Publication: Bazı kumarin türevlerinin sentezi ve elektrokimyasal davranışı
Abstract
BAZI KUMARİN TÜREVLERİNİN SENTEZİ VE ELEKTROKİMYASAL DAVRANIŞI Bu çalışma da, kumarin türevlerinden olan 6,7-dihidroksi-3-fenilkumarin, 7,8-dihidroksi-3-(4'-metil)fenilkumarin , 7,8-dimetoksi-3-(4'-metil)fenilkumarin bileşiklerinin, elektrokimyasal redüksiyon mekanizması incelenmiştir. Bunun için 2,3,4-trimetoksibenzaldehit ve 2,4,5-trimetoksibenzaldehit bileşiklerinin ilgili bileşiklerle reaksiyona girmesiyle oluşan akrilonitril türevleri, piridinhidroklorür ortamında 190 oC ye kadar ısıtılarak fenilkumarin türevleri elde edilmiş ve saflaştırılmıştır. 7,8-Dihidroksi-3-(4'-metil)fenilkumarin bileşiğinin uygun miktarının, ilgili moleküllerle reaksiyona sokulmasıyla, 7,8-Dimetoksi-3-(4'-metil)fenilkumarin bileşiği elde edilmiştir. Elde edilen bu bileşikler; metanol + su çözücü ortamı, 0.1 M LiCl taşıyıcı elektroliti ve H3PO4 bileşeni olmayan Britton-Robinson tamponu ortamında pH=2.5-10.5 arasında, referans elektrot olarak; doymuş kalomel elektrot, yardımcı elektrot olarak ; Pt elektrot ve çalışma elektrotu olarak; asılı cıva damla elektrodu kullanılarak, siklik voltamogramları alınmıştır. Voltamogramlardan, Pik akımları ve pik potansiyelleri saptanmıştır. Verilerin değerlendirilmesinden, çalışılan maddelerin bir elektronlu işlemle redüksiyona uğradığı, işlemin aynı anda elektron ve proton katılmasıyla irreversibil olarak gerçekleştiği bulunmuştur.
In this study, the mechanism of electrochemical reduction of coumarin derivatives 6,7-dihydroxy-3-phenylcoumarin, 7,8-dihydroxy-3-(4'-methyl)phenylcoumarin and 7,8-dimethoxy-3-(4'-methyl)phenylcoumarin were examined. In order to do this study, acrylonitrile derivatives were obtained by reacting 2,3,4-trimethoxybenzaldehyde and 2,4,5-trimethoxybenzaldehyde with certain compounds, phenylcoumarine derivatives were obtained by heating at 190 oC of acrylonitrile derivatives in pyridinehydrochloride media and were purifed. 7,8-dimethoxy-3-(4'-methyl)phenylcoumarin were prepared by reacting of certain amount of, 7,8-dihydroxy-3-(4'-methyl)phenylcoumarin with certaincompounds. The cyclic voltamograms of this compounds were taken using hanging mercury drop electrode, as study electrode saturated calomel electrode as reference electrode and Pt electrode as auxilary electrode, in a Britton Robinson buffer but not containing H3PO4 (pH 2.5 between 11.5) in a solution of 90 ml of methanol, 10 ml of water and 0.1 M LiCl. Peak currents peak potentials were determined from voltamograms. The assesment of voltametric indicated the following results : The substances were subjected to reduction by one-electron and the simultaneous electronic and protonic processes were irreversibil.
In this study, the mechanism of electrochemical reduction of coumarin derivatives 6,7-dihydroxy-3-phenylcoumarin, 7,8-dihydroxy-3-(4'-methyl)phenylcoumarin and 7,8-dimethoxy-3-(4'-methyl)phenylcoumarin were examined. In order to do this study, acrylonitrile derivatives were obtained by reacting 2,3,4-trimethoxybenzaldehyde and 2,4,5-trimethoxybenzaldehyde with certain compounds, phenylcoumarine derivatives were obtained by heating at 190 oC of acrylonitrile derivatives in pyridinehydrochloride media and were purifed. 7,8-dimethoxy-3-(4'-methyl)phenylcoumarin were prepared by reacting of certain amount of, 7,8-dihydroxy-3-(4'-methyl)phenylcoumarin with certaincompounds. The cyclic voltamograms of this compounds were taken using hanging mercury drop electrode, as study electrode saturated calomel electrode as reference electrode and Pt electrode as auxilary electrode, in a Britton Robinson buffer but not containing H3PO4 (pH 2.5 between 11.5) in a solution of 90 ml of methanol, 10 ml of water and 0.1 M LiCl. Peak currents peak potentials were determined from voltamograms. The assesment of voltametric indicated the following results : The substances were subjected to reduction by one-electron and the simultaneous electronic and protonic processes were irreversibil.