STUDI MENGENAI SENYAWA HASIL OKSIDASI CARA OPPENAUER PADA PENGUSABAN KININA MENJADI KINIDINA

• Main Author: Barus, Tonel
• Format: Dissertations
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/860
• Institution: Institut Teknologi Bandung

The aim of this research is to study the oxy-compound obtained as the intermediate in the conversion of quinine into quinidine which was carried out according to the Woodward method. In this method quinine was converted into quinidine through two reaction steps wherein the first step quinine was oxidized into its oxidized product (oxy-compound) by the Oppenauer method whereas in the second step the oxy-compound was subjected to reduction by the Meerwein-Ponndorf method giving a mixture of the four stereoisomeric bases where quinine and quinidine were obtained in equal quantities and which appeared to be the major products, besides small quantities of their epibases. Further efforts had been done by Uskokovic M.R. etal. to obtain higher yield of quinidine by reduction of the oxy-compound using several reductors such as diisobutylaluminum hydride and sodium boronhydride. These efforts have never been successful. Many attempts had been done by several workers to convert the oxy-compound into quinidine, but without studying the structure of the oxy-compound thoroughly first. Further work revealed that it was very important to know the structure of this compound in order to be able to suggest whether or not there will be a possibility of complete conversion of the oxy-compound into quinidine. No complete physical nor spectroscopical data has been published so far from this oxy-compound. So far there is no literature available which gives any explanation why the reduction of the oxy-compound always gives a mixture of quinine and quinidine. For these reasons, it is the aim of this work to give an explanation about the exact structure of the oxycompound. For this purpose the oxy-compound is prepared by oxidizing quinine and quinidine according to the Oppenauer method. After purifying both compounds obtained from the oxidation-reaction by preparative TLC, pale yellow crystals were obtained which had the same melting point of 88-89°C. The infrared spectra of the oxycompounds showed an absorption at 1675 cm-1 which is characteristic for the carbonyl stretching vibration for conjugated ketone with an aromatic nucleus, but showed no absorption which is characteristic for the 0-H stretching vibration of the enol. The NMR spectra in CDC13 didn\' t show any characteristic chemical shift for the enol proton at 15-16 ppm. The mass spectra showed that the oxycompounds had the same fragmentation pattern, and the same molecular weight i. e. 322. Reduction of these oxy-compounds using different alcohols gave two stereoisomeric bases viz. quinine and quinidine as the major products with a ratio of 35:65. Catalytic hydrogenation using Raney nickel catalyst either in absolute, ethanol or in chloroform gave a mixture of hydroquinine and hydroquinidine as the major products with a ratio of 35:65 as shown from the HPLC data. From the data obtained, we concluded therefore that the oxidation-reaction of quinine or quinidine produced the same mixture consisting of oxyquinine and oxyquinidine which both oxy-compounds on reduction according to the Meerwein-Ponndorf method always gave a mixture of quinine and quinidine as the major products.