A dithiocarbamate is a functional group in organic chemistry. It is the analog of a carbamate in which both oxygen atoms are replaced by sulfur atoms (when only 1 oxygen is replaced the result is thiocarbamate).
- R2NH + CS2 + NaOH → R2NCS2−Na+ + H2O
Ammonia reacts with CS2 similarly:
- 2 NH3 + CS2 → H2NCS2−NH4+
Dithiocarbamate salts are pale colored solids that are soluble in water and polar organic solvents.
- (CH3)2NCS2Na + (CH3O)2SO2 → (CH3)2NC(S)SCH3 + Na[CH3OSO3]
Oxidation of dithiocarbamates gives the thiuram disulfide:
- 2 R2NCS2− → [R2NC(S)S]2 + 2e−
Thiuram disulfides react with Grignard reagents to give esters of dithiocarbamic acid:
- [R2NC(S)S]2 + R'MgX → R2NC(S)SR' + R2NCS2MgX
Structure and bonding
Dithiocarbamates is described by invoking resonance structures that emphasize the pi-donor properties of the amine group. This bonding arrangement is indicated by a short C–N distance and the coplanarity of the NCS2 core as well as the atoms attached to N.
Because of the pi-donation from nitrogen, dithiocarbamates are more basic than structurally related anions such as dithiocarboxylates and xanthates. Consequently, they tend to bind as bidentate ligands. Another consequence of the C–N multiple bonding is that rotation about that bond is subject to a high barrier.
Dithiocarbamates specifically ethylene bisdithiocarbamates (EBDCs), in the form of complexes with manganese (maneb), zinc (zineb) or a combination of manganese and zinc (mancozeb), have been used extensively as fungicides in agriculture from the 1940s.
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