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PHENOLPHTHALEIN

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Originally appearing in Volume V21, Page 365 of the 1911 Encyclopedia Britannica.

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PHENOLPHTHALEIN , in organic See also:

chemistry, a See also:

compound derived from phthalophenone, or See also:

DIPHENYL (phenyl benzene), C6H5

diphenyl phthalide (See also:

formula I.), the anhydride of triphenyl-carbinol-ortho-carboxylic See also:

ACID (from the Lat. root ac-, sharp; acere, to be sour)

acid, which is obtained by condensing phthalyl chloride with See also:

BENZENE, C6H6

benzene in the presence of See also:

ALUMINIUM (symbol Al; atomic weight 27.0)

aluminium chloride. The phthaleins are formed from this anhydride by the entrance of hydroxyl or amino See also:

groups into the two phenyl residues, and are prepared by condensing phenols with See also:

PHTHALIC

phthalic anhydride, phenol itself giving rise to phenolphthalein (formula II.) together with a small quantity of fluorane (formula III.), whilst See also:

RESORCIN (meta-dioxybenzene), C5H4(OH)2i one of the dihydric phenols. It is obtained on fusing many resins (galbanum, asafoetida, &c.)

resorcin under similar conditions yields See also:

FLUORESCEIN

fluorescein (q.v.). The phthaleins on reduction yield phthalines, which are derivatives of See also:

TRIPHENYLMETHANE, (C6H6)3CH

triphenylmethane carboxylic acid; these reduction products are colourless and may be regarded as the leuco-compounds of the phthaleins, hus phenolphthalein itself gives phenolphthaline (formula IV.). Dehydrating agents usually convert the phenolphthalines into See also:

ANTHRAQUINONE, C14H802

anthraquinone derivatives.

End of Article: PHENOLPHTHALEIN

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