ఫినాప్తలీన్: కూర్పుల మధ్య తేడాలు

Phenolphthalein is insoluble in [[water]] and usually is dissolved in [[alcohol]]s for use in [[experiment]]s. It is a weak acid, which can lose H⁺ ions in solution. The phenolphthalein molecule is colorless, however, the phenolphthalein ion is pink. When a base is added to the phenolphthalein, the molecule {{unicode|⇌}} ions' equilibrium shifts to the right, leading to more ionization as H⁺ ions are removed. This is predicted by [[Le Chatelier's principle]].

 

Phenolphthalein is synthesized by condensation of [[phthalic anhydride]] with two equivalents of [[phenol]] under acidic conditions (hence the name). It was discovered in 1871 by [[Adolf von Baeyer]].<ref>{{cite journal | author = Baeyer, A. | year = 1871 | title = Ueber eine neue Klasse von Farbstoffen | journal = Berichte der Deutschen Chemischen Gesellschaft | volume = 4 | issue = 2 | pages = 555–558 | doi = 10.1002/cber.18710040209 }}</ref><ref>{{cite journal | author = Baeyer, A. | year = 1871 | title = Ueber die Phenolfarbstoffe | journal = Berichte der Deutschen Chemischen Gesellschaft | volume = 4 | issue = 2 | pages = 658–665 | doi = 10.1002/cber.18710040247 }}</ref><ref>{{cite journal | author = Baeyer, A. | year = 1871 | title = Ueber die Phenolfarbstoffe | journal = Polytechnisches Journal | volume = 201 | issue = 89 | pages = 358–362 | url = http://dingler.culture.hu-berlin.de/article/pj201/ar201089 }}</ref>

:[[File:Phenolphthalein Synthesis.svg|400px|Synthesis of phenolphthalein]]

 

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The acid-base indication abilities of phenolphthalein also make it useful for testing for signs of carbonation reactions in concrete. Concrete has naturally high pH due to the [[calcium hydroxide]] formed when [[Portland cement]] reacts with water. The [[pH]] of the ionic water solution present in the pores of fresh concrete may be over 14. Normal carbonation of concrete occurs as the cement hydration products in concrete react with carbon dioxide in the atmosphere, and can reduce the pH to 8½ to 9, although that reaction usually is restricted to a thin layer at the surface. When a 1% phenolphthalein solution is applied to normal concrete it will turn bright pink. If the concrete has undergone carbonation, no color change will be observed.

 

Despite concerns of its [[carcinogenicity]], the use of phenolphthalein as a laxative is unlikely to cause [[ovarian cancer]].<ref>{{cite journal | last = Cooper | first = G. S. | coauthors = Longnecker, M. P.; Peters, R. K. | title = Ovarian Cancer Risk and Use of Phenolphthalein-Containing Laxatives | journal = Pharmacoepidemiology and Drug Safety | year = 2004 | volume = 13 | issue = 1 | pages = 35–39 | pmid = 14971121 | doi = 10.1002/pds.824 }}</ref> Phenolphthalein has been found to inhibit human cellular calcium influx via store-operated calcium entry (SOCE) by inhibiting [[thrombin]] and [[thapsigargin]], two activators of SOCE that increase intracellular free calcium.<ref>{{cite journal | last = Dobrydneva | first = Y. | coauthors = Wilson, E.; Abelt, C. J.; Blackmore, P. F. | title = Phenolphthalein as a Prototype Drug for a Group of Structurally Related Calcium Channel Blockers in Human Platelets | journal = Journal of Cardiovascular Pharmacology | year = 2009 | volume = 53 | issue = 3 | pages = 231–240 | pmid = 19247192 | doi=10.1097/FJC.0b013e31819b5494}}</ref>

 

 

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{{Commons category|Phenolphthalein}}

*[http://www.chemguide.co.uk/physical/acidbaseeqia/indicators.html Page on different titration indicators, including phenolphthalein]