from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. Any of a group of chemical compounds formed by a reaction of phthalic anhydride with a phenol, from which certain synthetic dyes are derived.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. any of a range of lactones formed by the reaction of phenols with phthalic anhydride

from the GNU version of the Collaborative International Dictionary of English

  • n. One of a series of artificial organic dyes made as condensation products of the phenols with phthalic acid, and well represented by phenol phthale├»n. Their alkaline solutions are fluorescent.

from The Century Dictionary and Cyclopedia

  • n. One of the group of coloring-matters formed by the condensation of phthalic anhydrid with phenols. Some of the phthaleins have a purgative action when taken internally. They are of particular importance in the color-chemistry, and certain of their derivatives are valuable dyestuffs. See phenolphthalein and phthalic anhydrid.


phthal(ic) + -ein.
(American Heritage® Dictionary of the English Language, Fourth Edition)


  • Strasbourg with a thesis on fluoresceine and orcin-phthalein.

    Emil Fischer - Biography

  • Studying under von Baeyer, Fischer worked on the phthalein dyes which Rose had discovered and in 1874 he took his Ph.D. at

    Emil Fischer - Biography

  • _Free acidity_ is estimated by weighing out from 2 to 5 grammes of the fat or oil, dissolving in neutral alcohol (purified methylated spirit) with gentle heat, and titrating with a standard aqueous or alcoholic solution of caustic soda or potash, using phenol-phthalein as indicator.

    The Handbook of Soap Manufacture

  • To another 20 c.c. is added barium chloride solution (10 per cent.) until it ceases to give a precipitate, the precipitate allowed to settle, and the clear supernatant liquid decanted off, the precipitate transferred to a filter paper and well washed, and the filtrate titrated with N/1 acid, using phenol-phthalein as indicator.

    The Handbook of Soap Manufacture

  • About 2 grammes of the sample are dissolved in 50 c.c. distilled water, and titrated with N/1 sulphuric acid, using phenol-phthalein as indicator, the alkalinity so obtained representing all the caustic alkali and one-half the carbonate, which latter is converted into bicarbonate.

    The Handbook of Soap Manufacture

  • Na_ {2} O, and in soft soaps as K_ {2} O. _Free caustic alkali_ is estimated by dissolving 2 grammes of the soap, in neutral pure alcohol, with gentle heat, filtering, well washing the filter with hot neutral spirit, and titrating the filtrate with N/10 acid, to phenol-phthalein.

    The Handbook of Soap Manufacture

  • _ -- Some analysts determine the alkalinity to phenol-phthalein of the alcoholic soap solution without filtering, and express it as free alkali (caustic, carbonates, or any salt having an alkaline reaction).

    The Handbook of Soap Manufacture

  • After cooling, the liquid is titrated with N/2 aqueous KOH solution, using phenol-phthalein as indicator, this figure giving the amount of the total fatty acids present.

    The Handbook of Soap Manufacture

  • After cooling, sufficient pure neutralised glycerine is added to form one-third of the total volume, and the liquid titrated with N/2 caustic soda solution, using phenol-phthalein as indicator.

    The Handbook of Soap Manufacture

  • 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.

    The Handbook of Soap Manufacture


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