Fungicides manganese dithiocarbamates

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. 

Manganese Ethylenebis(thiocarbamate). Maneb [12427-38-2] (C4HgMnN2S (1), is a yellow powder used as a leaf and soil fungicide (see Fungicides, agricultural). Maneb is obtained by treating disodium ethylenebis(dithiocarbamate) with an aqueous solution of maganese(II) sulfate (37). 

The fungicidal dithiocarbamates Maneb and Zineb are the manganese and zinc salts, respectively of ethylene -1,2- bisdithiocarbamic acid ... 

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. 

Chemical Name manganese ethylenebis(dithiocarbamate) (polymeric) complex with zinc salt CAS Registry No 8018-01-7 Uses fungicide... 

Dithiocarbamates are normally prepared as alkali metal salts by the action of primary or secondary amines on CS2 in the presence of, say, NaOH. The zinc, manganese, and iron dithiocarbamates are extensively used as agricultural fungicides, and zinc salts as accelerators in the vulcanization of rubber. Alkali metal dithiocarbamates are usually hydrated and are dissociated in aqueous solution. When anhydrous, they are soluble in organic solvents in which they are associated. 

Several dithiocarbamates are important commercial fungicides,3 e.g. maneb, which is manufactured from carbon disulfide and ethylenediamine (5). The intermediate disodium dithiocarbamate (6) is finally treated with a solution of a soluble manganese salt to yield maneb (7) (Scheme 4). Maneb is a very widely used agricultural fungicide (see Chapter 11, p. 234).3... 

Meco G, Bonifati V, Vanacore N, and Fabrizio E (1994) Parkinsonism after chronic exposure to the fungicide maneb (manganese ethylene-bis-dithiocarbamate). Scandinavian Journal of Work Environment and Elealth 20 301-305. 

Rhodes RC. 1977. Studies with manganese [14C]Ethylenebis(dithiocarbamate)([14C]maneb) fungicide and [14C]Ethylenethiourea ([14C]ETU) in plants, soil, and water. J Agric Food Chem. 25 528-533. 

As there was an excess of resin compared to the amount of cations in the wine, stoichiometric H+ ions were released in exchange and assayed using sodium hydroxide. Wine contains the cations naturally present in grapes, with the addition of manganese and zinc, originating from vine sprays containing fungicides such as dithiocarbamates. 

Depending on their carbon skeleton, DTCs can be categorized into three subclasses, that is,dimethyldithio-carbamates (DMDs), ethylenebis(dithiocarbamates) (EBDs), and propylenebis(dithiocarbamates) (PBDs) (Table 26.1).They are mainly produced as complexes of transition metals, preferably manganese and zinc. In the case of EBD and PBD, it is unclear if the complexes are monomer or polymer in type. Therefore, the stmcture formulae presented in Table 26.1 only provide composition. The two metal-free fungicides in use are thiram and dazomet. Dazomet is mainly used as soil sterilant (precursor of methyl isothiocyanate), whereas DTCs are typically applied to aerial parts of plants. 

Derivatives of thiocarbamic acid are a family of very important fungicides used in many plant-care products. Manganese salts (maneb), zinc salts (zineb), sodium and iron salts have no action on aluminium, whatever their degree of dilution. On the other hand, copper salts of dithiocarbamic acid may attack aluminium. 

The manganese ethylene bis(dithiocarbamate) complex MANEB is used as a fungicide (15). Manganese is a well-known toxin for Parkinsonism in humans, while dithiocarbamates can induce extra-pyramidal syndromes. One publication details the development of permanent Parkinsonism in a 37-year old man exposed to MANEB for only 2 years (1134), and follows a previous report of the same symptoms developed after 10 years exposure (1135). 

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