Bromophenol blue reagent

Abbott et al. [I] have undertaken an exhaustive investigation of the separation of 16 chlorine-containing insecticides. They used kiesel-guhr G, alumina 6 and mixed layers of silica gel G and alumina G (1 + 1) as well as the ordinary silica gel G. The huB/-values found in five of the 15 solvents tried out are given in Table 142 (Nos. Ill and X—XIII). Colour differentiation was obtained with a silver nitrate-bromophenol blue reagent. 

Bromocresol Green — Bromophenol Blue — Potassium Permanganate Reagent... 

Bromocresol Green—Bromophenol Blue—Potassium Permanganate Reagent 229... 

Modras (51) reported spot test reactions to differentiate hydralazine from closely related drugs. Reagents used were aqueous copper (I) chloride, aqueous ammonium molybdate, iodine in potassium iodide solution, aqueous cobalt (II) nitrate, alcoholic ninhydrin, and alcoholic bromophenol blue. The tests were performed on paper or on Silica Gel G. 

Buffered Indicator Solution Prepare a mixture consisting of 700 mL of 0.1 M citric acid (anhydrous, reagent grade), 200 mL of 0.2 M disodium phosphate, and 50 mL each of 0.2% bromophenol blue and of 0.2% bromocresol green in spectrograde methanol. 

Colored reagents to follow the appearance or the disappearance of a functional group have been widely used to monitor reactions in classical organic chemistry, particularly in TLC analysis. This technique has been successfully adapted to SPS for example, ninhydrin (118), bromophenol blue (119), nitrophenyl isothiocyanate-O-trityl (120), picric acid (121), and malachite green isothiocyanate (122) have all been used to show the presence or the absence of free resin-bound amines. The presence of free resin-bound thiol groups can also be detected (123). 

Bromocresol Green—Bromophenol Blue—Potassium Pemumganate Reagent... 

The use of a low excess of the building block requires careful control of the progress of the acylation reaction. Besides the 3-hydroxy-4-oxo-3,4-dihydro-l,2,3-benzotriazine reagent 23, the incorporation of the building block can be monitored by addition of Bromophenol Blue (0.05% of the resin loading) [52,67,73] or Violet Acid 17 [20] to the reaction vessel, as well as the ninhydrin test [74]. If the coupling is carried out by in situ formation of the 1-hydroxybenzotriazole ester, an excess of 1-hydroxyben-zotriazole is required for reliable monitoring with Bromophenol Blue. 

A mixture of vinblastine sulfate and testolactone is determined by precipitation at pH 3.7 with a measured volume of Na tetraphenylborate solution, and titration of unconsumed reagent with hexadecylpyridinium chloride using bromophenol blue as an indicator (105). 

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