Please use this identifier to cite or link to this item: https://doi.org/10.1006/jcat.2001.3208
DC FieldValue
dc.titleCyclisation of citronellal to isopulegol catalysed by hydrous zirconia and other solid acids
dc.contributor.authorChuah, G.K.
dc.contributor.authorLiu, S.H.
dc.contributor.authorJaenicke, S.
dc.contributor.authorHarrison, L.J.
dc.date.accessioned2014-06-23T05:35:22Z
dc.date.available2014-06-23T05:35:22Z
dc.date.issued2001
dc.identifier.citationChuah, G.K., Liu, S.H., Jaenicke, S., Harrison, L.J. (2001). Cyclisation of citronellal to isopulegol catalysed by hydrous zirconia and other solid acids. Journal of Catalysis 200 (2) : 352-359. ScholarBank@NUS Repository. https://doi.org/10.1006/jcat.2001.3208
dc.identifier.issn00219517
dc.identifier.urihttp://scholarbank.nus.edu.sg/handle/10635/75845
dc.description.abstractThe cyclisation of citronellal to isopulegol is an important step in the synthesis of menthol. Several zirconia-based catalysts were evaluated for this reaction. Zirconium hydroxides and phosphated zirconia had very good activity and selectivity. Ammonia TPD and pyridine IR studies indicate the presence of strong Lewis together with weak Brønsted acid sites. Other strong acids like sulfated zirconia, Amberlyst, and Nafion were very active but the selectivity toward isopulegol was poor. They catalysed side reactions such as dehydration, cracking, and etherification of isopulegol. Silica, with only weak Lewis acidity, showed very low activity. The presence of both Lewis and Brønsted sites is therefore essential for the reaction. A reaction mechanism is proposed where the citronellal molecule binds to a zirconium Lewis acid site via the aldehyde oxygen and the π-electrons of the double bond so that the right configuration is attained for cyclisation. Subsequent protonation of the aldehyde via a neighbouring Brønsted acid site initiates the cyclisation to isopulegol. © 2001 Academic Press.
dc.description.urihttp://libproxy1.nus.edu.sg/login?url=http://dx.doi.org/10.1006/jcat.2001.3208
dc.sourceScopus
dc.subjectCitronellal
dc.subjectCyclisation
dc.subjectDual acid sites - Lewis and Brønsted
dc.subjectIsopulegol
dc.subjectPhosphated zirconia
dc.subjectZirconium hydroxide
dc.typeArticle
dc.contributor.departmentCHEMISTRY
dc.description.doi10.1006/jcat.2001.3208
dc.description.sourcetitleJournal of Catalysis
dc.description.volume200
dc.description.issue2
dc.description.page352-359
dc.identifier.isiut000169536100016
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