Fluorescein test

The DESC, NF31/DMAP, nondestructive NF31, TCT-AliR, and TCT-fluorescein tests described above also detect thiol groups. 

Comments Commercially available. Provides a fluorescent green color. May not be suitable for hindered or secondary halogens due to possible elimination reactions. 

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I. Fluorescein test. Fuse together carefully in a dry test-tube for about 1 minute a few crystals of resorcinol and an equal quantity of succinic acid or a succinate, moistened with 2 drops of cone. H2SO4. Cool, dissolve in water and add NaOH solution in excess. A red solution is produced which exhibits an intense green fluorescence.-f-... 

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. 

Fluorescein test paper Is prepared by dipping filter paper into a dilute solution of fluorescein in ethyl alcohol it dries rapidly and is then ready for use. The test paper lias a lemon yellow colour. 

A positive test is communicated by red beads for the AliR test and green or fluorescent beads in the case of the fluoresceine test. 

Fluorescein test Free bromine converts the yellow dyestuff fluorescein(I) into the red tetrabromofluorescein or eosin(II). Filter paper impregnated with fluorescein solution is therefore a valuable reagent for bromine vapour since the paper acquires a red colour. 

Treat one portion with barium chloride solution and filter off the precipitate formed. The residue consists of barium succinate. Confirm the succinate by the fluorescein test. Acidify the second portion of the filtrate with dilute hydrochloric acid, when benzoic acid will separate out on cooling. It can be identified by its melting point. 

Succinate, (i) Light-brown precipitate with FeCl3 solution, soluble in dilute HC1, but no precipitate of acid occurs (IV. 42, 3). (ii) Fluorescein test (IV.42,6). 

Chlorides do not affect the fluorescein test for bromides. Thus bromides may be detected in the presence of even large amounts (up to 1 10,000) of chlorides.2 Iodides, however, are oxidized to free iodine which forms red tetraiodofluorescein (erythrosine). In this case, the bromide can be identified by procedure (c). 

Comments Commercially available. Detects primary, secondary, and tertiary alcohols as well as phenols. Other nucleophilic groups, such as primary and secondary amines, and thiols can also be detected. Quantification analysis of primary and secondary alcohol groups can be performed with the TCT-AliR test. Provides a red color in the TCT-AliR test and a yellow-green color in the TCT-fluorescein test. 

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