PHENOLPHTHALEIN  , in organic See also:

• CHEMISTRY
• CHEMISTRY (formerly "chymistry"; Gr. xvµela; for derivation see ALCHEMY)

chemistry, a See also:

• COMPOUND
• COMPOUND (from Lat. componere, to combine or put together)

compound derived from phthalophenone, or See also:

• DIPHENYL (phenyl benzene), C6H5

diphenyl phthalide (See also:

• FORMULA
• FORMULA (Lat. diminutive of forma, shape, pattern, &c., especially used of rules of judicial procedure)

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
• GROUPS, THEORY

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 .