1825-21-4Relevant articles and documents
De Jongh et al.
, p. 1469,1471 (1971)
Simultaneous extraction and methylation of acidic analytes adsorbed onto ion exchange resins using supercritical carbon dioxide containing methyl iodide
Chatfield,Croft,Dang,Murby,Yu,Wells
, p. 945 - 951 (2007/10/02)
Methylation of a wide range of organic acids with methyl iodide was simply and efficiently performed on anion exchange resins with either supercritical carbon dioxide or acetonitrile as solvents. Analytes including chlorophenoxyacetic acids, pentachlorophenol, and quinoxaline-2-carboxylic acid were displaced from the resin in a single step as their methyl esters or ethers in high yield using the supercritical fluid extraction (SFE) system. The conversion of 2,4-D and 2,4,5-T (solutions of 100 and 35 ppb, respectively) to their methyl esters was complete in 30 min and gave yields of 92% and 99% with coefficients of variation of 10%. Analytes in up to 200 mL of aqueous solution could be trapped on 0.1 g of AG MP-1 anion exchange resin and derivatized and eluted using methyl iodide in supercritical carbon dioxide at 200 bar and 80°C. Less acidic compounds including albendazole, fenbendazole, triclabendazole, and sulfadimidine could also be derivatized on the resin under SFE conditions or in a quick and inexpensive procedure using acetonitrile; however, these compounds gave lower yields and multiple methylated products.
Nucleophilic Displacement in Polyhalogenoaromatic Compounds. Part 11. Kinetics of Protiodeiodination of Iodoarenes in Dimethyl Sulphoxide-Methanol
Bolton, Roger,Moore, Clive,Sandall, John P.B.
, p. 1593 - 1598 (2007/10/02)
The rates of methoxide-ion induced protiodeiodination of a number of polychloroiodobenzenes and their derivatives have been measured in dimethyl sulphoxide-methanol (9:1 v/v; 323.2 K).The true reagent under these conditions appears to be the dimethyl sulphoxide anion, and the rates of reaction in some cases appear to approach that expected of a diffusion controlled process.This corresponds to a major decrease in the efficacy of further activating substituents in the aromatic system, altough deactivating groups such as p-OMe still show large effects.Chlorine promotes protiodeiodination in the order of efficiency o-Cl > m-Cl > p-Cl; the trifluoromethyl group activates displacement in the order o-CF3 > p-CF3 > m-CF3, although with much less difference between isomeric sites. o-Nitro-groups promote protiodeiodination whereas the p-nitro-group encourages methoxydeiodination.No evidence of methoxydeiodination was found in attack of the polychloroiodobenzenes, although the rates of methoxydechlorination of the corresponding polychlorobenzenes suggest that in some cases this might occur.Evidence rejecting the possible SRN1 mechanism and supporting nucleophilic attack by a carbanionic species upon iodine is presented.
