improvement in the yield of the product coupled with similar or improved selectivity in its production was either not achieved or was actually impaired by a range of variations in the ratios and by omitting the solvent. The invention employs mole ratios of H.sub.2 O.sub.2 :substrate of 0.1:1 to 0.4:1, preferably 0.2:1 to 0.33:1 and of H.sub.2 O.sub.2 :bromide of 1:1.2 to 1:2, preferably about 1:1.3 to 1:1.8 and progressive introduction of the H.sub.2 O.sub.2, either in the presence or absence of the solvent, while irradiating with light preferably having principal emissions in the range of 250 to 600 nm, and the process thereby achieves either or both of improved yield and improved selectivity of the alpha monobrominated product. The reaction mixture is preferably maintained at 50.degree. to 70.degree. C. The process is especially suitable for deactivated alkylarenes, such as o-nitrotoluene.