Bei Zugabe von Alkalien öffnet sich der Lactonring und man erhält die chinoide Form. This is effected by its inhibiting thrombin and thapsigargin, two activators of SOCE that increase intracellular free calcium. Phenolphthalein was used widely in over-the-counter laxatives, but in 1999 the U.S. Food and Drug Administration banned its use in such medicines because animal studies indicated that it may cause cancer in humans. But this change in ph can be Or can't be significant depending upon the nature of solution in which it is added. [19], 3,3-Bis(4-hydroxyphenyl)-2-benzofuran-1(3, 3,3-Bis(4-hydroxyphenyl)isobenzofuran-1(3, InChI=1S/C20H14O4/c21-15-9-5-13(6-10-15)20(14-7-11-16(22)12-8-14)18-4-2-1-3-17(18)19(23)24-20/h1-12,21-22H, InChI=1/C20H14O4/c21-15-9-5-13(6-10-15)20(14-7-11-16(22)12-8-14)18-4-2-1-3-17(18)19(23)24-20/h1-12,21-22H, O=C1OC(C2=C1C=CC=C2)(C3=CC=C(C=C3)O[H])C4=CC=C(C=C4)O[H], Except where otherwise noted, data are given for materials in their, Calcium release activated channel § Structure, "Phenolphthalein Exposure Causes Multiple Carcinogenic Effects in Experimental Model Systems", 10.1002/(SICI)1098-2280(1998)31:2<113::AID-EM3>3.0.CO;2-N, "3 Versions of Ex-Lax Are Recalled After F.D.A. Despite concerns regarding its carcinogenicity, the use of phenolphthalein as a laxative is unlikely to cause ovarian cancer. A dry sample is collected with a swab or filter paper. At pH ranging from zero to 8.2 (acidic or weakly acidic conditions) it is colorless. Die Molekulargewicht beträgt 318,31 g/mol, die Dichte liegt bei 1,3 g/cm 3. 各pHにおけるフェノールフタレインの構造式 化学種 In + H 2 In In 2− In(OH) 3− 構造式 モデル pH <0 0−8.2 8.2−12.0 >12.0 酸性度 強酸性 酸性または中性 塩基性 強塩基性 色 オレンジ 無色 ピンクからフク … However it reacts with alkali to form a salt, and this has a pink colour. Phenolphthalein adopts at least four different states in aqueous solution as a result of pH changes. This reaction leads to the pH falling below the color change threshold as hydrogen ions are released by the reaction: To develop the hair and "magic" graphical patterns, the ink is sprayed with a solution of hydroxide, which leads to the appearance of the hidden graphics by the same mechanism described above for color change in alkaline solution. In strongly basic solutions, phenolphthalein is converted to its In(OH)3− form, and its pink color undergoes a rather slow fading reaction[citation needed] and becomes completely colorless above 13.0 pH. Phenolphthalein is a chemical compound with the formula C20H14O4 and is often written as "HIn" or "phph" in shorthand notation. When a 1% phenolphthalein solution is applied to normal concrete, it turns bright pink. Let us know if you have suggestions to improve this article (requires login). Im sauren und neutralen Bereich liegt das Phenolphthalein in der lactoiden Form vor. Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree.... Phenolphthalein, normally colourless, attains a deep red hue above pH 10.0. 2 Eigenschaften. It is an organic molecule with neutral pH. [12] Phenolphthalein has been found to inhibit human cellular calcium influx via store-operated calcium entry (SOCE, see Calcium release activated channel § Structure). Colurs of Phenolphthalein at different pH's are as follow, When pH is less than zero, means when the conditions are strongly acidic then it imparts Orange Color. Hence Phenolphthalein is used in toys, for example as a component of disappearing inks, or disappearing dye on the Hollywood Hair Barbie hair. Aqueous solution is acidic. A molecular structural illustration clarifies phenolphthalein's behavior as an indicator. The pH of the solution at its turning point is called the pK ln and is the pH at which half of the indicator is in its acid form and the other half in the form of its conjugate base. Since phenolphthalein is colourless in acid and intensely red in base, it is commonly used as a pH indicator in titrations and also as the active ingredient…, In general, organic compounds are substances that contain carbon (C), and carbon atoms provide the key structural framework that generates the vast diversity of organic compounds. Phenolphthalein is often used as an indicator in acid–base titrations. Colurs of Phenolphthalein at different pH's are as follow, When pH is less than zero, means when the conditions are strongly acidic then it imparts Orange Color. A reduced form of phenolphthalein, phenolphthalin, which is colorless, is used in a test to identify substances thought to contain blood, commonly known as the Kastle–Meyer test. Such adverse reactions as kidney irritation or skin rash may occur. Updates? However, if it remains colorless, it shows that the concrete has undergone carbonation. It was discovered in 1871 by Adolf von Baeyer. Phenolphthalein | chemical compound | Britannica The pattern will eventually disappear again because of the reaction with carbon dioxide. Phenolphthalein is a potent laxative, which acts within 6–8 hours; its effects may last 3–4 days. The doubly deprotonated (In2-) phenolate form (the anion form of phenol) gives the familiar pink color. The chemical formula for phenolphthalein is C 20 H 14 O 4 . Definition and Examples of Acid-Base Indicator Between strongly acidic and slightly basic conditions, the lactone form (HIn) is colorless. This test is not destructive to the sample; it can be kept and used in further tests. Phenolphthalein is a crystalline solid which is almost insoluble in water, so is supplied as a solution in ethanol. Phenolphthalein's pH sensitivity is exploited in other applications: concrete has naturally high pH due to the calcium hydroxide formed when Portland cement reacts with water. Colorless in presence of large amounts of alkali A false positive can result from the presence of substances with catalytic activity similar to hemoglobin.
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