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phthal·einalso phthal·eine (thăl′ēn′, thăl′ē-ĭn, thā′lēn′, thā′lē-ĭn, fthăl′-)
Any of a group of chemical compounds formed by a reaction of phthalic anhydride with a phenol, from which certain synthetic dyes are derived.
phthalein(ˈθeɪliːn; -lɪɪn; ˈθæl-; ˈfθæl-)
(Elements & Compounds) any of a class of organic compounds obtained by the reaction of phthalic anhydride with a phenol and used in dyes
[C19: from phthal-, shortened form of naphthalene +-in]
phthal•ein(ˈθæl in, -i ɪn, ˈfθæl-)
any of a group of compounds formed by treating phthalic anhydride with phenols, from which certain important dyes are derived.