Analytical chemistry dithiocarbamates

It is well known that the secondary amines form dithiocarbamates with carbon disulfide, which are important complexing agents in analytical chemistry [84], Therefore, PS-g-PEI was allowed to react with carbon disulfide to obtain a resin with a higher affinity to Hg(II) than the resin with thiol groups [83]. 

Laintz, K.E., Yu, J.J., and Wai, C.M. 1992. Separation of metal ions with sodium bis(trifluoroethyl) dithiocarbamate chelation and supercritical fluid chromatography. Analytical Chemistry, 64 311-5. 

Dithiocarbamates (RCS2") have been applied widely in the analytical chemistry of trace metals in natural water 1, 2, 3). The ammonium salt of the dithiocarbamate of pyrrolidine (APDC) is a water-soluble compound which forms water-insoluble uncharged chelates with a variety of metals. At the very low metal concentration levels found in natural waters, dithiocarbamate chelates form colloids (4). At higher concentration levels the chelates precipitate (5). Since the metal ion in the chelate is eflFectively shielded by hydrophobic groups, precipitation in a multi-metal system is relatively nonselective the chelates of several metals precipitate together rather than as separate phases. If one transition metal is present in suflBcient concentration to form particles, other metals will be incorporated into the particles regardless of their concentration. The analytical implication of this behavior is clear— APDC chelates of trace transition elements can be co-precipitated by addition of one transition element up to suflBcient concentration to form chelate particles. 

This chapter is aimed at inorganic chemists and as such it focuses on the synthesis, properties, and reactivity of transition metal dithiocarbamate complexes. A flavor of the established and potential applications of each metal type is given in Section IV, but space restrictions nessetate that their applications in analytical chemistry and the agricultural industry (27), together with their widespread biological applications (45—48) are not fully developed. 

The bis(2,2,2-triiluoroethyl) dithiocarbamate salt, NaS2CN(CH2CF3)2, is a valuable precursor to a range of complexes that find widespread uses in analytical chemistry (74-82). It can be readily prepared from the amine using sodium amide as the base in the presence of carbon disulfide (Eq. 5) (76, 75), and a synthesis of the lithium salt has also been reported (83, 84). 

The dithiocarbamate chemistry of the group 12 (11B) elements is well developed, with applications in the areas of analytical chemistry, agriculture, rubber vulcanization, and as molecular precursors to metal sulfides. As expected, their chemistry is constrained to the - -2 oxidation state and it is the bis(dithiocarbamate) complexes [M(S2CNR2)2], which are the most common, being first prepared in 1907 (2). 

Dithiocarbamates have been covered in CCC (1987),378 in a comprehensive early review (together with xanthates)379 and in a book.380 They continue to be extensively used and much interesting novel chemistry has been reported since. Several reviews on dithiocarbamates cover the electro-chemistry, photoelectron spectroscopy, analytical applications of dithiocarbamates (e.g., for the determination of metals in foodstuff, water and environmental samples and the analysis of dithiocarbamate pesticides),383-386 their use as NO trapping agents,387-389 or in the heavy-metal removal from wastewaters.390... 

Dithiocarbamates are subject to uninterrupted research, and interesting chemistry is frequently reported. In addition to their academic interest, dithiocarbamates have useful applications as analytical reagents for the determination of metals in foodstuff, water, and environmental samples, as NO trapping... 

---