Comparative analysis of the influence of Lewis' acid catalysts for the preparation of methyl-גּ-D-Glucopyranoside

• Main Authors: Calinawan, Nathaniel Esteban, Juat, Necy Saguisag
• Format: text
• Language: English
• Published: Animo Repository 1993
• Subjects: Lewis acids; Acid-base chemistry
• Online Access: https://animorepository.dlsu.edu.ph/etd_bachelors/8163
• Institution: De La Salle University

Three separate samples of glucose are each suspended in methanol. Three different catalysts are used and these are: for reaction mixture (1) concentrated phosphoric acid and zinc (II) chloride, for reaction mixture (2) p-toluene sulfonic acid and for reaction mixture (3) ion-exchange resin. These samples are carried out on the same reaction condition. The progress of the reaction is monitored for every hour using thin layer chromatography. Reaction mixtures (1) and (2) are neutralized and filtered by simple gravity filtration. Reaction mixture (3) is filtered. The samples are then concentrated under vacuum. The samples are characterized using infrared spectroscopy. Acetic anhydride and pyridine are added for the complete acetylation. The reaction is kept overnight. The crude products are extracted several times with dichloromethane. Column chromatography is employed to isolate and purify the product. The highest yield of 78.51% is obtained in the synthesis of Methyl-2,3,4,6-tetra-O-acetyl-D-glucopyranoside involving p-toluene sulfonic acid as the catalyst.