| 单词 |
phenolphthalein |
| 释义 |
phenolphthalein|fiːnɒlˈfθeɪliːn|
[f. phenol + phthalein.]
A whitish or yellowish crystalline solid, (HO·C6H4·)2C{bbr1}·C6H4·OC{bbl1} , which is used in alcoholic solution as an indicator in the pH range 8 to 10, in which it changes from colourless to red, and is also used medically as a laxative.
1875Jrnl. Chem. Soc. XXVIII. 67 When phenol is gently warmed with phthalic anhydride and sulphuric acid the mixture assumes a brownish yellow colour, from the formation of phenol-phthalein. 1881J. Attfield Chem. (ed. 9) 658 In delicate experiments turmeric, ‘eosin’, ‘phenolphthalein’, etc., may be used instead of litmus. 1893Photogr. Ann. 287 For testing the alkalinity of sulphites... The best [indicator] is phenol-phthalein in alcoholic solution. 1946Nature 23 Nov. 744/2 Back titration of the solution immediately after the substance had dissolved, using phenolphthalein as an indicator, indicated an apparent equivalent weight of 325. 1951R. Mayer Artist's Handbk. ii. 97 Acids and alkalis are detected by the use of litmus, phenolphthalein, or other indicators. 1974M. C. Gerald Pharmacol. ii. 31 In some laxatives, such as Ex-Lax and Feen-A-Mint, the active ingredient is phenolphthalein. |
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