thiourea and phosphoric-acid

We developed an asymmetric organocatalytic synthesis of 4,6-bis(1H-indole-3-yl)-piperidine-2-carboxylates using 10 mol% of a chiral phosphoric acid. The products, which are novel bisindole-piperidine-amino acid hybrids, can be obtained in one step from 3-vinyl indoles with imino esters in dichloromethane at room temperature after 1 h of reaction time. A variety of these compounds could be synthesized in up to 70% yield and 99% ee, and they were experimentally and computationally analyzed regarding their relative and absolute stereochemistry.

Topics: Amino Acids; Catalysis; Chemistry, Organic; Circular Dichroism; Imines; Indole Alkaloids; Phosphoric Acids; Piperidines; Thiourea

A highly sensitive, selective and simple kinetic method was developed for the determination of trace levels of thiourea based on its catalytic effect on the oxidation of janus green in phosphoric acid media and presence of Triton X-100 surfactant without any separation and pre-concentration steps. The reaction was monitored spectrophotometrically by tracing the formation of the green-colored oxidized product of janus green at 617 nm within 15 min of mixing the reagents. The effect of some factors on the reaction speed was investigated. Following the recommended procedure, thiourea could be determined with linear calibration graph in 0.03-10.00 microg/ml range. The detection limit of the proposed method is 0.02 microg/ml. Most of foreign species do not interfere with the determination. The high sensitivity and selectivity of the proposed method allowed its successful application to fruit juice and industrial waste water.

Topics: Animals; Azo Compounds; Beverages; Biological Assay; Catalysis; Detergents; Fruit; Humans; Indicators and Reagents; Industrial Waste; Micelles; Molecular Structure; Octoxynol; Oxidation-Reduction; Phosphoric Acids; Sensitivity and Specificity; Sewage; Thiourea