Phthalein test

Phenyl iso-thiocyanate, 642,643 Phenylthioureas, 422, 655 Phenylurea, 644, 645 Phenylurethanos, 264 Phloroacetophenone, 727, 736 Phosgene, 185 Phosphoric acid, 189, 284 Phosphorus, detection of, 1043 Phosphorus, red, purification of, 193 Phosphorus oxychloride, 367 Phosphorus pentabromide, 489, 492 Phosphorus pentachloride, 799, 822, 974 Phosphorus pentoxide, handling of, 407 Phosphorus tribromide, 189, 492 Phosphorus trichloride, 367 Phosphorus trisulphide," 836 Phthalamide, 983 Phthalein test, 681 ... 

Phthalein test. Many phenols yield phthaleins, which give characteristic colorations in alkaline solution, when fused with phthalic anhydride and a little concentrated sulphuric acid. Place in a dry test tube 0.5 g of the compound and an equal bulk of pure phthalic anhydride, mix well together and add 1 drop of concentrated sulphuric acid. Stand the tube for 3-4 minutes in a small beaker of Silicone oil (or paraffin oil) previously heated to 160 °C. Remove from the bath, allow to cool, add 4 ml of 5 per cent sodium hydroxide solution and stir until the fused mass has dissolved. Dilute with an equal volume of water, filter and examine the colour of the filtrate against a white background if the solution exhibits a fluorescence, observe the colour against a black background. 

The pH required for the precipitation of C is about 5-5 this can be more conveniently achieved by the use of either nitrazine (sodium dinitrophenyl-azo-naphthol sulphonate) or bromocresol purple (dibromo-o-cresol-sulphone-phthalein) test-papers. All that is necessary is to add the sodium hydroxide solution until the appropriate colour change is produced it is best to use a... 

M13. Mateer, J. G., Baltz, J. I., Marion, D. F., and MacMillan, J. M., Liver function tests general evaluation of liver function tests, and appraisal of comparative sensitivity and reliability of newer tests, with particular emphasis on cephalin-cholesterol flocculation test, intravenous hippuric acid test and improved bromsul-phthalein test with new normal standard. J. Am. Med. Assoc. 121, 723-728 (1943). 

NOTE. It is not expected that a student xvill attempt to memorise all the colour tests given in Part III. He might for example be expected to know the Phthalein Reaction for phenol itself (p. 339). Details of the divergence from the standard result are recorded primarily for reference, so that a student will not be diverted from his line of investigation if he observes that a suspected phenol does not respond exactly to the standard colour changes. 

Phthalein reaction. Place in a dry test-tube about 0 2 g. of the phenol and an equal quantity of phthalic anhydride (or acid), moisten with 2 drops (not more) of cone. H2SO4 and gently fuse together for about 1 minute. Allow to cool somewhat, and then add 10% NaOH solution in excess. 

Phthalein formation Fuse together carefully in a dry test-tube a few crystals of salicylic acid or of a salicylate with an equal quantity of phthalic anhydride rnoistened with 2 drops of cone. HjSO. Cool, dissolve in water and... 

The fluorescein test for succinic acid (p. 349) and the phthalein and fluorescein tests for phthalic acid (p. 351) are obviously given also by succinic anhydride and phthalic anhydride, as these tests depend upon the initial formation of the anhy dride in each case. 

In this case the sulphonic acid group is present in a sulphon-phthalein dye namely the indicator bromophenol blue. As in the previous example, the species (R3NH + )(R S03 ) can be extracted into chloroform whilst the indicator itself is not extracted, and the colour of the extract is proportional to the quantity of surfactant in the material under test. 

Considerable heat is evolved in the neutralization of the acid with the sodium hydroxide. The extraction can be carried on faster and without loss if the solution is cooled by the direct addition of ice. It is convenient to test the extracts with phenol-phthalein to determine when all of the acid has been removed. 

Acidity Dissolve 1.0 g of sample in 25 mL of a 1 1 (v/v) alcohokether mixture that has been neutralized to phenol-phthalein TS with 0.1 N sodium hydroxide. Add 0.5 mL of phenolphthalein TS, and titrate with 0.1 A sodium hydroxide until the solution remains faintly pink after shaking for 30 s. Not more than 1.0 mL of 0.1 A sodium hydroxide is required. Lead Determine as directed in the Flame Atomic Absorption Spectrophotometric Method under Lead Limit Test, Appendix MB, using a 10-g sample. 

Carbonation begins at exposed surfaces, and spreads inwards at a rate proportional to the square root of time (K66). The thickness of the affected layer can be approximately determined by testing a section with phcnol-phthalein. Chloride ion from an external source similarly penetrates inwards. The age at which corrosion is liable to begin thus depends on the minimum thickness of concrete covering the reinforcement, the resistance to penetration and the conditions to which the concrete is subjected. The depth of cover needed to provide protection over a given period can be calculated (SI 17.B154). 

Another delicate test for copper salts is afforded by the use of the solution obtained by addition of a trace of hydrogen peroxide to the Kastle-Meyer reagent, which consists of a 2 per cent, solution of phenol-phthalein in a 20 per cent, solution of potassium hydroxide decolorized by boiling with zinc-powder. The liquid gives a pink coloration with one part of a copper salt dissolved in 100,000,000 parts of water.4... 

Acetone should be colourless and completely miscible with water. Its specific gravity should not exceed 0 800 at 15 It should give no turbidity on mixing with twenty times its volume of carbon disulphide, and no residue on evaporation. It should be free from acidity, except for traces of dissolved carbon dioxide (approximately o oi per cent,). To test acidity the acetone is boiled to remove carbon dioxide, diluted with an equal volume of water (free from carbon dioxide) and titrated with alkali, using phenol phthalein as indicator. Alkalinity should be absent, as it indicates the presence of amines it is tested for by diluting... 

Urea is tested for the content of nitrogen using H,SO and formaldehyde. The indicator used is a mixed indicator containing 0.5 g phenolphthalein and 0.5 g thymol phthalein dissolved in 100 ml ethanol. A 25% formaldehyde solution used should be neutralised before use. The procedures of the method is briefly described below. 

Rotor, A. B., Manahan, L., and Florentin, A., Familial non-hemolytic jaundice with direct van den Bergh reaction. Acta Med. Philippina 6, 37-47 (1966). Rowntree, L. G., Hurvitz, S. H., and Bloomfield, A. L., An experimental and clinical study of the value of phenol tetrachloro-phthalein as a test for hepatic function. Bull. Johns Hopkins Hosp. 24, 327—342 (1913). 

A good method, which can be recommended for employment where many determinations have to be performed, is to dissolve 10 grammes of soap in 50 c.c. neutral alcohol and titrate to phenol-phthalein with N/1 acid. Add 3-5 drops HGl and boil to expel carbonic acid, neutralise with alcoholic KOIi solution and add exactly 10 c.c. in excess, boil for fifteen minutes under a refiux condenser and titrate with N/1 acid. The difference between this latter figure and the amount required for a blank test with 10 c.c. alcoholic KOH, denotes the amount of alkali absorbed by the uncombined fat. 

A leak in an ammonia system can be detected by odor. The location of the leak may be determined with moist red litmus paper or moist filter paper impregnated with phenol-phthalein or detection instruments. These chemical test papers change color in ammonia vapor. Other means of detection involve the use of sulfur dioxide, which forms a white fog in contact with ammonia vapor. 

In order to test the reliability of compositional results obtained by the 13c NMR, analyses of several copolymers were carried out by both 13c NMR and titration. Titrations were carried out in 50% aqueous ethanol medium to the phenol phthalein endpoint using 0.15 N aqueous potassium hydroxide as the titrant. As evidenced in Table 7.49 there is an excellent correlation between the compositional analysis by NMR and titration (correlation coefficient = 0.998) with most of the comparative analyses differing by 2% or less. 

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