Phenolphthalein, similarity

A special feature of the fixed eruption is shown by certain observations of double or triple sensitization at separate sites of the skin. In a large series comprising 484 cases, Furuya et al. (1966) found double sensitization to barbital and amidopyrine in two patients, and in another sulfadiazine and phenobarbital were the causes. In a female patient investigated in collaboration with P. Schmidt (Schulz and Schmidt 1967) fixed eruptions appeared consecutively at different sites. Some of the lesions were induced by barbiturates (right hand), while a second group was due to aminophenazone (left forearm) and another lesion (on the back) was provoked by phenolphthalein. Similar phenomena have been described by Sulzberger (1940). 

Example. Dissolve 0 3 g. of />-chlorobenzoic ncid in a small quantity of warm ethanol (about 10 ml.), and ctlrefully add 5 o aqueous sodium hydroxide drop- wise until the solution is just pink to phenolphthalein. Evaporate to dryness on a water-bath. Dissolve the sodium -chlorobenzoate in a minimum of water, add a solution of 0-5 g. of phenacyl bromide in ethanol (about 5 ml.), and boil the mixture under reflux for i hour, and then cool. The phenacyl ester usually ciy stallises on cooling if it does not, add water dropnise with stirring to the chilled solution until separation of the ester just begins. Filter the ester, wash on the filter with water, drain and recrystallise from ethanol m.p. 90 . The /)-bromophenacyl ester is similarly prepared, and after recrystallisation from aqueous ethanol has m.p. 128 . (M.ps., pp. 543-545.)... 

Most water analysis results are rather easily interpreted. However, two simple and useful tests need explanation. These are the P and M alkalinity. The water is titrated with N/30 HCl to the phenolphthalein end point at pH 8.3. This is called the P alkalinity. Similar titration to the methyl orange end point at pH 4.3 is called the M alkalinity. They are reported as ppm CaCO,. 

It IS by a similar process that alizaiin has been synthesised w ith the oliject of ascertaining its constitution (see Notes on Prep. 110, p. 316), When two molecules of phenol and one molecule of phthalic anhydride are heated together with cone, sulphuric acid, then phenolphthalein is formed (Baeyei). Its constitution has been determined by its synthesis from phthalyl chloride and benzene by means of the Friedel-Crafts leaction (see Notes on Piep. 100, p. 309). Phthalyl chloride and benzene yield in presence of AlCl., phthalophenone. 

Electrolysis of potassium iodide (Kl) solution. The electrolysis of aqueous Kl is similar to that of aqueous NaCI. The cathode reaction (left/ is the reduction of water to H2(g) and OH-, as shown by the pink color of phenolphthalein indicator in the water. The anode reaction fright) is the oxidation of l (aq) to Ijfaq), as shown by the brown color of the solution. 

If the solution contains carbonate (Procedure A), methyl orange, methyl orange-ihdigo carmine, or bromophenol blue must be used in standardisation against hydrochloric acid of known molar concentration. Phenolphthalein or indicators with a similar pH range, which are affected by carbon dioxide, cannot... 

Benzoic acid is sparingly soluble in water (which is a disadvantage) and must therefore be dissolved in 95 per cent ethanol. The mode of use is similar to that already described for potassium hydrogenphthalate (Section 10.27, Procedure B). For a 0.1 M solution, of, say, sodium hydroxide, weigh out accurately 0.4 g portions of the acid into a 250 mL conical flask, add 10- 20 mL of ethanol, shake until dissolved, and then titrate the solution with the strong alkali using phenolphthalein as indicator. A blank test should be made with the same volume of ethanol and the indicator deduct, if necessary, the volume of the alkali solution consumed in the blank test. 

Procedure B. The experimental details for the preparation of the initial solution are similar to those given under Procedure A. Titrate 25 or 50 mL of the cold solution with standard 0.1M hydrochloric acid and methyl orange, methyl orange-indigo carmine, or bromophenol blue as indicator. Titrate another 25 or 50 mL of the cold solution, diluted with an equal volume of water, slowly with the standard acid using phenolphthalein or, better, the thymol-blue cresol red mixed indicator in the latter case, the colour at the end point is rose. Calculate the result as described in the Discussion above. 

Procedure. To determine the purity of a sample of boric acid, weigh accurately about 0.8 g of the acid, transfer quantitatively to a 250 mL graduated flask and make up to the mark. Pipette 25 mL of the solution into a 250 mL conical flask, add an equal volume of distilled water, 2.5-3 g of mannitol or sorbitol, and titrate with standard 0.1 M sodium hydroxide solution using phenolphthalein as indicator. It is advisable to check whether any blank correction must be made dissolve a similar weight of mannitol (sorbitol) in 50 mL of distilled water, add phenolphthalein, and ascertain how much sodium hydroxide solution must be added to produce the characteristic end point colour. 

Phenol red immobilized PVA membrane for an optical pH sensor is developed based on the same approach, since the molecular structure of phenol red is similar to that of phenolphthalein. Phenol red was first reacted with the formaldehyde to produce hydroxymethyl groups, and then it was attached to PVA membrane via the hydroxymethyl groups. The changes of spectra characteristics after immobilization, the ionic strength effects, response time, reproducibility and long-term stability of the sensor membrane are discussed by Z. Liu et al. [170],... 

In complete accordance with Willstatter s theory, fuchsone is only yellowish-orange in colour. But if, in addition, one of the two free benzene rings has an OH-group in the p-position, we have the dye benzaurin already mentioned on p. 328. The o-carboxylic acid of this dye is the quinonoid form of phenolphthalein. In fact, the colour tones of these two substances are very similar. Phenolphthalein is decolorised by concentrated alkali NaOH (KOH) is added on and the trisodium (or potassium) salt of the benzenoid carbinol form is produced. (Try these reactions with phenolphthalein.)... 

Pour 2-3 ml each of 1 iV solutions of hydrochloric and acetic acids, sodium hydroxide, and an aqueous ammonia solution into test tubes. Pour one or two drops of a phenolphthalein solution into each of the tubes and see whether the colour of the solution changes. Perform similar experiments with other indicators, namely, methyl red, litmus, methyl orange (see Appendix 1, Table 6). Enter your observations into your laboratory notebook using Form 14. 

The primary aromatic amines are most readily estimated by means of nitrous acid (see p. 493). Primary or secondary amines, either alone or in presence of tertiary amines, may be estimated by acetylation, since the last do not react. About 1 gm. of the substance or mixture is weighed into a small flask provided with a reflux air condenser, and 5 c.cs. of acetic anhydride added from a pipette having a soda-lime guard tube. In another flask, also provided with a similar condenser, 5 c.cs. acetic anhydride are placed. The two flasks are allowed to stand at room temperature for 30 minutes to 1 hour, after which time 50 c.cs. of water are added to each, and both are placed on the steam bath for an hour in order to convert the remaining acetic anhydride into acetic acid. After cooling, the amount of acetic acid in each flask is titrated with standard sodium hydroxide or standard baryta, using phenolphthalein as indicator. The difference in the two titrations corresponds to the amount of primary or secondary amine present. 

The flask A is immersed in a boiling water-bath and connected with a receiver, which is then evacuated by means of a water-pump Exactly 5 c c of the vinegar are next introduced into the funnel, allowed to flow into the flask, and there distilled until the volume is reduced to 2-3 c c, without interruption of the operation, 20 c c of distilled water are then introduced and the volume again reduced to 2-3 c c, two similar additions of distilled water being subsequently made When the volume in the flask is finally reduced to about 5 c c, the operation is stopped and the liquid transferred quantitatively into a conical flask, the fixed acidity being then determined by titration with N/io-sodium hydroxide either m presence of phenolphthalein or, with a highly coloured residue, with the help of litmus paper. 

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