Thiobenzoic acid

Thiobenzoic acid is an organosulfur compound with molecular formula C6H5COSH. It is the parent of aryl thiocarboxylic acids. It is a pale yellow liquid that freezes just below room temperature.

Thiobenzoic acid
Names
Preferred IUPAC name
Benzenecarbothioic S-acid
Other names
  • Benzoyl thiol
  • Monothiobenzoic acid
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.002.466
EC Number
  • 202-712-9202-712-9
1071790
RTECS number
  • DH6839000
UNII
  • InChI=1S/C7H6OS/c8-7(9)6-4-2-1-3-5-6/h1-5H,(H,8,9)
  • C1=CC=C(C=C1)C(=O)S
Properties
C7H6OS
Molar mass 138.18 g·mol−1
Appearance yellow liquid
Density 1.1775 g/cm3
Melting point 24 °C (75 °F; 297 K)
Boiling point 222 °C (432 °F; 495 K)
soluble
Vapor pressure 0.1
Acidity (pKa) 3.61
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Thiobenzoic acid is prepared by treatment of benzoyl chloride with potassium hydrosulfide:[1]

C6H5C(O)Cl + KSH → C6H5C(O)SH + KCl

Acidity

With a pKa near 2.5, this acid is almost 100x more acidic than benzoic acid.[2] The conjugate base is thiobenzoate, C6H5COS−.

See also

References
  1. Noble, Paul Jr.; Tarbell, D. S. (1952). "Thiobenzoic Acid". Organic Syntheses. 32: 101. doi:10.15227/orgsyn.032.0101.
  2. Matthys J. Janssen "Carboxylic Acids and Esters" in PATAI's Chemistry of Functional Groups: Carboxylic Acids and Esters, Saul Patai, Ed. John Wiley, 1969, New York: pp. 705–764. doi:10.1002/9780470771099.ch15
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