Bromophenols, simple

Effective use can sometimes be made of removable blocking groups on the ring. Suppose you are set the task of making pure < -bromophenol. Simple bromination of phenol will fail because of the dominant formation of the para isomer or of poly-brominated compounds (Fig. 14.90). A solution to this problem is first to sulfonate... 

Because of its mild reaction conditions, simple experimental operations, and generally excellent yields of o/t/zo-bromophenols, our method is practical for a wide variety of bromination of phenols (Scheme 6) and expected for industrial preparation of fine chemicals. 

El-Ashry et al. [36] studied the complex formation between the bromophenol blue, primaquine, and other important aminoquinoline antimalarials. The colorimetric method used was described as simple and rapid and is based on the interaction of the drug base with bromophenol blue to give a stable ion-pair complex. The spectra of the complex show maxima at 415 420 nm with high apparent molar absorptivities. Beer s law was obeyed in the concentration range 1-8,2-10, and 2-12 pg/mL for amodiaquine hydrochloride, primaquine phosphate, and chloroquine phosphate, respectively. The method was applied to the determination of these drugs in certain formulations and the results were favorably comparable to the official methods. 

DMAC does not detect urea, but uronium ion (8). Another color test for urea nitrate, which is less specific but is simple and quick, was developed in Israel by A. Bomstein. It is based on the fact that urea nitrate is highly acidic thus, the pH indicator bromophenol blue changes its color from blue to yellow upon reaction with trace amounts of urea nitrate [95]. Red pigment formation in the reaction between p-DMAC and urea nitrate [91, 92] is as follows ... 

In closing this section, it should be mentioned that simple bromophenols (2-bromophenol, 4-bromophenol, 2,4-dibromophenol, 2,6-dibromophenol, and 2,4,6-... 

Cinchona diimides have also been used to develop a simple colorimetric indicator displacement assay for the determination and chiral discrimination of tartaric acid. Thus, conjugation of 72 with bromophenol blue 73 resulted in the formation of a dark blue complex (A,m lx at 597 nm) that after treatment by an appropriate acid released the protonated form of the indicator with a well-separated absorption maximum at 426 nm. This assay allowed to determine (R,R)-tartaric acid with the detection limit as low as 0.02 mg/ml and efficiently discriminated the enantiomers of tartaric adds,... 

Similarly, reaction with, V-acetyI-2-bromoaniline gives quinolones after retro-Diels-Alder cleavage13. With 2-bromophenol and norbornadiene under similar conditions, a competitive pathway results in simple hydrocarboxylation without cleavage of the C-Br bond13. The reaction of 2-iodophenol with ethynylbenzene leads to an alkylidenebenzofuranone,3. 

The formation of the imines and their subsequent reduction was monitored by the disappearance of the starting amine (ninhydrin staining, TLC). Simple quenching with water and drying of the organic solutions with MgS04 constituted the reaction work-up. The condensation of the amines with isothiocyanates and TEA was monitored by TLC (blue bromophenol staining, disappearance of... 

The recipe is simple 4 g potassium chlorate, KCIO3, (or 3.3 g sodium chlorate) and 12.5 g sodium sulfite, are dissolved in about 75 mL of distilled or deionized water. Add a few milligrams of bromophenol blue. (The solution should be a dark blue.) Slowly add 4 mL of 3 M sulfuric acid while the solution is stirred, and dilute... 

A brominated diterpene, concinndiol, an isomer of aplysin-20, has been recently described from the alga Laurencia concinna (171). Some simple bromophenols also occur in algae (160, p. 88) and a highly brominated phenolic pyrrole has been found in a marine bacterium (111, 132). 

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