Aplikasi Trifenilfosfin dalam transformasi N, N-Dimetil Piperidinium Klorida menjadi N-Metilpiperidin.

Abstract

Demethylation is considered as an effective method in synthesis and transformation process of tertiary amine compounds. Using convenient nucleophile is an important factor that determines a favorable result in demethylation. In this research, triphenylphosphine (written as PPh3 in next sentences), a soft nucleophile which in previous research had been used in demethylation of aromatic ammonium compounds, was employed in demethylation of quaternary aliphatic ammonium (N,N-dimethylpiperidiniurn chloride). This research was aimed to study systematically the effect of temperature and of using PPh3 upon demethylation of N,N-dimethylpiperidiniurn chloride. Reaction was carried out by refluxing piperidinium with PPh3 mole by mole in acetonitrile and dimethylformamide (DMF). Reaction was also done without using PPh3 for the purpose of comparing the nucleophilicity of PPh3 and that of chloride ion from piperidinium salt. Analysis of reaction product was performed by using gas chromatography (GC) and II-I-NMR spectroscopy. Based on the resulting analysis, it was known that reaction in acetonitrile did not take place, whereas it did proceed in DMF with chloride ion as nucleophile. Furthermore, it was proposed that PPh3 served as trapping agent for methyl chloride formed in the course of reaction. From this research, it was concluded that demethylation of aliphatic ammonium occurred at high temperature (153°C) and that nucleophilicity of chloride ion was stronger than that of PPh3.