Thiocarbamates derivatives

Solvent extraction is probably the separation technique which is most widely used in conjunction with AAS. It often allows the extraction of a number of elements in one operation and, because of the specific nature of AAS, non-selective reagents such as the thiocarbamate derivatives (e.g. APDC) may be used for the liquid-liquid extraction (see Section 6.18). 

It is claimed that this reaction proceeds via a 2, 3 -thionocarbonate or a thiocarbamate derivative. If the 5 -OH group of uridine was not protected, the yield of the 2,2 -anhydro-l-(j -D-arabinofuranosyl)uracil was low. 

An example of the profound effect which change in physical property may have on the toxicological properties of a methylcarbamate insecticide is made apparent from toxicological data for a series of thiocarbamate derivatives of carbofuran (Table 1) (12). 

Table I. Toxicity of Thiocarbamate Derivatives of Carbofuran to House Flies, Mosquito Larvae and Mice...

Figure 1. Relationship between the mosquito larvicidal toxicity (log LC50) of the thiocarbamate derivatives of carbofuran, propoxur and m-isopropylphenyl methylcarbamate (MIP) and logarithm of the octanol/water partition coefficient (log P).

As In the case of the examples given in Tables I and III, the N-thiocarbamate derivatives were generally equal to the parent methylcarbamate in toxicity to house flies, particularly after taking into consideration Increase in molecular weights. Except for the methomyl and oxan l derivatives, substantial improvement in mosquito larvlcldal activity again appeare d to be a function of the lipophilic properties of the derivative. With the exception of the oxanyl derivatives, the data clearly indicate that the N-thiocarbamate derivatives are markedly less toxic to the white mouse than the parent methylcarbamate. Since... 

The reaction of 2-aminobenzyl alcohol 376 with 2-chloro-4,5-dihydroimidazole afforded [2-(4,5-dihydro-177-imidazol-2-ylideneamino)phenyl]methanol hydrochloride 377, which upon treatment with carbon disulfide gave l-(477-3,l-benzoxazin-2-yl)imidazolidine-2-thione 378 (Scheme 71). The assumed reaction mechanism involved the initial formation of the dithiocarbamate 379, which underwent intramolecular nucleophilic addition to furnish the unstable thiazetidine 380. By nucleophilic attack of the hydroxy group on the carbon atom of the thiazetidine ring, thiocarbamate derivative 381 was formed, which gave the final 3,1-benzoxazine 378 by an intramolecular cyclocondensation with the evolution of H2S <2006H(68)687>. 

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. 

Thiocarbamate derivatives, (VI), effective as a4 integrin inhibitors having enhanced resistant to metabolism were prepared by Jackson (6) and used in treating diseases mediated by the binding interaction of a4 integrin such as inflammatory disorders. 

Benzoyl-anilino podophyllotoxin derivatives, (III), prepared by Kamal (2) and carbamate and thiocarbamate derivatives, (IV), prepared by Monneret (3), respectively, were effective against murine leukemia from L1210 cells. 

Thiocarbamate derivatives, (III), prepared by Rink [2] were effective as free radical regulators in the 2,2-azobisisobutyronittiIe-initiated polymerization of styrene. 

Rink [4] prepared thiocarbamate derivatives, (VI), that were used as regulators in the (co)polymerization of styrene using 2,2 -azobisisobutyronitrile as the free radical initiator. 

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. 

Mercury dimethoxide and phenyhnercury methoxide also react with organic isocyanates and isothiocyanates to form carbamate and thiocarbamate derivatives, respectively. " ... 

The thiocarbamate derivatives can be obtained by reaction of the aryl- or alkylthiocarbonyl chloride with two equivalents of an amine in an organic solvent (equation 29) When the alkylation is carried... 

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