ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Effect of reactants’ concentration on the ratio and yield of E,Z isomers of isatin-3-(4-phenyl)semicarbazone and N-methylisatin-3-(4-phenyl)semicarbazone

Klaudia Jakusová, Martin Gáplovský, Jana Donovalová, Marek Cigáň, Henrieta Stankovičová, Robert Sokolík, Jan Gašpar, and Anton Gáplovský

Institute of Chemistry, Faculty of Natural Sciences, Comenius University, Mlynská dolina CH-2, 842 15 Bratislava, Slovakia

E-mail: jakusova@fns.uniba.sk

Abstract: In this work, the effect of inter- and intramolecular interactions of reactants and products, reactants concentration as well as the solvent effect on the ratio of E and Z isomers of isatinphenylsemicarbazones in the reaction mixture is examined. Theoretical calculations proved that Z isomers are more stable than E isomers. Experimental results confirmed the noncovalent intermolecular donor-acceptor interactions of the reactants in the reaction mixture at concentrations above 0.1 mol L⁻¹. The E/Z isomer ratio of isatin-3-(4-phenyl)semicarbazone (I) and N-methylisatin-3-(4-phenyl)semicarbazone (II) depends on the initial concentrations of 3-amino-1-phenylurea (phenylsemicarbazide; V) and 1H-indole-2,3-dione (isatin; III), or 3-methylindol-2,3(1H)-dion (3-methylisatin; IV), respectively. Both isomers exhibit high thermal stability. Thermal E-Z isomerization takes place at temperatures above 70°C in N,N-dimethylformamide.

Keywords: isatinphenylsemicarbazones – synthesis of E,Z isomers – concentration and solvent dependence – intermolecular interactions

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-012-0248-x

Chemical Papers 67 (1) 117–126 (2013)