14426-28-9Relevant articles and documents
Synthesis and characterization of N-demethylated metabolites of malachite green and leucomalachite green
Cho, Bongsup P.,Yang, Tianle,Blankenship, Lonnie R.,Moody, Joanna D.,Churchwell, Mona,Beland, Frederick A.,Culp, Sandra J.
, p. 285 - 294 (2007/10/03)
Malachite green (MG), a triphenylmethane dye used to treat fungal and protozoan infections in fish, undergoes sequential oxidation to produce various N-demethylated derivatives (monodes-, dides(sym)-, dides(unsym)-, trides-, and tetrades-) both before and after reduction to leucomalachite green (LMG). The close structure resemblance of the metabolites with aromatic amine carcinogens implicates a potential genotoxicity from exposure to MG. The availability of the synthetic standards is important for metabolic and DNA adduct studies of MG. This paper describes a simple and versatile method for the synthesis of MG, LMG, and their N-demethylated metabolites. The synthesis involves a coupling of 4-(dimethylamino)-benzophenone or 4-nitrobenzophenone with the aryllithium reagents derived from appropriately substituted 4-bromoaniline derivatives, followed by treatment with HCl in methanol. The resulting cationic MG and their leuco analogues showed systematic UV/vis spectral and tandem mass fragmentation patterns consistent with sequential N-demethylation. The extensive 1H and 13C spectral assignments of the metabolites were aided by the availability of 13C7-labeled MG and LMG. The results indicate the existence of a resonance structure with the cationic charge located in the central methane carbon (C7). The synthetic procedure is general in scope so that it can be extended to the preparation of N-demethylated metabolites of other structurally related N-methylated triphenylmethane dyes.
The Relative Electrophilic Reactivities of Tropylium Cation and its (OC)3M ?-Complexes: Kinetic Studies of Alkoxide Transfer and Reversible Nucleophilic Addition
Lal, Kasturi,Leckey, Nigel T.,Watts, William, E.,Bunton, Clifford A.,Mhala, Marutirao M.,Moffatt, John R.
, p. 1091 - 1098 (2007/10/02)
?-Complexation of the tropylium cation (Tr)(1+) with an (OC)3Cr group increases thermodynamic stability (ΔpKR+ ca. 4.3 in methanol) and reduces reactivity towards abstraction of methoxide ion from Malachite Green methyl ether (MG)OMe (krel. ca. 110) in MeNO2 - MeCOEt (40:60 v/v) and nucleophilic exoaddition of methanol (krel. ca. 2100) in methanol.The organometallic cation (1a) is stable in aqueous solutions of pH(1+), (1+), and (1+) in MeNO2-MeCOEt (40:60 v/v) are 1:10:6, respectively.The rates of transfer to (Tr)(1+) of alkoxide ion from (η-7-exo-alkoxycycloheptatriene)Cr(CO)3 complexes (2a-d) in MeCN decrease through the series: alkoxy=methoxy>ethoxy>isopropoxy>t-butoxy, but the overall rate change is only about five-fold.In methanol, the 7-exo-methoxycycloheptatriene complex (2a) is about ten times more reactive towards acid heterolysis than is methyl tropyl ether.This conversion is general acid-catalysed.In aqueous solutions of pH>ca. 6, the rate of spontaneous heterolysis of the ether (2a) is substantially faster than that of consumption of the resulting cation (1a) which increases with increasing pH.The 7-endo-methoxy stereoisomer (3) is inert to acid heterolysis in aqueous solutions to give cation (1a), but undergoes decomplexation to give (Tr)(1+).
Reaction of Leucomalachite Green with Chloranil
Nishimura, Norio,Motoyama, Takushi
, p. 3639 - 3640 (2007/10/02)
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