ESTERIFICATION OF 4-HYDROXYPHENILGLYSINE WITH METHANOL USING SULFURIC ACID AS CATALYST

• Main Author: Abd. Holik, Holis
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/86992
• Institution: Institut Teknologi Bandung

Background and purpose : Degner (1982) reported that, D-(-)-4-hydroxyphenylglysine, a pure enantiomer can be produced by chemical synthesis using 4-tertierbutoxybenzaldehide, cyanide in anhydrous N,N’-dimethylethanolamine, anhydrous ammonia, L-(+)-tartaric acid and hydrochloric acid solution 20% w/w as reagent. The other researcher, Elton (1980) synthesized this compound without toxic cyanide. However applying this method, instead of enantiomeric, racemic 4- hydroxyphenylglysine was produced. Rehana (2010) modified the Elton’s procedure by introducing chiral selector, however the optical purity of the product was still low which, i.e. only 10.77%. Racemic 4-hydroxyphenylglycine contains both carboxylic acid and amin base functional groups, so that racemate separation applying diastereomeric salt formation cannot be carried out. The objective of this research was to obtain 4-hydroxyphenylglycine methylester by esterification method with absolute methanol as reactant and sulfuric acid as catalyst. Method : Synthesis of 4-hydroxyphenylglysine was carried out by condensation of glyoxylic acid and ammonia to form azomethine which was continued by regioselective aromatic electrophylic substitution of azomethine in phenolic ring at para position. Esterification of the synthesized product has been carried out with absolute methanol as reactant and sulfuric acid as catalyst. The purity of the product was tested by TLC and melting point. The synthesis product was characterized by IR Spectroscopy, mass Spectroscopy and 1 H-NMR Spectroscopy. Result : Synthesis with Elton’s procedure produced racemic 4-hydroxyphenylglysine with yield of 41.5%, while esterification of 4-hydroxyphenylglysine produced of 4- hydroxyphenylglysine methylester with yield of 13.37% Conclution : Esterification of 4-hydroxyphenylglysine with absolute methanol as reactant and sulfuric acid as catalisator produced 4-hydroxyphenylglysine methylester with yield of 13.37%.