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8442549 
Journal Article 
Isomerization of d-limonene oxide over solid acids and bases 
Arata, K; Akutagawa, S; Tanabe, K 
1976 
Yes 
Journal of Catalysis
ISSN: 0021-9517
EISSN: 1090-2694 
41 
1 
173-179 
English 
The reaction of d-limonene oxide (a mixture of cis and trans forms) (I) over solid acids and bases was found to give the following products; cymene (II), 1-methyl-3-isopropenylcyclo-pentyl-1-carboxaldehyde (III), 1-methyl-3-isopropylidenecyelopentyl-1-carboxaldehyde (IV), carvenone (V), carvone (VI), cis- and trans-dihydrocarvone (VII), cis- and trans-exo-carveol (VIII) and cis- and trans-endo-carveol (IX). A large amount of II was formed over H2SO4 SiO2, III and IV over SiO2-Al2O3, V over H2SO4 SiO2 and SiO2-Al2O3, VII over SiO2-Al2O3 and BF3 and VIII and IX over Al2O3. Solid H3PO4 heat-treated at low temperature gave comparatively uniform yields of all the compounds. Solid LiClO4 was surprisingly active for the formation of VII, but Li3PO4 was quite inactive. ZnO, MgO, and CaO were almost inactive. From the time variations of yields, IV and V were found to be formed by the rearrangments of III and the cis form of VII, respectively. The formations of carbonyl compounds (III and VII) and cymene (II) were explained by the isomerization over strong acid sites, while the allyl alcohol formation (VIII and IX) by an acid-base bifunctional mechanism over A12O3. © 1976.