Dithiobenzoic acid

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Dithiobenzoic acid
Preferred IUPAC name
Benzenecarbodithioic acid
3D model (JSmol)
ECHA InfoCard 100.004.084 Edit this at Wikidata
EC Number
  • 204-491-4
  • InChI=1S/C7H6S2/c8-7(9)6-4-2-1-3-5-6/h1-5H,(H,8,9)
  • C1=CC=C(C=C1)C(=S)S
Molar mass 154.25 g·mol−1
Appearance dark red sticky solid or viscous oil
Acidity (pKa) 1.92[1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Dithiobenzoic acid is the organosulfur compound with the formula C6H5CS2H. It is a dithiocarboxylic acid, an analogue of benzoic acid, but more acidic and deeply colored.

Synthesis and reactions[edit]

It can be prepared by sulfiding benzal chloride:[2]

C6H5CCl3 + 4 KSH → C6H5CS2K + 3 KCl + 2 H2S
C6H5CS2K + H+ → C6H5CS2H + K+

It also arises by the reaction of the Grignard reagent phenylmagnesium bromide with carbon disulfide, followed by acidification:[3]

C6H5MgBr + CS2 → C6H5CS2MgBr
C6H5CS2MgBr + HCl → C6H5CS2H + MgBrCl

It is about 100x more acidic than benzoic acid. Its conjugate base, dithiobenzoate, undergoes S-alkylation to give dithiocarboxylate esters.[2] Similarly, dithiobenzoate reacts with "soft" metal salts to give complexes, e.g. Fe(S2CC6H5)3 and Ni(S2CC6H5)2.

Chlorination of dithiobenzoic acid gives the thioacyl chloride C6H5C(S)Cl.

Structure of the trimer [Ni(S2CPh)2]3.[4]


  1. ^ M. R. Crampton (1974). "Acidity and hydrogen-bonding". In Saul Patai (ed.). The Chemistry of the Thiol Group. Chichester: John Wiley & Sons Ltd. p. 402.
  2. ^ a b Frederick Kurzer, Alexander Lawson (1962). "Thiobenzoylthioglycolic Acid". Org. Synth. 42: 100. doi:10.15227/orgsyn.042.0100.{{cite journal}}: CS1 maint: uses authors parameter (link)
  3. ^ J. Houben (1906). "Ueber Carbithiosäuren. I. Arylcarbithiosäuren" [About Carbothioic Acids I. Arylcarbothioic Acids]. Berichte der Deutschen Chemischen Gesellschaft. 39 (3): 3219–3233. doi:10.1002/cber.190603903140.
  4. ^ Bonamico, M.; Dessy, G.; Fares, V.; Scaramuzza, L. (1975). "Structural Studies of Metal Complexes with Sulphur-Containing Bidentate Ligands. Part I. Crystal and Molecular Structures of Trimeric Bis-(dithiobenzoato)-nickel(II) and -palladium(II)". Journal of the Chemical Society, Dalton Transactions (21): 2250–2255. doi:10.1039/DT9750002250.{{cite journal}}: CS1 maint: uses authors parameter (link)