TANG. Can. J . Chcm. 62, 741 (1984).The synthesis of somc ncw I-aryl-3-alkyl-3-hydroxymcthyltriazcncs is dcscribcd. Thc mcthod of coupling a diazonium salt with an alkylamine/formaldchyde mixture has been cxtcndcd to (a) somc diazonium ions withl~trrtr substituents other than -M groups, (b) those with substituents in thc nrthn position. and (c) to homologous alkylamincs (c.g. cthylamine, propylaminc, ctc.). Hydroxymethyltriazencs can also bc prcparcd by the rcaction of a I-aryl-3-mcthyltriazene with formaldchydc. Scvcral new derivatives of thc hydroxymcthyl function havc bccn prcparcd. Rcaction with acctic anhydridc or bcnzoyl chloride in pyridine affords respcctivcly the acctoxymcthyl-ant1 benzoyloxymcthyl-trinzcncs; thc acctatcs and bcnzoatcs rcact rcadily with methanol to give the novel mcthoxymethyltriazcncs. This is the first rcport of a scrics of dialkyltriazcncs with an ether linkagc in the a position. An ether of this type has also bccn obtaincd directly from thc diazonium tluoroboratc salt by coupling with a mixturc of benzylamine and formaldchydc in cthanolic solution.
The first-order rate constants of the reactions of acetoxymethyltriazenes with nucleophiles have been measured. Acetoxymethyltriazenes undergo hydrolysis in phosphate buffer to give the corresponding arylamines, presumably via the hydroxymethyl-and monomethyl-triazenes. The acetoxymethyltriazenes undergo solvolysis in alcohols and in mixtures of alcohols and other solvents; the rate of solvolysis has been correlated with the Grunwald-Winstein parameter (Y) for solvent ionising power, thus supporting the hypothesis of an S,1 mechanism and the intermediate formation of iminium ions during the solvolysis. The hypothesis is further supported by the non-common-ion effect; the presence of lithium chloride in the solvent greatly increases the rate of reaction, whereas lithium acetate causes a slight decrease in rate, attributable to a common-ion effect. Reaction of the acetoxymethyltriazene with sodium azide in aqueous acetone affords the a-azidomethyltriazene (a new type of triazene not previously reported) and provides supporting evidence for the iminium ion hypothesis. On the other hand, the acetoxymethyltriazene did not react with neat ethanethiol, providing further evidence for an S,1 mechanism; and S,2 reaction would be expected to proceed more quickly in the thiol than in the alcohol. It is shown that hydroxymethyltriazenes do not react via iminium ions and that functionalisation to a derivative such as the acetate is necessary for iminium ion generation. The implications of these results for the metabolism of xenobiotic N-alkyl compounds are discussed.
, 749 (1984). The synthesis of a series of N,N-bis(l-aryl-3-methyltriazen-3-ylmcthyl) methylamines from coupling diazonium salts with mixtures of methylamine and formaldehyde is described. These novcl bis-triazenes, or heptazanonadienes, have'significant anti-tumour activity against the TLXS lymphoma in mouse. The mechanism of formation of these triazenes is discussed with reference to the implication to the presumed cquilibria taking place in the methylaminc/formaldehyde solution. The formation of the bis-triazenc is usually accompanied by the formation of a 3-hydroxymcthyltriazene, and it has been shown that the hydroxymethyltriazene can be transformed into the bis-triazcne. The proportions of the two products are strongly influenced by the relative amounts of methylamine and formaldehyde. Coupling the p-bron~obenzenediazonium salt to a 1 : 1 methylaminc/formaldehyde mixture affords malnly the bis-triazene, whereas a 1 : 50 mixture gives almost totally the hydroxymethyl triazene. These results suggest that the two triazcnes arise from diazonium coupling to different species in the amine/formaldehyde mixture; this hypothesis is supported by the format~on of identical product mixtures from coupling the dlazonium ion with (a) a 1 : I MeNH2/CHZ0 mixture, and (b) the cyclic trimer of thc carbinolamine MeNHCHZOH, and by thc identification of a minor product from the reaction of p-chlorobenzencd~azonium tluoroborate with MeNH2/CH20 as bis(1 -p-chloropheny I-3-methyltriazen-3-y I) methane. 62, 749 (1984). On decrit la synthkse d'une sCrie dc N,N-bis-(aryl-l methyl-3 triazkne-3 ylmethyl) mCthylamines provenant du couplage de sels de diazonium avec des melanges de mithylamine et de formaldehyde. Ccs nouveaux bis-triazknes ou heptazanonadiknes ont une activitC anti-tumorale importante contre les lymphomes TLXS chez la souris. On discute du mecanisme de formation de ces triazknes en se rCfCrant i l'implication possible de I'Cquilibre qui est sensC s'Ctablir dans une solution de mCthylamine/ formaldkhyde. La formation du bis-triazkne est habituellement accompagnie par la formation de I'hydroxymCthyl-3 triazkne et on a montrk que I'hydroxymCthyltriazkne peut &tre transform6 en bis-triazene. Les proportions des deux produits sont fortement influencees par les quantitCs relatives de mithylamine et de formaldehyde. Le couplage du sel de pbromobenzknediazonium avec un mClange I : I de mCthylamine/formaldChyde conduit presqu'exclusivement au bis-triazkne alors qu'un melange 1 :50 foumit presque complktement I'hydroxymCthyltriazkne. Ces rksultats suggkrent que ces deux triazknes proviennent d'un couplage du diazonium avec diverses espkces prksentes dans un mClange aminelforma1dChyde; cette hypothkse est supportie par le fait qu'il y a formation de mClanges identiques de produits lorsqu'on couple I'ion diazonium avec (a) un melange I : I d'amine et de formaldkhyde et (b) le trimkre cyclique de la carbinolamine MeNHCHzOH ainsi que par le fait que l'on a pu identifier un produit mineur de la reaction du fluoroborate de p-chlorobenz~...
A method is described for the determination of microgram amounts of zirconium in complex matrices, based on the coprecipitation of zirconium with iron(ll1) hydroxide and the direct analysis of the precipitate by X-ray fluorescence spectrometry. The amount of iron in the digested sample is controlled by a solvent extraction step which precedes the formation of the precipitate. The method is free from interferences, takes advantage of the analysis of thin-film samples and has a detection limit of 0.9 pg 9-1 for a 10-s count; this is 20 times lower than that for the standard method of XRF analysis. The method has been applied to the analysis of a set of geological reference materials.
Quantitative analyses of light elements using energy‐dispersive x‐ray microanalysis (EDX) is increasingly possible since the development of sealed light element ultra‐thin window detectors. However, the computer programs available for quantitative analyses fail for light elements because the correction and background modelling parameters are not accurately known. Therefore, we have developed a simple method of light element quantitative analysis using the peak ratios of two elements as the basis for calibration curves using stable standards. The use of peak ratios avoids the need for accurate ZAF corrections and minimizes many experimental variables. This article describes the criteria for the selection of standards, and the development of the calibration curve in the case of compounds containing oxygen and carbon. The success of the method depends on careful sample preparation and predetermined experimental parameters. The method has been successfully applied to the surface analysis of fresh and oxidized Western and Eastern Canadian coals.
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