Dithiocarbamic acid salts, from

The N-substituted derivatives (175) are also obtained from salts of N-monosubstituted dithiocarbamic acid (174) (Scheme 89) (35, 348). 

Salts of dithiocarbamic acid can be prepared by the addition of primary or secondary amines to carbon disulfide. This reaction is similar to 16-9. Hydrogen sulfide can be eliminated from the product, directly or indirectly, to give isothiocyanates (RNCS). Isothiocyanates can be obtained directly by the reaction of primary amines and CS2 in pyridine in the presence of DCC. ° In the presence of diphenyl phosphite and pyridine, primary amines add to CO2 and to CS2 to give, respectively, symmetrically substituted ureas and thioureas ... 

Syntheses Starting from Dithiocarbamic Acids, Their Ammonium Salts. 

This section will be divided into a discussion of reactions carried out starting from thioamides, thioureas, substituted thioureas, dithiocarbamic acids and their ammonium salts, and miscellaneous syntheses. 

Disulfur dinitride, 6 126 Disulfur pentoxydiehloride, 3 124 analysis of, 3 126 Dithiocarbamates, of selenium(II) and tellurium(II), 4 91 Dithionic acid, salts of, 2 167 Dithionite ion, formation of, from sulfur dioxide by sodium hydride, 5 13... 

Despite the chemical diversity of the several hundred structures representing herbicidal activity, most reactions of herbicides fall within only a limited number of mechanistic types oxidation, reduction, nucleophilic displacements (such as hydrolysis), eliminations, and additions. "Herbicides", after all, are more-or-less ordinary chemicals, and their principal transformations in the environment are fundamentally no different from those in laboratory glassware. Figure 2 illustrates three typical examples which have received their share of classical laboratory study—the alkaline hydrolysis of a carboxylic ester (in this case, an ester of 2,4-dichlorophenoxyacetic acid, IX), the cycloaddition of an alcohol to an olefin (as in the acetylene, VI), and the 3-elimination of a dithiocarbamate which provides the usual synthetic route to an isothiocyanate (conversion of an N.N-dimethylcarbamic acid salt, XI, to methyl isothiocyanate). Allow the starting materials herbicidal action (which they have), give them names such as "2,4-D ester" or "pronamide" or "Vapam", and let soil form the walls of an outdoor reaction kettle the reactions and products remain the same. 

Halo ketones react with thioacids to form 1,3-dithiolylium salts 225 which are also obtained from -dimercaptoethy-lenes 224 (Scheme 110) . A new approach to the synthesis of 1,3-dithiolylium salts 228 involves an acid-catalyzed cyclization of the corresponding dithiocarbamates 227, obtained from -bromo ketones 226 in a high yield (Scheme 111) <2001SC1271, 2003SUL155, CHEC-III(4.12.9.1)1015>. 

Dithiocarbamic acid itself and its alkali metal salts are unstable towards hydrolysis but metal chelates are known and a structure of [Co(S,CNH2)3] is available (Table 96). This complex is probably unstable towards hydrolysis giving [Co(S2CO)3]3. Salts of dithiocarbamates derived from primary amines are also unstable under alkaline conditions, although N(3)-substituted dithiocar-bazic acid forms green tris(S,S) chelates (336).1133 The similar N(3)-unsubstituted acids form (N,S) chelates (337) which can be deprotonated when R = H with possible isomerization to the (S,S) dithiocarbimate chelate (339).1133 The (N,S) chelate (338) has been positively identified by a crystal structure of its 5-methyl ester, R = H (Table 96).1134... 

Dithioacetic acid derivatives add to 1,4-benzo- or 1,4-naphthoquinones to give, after oxidation of the adduct with silver oxide or chloranil, the quinones 217 and 218 (69LA103). Quinones 218 were prepared also from 2,3-dichloro-1,4-naphthoquinone and salts of dithiocarbamic acids (51JA3459) and those of type 219 by oxidation of the corresponding hydroquinones. From reduction potentials and the semiquinone formation constants, it was concluded that their anion radicals are thermodynamically stable (86CC1489). 

These products can also be obtained from the esters of dithiocarbamic acid and sodium azide 21S). The two reagents are dissolved in a suitable solvent, usually a water-ethanol mixture, and heated until no more alkane thiol is split off. The thione is isolated by acidifying the sodium salt. This method of preparation avoids the use of the difficult to prepare isothiocyanates. 

Synthesis of Dithiocarbamates from CSj. The addition of ammonia or alkylamines to CS2 to form the amine salts of dithiocarbamic acids is analogous to their addition to CO2 to form the corresponding carbamate salts. 

Sodium dibenzyldithiocarbamate [55310-46-8] M 295.4, m 230"(dec), pK 3.13 (for monobenzyl-dithiocarbamic acid). The free acid, when recrystallised twice from dry Et20, has m 80-82". The Na salt is reprecipitated from aqueous EtOH or EtOH by addition of Et20 or Me2CO [Lindler.4 o/ Chem 50 896 1978], The NH4 salt has m 130-133", the Cu salt (yellow crystals) has m 284-286°, and the Ti salt has m 64-70". [Beilstein niY2215.]... 

Salts of dithiocarbamic acids from amines NH NCSS ... 

The conversion of the weakly UV-absorbing primary and secondary amines to the more strongly absorbing dithiocarbamic acids has been used to reveal the firee amines on thin-layer plates [47]. The plates were sprayed with dilute ammonia to free the bases from their salts before exposure to carbon disulfide. 

TABLE 26.2 Conversion Factors to Calculate the Concentration of FVee Dithiocarbamic Acids from the Used TEA Salts and to Calculate the Respective CS2 Residues from Dithiocarbamic Acid Values... 

Carbamates comprise the esters and the salts of carbamic acids. This is a systematic classification from chemical aspects. Microbicides of this class of substances widely differ in terms of both efficacy and mechanisms of activity. The carbamic and dithiocarbamic acids, the basis of the carbamates, lack chemical stability they occur only intermediarily and disintegrate instantly to form carbon dioxide (CO2), carbon disulphide (CS2) and amine (see Fig. 31). 

All secondary amines react with carbon disulfide in ammoniacal solution with the formation of ammonium salts of dithiocarbamic acids, which do not decompose in the presence of metal salts (in contrast to similar compounds derived from primary amines), but give, for example, an insoluble salt with a nickel salt (16) ... 

Method 1. Polymerization of Bis(dithiocarbamates) with Metal Salts Polymeric metal bis(dithiocarbamates) have been prepared by polymerization of disodium salts of bis(dithiocarbamic acids) with metal acetates (/9). Polymers prepared from nickel, zinc, and cobalt were prepared in aqueous media and were shown to possess structure [20]. 

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