A facile, practical and environmentally attractive protocol for the direct diversification of N-heterocycles under ambient, metal- and base-free conditions was developed.

Without employing any base and organic solvent, an economical, practical and eco-friendly protocol has been developed for the ultrasound accelerated one-pot synthesis of various functionalized 2-sulfonylquinolines from easily accessible starting materials in water under open-air conditions.

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A convenient and sensitive method for determination of sulfanilamide (SNA) was described based on the Mn(II)-catalyzed oscillating chemical reaction. Under optimum conditions, a linear relationship existed between the changes of oscillating period or amplitude and the negative of logarithm of SNA concentration in the range of 4.27 × 10 −8 mol ·L −1 ∼ 7.41 × 10 −6 mol ·L −1 (RSD, 0.85%) and 9.33 × 10 −8 mol ·L −1 ∼ 3.02 × 10 −6 mol ·L −1 (RSD, 1.08%), respectively. The lower limit of detection was found to be 2.69 × 10 −8 mol ·L −1 and 6.03 × 10 −8 mol ·L −1 , respectively.

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A simple and rapid method was devised for determination of tryptophan, based on the Belousov-Zhabotinskii (B-Z) oscillating chemical system. Changes in oscillating period and amplitude were linearly proportional to the negative logarithm of L-tryptophan concentration over the range of 6.44 x 10(-7)-2.55 x 10(-4) M, with the regression coefficients of near unity and a lower detection limit of 6.5 x 10(-8) M. D-tryptophan was also examined although it is rarely found in most biological fluids, and perhaps not at all in natural proteins. The change of period against to negative logarithm of D-tryptophan concentration over the range of 4.9 x 10(-5)-8.24 x 10(-4) M is linear. Because the optimum conditions for determination of L- and D-tryptophan are not the same, a little amount of D-tryptophan does not affect the determination of L-tryptophan. Various influences were studied and a possible mechanism of perturbation to the B-Z oscillator by tryptophan was also discussed. Spectrophotometry and fluorescence spectrophotofluorimetry were used for comparison and confirmation of the results.

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A sensitive and convenient method is described for the determination of trace amounts of S 2− ion in aqueous solution based on the classical Belousov-Zhabotinskii (B-Z) oscillating reaction. The results showed that the change in the oscillating period was linearly proportional to the concentration of the S 2− ion with a wider range from 7.94 × 10 −8 to 3.16 × 10 −5 mol·L −1 . Various influencing factors are studied and a possible reaction mechanism is also discussed by means of the well-known FKN model. A comparison with the other methods used to determine the S 2− ion is given, too.