CYCLISATION-ACETYLATION KINETIC OF (<i>R</i>)-(+)-CITRONELLAL BY Zn<sup>2+</sup>–NATURAL ZEOLITE AS SOLID SOLVENT CATALYST
Kinetic in cyclisation-acetylation of (R)-(+)-citronellal with acetic anhydride was investigated over Zn2+-Natural zeolite (Zn2+-Natzeo) as a catalyst. (R)-(+)-citronellal has been isolated from citronella oil by fractional distillation under reducing pressure. Enantioselective capillary GC on a Sup...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Department of Chemistry, Universitas Gadjah Mada
2010-07-01
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| Series: | Indonesian Journal of Chemistry |
| Online Access: | https://jurnal.ugm.ac.id/ijc/article/view/21459 |
| Summary: | Kinetic in cyclisation-acetylation of (R)-(+)-citronellal with acetic anhydride was investigated over Zn2+-Natural zeolite (Zn2+-Natzeo) as a catalyst. (R)-(+)-citronellal has been isolated from citronella oil by fractional distillation under reducing pressure. Enantioselective capillary GC on a Supelco β-DEX 225 column has been used for analysis the enantiomers ratio of citronellal. Catalyst Zn2+-Natzeo has prepared through acid activation of natural zeolite from Malang using HF 1% and HCl 6 M, followed by ion-exchange with 3 M NH4Cl and calcination at 450 °C for 1 h under nitrogen to obtained H-natural zeolite (H-Natzeo). H-Natzeo was modified to Zn2+-Natzeo by ion exchange with 0.1 M ZnCl2. Cyclisation-acetylation reaction was carried out by heating (R)-(+)-citronellal (CIT), acetic anhydride (AA), and 1 g catalyst in glass batch reactor with vigorous stirring at 80 °C. Molar ratio CIT/AA that used, i.e. 0.25; 0.5; 1.0; 1.2 and 1.5. As the reaction proceeded, 1 mL sample was taken off at 10; 20; 30; 60; 120; 180 min and extracted using n-hexane for every molar ratio. Structure analysis of product was conducted by GC-MS. Kinetic of the cyclisation-acetylation reaction was analyzed according to the Langmuir-Hinshelwood mechanism. Increasing molar ratio of CIT/AA will decrease the isopulegyl acetate (IPA) and neo-isopulegyl acetate (NIPA) formation. Rate constant of cyclisation-acetylation reaction catalyzed by Zn2+-Natzeo was 30.964-47.619 mmol(min. g cat)-1 at 80 °C, 30 min and the ratio adsorption equilibrium constant KCIT/KAA was 7.09.
Keywords: Cyclisation-acetylation, (R)-(+)-citronellal, Zn2+-natural zeolite, kinetic |
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| ISSN: | 1411-9420 2460-1578 |