Dialkyl-dithiocarbamates

The salts of alkyl xanthates, A/,A/ -di-substituted dithio-carbamates and dialkyidithiophosphates [26] are effective peroxide decomposers. Since no active hydrogen is present in these compounds, an electron-transfer mechanism was suggested. The peroxide radical is capable of abstracting an electron from the electron-rich sulfur atom and is converted into a peroxy anion as illustrated below for zinc dialkyl dithiocarbamate [27] ... 

The processes described in this section should be contrasted with RAFT polymerization (Section 9.5.3), which can involve the use of similar thioearbonylthio compounds. A. A -dialkyl dithiocarbamates have very low transfer constants in polymerizations of S and (mctb)acrylatcs and arc not effective in RAFT polymerization of these monomers. However, /V,A -dialkyl dithiocarbamates have been successfully used in RAFT polymerization of VAc. Certain O-alkyl xanthates have been successfully used to control RAFT polymerizations of VAc, acrylates and S. The failure of the earlier experiments using these reagents and monomers to provide narrow molecular weight distributions by a RAFT mechanism can he attributed to the use of non-ideal reaction conditions and reagent choice. A two part photo-initiator system comprising a mixture of a benzyl dithiocarhamate and a dithiuram disulfide has also been described and provides better control (narrower molecular weight distributions).43... 

Metal dialkyl dithiocarbamates inhibit the oxidation of hydrocarbons and polymers [25,28,30,76 79]. Like metal dithiophosphates, they are reactive toward hydroperoxides. At room temperature, the reactions of metal dialkyl dithiocarbamates with hydroperoxides occur with an induction period, during which the reaction products are formed that catalyze the breakdown of hydroperoxide [78]. At higher temperatures, the reaction is bimolecular and occurs with the rate v = k[ROOH][inhibitor]. The reaction of hydroperoxide with dialkyl dithiocarbamate is accompanied by the formation of radicals [30,76,78]. The bulk yield of radicals in the reaction of nickel diethyl dithiocarbamate with cumyl hydroperoxide is 0.2 at... 

Measurements of solubilities in supercritical CO2 corroborated the hypothesis that the nonpolar character of a series of tetraaUsylammonium dialkyl-dithiocarbamate ion pairs was influenced... 

Treatment of [ MoX2(NO)2 ] with sodium dialkyl dithiocarbamates (Nadtc) affords the dinitrosyl complexes cis-[Mo(NO)2(S2CNR2)2] (R = Me or Et). These compounds may also be prepared by treatment of [Mo(NO)2(MeCN)4][PF6]2 with Nadtc and the complex [Mo(NO)2(acac)2] is obtained using Na[acac].26,27... 

In 1959, it was reported that on mixing silver(I) A.A-dialkyl dithiocarbamates with the corresponding thiuram disulfide, dissolved in benzene or chloroform, the solution immediately turned blue. 8,539 ESR spectra of these solutions showed the formation of paramagnetic d9 Agn complexes. The reaction was explained by the equilibrium expressed in equation (37). 

A kinetic study of the oxidation of some hexameric silver(I) dialkyl dithiocarbamate complexes by thiuram disulfides to the silver(II) complexes has been reported.543 Although a 100-fold excess of the thiuram disulfide was used, the formation of the Ag111 complex reported earlier was not considered. 

By analogy to the zinc structure, the coordination sphere around the silver(II) ion was anticipated to contain four sulfur atoms from two dialkyl dithiocarbamates in a square planar arrangement. Dimerization would occur by interaction via two Ag—S bridges (8S).538... 

The metal complexes of diethyl dithiophosphate were first investigated in 1931,134 when it was shown that the transition metal complexes [M((EtO)2PS2 ] (n = 2 or 3) were similar to those of xanthates and dialkyl dithiocarbamates, containing a four-membered XSMS (X = C or P) ring. A... 

Phosphorus is present in zinc dialkyldithiophosphate and deactivate platinum catalysts in engine exhaust systems. Using zinc, antimony and oxothiomolybdate dialkyl-dithiocarbamate (MoDTC) complexes alone or in combination with other lubricating oil additives appears to solve this problem. Antimony complexes are used also as extreme pressure agents while molybdenum ones as friction modifier additives (Hill et al., 1994). Analyses of Zn(dtc)2 decomposition using the thermogravimetric method, flash vacuum pyrolysis, and four-ball machine... 

Two types of antioxidants are used One type—amines and phenolics —reacts with the peroxy radicals to form more stable free radicals. The second type—sulfur compounds and phosphites—decomposes the hydroperoxides without formation of free radicals. The effect of sulfur compounds, such as dialkyl dithiocarbamates and alkyl thiols on the hydroperoxide decomposition has been investigated by Marshall. 

Another entry to 1,3-dithiolylium salts starts from 5-vinyl Af,iV-dialkyl dithiocarbamates (239) which are easily obtained by reaction of sodium dithiocarbamates with 1,2-dibromoethane. Treatment of the dithiocarbamates (239) with bromine gives the 1,3-dithiolylium bromides (242) via the intermediates (240) and (241) (73CL867). 

Tellurium was dissolved in aqueous sodium hydroxide. The solution was acidified with perchloric acid and an excess of sodium dialkyldithiocarbamate was added. Tris[dialkyl-dithiocarbamate] perchlorates of tellurium percipitated4. The X-ray structure analysis investigation of tellurium tris[dimethyldithiocarbamate] perchlorate revealed that all three dithiocarbamate groups and the perchlorate ion are bidentate4. 

N,N-Dialkyl dithiocarbamates were subjected to S-alkylation prior to GC analysis and the derivatives have been used even for GC-MS. S-alkylation is performed by the reaction with diazomethane, iodoethane or iodopropane. GC data on Apiezon L and mass spectra of a number of these compounds have been published [123]. 

The preparation of disulfides can be achieved by reacting the thiol or its salts with aqueous hydrogen peroxide358 under alkaline conditions. However, the pH needs to be closely monitored, since if too high, the disulfide selectivity will drop.359 Dialkyl dithiocarbamates can be oxidized to tetraalkylthiuram disulfides (Figure 3.92).360... 

Gold(I) forms dinuclear complexes with A,A-dialkyl dithiocarbamates, -diisopropyl dithiophosphate, aud... 

Scheme 19 Preparation of a bicyclic p-lactam from an N,N-dialkyl dithiocarbamate...

By a similar approach 5-vinyl-A7,A7-dialkyl-dithiocarbamates (214) afford, upon reaction with bromine, the 1,3-dithiolylium bromides (215) (Equation (35)) <73CL867,75S277>. 

Table 2. Molar Antioxidant Effectiveness of the Zinc Dialkyl Dithiocarbamate Homologous Series as UV Stabilizers Polypropylene (3 x 10 mol/100 g)...

In the investigation of the mode of action of dialkyl dithiocarbamates, tetramethylthiuram monosulfide (TMTM) revealed a systemic action (Pluijgers and Kerk, 1961 Kaslander, 1966). It is thought that the dimethylthiocarbamoyl part of TMTM is the carrier of the protective effect of the molecule. On this basis, several derivatives with systemic action have been synthesised (Carter et ai, 1963 Banki et al., 1966 Matolcsy and Josepovits, 1967), an example of which is N,N-(dimethylthiocarbamoyl)thioacetic acid (12). 

Certain yY V-dialkyl dithiocarbamates e.g. benzyl A At-diethyl dilhiocarbamate... 

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