Metilasi Asam Galat Menggunakan Agen Metilasi Dimetil Sulfat (DMS) atau Dimetil Karbonat (DMC)

Methylation of gallic acid has been conducted by the use of dimethyl sulfate (DMS) or dimethyl carbonate (DMC) as methylating agents. Methylation of gallic acid using DMS was carried out by various methods, i.e. mild condition at ambient temperature, reflux and sonication. The best method was achieved by methylation under reflux yielded 48.9% efficiency of 3,4,5-trimethoxybenzoic acid. Methylation of gallic acid with DMC was performed with several variations on the type and amount of base and phase transfer catalyst (PTC). In addition, green methods sonochemistry and microwave irradiation have also been done. Unfortunately, the methylation of gallic acid failed to give 3,4,5-trimethoxybenzoic acid. Methylation of gallic acid using green reagent DMC gave high yield at mole ratio of gallic acid : DMC : K2CO3 : KI : PTC of tetrabuthyl ammonium bromide (TBAB) = 5 : 320 : 20 : 5 : 8 under reflux for 10 hours and produced 75.96% of methyl 3,4,5-trimethoxybenzoate. Atom economy of gallic acid methylation method using DMC is 37.95%, which is not very different from that of DMS method (30.47%). However, the methylation method using DMC produced by products, which have the lower toxicity compared to that of methylation using DMS

The Kinetic of Cyclization-acetylation (R)-(+)-citronellal with Anhydride Acetic Acid Which Catalyzed of Zn2+-natural Zeolite

Reaction kinetic of acetylation-cyclization (R)- (+)-citronellal with acetic acid anhydride which catalyzed Zn2+-zeolite (Zn2+-Za) was analyzed by Langmuir- Hinshelwood Models. (R)-(+)-citronellal isolated from lemongrass oil with fractionation distillation reduced pressure and analyzed anantiomer ratio with GC chiral column β- DEX 225. Catalyst preparation of Zn2+-Za conducted by acid activation on natural zeolite Malang 100 mesh using 1% HF and 6 M HCl, then soaked on 0,1 M NH4Cl. Calcination was done at 450oC during 1 hour with N2 flow to achieved H-natural zeolite (HZa). Cation exchange H-Za with 0,1 M ZnCl2 conducted to obtain Zn2+-natural zeolit (Zn2+-Za). Reactions of Cyclization-acetylation (R )-(+)- citronellal using a catalyst of Zn2+-Za was done by varying molar ratio of (R )-(+)- citronellal with acetic acid anhydride, namely 0.25, 0.5, 1.0; 1 , 25; 1.5. During the reaction, into system, samples were taken each 1 mL of reaction with duration 10, 20, 30, 60, 120, 180 minutes. Reaction product was extracted with n-hexana. Structure elucidation was done by GC-MS, FTIR spectrophotometer, and 1H-NMR spectrometer. The result showed a greater molar ratio (R)-(+)-citronellal against quantity of acetic acid anhydride acetic, pulegil total was decline. Acetylation-cyclization catalyzed with Zn2+-Za on duration of 30 minutes and 80°C has k of 30.964 to 47.619 mmol (minute.gram catalyst)-1 and KSIT/KAA of 7.09