Metalation thiocarbamates

Rate Constants of Reactions of Metal Thiophosphates and Metal Thiocarbamates with Cumylhydroperoxide (Experimental Data)... 

Rate Constants of Reactions of Peroxyl Radicals with Metal Thiocarbamates and Thiophosphates in Hydrocarbon Solutions (Experimental Data)—continued... 

Organosulfur Adsorbates on Metal and Semiconductor Surfaces. Sulfur compounds (qv) and selenium compounds (qv) have a strong affinity for transition metal surfaces (206—211). The number of reported surface-active organosulfur compounds that form monolayers on gold includes di- -alkyl sulfide (212,213), di- -alkyl disulfides (108), thiophenols (214,215), mercaptopyridines (216), mercaptoanilines (217), thiophenes (217), cysteines (218,219), xanthates (220), thiocarbaminates (220), thiocarbamates (221), thioureas (222), mercaptoimidazoles (223—225), and alkaneselenoles (226) (Fig. 11). However, the most studied, and probably most understood, SAM is that of alkanethiolates on Au(lll) surfaces. 

Tseng et al. [69] determined 60cobalt in seawater by successive extractions with tris(pyrrolidine dithiocarbamate) bismuth (III) and ammonium pyrrolidine dithiocarbamate and back-extraction with bismuth (III). Filtered seawater adjusted to pH 1.0-1.5 was extracted with chloroform and 0.01 M tris(pyrrolidine dithiocarbamate) bismuth (III) to remove certain metallic contaminants. The aqueous residue was adjusted to pH 4.5 and re-extracted with chloroform and 2% ammonium pyrrolidine thiocarbamate, to remove cobalt. Back-extraction with bismuth (III) solution removed further trace elements. The organic phase was dried under infrared and counted in a ger-manium/lithium detector coupled to a 4096 channel pulse height analyser. Indicated recovery was 96%, and the analysis time excluding counting was 50-min per sample. 

Metal complexes, dialkyl thiophosphates and dialkyl thiocarbamates of Zn, Ni, Ba, and Ca, in particular, are widely used for the stabilization of lubricants [30-32,34]. At moderate temperatures (350 400 K), these inhibitors are less efficient than phenols, but they are more potent at higher temperatures (430 480 K). The sophisticated mechanism of action of these antioxidants involves their reactions with hydroperoxide. The interaction of hydroperoxide with metal dialkyl thiophosphates induces a cascade of reactions [5,66-69],... 

Reaction with Peroxyl Radicals Metal Thiophosphates and Thiocarbamates Metal Complexes with Phosphites... 

A logical progression of O-carbamate DoM chemistry, to metalate S-thiocarbamates 103, E = H, proved unsuccessful, but turning attention to the corresponding O-thiocarbamates... 

Substituted thiazolidin-4-ones (449) are easily prepared by the reaction between chloracetic acid, or its derivatives (447), and a thiourea, a thiosemicarbazide, or a mono-or di-thiocarbamate (448 Scheme 255). The same a-chloro acid derivatives react with metallic thiocyanates yielding an intermediate (450), the cyclization of which gives a 2-iminothiazolidin-4-one (451). In these reactions a -chloracetic acid may be replaced by... 

Figure 5-1 Examples of Metal Chelates. Only the relevant portions of the molecules are shown. The chelate formers are (A) thiocarbamate, (B) phosphate, (C) thioacid, (D) diamine, (E) o-phenantrolin, (F) a-aminoacid, (G) o-diphenol, (H) oxalic acid. Source From K. Pfeilsticker, Food Components as Metal Chelates, Food Sci. Technol., Vol. 3, pp. 45-51, 1970.

The most widely applied reagents have been chelating agents which will complex with many metals, e.g. dithizone and the various thiocarbamate derivatives such as diethyldithiocarbamate and pyrrolidine dithiocarbamate. The latter agent as the ammonium salt (APDC) has been shown to complex some thirty elements [19] most of which can be readily extracted into various solvents. 4-Methylpentane-2-one (methyl isobutyl ketone or MIBK) is usually the favoured solvent because of its excellent compatibility with flames. The solubility of MIBK in water is not negligible and this limits the available concentration factor to ten higher molecular weight ketones (e.g. decan-2-one) offer better concentration factors and chloroform up to fifty times, but this latter solvent is only really suitable for electrothermal atomisation. 

Methoxyfuran also reacted with vinylcarbenes that were derived from sec-O-propargyl thiocarbamates in a transition metal-catalyzed ring opening to give a mixture of geometrical isomers, as depicted below <07TL6651>. 

Alkylzinc thio- and selenocarbamate derivatives are coimnonly air-sensitive white crystalline solids, with the thiocarbamate derivatives being more soluble in organic solvents than the selenocarbamate derivatives. They have been found to be dimers of general formula [RZnE2CNRy2, in which each carbamate chelates one metal atom and bridges to the next one (Figure 41). The zinc atoms are four-coordinate with a distorted tetrahedral geometry. 

Allylic Thioamides and Thiocarbamates by Metal-Catalyzed 3-Aza-l-Thia-Cope... 

The starting thiocarbamates can also be used for selective introduction of further substitution at 2-position via 2-directed metallation [60]. Indeed, s-BuLi in TMEDA selectively furnished the 2-lithiated product, which was reacted with electrophiles to produce the corresponding compounds shown in Scheme 20 [61]. 

Thiocarbamates and dithiocarbonates, which have attracted interest as possible sources of metal sulfides, are known with a variety of x-block metals, including lithium, calcium, ... 

Thiocarbamate herbicides can be prepared by the following reaction routes (1) Reaction of metal mercaptide with dialkylcarbamoyl chloride in anhydrous, nonreactive solvent (Tilles and Antognini, 1956) ... 

According to Riemschneider and Lorenz (1953) the respective chloroformic acid thiolester is prepared in the first step from metal mercaptide and phosgene this then reacts with the respective amine in the presence of alkali. The following example reaction scheme shows this method for S-ethyl N,N-dipropyl-thiocarbamate ... 

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