Bromo phenols

Distillation should be as rapid as possible, as the o-bromo-phenol is somewhat unstable and decomposes rapidly at the high temperature. Distillation at reduced pressure has not been found to offer much improvement. 

Reagent /PhOH 2,6-dibromo- phenol 2,4,6-tribromo- phenol 2-bromo- phenol 2,4-dibromo- phenol 4-bromo- phenol ... 

Such a behavior was first observed with 1,10-phenanthroline [235,236] and bromo-phenol blue [237], and the above relationships were confirmed by measuring the voltam-mograms of various drugs as a function of pH [238 240]. 

Becker (4) has found that oxidation of 2.6-di- -butyl-4-bromo-phenol in the presence of pentachlorophenol gives the cyclohexadienone (XXVIII). 

When the solution is complete, add 50 ml of 0.05N hydrochloric acid, the first 10 ml drop by drop to precipitate the NC in a fine state of division, and then the remainder quickly until the whole quantity has been added. After 10 minutes add 2 ml of bromo-phenol blue solution and titrate with 0.1N sodium hydroxide. To confirm the endpoint, stop the stirrer, allow the NC to settle and compare the color of the supernatant liquid with that in a blank experiment, which must be carried out in an exactly similar manner, except that the propellant is omitted... 

Many color reagents are applicable to the oligosaccharides. Some of those used are ammoniacal silver nitrate,60 resorcinol-hydrochloric acid for inulin hydrolyzates,137 acidic benzidine for maltodextrins,138 Bromo-phenol Blue or p-anisidine-hydrochloric acid for galactosiduronic acids,130 and alkaline copper reagent with phosphomolybdic acid for dextrins.71... 

The lifetimes of some of these carbanions may be limited by their dissociation to a phenyl radical and a stable anion. This pattern of reaction has been demonstrated in the -induced quantitative deiodina-tion of the iodobenzoic acids, as well as in the debromination of p-bromo-phenol (Anbar et al., 1967). 

Poly(oxy-1,4-phenylene) is obtained by electrooxidative polymerization of / -bromo-phenol in aqueous NaOH solution. The yield increases when aqueous NaOH is replaced by aqueous KOH or when the reaction is conducted at higher temperature. In contrast, p-chlorophenol electrooxidatively dimerizes to give the biologically and pharmacologically important dioxin, 2,7-dichlorodibenzo[, ][l,4]dioxine254. In an effort to find protective chemical coatings, electrooxidative polymerization of ra-chlorophenol and ra-bromophenol was observed255. 

Gently stir 100 ml formamide with 5 g Amberlite MB1 (mixed bed resin) for 30 min. Remove resin by filtration. Add 0.3 g xylene cyanol FF, 0.3 g bromo-phenol blue and Na2EDTA to 10 mM. Store at 4°C. 

EDTA, 0.1% (wt/vol) xylene-cyanol, 0.1% (wt/vol) bromo-phenol blue... 

Oxidation of the phenol (108 R = H) with Fremy s salt gives an orthoquinone that is reducible to (108 R = OH) the same sequence of reactions with the bromo-phenol (108 R = Br) is accompanied by a shift of bromine to position 4.201... 

A comparison between the photoreactions of 2-chlorophenol and 2-bromo-phenol in a low-temperature argon matrix was carried out by Akai et al. by means of IR spectroscopy [17,18]. The formation of fulvene 6-oxide was evidenced in both systems. Homolytic C - Br cleavage was found as an additional pathway in the case of 2-bromophenol. 

As previously described for aromatic carboxylic acids, measurements of the line-widths of the CH3 resonance in methanol give the rate of exchange of hydroxylic protons on methanol, and measurements of the line-widths of the OH resonance give the rate of exchange of protons on phenol. Values of ft, k2 and k3 have been determined for p-bromo-phenol and p-nitrophenol [67], and are tabulated in Table 11. 

Applying the sample The sample with added sucrose and bromo-phenol blue as before ( 8.3.1.1), or xylene cyanol FF for acid electrophoresis, is carefully pipetted onto the surface of the gel in the slot. The volume should be such that the depth of the layer is no more than about 1 mm. The maximum volume thus ranges from 20 /A for a 1 cm slot on a 2 mm gel to 500 p for a 13 cm slot on a 4 mm gel. Up to 10 pg of RNA per pi sample volume or per square mm of gel surface can be loaded on the gels. On the acid gels, De Wachter and Fiers state that carrier yeast RNA (BDH) should be added to the samples to give this total concentration. This evidently reduces spreading of labelled RNA behind and in front of the strongest zones which is otherwise observed in the acidic system. 

The greater fiexibility of the 1 1 phenol-4-bromo-phenol system indicated by these results is consistent with NMR observations. Analysis of the C-Br carbon absorptions confirmed that the phenol and 4-bromophenol rings are connected through primary bonds. Additionally, the 1 1 phenol-4-bromophenol resol contains the most ether linkages. The ether connections between the aromatic rings are more fiexible... 

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