2,6-Dichlorophenol

2,6-Dichlorophenol is a compound with formula C₆H₃Cl₂OH. It is one of the six isomers of dichlorophenol. It is a colorless solid. Its pK_a is 6.78, which is about 100x more acidic than 2-chlorophenol (8.52) and 1000x more acidic than phenol itself (9.95).^[3]

Preparation

It can be produced in a multistep process from phenol, which is converted to its 4-sulfonic acid derivative. The resulting phenol sulfonic acid chlorinates at the positions flanking the phenol. Hydrolysis releases the sulfonic acid group.^[4]

An alternative synthesis starts with the ethyl ester of 4-hydroxybenzoic acid, which chlorinates at the positions flanking the phenolic center. Ester hydrolysis followed by decarboxylation affords 2,6-dichlorophenol.^[5]

References

^ 2,6-Dichlorophenol at Sigma-Aldrich
^ a b c Haynes, p. 3.166
^ François Muller; Liliane Caillard (2011). "Chlorophenols". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a07_001.pub2. ISBN 978-3527306732.
^ Otto Lindner; Lars Rodefeld (2005). "Benzenesulfonic Acids and Their Derivatives". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a03_507. ISBN 978-3527306732.
^ D. S. Tarbell; J. W. Wilson; Paul E. Fanta (1949). "2,6-Dichlorophenol". Org. Synth. 29: 35. doi:10.15227/orgsyn.029.0035.

Cited sources

Haynes, William M., ed. (2016). CRC Handbook of Chemistry and Physics (97th ed.). CRC Press. ISBN 9781498754293.