2- ethanol related reagents

An alternative to qdt, (.S )-2-(3-mercaptoquinoxalinyl)thiourinium, is stable and soluble in aqueous ethanol solutions unlike qdt (27). At pH 10 in ammonia-ammonium chloride buffer, this reagent hydrolyzes to qdt. (5)-2-(3-Mercapto-quinoxalinyl)thiourinium has been used for the simultaneous detection of nickel and cobalt and the determination of palladium (27, 28). A related reagent, 6-nitro-(S)-2-(3-mercaptoquinoxalinyl)thiourinium has also been used in metal analysis (7). This reagent is hydrolyzed in ammonia buffer to generate 6-nitro-2,3-quinoxalinedithiol (nqdt). Following adjustment to pH 2.0, the mixture is extracted with methyl isobutyl ketone and spectrophotometrically analyzed. 6-Nitro-(5)-2-(3-mercaptoquinoxalinyl)thiourinium has been used for the simultaneous spectrophotometric determination of nickel and cobalt by the quantification of [Ni(nqdt)2]2 (710 nm, e = 20,700 L mol 1cm 1) and [Co(nqdt)2]2 (530 nm, e = 40,000 L moE cm-1), respectively. 

Related Reagents. Bis(bicyclo[2.2.1 ]hepta-2,5-diene)rho-dium Perchlorate Bis(bicyclo[2.2.1]hepta-2,5-diene)rhodium Perchlorate-(i )-l-(5 )-l, 2-Bis(diphenylphosphino)ferrocenyl-ethanol 2,2 -Bis(diphenylphosphino)-l,r-binaphthyl Chloro-tris(triphenylphosphine)rhodium(I). 

The following bisazo derivatives of chromotropic acid have been proposed as related reagents for barium Nitchromazo [38], Chlorophosphonazo DI [47], Carboxyarsenazo (in 50% ethanol, pH 5.6, e = 4.1-10 at 640 nm) [48], and Arsenazo III [42]. 

The 2-(phenylsulfonyl)ethyl ester Is stable to acidic conditions [tetrahydropyranyl (THP), tert-butoxycarbonyl (BOC), and ethoxyethyl (EE) groups can be selectively removed], and to oxidation (peroxide) but can be readily removed by treatment with DBU. Note that In both examples cited above, the 2- (phenylsulfon-yl) ethyl ester was cleaved without causing epimerization of the acid. The closely related reagent, 2 (p-toluenesulfonyl)ethanol. 

Related Reagents. BenzylChloromethyl Ether r-Butyl Chloromethyl Ether 2-(Chloroethyl) chloromethyl Ether Chloromethyl Methyl Ether Chloromethyl Methyl Sulfide (p-Methoxybenzyloxy)methyl Chloride 2-Methoxyethoxymethyl Chloride 2-(Trimethylsilyl)ethanol. 

In addition to enzyme activity, the concentration of an nonelectroactive substrate can be determined electrochemically by this technique. By keeping the substrate (analyte) the limiting reagent, the amount of product produced is directly related to the initial concentration of substrate. Either kinetic or equilibrium measurements can be used. Typically an enzyme which produces NADH is used because NADH is readily detected electrochemically. Lactate has been detected using lactate dehydrogenase, and ethanol and methanol detected using alcohol dehydrogenase... 

C is-fused tetrahydrofurans are produced when 2-cycloalkenyl-substituted ethanol derivatives are cy-clized via 5-exo ring closure (equation 14 and Table 5). The related 1-cycloalkenyl alcohol systems also yield cri-fused tetrahydrofurans upon reaction with phenylselenyl reagents, similar to their carboxylic acid analogs (see equation 12).60 A sulfoetherification to a fused ring tetrahydrofuran from a system with an exocyclic methylene provided an 86 14 ratio of cis- and frans-fused isomers.61... 

The free enzymes FIA system permitted analysis in a linear range of 0.05-1.0 g of ethanol/L, a sampling frequency of 15 analyses/h, and a relative SD of 3.5%. The total volumetric flow was 5 mL/min, and the six-channel injection valve permitted the introduction of 0.185 mL (loop volume) of enzymes-reagents solution per analysis (4). Ethanol solutions of different concentrations were used to determine the linear working range and for the calibration curve construction (Fig. 4), presenting a linear relation up to 1 g of ethanol/L with a correlation factor of 0.9899 for six samples. 

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