Can. J. Chem. 56, 1455.The thernial decomposition of methylamine solutions of potassium methylaniide (PMA) t o form the potassium salt (PDMFA) of N,N'-dimethylformaniidine (DMFA) has been studied as a function of PMA concentration at 60°C. Although concentrated solutions yield normal pseudo-first-order plots (analysis by ultraviolet-visible spectrophotornetry), dilute solutions (<0.05 mol L-' PMA) show an increase to a new rate after about 20 h reaction.The mechanism for this novel amidine salt synthesis is discussed in terms of rate-limiting e-hydride elimination from the PMA ion pair. The relatively sharp rate increase with time for the low concentration runs may arise from a slow buildup of one or more intermediates. The resulting inverse dependence of k,,, on PMA concentration is probably related to ion pairdimer association phenomena.Pure DMFA has been produced by this reaction, and its thernial stability examined. DMFA decomposes above 100'C to form bis-N-(N'-methylmethylenin~ine)methylamine and niethylamine; the series of equilibria involved have been shown to be reversible.On a etudie, en fonction de la concentration de la MAP a GOT, la deconlposition thermique On a pu produire de la DMFA pure par cette rtaction et on a tvalue sa stabilitk thermique. La DMFA se decompose au-dessus de 100°C pour conduire a de la bis-N-(N'-methylmethylcnimine) methylamine et a de la methylamine; on a montre que la strie des iquilibres impliques est reversible.[Traduit par le journal]Although there are few references in the literThe potassium salt of DMFA had been identified2 ature to N,Nf-dimethylformamidine (DMFA) (I), as one of the major products formed when a solution ~ -the general chemistry of the amidine group,
In this study we compared the sensitivity of immunoqtochemical procedures, using conventional and time-resolved fluorescent dyes, in a model system consisting of paraformaldehyde-fixed human lymphocytes. The lymphocytes were stained for the presence of the CD4 epitope by indirect immunofluorescence using FITC as label or by using timeresolved luminescent immunophosphors. These immunophosphors were primarily developed for use under time-resolved fluorescence conditions, but they are also very well suited for use in conventional fluorescence microscopes. The differently labeled cells were fmt examined visually with a conventional fluorescence microscope in a double-blind study. The fluorescence 'wds also measured w i t h a CCD camera mounted on a specially constructed time-resolved fluorescence microscope which allows the suppression of the fast
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