Structural Formula Vector Image
Title: Gallein
CAS Registry Number: 2103-64-2
CAS Name: 3¢,4¢,5¢,6¢-Tetrahydroxyspiro[isobenzofuran-1(3H),9¢-[9H]xanthen]-3-one
Additional Names: 3¢,4¢,5¢,6¢-tetrahydroxyfluoran; 3¢,4¢,5¢,6¢-tetrahydroxyspiro[phthalan-1,9¢-xanthen]-3-one; pyrogallolphthalein; C.I. 45445; mordant violet 25
Molecular Formula: C20H12O7
Molecular Weight: 364.31
Percent Composition: C 65.94%, H 3.32%, O 30.74%
Literature References: Obtained by heating 1 part phthalic anhydride with 2 parts of pyrogallol or gallic acid: Baeyer, Ber. 4, 457 (1871); Buchka, Ann. 209, 261 (1881). Use as a biological stain: R. D. Lillie et al., Stain Technol. 49, 339 (1974); R. Welsh, ibid. 52, 261 (1977). See also H. J. Conn's Biological Stains, R. D. Lillie, Ed. (Williams & Wilkins, Baltimore, 9th ed., 1977) p 351.
Properties: Brownish-red powder or crystals with 1½ H2O, or red crystals with greenish-yellow color when anhydr. Loses the water of crystn at about 180° and blackens above this temp. Does not melt even at 300°. pH 3.8 brownish-yellow; pH 6.6 rose-red. Almost insol in water, benzene, chloroform. Slightly sol in ether; sol in alc, acetone, alkalies.
Derivative Type: Disodium salt
Additional Names: Alizarin violet
Molecular Formula: C20H10Na2O7
Molecular Weight: 408.27
Percent Composition: C 58.84%, H 2.47%, Na 11.26%, O 27.43%
Properties: pH 10.6 rose; pH 13.0 violet.
Use: Clinical reagent (phosphates in urine). Monophosphates give a yellow, dibasic a red, tribasic a violet color. Used in soln of 0.5 g in 100 ml 50% alc; 2-3 drops for 100 ml liq. As sensitive indicator for acids, alkali hydroxides, NH3, but not for carbonates. Biological stain.

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