Isomerisation of (+)citronellal over Zn(II) supported catalysts

Milone, Candida; Perri, A.; Pistone, Alessandro; Neri, G.; Galvagno, S.

doi:10.1016/s0926-860x(02)00136-9

Cited by 37 publications

(43 citation statements)

References 14 publications

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“…Possible side reactions are subsequent etherification, cracking, or dehydration of 4. [25][26][27] Results of reactions at 383 K in toluene, DCE, and chlorobenzene (Table 5) show that no products other than 4 were formed when using [Cu 3 A C H T U N G T R E N N U N G (btc) 2 ] obtained by means of different synthesis procedures or pretreatments. Again, selectivities remained constant till complete conversion, with a selectivity for 5 between 65 and 69 %.…”

Section: Cyclization Of Citronellalmentioning

confidence: 99%

Probing the Lewis Acidity and Catalytic Activity of the Metal–Organic Framework [Cu₃(btc)₂] (BTC=Benzene‐1,3,5‐tricarboxylate)

Alaerts

Séguin

Poelman

et al. 2006

Chemistry A European J

663

439

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An optimized procedure was designed for the preparation of the microporous metal–organic framework (MOF) [Cu3(btc)2] (BTC=benzene‐1,3,5‐tricarboxylate). The crystalline material was characterized by X‐ray diffraction, optical microscopy, SEM, X‐ray photoelectron spectroscopy, N2 sorption, thermogravimetry, and IR spectroscopy of adsorbed CO. CO adsorbs on a small number of Cu2O impurities, and particularly on the free CuII coordination sites in the framework. [Cu3(btc)2] is a highly selective Lewis acid catalyst for the isomerization of terpene derivatives, such as the rearrangement of α‐pinene oxide to campholenic aldehyde and the cyclization of citronellal to isopulegol. By using the ethylene ketal of 2‐bromopropiophenone as a test substrate, it was demonstrated that the active sites in [Cu3(btc)2] are hard Lewis acids. Catalyst stability, re‐usability, and heterogeneity are critically assessed.

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Section: Cyclization Of Citronellalmentioning

confidence: 99%

Probing the Lewis Acidity and Catalytic Activity of the Metal–Organic Framework [Cu₃(btc)₂] (BTC=Benzene‐1,3,5‐tricarboxylate)

Alaerts

Séguin

Poelman

et al. 2006

Chemistry A European J

663

439

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“…With Brønsted acids the selectivity is significantly lower but still (-)-isopulegol is the most abundant product. The reaction is also sensitive to side reactions such as subsequent, cracking or dehydration [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Insight in the activity and diastereoselectivity of various Lewis acid catalysts for the citronellal cyclization

Vandichel

Vermoortele

Cottenie

et al. 2013

Journal of Catalysis

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RECEIVED DATE (to be automatically inserted after your manuscript is accepted if required according to the journal that you are submitting your paper to) TITLE RUNNING HEAD Kinetics of the Lewis acid catalyzed citronellal cyclization 2 ABSTRACT Industrial (-)-menthol production generally relies on the hydrogenation of (-)-isopulegol, which is in turn produced with high selectivity by cyclization of (+)-citronellal. This paper uses a combined theoretical and experimental approach to study the activity and selectivity of three Lewis acid catalysts for this reaction, namely ZnBr 2 , aluminum tris(2,6-diphenylphenoxide) (ATPH) and the heterogeneous metal-organic framework Cu 3 BTC 2 (BTC = benzene-1,3,5-tricarboxylate). ATPH is a strong Lewis acid homogeneous catalyst with bulky ligands which provides very high selectivities for the desired stereoisomer (> 99 %). The performance of the catalysts was evaluated as a function of temperature, which revealed that higher catalyst activity allows working at lower temperatures and improves the selectivity for isopulegol. The selectivity distribution is kinetically driven for ZnBr 2 and ATPH. The theoretical selectivity distributions rely on the determination of an extensive set of diastereomeric transition states, for which the differences in free energy have been calculated using a complementary set of ab initio techniques. Given the sensitivity of the selectivity to small Gibbs free energy differences, the agreement between experimental and theoretical selectivities is satisfactory. On basis of the obtained insights rational design of new catalysts may be obtained. As proof of concept, the hypothetical Cu 3 (BTC-(NO 2 ) 3 ) 2 Lewis catalyst -in which each phenyl hydrogen of the BTC ligand is replaced by a nitro group -is predicted to be very selective.

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“…However, in this case, the catalyst is destroyed with NaOH after the reaction and cannot be recovered. Typical acid catalysts transform citronellal not only to the desired product, isopulegol, but also to the other three stereoisomers and other side products [4][5][6][7][8][9][10][11][12][13]. Most heterogeneous catalysts, such as hydrous zirconia [4], zeolites or mesoporous materials [5] do not allow to surpass the thermodynamic 75:25 equilibrium ratio of isopulegol:diastereoisomers.…”

Section: Introductionmentioning

confidence: 99%

“…94:6 for the Sc(OTf) 3 catalyst [6], or 79:21 for the Bi(OTf) 3 catalyst [7]. Milone et al [8] reported a 86% selectivity for (-)-isopulegol with a SiO 2 -supported ZnBr 2 catalyst, but the amount of Zn was very high (14% wt%) and the use of ZnBr 2 is not environmentally friendly. Recently, novel solid Lewis acids were also proposed like heteropolyacids [12], Sn-Beta zeolite [13] or Zr-Beta zeolite [14,15].…”

Section: Introductionmentioning

confidence: 99%

Heterogeneous Catalytic Transformation of Citronellal to Menthol in a Single Step on Ir-Beta Zeolite Catalysts

et al. 2009

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The synthesis of menthol from citronellal was studied on bifunctional Ir/Beta zeolite catalysts, prepared via impregnation of Beta zeolite with different concentrations of Ir. The results show that Beta zeolites, impregnated with Ir, catalyze the one-pot full conversion of citronellal to menthol by consecutive acid-catalyzed cyclization and Ir-catalyzed hydrogenation. The best results (95% selectivity for the menthol isomers, of which 75% is the desired (±)-menthol) were recorded on 3% Ir/Beta zeolite catalyst. In contrast with earlier studies, 0.05 g Ir/Beta catalyst per mL of substrate leads to complete and selective substrate transformation. The textural properties, acidity and hydrogenation function were studied by liquid N 2 adsorption-desorption, FT-IR, XPS and hydrogen chemisorption techniques. To clarify the mechanism of the cyclization of citronellal, tests were also performed using zeolites with different acidity and loaded with other metals (Pt, Pd, Rh, Ru).

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Isomerisation of (+)citronellal over Zn(II) supported catalysts

Cited by 37 publications

References 14 publications

Probing the Lewis Acidity and Catalytic Activity of the Metal–Organic Framework [Cu₃(btc)₂] (BTC=Benzene‐1,3,5‐tricarboxylate)

Probing the Lewis Acidity and Catalytic Activity of the Metal–Organic Framework [Cu₃(btc)₂] (BTC=Benzene‐1,3,5‐tricarboxylate)

Insight in the activity and diastereoselectivity of various Lewis acid catalysts for the citronellal cyclization

Heterogeneous Catalytic Transformation of Citronellal to Menthol in a Single Step on Ir-Beta Zeolite Catalysts

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Isomerisation of (+)citronellal over Zn(II) supported catalysts

Cited by 37 publications

References 14 publications

Probing the Lewis Acidity and Catalytic Activity of the Metal–Organic Framework [Cu3(btc)2] (BTC=Benzene‐1,3,5‐tricarboxylate)

Probing the Lewis Acidity and Catalytic Activity of the Metal–Organic Framework [Cu3(btc)2] (BTC=Benzene‐1,3,5‐tricarboxylate)

Insight in the activity and diastereoselectivity of various Lewis acid catalysts for the citronellal cyclization

Heterogeneous Catalytic Transformation of Citronellal to Menthol in a Single Step on Ir-Beta Zeolite Catalysts

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Product

Resources

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Probing the Lewis Acidity and Catalytic Activity of the Metal–Organic Framework [Cu₃(btc)₂] (BTC=Benzene‐1,3,5‐tricarboxylate)

Probing the Lewis Acidity and Catalytic Activity of the Metal–Organic Framework [Cu₃(btc)₂] (BTC=Benzene‐1,3,5‐tricarboxylate)