Fungicides Dimethyldithiocarbamates

Dithiocarbamate fungicides consist of metal salts of dimethylthiocarbamate and ethylenebis-dithiocarbamate anions, as shown in Figure 17.5. These fungicides are named in accordance with the metal ion present. For example, the manganese salt of dimethyldithiocarbamate is called maneb, and the zinc and sodium salts are zineb and nabam, respectively. The iron salt of ethylenebisdithio-carbamate is called ferbam, and the zinc salt of this ion is called ziram. These salts are chelates (Section 2.3) in which two S atoms from the ethylenebisdithiocarbamate anion are bonded to the same metal ion in a ring structure. 

The traditional copper fungicides are in fact inorganic copper coordination compounds The still most important group of organic protectant fungicides, the dithiocarbamates, are applied in the form of their metal-coordination compounds. Dimethyldithiocarbamate as the iron complex ferbam and the zinc complex ziram, ethylenebisthiocarbamate as the zinc complex zineb and the manganese complex maneb. 

Sodium dimethyldithiocarbamate and sodium 2-raercaptobenzo-thiazole supplied as a 30% solution. Industrial bactericide/ fungicide for textiles and for agriculture. 

N,N-Dimethyldithiocarbamates do not form isothiocyanates, so their mode of action as fungicides is different from that of the afore-mentioned substances. TMTD penetrates the cell membrane of fungi more easily than dimethyldithio-carbamates, and is then reduced within the cell (Richardson and Thorn, 1961) so that its action is the same as that of dimethyldithiocarbamates. However, the fact that TMTD is more toxic to several microorganisms than the sodium salt of dimethyidithiocarbamic acid indicates that there must be a certain nonessential difference between the two active substances. Owens and Rubinstein (1964) proved in vitro the different reactivity of TMTD and of the other dimethyldithiocarbamates towards 4-nitrothiophenol. However, in the primary reaction of TMTD dimethyl-... 

The antifungal effect of the 2 1 complex nontoxic in itself, is an unsettled question. According to certain authors, it is converted within the cell into the 1 1 complex. However, this is inconsistent with the fact that the 2 1 complex cannot penetrate the cell with its very low water solubility. According to recent theories, the stabilities of the complexes play the decisive role. The stability of the metal complexes of identical dialkyldithiocarbamates depends on the metal. The order of stability of dimethyldithiocarbamate complexes used as fungicides is, according to Eckert (1957), Mn[Pg.360]

Pesticides N-nitrosated under 1m vitro and vivo conditions in the laboratory have included the fungicide ziram (zinc dimethyldithiocarbamate), the insecticides carbaryl (1-naphthyl methyl carbamate) and propoxur (o-isopropoxy phenyl methyl carbamate) and the herbicides benzthiazuron [N-(2-benzothiazolyl)-N -methylurea], simazine [2-chloro-4,6-bis(ethylamino)-s-triazine] and atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine). 

Tetramethylthiuram disulfide (3.56), which is used to check the growth of fungi in seeds and turf, acts by reduction to dimethyldithiocarbamic acid (3.57) which is a widely used chelating fungicide (see Section 11.7.3). 

Dimethyldithiocarbamic acid, or DMDC (5.57), is a potent fungicide much used in agriculture as the sodium ( NaDDC ), iron (Termate or ferbam), and zinc ( Zerlate or ziram) salts. Formula (77.75) shows the 1 1 copper complex. 

Fungicides sodium A -methyldithiocarbamate, sodium MA -dimethyldithiocarbamate, ammonium tetramethylenedithiocarbamate, sodium, iV-diethyldithiocaibamate, and disodium ethylenebisdithiocarbamate Pond water p-Bondapak CN 0.0125 M CTAB-30% methanol in 0.018 M phosphate buffer at pH 6.8 254 nm. 3... 

Synonyms Aafertis Bercema Fertam 50 Carbamate Dimethylcarbamodithioc acid iron complex Dimethylcarbamodithioc acid iron(3+) salt Dimethyldithiocarbamic acid iron salt Dimethyldithiocarbamic acid iron(3+) salt ENT 14689 Ferbam 50 Ferbame Fer-bam, iron salt Ferbeck Ferberk Fermate Fermate ferbam fungicide Fermocide Ferra-dow Ferric dimethyldithiocarbamate Fuklasin Fuklasin ultra Hexaferb Hokmate Iron flowable Iron tris(dimethyldithiocarbamate) Karbam black Trifimgol Tris(dimethyl-carbamodithioato-S,y)iron Tris(dimethyldithiocarbamato)iron Vancide FE95. 

The dithiocarbamates include zinc dibutyldi-thiocarbamate (ZDBC), zinc diethyldithiocarbamate (ZDEC) and zinc dimethyldithiocarbamate (ZDMC). In the rubber industry, the carbamates are principally used in gloves, condoms and elastic bands. Due to their chemical similarity with thiurams, the potential for cross-reactivity between these groups exists (Con-de-Salazar 1990a Knudsen and Menne 1996). The greatest use of carbamates is not in rubber but in pesticides and fungicides (Table 8). 

Metallic mercury is used as an electrode in the electroljdic generation of chlorine gas, in laboratory vacuum apparatus, and in other applications. Significant quantities of inorganic mercury(I) and mercury(ll) compounds are used annually. Organic mercury compounds used to be widely applied as pesticides, particularly fungicides. These mercury compounds include aryl mercurials such as phenyl mercuric dimethyldithiocarbamate... 

The first report of iron dithiocarbamate chemistry was in 1907, when Delepine (2) detailed the synthesis of the iron(III) tris(dithiocarbamate) complex [Fe(S2CN i-Bu2)3]. Later the dimethyldithiocarbamate complex [Fe(S2. CNMe2)3l (Ferbam) found widespread use as a fungicide (14). Iron(ll)... 

Other chelating antimicrobials have been found that, while having a totally different structure, mimic the action of oxine by being active only in the presence of a variable-valence metal, and hence show concentration quenching. Such a substance is i-hydroxypyridine-2-thione (pyrithione), (2.2j) (Albert, Rees, and Tomlinson, 1956), which is much used in the dermatology of the scalp. Another example is dimethyldithiocarbamic acid (2.2 ), whose salts are widely used as selective fungicides in agriculture. 

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