Cadmium dithiolate

Many heavy metals react with dithiol to give coloured precipitates, e.g. bismuth, iron(III), copper, nickel, cobalt, silver, mercury, lead, cadmium, arsenic, etc. molybdate and tungstate also react. Of the various interfering elements, only arsenic distils over with the tin when a mixture is distilled from a medium of concentrated sulphuric acid and concentrated hydrobromic acid in a current of carbon dioxide. If arsenic is present in quantities larger than that of the tin it should be removed. 

Arsenic uptake in rabbit intestine is inhibited by phosphate, casein, and various metal-chelating agents (USEPA 1980). Mice and rabbits are significantly protected against sodium arsenite intoxication by (V-(2,3-dimercaptopropyl)phthalamidic acid (Stine et al. 1984). Conversely, the toxic effects of arsenite are potentiated by excess dithiols, cadmium, and lead, as evidenced by reduced food efficiency and disrupted blood chemistry in rodents (Pershagen and Vahter 1979). 

The great drawback to this reagent is its proneness to oxidation and it is often stored as the zinc complex from which it is released by dissolving in acid or alkali. The analogous quinoxaline-2,3-dithiol has been recommended for the determination of Ni and Co, and 2-mer-captobenzothiazole (28) for cadmium through extraction of its complex into chloroform.52... 

N-(2,3-Dimercaptopropyl)phthalamidic acid (41, DMPA) has been shown to form relatively stable complexes with cadmium, zinc and mercury312. DMPA has also been shown to enhance faecal and urinary excretion of mercury in mice and arsenic in mice and rabbits. For the decorporation of arsenic, taken in as arsine, the administration of 3-(tolylthio)propane-l, 2-dithiol (42) has been proposed in the USSR313. ... 

Mills and Clark (1936) investigated the salts (XL) which 4-coordinated mercury(II), cadmium(II), and zinc(II) form with toluene-3,4-dithiol... 

EXTRACTION OF CADMIUM FROM AQUEOUS SOLUTION USING 1,3,4-THI ADI AZOLE-2,5-DITHIOL... 

In addition to the adsorption studies of carbonyl, phosphine oxide, and sulfide adsorbates noted in Ref. 10, the studies of interaction of anionic S donors such as dithiocarbamates [17], anionic S-containing species (MoS and Et2NCS ) [18], thiolates [19], and polysulfides [20] with cadmium chalcogenides have been characterized by Wrighton and coworkers [17-20]. This chapter will focus on surface modification of cadmium chalcogenides with thiols, dithiols, sulfides, and disulfides. 

The layer-by-layer structure of dithiol SAM and CdS monolayer was confirmed with X-ray photoelectron spectroscopy, Fourier transform infrared reflection-absorption spectroscopy, and inductively coupled plasma mass spectroscopy at each step of composite-film preparation. Photocurrent measurements revealed that the mono-layers of CdS nanoparticles were immobilized without mutual aggregation of particles [36]. Cadmium selenide nanoparticles were prepared electrochemically on gold substrates modified with alkanethio-lated -cyclodextrin SAMs [37]. 

The self-assembly of molecules such as thiols and dithiols on metal surfaces is well-established and has been used to attach cadmium chalcogenide nanocrystals, for example, to Au surfaces [42], and to measure their electrical properties [43,44]. Attachment of CdS nanoparticle mono-layer onto bifunctional 1,5-hexanedithiol or 1,10-decanedithiol SAM has been reported [36, 42, 45]. In addition, various authors have also demonstrated assembly of monolayers of alkanethiols and other molecules on GaAs surfaces [46-49]. The alkanethiols were presumed to bind selectively to arsenic atoms on GaAs (100) surface [48, 49]. 

F) Preparation and Testing of Candidate Structures. Suitable candidate structures were then examined for relative efficacy in the mobilization of lead from lead-loaded mice. On the basis of previous studies in which we examined the relative ability of many compounds to remove cadmium from its aged deposits in the liver and the kidneys, six vicinal dithiols were selected, which were all monoesters of meso-2,3-dimercaptosuccinic acid. The compounds selected were the mono esters of meso- 2,3-dimercaptosuccinic acid with the following alcohols n-propyl, wo-propyl, n-butyl, wo-butyl, n-amyl, and iso-dmy (Figure 3). The results of experiments comparing these compounds showed that the n-butyl, iso-butyl, n-amyl, and isoamyl monoesters of m j<>-2,3-dimercaptosuccinic acid were the most effective compounds and that all were capable of reducing both kidney and brain lead levels in lead-intoxicated mice (45). The data collected on lead-intoxicated mice treated with the most effective of such compounds are compared with the results obtained with DMSA in Table I. 

Mabrouk, H.E. and Tuck, D.G. (1988) The direct electrochemical synthesis of zinc and cadmium derivatives of a,co-dithiols, and their reaction with carbon disulphide , Inorg. Chim. Acta, 145, 237-241. 

Although a cyclic structure was not considered for the product prepared from 2,9-p-menthane dithiol and cadmium acetate, it is included in this section and Table X.l (pp. 308-312) (23). 

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