Dithiobenzoic acid explained

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

It can be prepared by sulfiding benzal chloride:[1]

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:[2]

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.[1] 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.

References

  1. Org. Synth.. 1962. 42. 100. 10.15227/orgsyn.042.0100. Frederick Kurzer . Alexander Lawson . Thiobenzoylthioglycolic Acid.
  2. Ueber Carbithiosäuren. I. Arylcarbithiosäuren. About Carbothioic Acids I. Arylcarbothioic Acids. 3219–3233. J. Houben. 10.1002/cber.190603903140. Berichte der Deutschen Chemischen Gesellschaft. 1906. 39. 3.