To-Bromophenol

Now 4 mol. are required to effect complete hydrolysis to sodium orthophosphate according to equation (c), but only 2 mol. are required either for the removal of fluorine alone and conversion into sodium di-isopropyl phosphate (d) or for conversion into disodium fluorophosphonate (e). To decide between these reactions, half of the above hydrolysis product was rendered acid to bromophenol Hue... 

A weight of compound, containing about 0-05 g. of fluorine, was dissolved in 10 ml. of dry alcohol and metallic sodium (about 0 5 g., i.e. at least 5 equivalents) was added. After the sodium had dissolved, the mixture was gently heated under reflux for 5 min.,8 and then washed out with about 100 ml. of water into a beaker, made acid to bromophenol blue with dilute nitric acid and then just alkaline with 10 per cent sodium hydroxide solution. Three ml. of 10 per cent sodium chloride solution were added and the solution was diluted to 250 ml. One ml. of concentrated hydrochloric acid was added, and the solution heated on a water-bath to about 80°. Then 5-0 g. of finely powdered A.R. lead nitrate were added with stirring (still at 80°). As soon as all the lead nitrate had dissolved, 5-0 g. of crystalline sodium acetate were added, with vigorous stirring. The product was then heated on the water-bath for 15 min. and cooled in ice, and the precipitate was filtered off on a Swedish filter paper. It was washed once with water, four times with saturated PbClF solution... 

At a temperature of 78° C. the velocity constant whether referred to a unimolecular or a bimolecular reaction diminished with time after an hour rather less than three-quarters of the original metaphosphate remains.6 The product is mainly orthophosphate, as was proved by titration with methyl orange and phenolphthalein, although small quantities of pyrophosphate were formed by a side reaction. The pyro-acid was determined by titration to bromophenol blue in the presence of zinc sulphate, which leads to a complete precipitation of pyrophosphate, the ortho-acid being unaffected, thus... 

Alternatively, bromination of phenol red to bromophenol blue may be used (29). 

Soap in oil (ppm) Measures alkalinity (as sodium oleate) of oil sample by titration to bromophenol blue endpoint with 0.01 N HCI Cd 17-95... 

Fig. 9.4. Densitometer traces of stained poly(rA) zones after electrophoresis in 2.4% gels, a) Typical unfractionated sample, b) Fractions prepared by salt precipitation, c) Fractions made by preparative electrophoresis. The broken line is the profile of tRNA. Intensities are normalised at the peak. Mobilities are relative to bromophenol blue. The arrow indicates the end of the gel (from Finder and Gratzer 1974).

Dissolve the sample in ethanol and titrate with alcoholic alkali to bromophenol blue, or potentiometrically to the first point of inflection, at a pH around 3. 

Titrate one with alcoholic alkali to phenolphthalein (or pH around 9), and the other with alcoholic acid to bromophenol blue (or pH around 3 or 4). 

Continue titrating with the same acid to bromophenol blue. 

Neutralise to phenolphthalein with 1.0 M ethanolic sodium hydroxide and titrate to bromophenol blue with 1.0 M ethanolic hydrochloric acid to determine the alkanolamine. 

Titrate the combined effluent to bromophenol blue with carbonate-free 0.1 M sodium hydroxide (see Note 1). 

Add 100 ml neutral ethanol and either titrate potentiometrically with 0.5 M ethanolic sodium hydroxide through end-points at pH about 3.0 and 7.7, or make just alkaline to phenolphthalein with ethanolic 3M sodium hydroxide and titrate with 0.5 M ethanolic hydrochloric acid, first to phenolphthalein and then to bromophenol blue. 

Cool and titrate first to phenolphthalein and then to bromophenol blue with 0.5 M hydrochloric acid. 

Make the solution acid to bromophenol blue with ethanolic 1 M hydrochloric acid. 

Titrate with 0.5 M ethanolic sodium hydroxide, first to bromophenol blue and then to phenolphthalein. The volume of titrant between the end-points measures unesterified carboxyl groups plus aspartate, if present. 

Acidify the aqueous layer to bromophenol blue with concentrated hydrochloric acid and extract the free fatty acid with petroleum ether. Evaporate to dryness (caution flammable vapour), dry, cool and weigh. 

Titrate with 1.0 M hydrochloric acid either first to phenolphthalein and then to bromophenol blue, or potentiometrically through two endpoints at high and low pH. The acid consumed between the end-points measures the ethanolamine. 

Note 1. If the solution is yellow at this point, the presence of free hydrochloric acid is indicated. In this case take a fresh sample, dissolve in propan-2-ol, add a measured excess of 0.1 M sodium hydroxide in propan-2-ol and titrate to phenolphthalein with 0.2 M hydrochloric acid in the same solvent. Then determine amine hydrochloride by titrating to bromophenol blue as described. 

Pipette 50 ml of the original solution (step 3) into a 150 ml beaker. Either acidify to bromophenol blue with a few millilitres of 1M hydrochloric acid and titrate potentiometrically with ethanolic 0.1 M sodium hydroxide as in step 5, or make alkaline to phenolphthalein with a few millilitres of 1 M sodium hydroxide and titrate potentiometrically with ethanolic 0.1 M hydrochloric acid as in step 6. 

Dissolve in neutral ethanol or titrate with ethanolic hydrochloric acid, either potentiometrically or to bromophenol blue, to determine the weak base. 

The B.P, avoids this error by precipitating the carbonates with barium chloride and then titrating the hydroxides with N hydrochloric acid, without filtration, to phenolphthalein (a) the titration can be continued to bromophenol blue (b) for carbonate, 1 ml N HCl = 0 06911 g K2CO3 and 0 05300 g Na2C03 total alkali (a + 6), 1 ml N = 0 05611 g KOH and 0 0400 g NaOH. Potassium hydroxide, KOH, Mol. Wt. 56 11 sodium hydroxide, NaOH, Mol. Wt, 40 00. 

To a solution of about 3 g of sample dissolved in 50 ml of water in a separator and neutralised, if necessary, to phenolphthalein, add 50 ml of ether, shake and titrate to bromophenol blue with 0-5N acid until the indicator changes to green. Then separate the aqueous layer, wash the ether with water, add 20 ml of fresh ether to the aqueous layer and washings, and continue the titration with constant shaking until the end-point is reached, only a few drops being required in the second stage. 

For bicarbonate Boil 10 g of an aqueous suspension of the powder with 150 ml of water for ten minutes, cool, filter, washing the residue with 100 ml of warm water, and titrate the filtrate to bromophenol blue. 

Dissolve 0 15 g in 200 ml of water and add dilute nitric acid until almost neutral to bromophenol blue. Heat to boiling-point and add 20 per cent sodium hydroxide solution, dropwise, until just alkaline. Then add a solution of 0-3 g of sodium chloride in 5 ml of water followed by 3 ml of dilute hydrochloric acid, 5 g of lead nitrate dissolved in 50 ml of hot water and finally 5 g of sodium acetate, stirring vigorously. Heat on a water-bath for thirty minutes with occasional stirring, cool and allow to stand for sixteen hours. Filter and wash the residue first with 10 ml of water and then with four quantities, each of 5 ml, of lead chlorofluoride solution (prepared as follows dissolve 10 g of lead nitrate in 200 ml of water and add a solution of 1 g of sodium fluoride in 100 ml of water followed by 2 ml of concentrated hydrochloric acid. Mix, allow to settle, decant the supernatant liquid and wash the precipitate by decantation with successive quantities, each of 200 ml, of water. Add 1 litre of water to the precipitate, shake thoroughly, allow to stand for one hour and filter). Final v wash with 5 ml of water, transfer the residue to a... 

Dissolve about 0 6 g in 10 ml of dehydrated ethanol, add and dissolve 0-5 g of sodium. Reflux gently for five minutes and then dilute with 100 ml of water. Make just acid to bromophenol blue with dilute nitric acid and then just alkaline with 5 per cent sodium hydroxide solution. Add 3 ml of 10 per cent sodium chloride solution, dilute to 250 ml with water, add 1 ml of concentrated hydrochloric acid and heat to about 80°. Add, with stirring, 5 g of finely powdered lead nitrate and when dissolved add, w ith vigorous stirring, 5 g of sodium acetate trihydrate. Filter, wash the residue first with water and then with four successive quantities of lead chlorofluoride solution (prepared as follows dissolve 0 1 g of sodium fluoride in 100 ml of water and add 0-25 ml of bromophenol blue indicator, 3 ml of 10 per cent sodium chloride solution and 200 ml of water. Then add concentrated nitric acid, dropwise, until the solution turns yellow followed by 5 per cent sodium hydroxide solution until the solution turns faintly blue add 1 ml of concentrated hydrochloric acid, maintain at 80° for ten minutes, add 5 g of finely powdered... 

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