Demethylative coppering

A special process for the production of coppered l,5-bis(2-hydroxyphenyl)-formazans 32 is based on the demethylative copperization of 1,5-bis(2-methoxy-phenyl)formazans [63], The method involves heating for a short time in pyridine, formamide, or dimethylformamide. 

In demethylative coppering to give the bis-copper complex 22 [74592-99-7] (3 Na, Li salt) [36], the sodium salt of the disazo compound made by coupling of bis-diazotized 3,3 -dimethoxy-4,4 -diaminodiphenyl with two equivalents of 8-amino-l-hydroxynaphthalene-3,6-disulfonic acid in alkaline medium is dissolved in water by adding diethanolamine. An ammonia alkaline copper(n) sulfate solution made from CuS04-5 H20 and of ammonia are added. The mixture is heated at 80-90 °C for 14 h. The solution is then cooled to 40 °C and the bis-coppered dye 22 salted out with sodium chloride. It dyes cotton in lightfast blue shades. 

As a rule many of these dyes only have moderate lightfastness on paper. To improve this metal complexes are used, particularly with the blue azo dyes. Because planarity of the dye molecule is advantageous for a good dyeing, virtually only Cu2+ complexes such as C.I. DirectBlue 218,24401 28407-37-6] (18) are of interest for paper. 3.3 -Dimcthoxy-4,4 -biphcnyldiaminc (o-dianisidine) has proved particularly suitable, because after coupling with a 1-naphthol derivative demethylative copperization can take place. 

Sakano, K. Inagaki, Y. Oikawa, S. Hiraku, Y. Kawanishi, S. Copper-mediated oxidative DNA damage induced by eugenol possible involvement of O-demethylation. Mutat. Res. 2004, 565, 35 44. 

Many of the premetallised direct dyes are symmetrical structures in the form of bis-1 1 complexes with two copper(II) ions per disazo dye molecule. Scheme 5.12 illustrates conversion of the important unmetallised royal blue Cl Direct Blue 15 (5.43), derived from tetrazotised dianisidine coupled with two moles of H acid, to its much greener copper-complex Blue 218 (5.44) with demethylation of the methoxy groups as described above. Important symmetrical red disazo structures of high light fastness, such as Cl Direct Red 83 (5.45), contain two J acid residues linked via their imino groups. Unsymmetrical disazo blues derived from dianisidine often contain a J acid residue as one ligand and a different coupler as the other, such as Oxy Koch acid in Cl Direct Blue 77 (5.46), for example. 

Demethylating while copperizing is achieved only under severe conditions, i.e., at temperatures in excess of 100°C, frequently under pressure. Suitable starting materials are o-hydroxy-o -methoxyazo compounds. 

Olivetol. 3,5-Dimethoxybenzyl alcohol. (This can be made by reducing 3,5-dimethoxybenzoic acid, or it can be purchased.) (10 g) in 100 ml of methylene chloride is cooled to 0° and 15 g of PBrs is added. Warm to room temp and stir for 1 hour, then add a little ice water followed by more methylene chloride. Add petroleum ether to precipitate the benzyl bromide, which is separated off. 9.3 g of the benzyl bromide is put in a flask with 800 ml of dry ether and then add 15 g of copper iodine at 0°. Add butyl lithium (16% in hexane) and stir for four hours at 0°. Add saturated NH4CI and extract with ether. The ether is removed by evaporating in vacuo to give the olivetol dimethyl ether which must be demethylated by one of the methods given in the above formulas. Yield A little over 4 g. Taken from HCA, 52, 1132. 

Dithioacetals derived from heteropine 177 smoothly react with methylene iodide in the presence of a zinc-copper couple in refluxing ether to give the corresponding fused thiophenes 178. The suggested mechanism involves formation of an ylide which undergoes intramolecular aldol-type condensation assisted by coordination of zinc with a carbonyl followed by demethylation of the S-methylthiophenium species (Scheme 35 (1989TL3093)). 

Metal complex dyestuffs derived from tetradentate azo compounds (147) have very limited commercial significance but merit brief discussion on chemical grounds. The first dyestuffs of this type to be used commercially contained the o-hydroxy-o -carboxymethyleneoxydiarylazo system, e.g. (148). These were dyed on cotton and aftertreated with a copper salt to produce the copper complex dyestuff which was reported71 to be a triannelated species (149). Formation of complexes of this type has been confirmed105 in the case of 2-hydroxy-5-methyl-2 -carboxymethyleneoxy-azobenzene, which yields the complex (150) on treatment with copper acetate under mild conditions. Under more severe conditions, however, the complex (151) is produced. Loss of the carboxymethyl group from dyes of this type has also been shown105 to occur under dyebath conditions. This may be compared with the demethylation of o-methoxy-o -hydroxydiarylazo compounds (Section 58,2.3. l(iii)(a)) under similar conditions. 

During an attempt to prepare 3-methoxy-2-nitrobenzoyl cyanide by heating the title chloride with copper cyanide to over 200°C, the reaction mixture had decomposed vigorously at around 60°C. This was attributed to thermal instability of the intended product [1], but available evidence suggests that instability of the title nitroacyl halide is a much more likely cause. However, there is also the possibility of a reaction involving demethylation of the methoxynitrobenzoyl chloride by traces of hydrogen... 

Thiram and other dithiocarbamates are metabolic poisons. The acute effects of thiram are very similar to that of carbon disulfide, supporting the notion that the common metabolite of this compound is responsible for its toxic effects. The exact mechanism of toxicity is still unclear, however it has been postulated that the intracellular action of thiram involves metabolites of carbon disulfide, causing microsome injury and cytochrome P450 disruption, leading to increased heme-oxygenase activity. The intracellular mechanism of toxicity of thiram may include inhibition of monoamine oxidase, altered vitamin Bg and tryptophan metabolism, and cellular deprivation of zinc and copper. It induces accumulation of acetaldehyde in the bloodstream following ethanol or paraldehyde treatment. Thiram inhibits the in vitro conversion of dopamine to noradrenalin in cardiac and adrenal medulla cell preparations. It depresses some hepatic microsomal demethylation reactions, microsomal cytochrome P450 content and the synthesis of phospholipids. Thiram has also been shown to have moderate inhibitory action on decarboxylases and, in fish, on muscle acetylcholinesterases. 

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