Dithiobenzoic acid

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.

Dithiobenzoic acid
Names
Preferred IUPAC name
Benzenecarbodithioic acid
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.004.084
EC Number
  • 204-491-4
UNII
  • InChI=1S/C7H6S2/c8-7(9)6-4-2-1-3-5-6/h1-5H,(H,8,9)
    Key: ZGRWZUDBZZBJQB-UHFFFAOYSA-N
  • C1=CC=C(C=C1)C(=S)S
Properties
C7H6S2
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).
Infobox references

Synthesis and reactions

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]

References
  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. Frederick Kurzer; Alexander Lawson (1962). "Thiobenzoylthioglycolic Acid". Org. Synth. 42: 100. doi:10.15227/orgsyn.042.0100.
  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.
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