Jensens’s reagent

Fig. 1 Chromatogram of a lily of the valley extract - left before and right after treatment with Jensen s reagent, photographed in long-wavelength UV light (X = 365 nm) [13].

Elemental sulfur is present in most soils and sediments (especially anaerobic), and is sufficiently soluble in most common organic solvents that the extract should be treated to remove it prior to analysis by ECD-GC or GC-MS. The most effective methods available are (1) reaction with mercury or a mercury amalgam [466] to form mercury sulfide (2) reaction with copper to form copper sulfide or (3) reaction with sodium sulfite in tetrabutyl ammonium hydroxide (Jensen s reagent) [490]. Removal of sulfur with mercury or copper requires the metal surface to be clean and reactive. For small amounts of sulfur, it is possible to include the metal in a clean-up column. However, if the metal surface becomes covered with sulfide, the reaction will cease and it needs to be cleaned with dilute nitric acid. For larger amounts of sulfur, it is more effective to shake the extract with Jensen s reagent [478]. 

Sulfur removal Elemental sulfur removal prior to analysis by ECD-GC or GC-MS by the reaction with (a) mercury or a mercury amalgam to form mercury sulfide, (b) copper to form copper sulfide, or (c) sodium sulfite in tetrabutyl ammonium hydroxide (Jensen s reagent) Removal of sulfur with mercury or copper requires the metal surface to be clean and reactive The need to dean with dilute HNO3 if the metal surface becomes covered with sulfide 1... 

They also showed that if Olivier s data183 for this system was treated as three-halves-order instead of second-order as he had assumed, then the initial rate coefficients in his kinetic runs were satisfactorily consistent, contrary to his observation (Table 50). It was necessary to use the initial values since Olivier found a decrease in the rate coefficients with time, contrary to the observations of Jensen and Brown, who assumed, therefore, that Olivier s reagent may have contained impurities. 

In the first systematic study on nucleophilic substitutions of chiral halides by Group IV metal anions, Jensen and Davis showed that (S )-2-bromobutane is converted to the (R)-2-triphenylmetal product with predominant inversion at the carbon center (Table 5)37. Replacement of the phenyl substituents by alkyl groups was possible through sequential brominolysis and reaction of the derived stannyl bromides with a Grignard reagent (equation 16). Subsequently, Pereyre and coworkers employed the foregoing Grignard sequence to prepare several trialkyl(s-butyl)stannanes (equation 17)38. They also developed an alternative synthesis of more hindered trialkyl derivatives (equation 18). 

With a generalized unsymmetrical alkene, RCH=CH2, the products from these reagents are RCHCICH2CCI3, RCHBrCHsCBrj, RCHjCHjCQj, and RCHBrCH2CCl3, respectively. Kharasch, M. S. Jensen, E. V. Urry, W. H. /. Am. Chem. Soc. 1947,69,1100. 

Kj0sen, H., and S. Liaaen-Jensen Application of the tris (dipivalomethanato)euro-pium (III) nuclear magnetic shift reagent to carotenoids. Acta Chem. Scand. 26, 2185 (1972). 

Sachon, E. Mohammed, S. Bache, N. Jensen, O. N. Phosphopeptide quantitation using amine-reactive isobaric tagging reagents and tandem mass spectrometry Application to proteins isolated by gel... 

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