Abstract: Substituting aqueous hydrogen peroxide/hydrogen bromide for bromine in a known process for producing a ditertiaryalkyl substituted hydroxybenzaldehyde such as ditertiarybutyl hydroxybenzaldehyde from the corresponding ditertiaryalkyl substituted methylphenol results in a substantially impaired yield of product.Improved yields are obtained by employing a reaction temperature of at least 40.degree. C., preferably 50.degree. to 80.degree. C. in conjunction with a hydrophobic solvent such as chloroform. Preferably, the process employs very concentrated hydrogen peroxide solution, 65% to 75% w/w, introduced into the bromide-containing reaction mixture during a period of from 25 to 75 minutes.

Abstract: A multi stage process for the conversion of 2-chloro-4-sulphotoluene (SCT) to 2-chloro-4-sulphobenzoic acid (SCUBA). Stage (a) comprises a process S1 for the selective side chain bromination of SCT to 2-chloro-4-sulpho-dibromotoluene (SCDBT) or 2-chloro-4-sulpho-bromotoluene (SCMBT) by contacting the starting material with bromine in chloroform or trichloroethane and irradiating the mixture with light that dissociates bromine. Subsequently, in stage (b), process S2, the product of S1 can be hydrolysed at elevated temperature after separation from the organic solvent to the corresponding alcohol (SCOL) or aldehyde (SCAB). In stage (c), the product of S2 can be oxidized to SCUBA either by oxidation with a peroxyacid, optionally generated in situ, provided that the aqueous solution has previously been stripped of bromide/bromine in process S3.

Abstract: Selective bromination of alkylarenes to the alpha dibrominated derivative is desirable as a precursor for the selective production of, for example, the corresponding aromatic aldehyde.Improvements in the extent of selectivity of the product and/or its rate of production can be obtained by employing a photolytic reaction between the substrate, hydrogen peroxide and hydrogen bromide using mole ratios of H.sub.2 O.sub.2 : substrate of about 2.8:1 or higher, preferably 3,2: to 3.5:1 and of bromide:substrate of over 2.5:1, preferably about 2.8:1 to 3.2:1 and progressive controlled introduction of the H.sub.2 O.sub.2, the reaction being carried out in the presence of a substantial amount of an organic solvent, and preferably more than 5.5 volumes per volume of substrate, whilst irradiating with light preferably having principal emissions in the range of 250 to 600 nm. The reaction mixture is preferably maintained at 50.degree. to 60.degree. C.