Chemistry:Chlorophenol red

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Chlorophenol red
Skeletal formula of chlorophenol red in cyclic form
Ball-and-stick model of the chlorophenol red molecule in cyclic form
Names
Preferred IUPAC name
3,3-Bis(3-chloro-4-hydroxyphenyl)-2,1λ6-benzoxathiole-1,1(3H)-dione
Other names
3′,3′-Dichlorophenolsulfonaphthalein
Identifiers
3D model (JSmol)
ChemSpider
EC Number
  • 224-619-2
UNII
Properties
C19H12Cl2O5S
Molar mass 423.26 g·mol−1
Melting point 261 °C (502 °F; 534 K)[1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references
Tracking categories (test):
Chlorophenol red (pH indicator)
below pH 5.4 above pH 6.8
5.4 6.8

Chlorophenol red is an indicator dye that changes color from yellow to violet in the pH range 5.4 to 6.8.[2] The pH of a substance is determined by taking the negative logarithm of the Hydronium ion concentration and the indictor changes color due to the dissociation of H+ ions.[3] The lambda max is at 572 nm.[4]

Properties and uses

The dissociation mechanism of chlorophenol red is similar to that of phenolphthalein meaning it can be used as a color indicator. The dissociation of hydroxyl and hydrogen atoms creates the dissociate scheme of chlorophenol red to change color from yellow to red.[5] The pH properties of chlorophenol red are used to selectively determine the amount of chlorine dioxide in drinking water. Chlorophenol red selectively reacts with 0.1–1.9 mg/L chlorine dioxide at pH 7. [6] The electrochemical properties of Chlorophenol red allows it to be a chromogenic label and can undergo oxidation creating several phenolic intermediates. The bacterial hydrolysis of a chlorophenol red labelled substrate produces chlorine retaining intermediates on electrodes. [7]

References

  1. Haynes, p. 3.116
  2. Haynes, p. 8.88
  3. "pH Indicators" (in en). 2013-10-02. https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Acids_and_Bases/Acid_and_Base_Indicators/PH_Indicators. 
  4. "Chlorophenol Red". https://www.sigmaaldrich.com/catalog/product/aldrich/199524. 
  5. Hanai, Toshihiko (2016). "Quantitative Evaluation of Dissociation Mechanisms in Phenolphthalein and the Related Compounds.". Journal of Computer Chemistry 15: 13–21. https://www.researchgate.net/publication/301942181. 
  6. Sweetin, Deborah L.; Sullivan, Elizabeth; Gordon, Gilbert (1996-01-01). "The use of chlorophenol red for the selective determination of chlorine dioxide in drinking water". Talanta 43 (1): 103–108. doi:10.1016/0039-9140(95)01721-6. PMID 18966469. 
  7. Casimero, Charnete; Bigham, Teri; McGlynn, Ruairi J.; Dooley, James S. G.; Ternan, Nigel G.; Snelling, William J.; Critchley, Megan E.; Zinkel, Cameron L. et al. (2019-12-01). "Electroanalytical properties of chlorophenol red at disposable carbon electrodes: Implications for Escherichia coli detection". Bioelectrochemistry 130: 107321. doi:10.1016/j.bioelechem.2019.06.006. PMID 31306878. 

Cited sources