KAJIAN REAKSI SIKLISASI DAN HIDROGENASI (R)-(+)-SITRONELAL MENGGUNAKAN KATALIS BERBASIS ZnBr2/Î3-Al2O3 dan Ni/ Î3-Al2O3 (STUDY ON CYCLISATION AND HIDROGENATION OF (R)-(+)-SITRONELAL BASED ON ZnBr2/Î3-Al2O3 dan Ni/ Î3-Al2O3 CATALYSTS)
| Main Authors: | , ELVINA DHIAUL IFTITAH, S.SI, M.SI, , Prof.(ret). Dr. Muchalal, DEA, |
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| Format: | Thesis NonPeerReviewed |
| Terbitan: |
[Yogyakarta] : Universitas Gadjah Mada
, 2012
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| Subjects: | |
| Online Access: |
https://repository.ugm.ac.id/97629/ http://etd.ugm.ac.id/index.php?mod=penelitian_detail&sub=PenelitianDetail&act=view&typ=html&buku_id=54015 |
Daftar Isi:
- The results showed that the citronella from citronella plant oils (Cimbopogon winterianus Java Type) from Majingklak, Cilacap is 2/Î3-Al2O3 dan Ni/ Î3-Al2O3 CATALYSTS By Elvina Dhiaul Iftitah 07/263101/SPA/00175 Menthol can be synthesized through two consecutive reaction steps, selective cyclization (isomerisation) of 3R-(+)-3,7-dimethyl-6-okten-al ((R)-(+)-sitronelal) with ZnBr2 catalyst to (1S,2S,5R)-(-)-2-isopropenil-5-metilsikloheksanol ((-)-isopulegol) and hydrogenation of (-)-isopulegol with Ni catalyst to (1S,2S,5R)-(-)-2-isopropil-5-metil-sikloheksanol ((-)-mentol). One of the most interesting in the synthesis of isopulegol and menthol is a stereoselectivity of their product. Stereoselectivity can be improved by selection of suitable catalysts. Selected catalyst based on ZnBr2/Î3-Al2O3 and Ni/Î3-Al2O3 could be expected to obtain (-)-menthol from (R)-(+)-sitronelal in one step reaction. The presence of both acid and metal sites in one batch reaction sistem is the best way for improve the stereoselectivity of reaction product. The primary objective of this research is to examine stereoselectivity and mechanism of cyclization and hydrogenation reaction toward (R)-(+)-sitronelal based on ZnBr2/Î3-Al2O3 and Ni/Î3-Al2O3 as catalysts. Study was designed as an experimental research study supported with theoretical computational chemistry approach. Experiments in the laboratory includes several stages such as determination of the absolute configuration of citronellal, preparation and characterization of catalysts and catalytic activity test. While the theoretical approach was done by modeling the interaction between (R)-(+)-citronellal and products of its cyclisation with the site active on Î3-Al2O3 surface catalyst using DFT calculation methods. Characterization and catalytic activity tests were conducted on a series of single catalyst ZnBr2/Î3-Al2O3, Ni/Î3-Al2O3, dual catalysts ZnBr2/Î3-Al2O3 and Ni/Î3-Al2O3, and bifunction catalysts Ni-ZnBr2/Î3-Al2O3 and ZnBr2-Ni/Î3-Al2O3. Some of parameters which would be evaluated were the influence of a variation of precursor loading, the temperature of catalyst calcination and reduction, the sequence of precursor compound developing in the catalyst, the type of gas flow or gas atmosphere, as well as temperature and duration of catalytic cyclization and/or hydrogenation reaction of (R)-(+)-citronellal toward activity and selectivity of catalysts. Mechanism of cyclization and hydrogenation reactions was studied both without and with catalyst utilization, and supported by modeling the interaction between (R)-(+)-citronellal and cyclisation product with the Î3-Al2O3 surface using DFT/B3PW91/3-21-G calculation method. enantiomerically pure compounds with absolute configuration of (R)-(+)-citronellal. Crystallinity, acidity and metal content, specific surface area and porosity and also morphology of the catalyst ZnBr2/Î3-Al2O3, Ni/Î3-Al2O3, Ni-ZnBr2/Î3-Al2O3 and ZnBr2-Ni/Î3-Al2O3 were influenced by variations in the composition of added the active precursor compounds, temperature of calcination and reduction as well as the order of addition of the active compound into the catalyst precursor bearers. Two-stage cyclization and hydrogenation reaction of (R)-(+)-citronellal with a single catalyst ZnBr2/Î3-Al2O3 (Zn = 9.1%