Acid base indicator, the color changes from light yellow to purple red, and the pH value of the color change range is 5.2-6.8. Uses Bromocresol violet is mainly used as acid-base indicator and nonaqueous solution titration indicator. Uses Used as acid base indicator and non-aqueous solution titration indicator Uses Acid base indicator, chromatographic analysis, non-aqueous solution titration indicator. PH discoloration range: 5.2 (yellow) - 6.8 (purple). Adsorption indicator. Internal standard of amino acid chromatography. Titrate thiocyanate by silver salt method. The serum protein was precipitated by spectrophotometry. The production method is to dissolve o-toluidine in dilute sulfuric acid, cool it, add sodium nitrite solution under stirring, and control the reaction temperature below 5 ℃. After the reaction, heat it to 40-50 ℃ until there is no bubble, cool it, filter it, and fractionate o-cresol. Mix o-cresol, o-toluenesulfonic anhydride and zinc chloroform, stir and heat them, react at 115-120 ℃ for 7h, remove the remaining o-cresol with steam, and filter to obtain o-cresol red: o-cresol red is refined and dissolved in glacial acetic acid, add the mixed solution of bromine and glacial acetic acid under stirring, heat at 40-50 ℃ for 4h, cool and filter to obtain bromocresol violet.
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