- Mesoporous tin phosphate as an effective catalyst for fast cyclodehydration of bio-based citral into p-cymene
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Effective synthesis of aromatic compounds from renewable biomass is highly important yet challenging. p-Cymene is an attractive aromatic compound with various promising applications in the manufacture of fine chemicals. In this study, a novel and effective catalytic system based on mesoporous tin phosphate (M-SnPO) with Lewis-Br?nsted dual acidity was developed for the fast synthesis of p-cymene from the cyclodehydration of bio-based citral. Up to 78.5% yield of p-cymene was achieved from the cyclodehydration of citral at 180 °C within only 0.5 h, superior to the results reported for benchmark homogeneous acid catalysts. Characterization of as-prepared M-SnPO catalyst via various techniques indicates that the synergic effect of Lewis and Br?nsted acidic sites, large pore-sized structure, and high surface area are responsible for its remarkable catalytic performance. In addition, the effectiveness of the M-SnPO catalyst could be almost sustained over multiple cycles without significant loss. The work herein is the first example of developing a Lewis-Br?nsted dual acidic heterogeneous catalyst for the fast synthesis of p-cymene from the cyclodehydration of citral.
- He, Jian,Li, Hu,Wu, Hongguo,Yang, Song,Yu, Zhaozhuo
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- Ionic-liquid-stabilized rhodium nanoparticles for citral cyclodehydration
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Smells nice, too: The cyclodehydration of citral is achieved by using rhodium nanoparticles dispersed in an imidazolium-based ionic liquid. p-Cymene, p-α-dimethylstyrene, and limonene are obtained with selectivity greater than 75-%. The interaction between the imidazolium cations and the metal nanoparticles results in an acidic catalyst, which plays a similar function as a mineral acid but has a one order of magnitude higher activity.
- Quek, Xian-Yang,Guan, Yejun,Van-Santen, Rutger A.,Hensen, Emiel J. M.
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experimental part
p. 1264 - 1267
(2011/12/02)
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- Manganese(III) porphyrin catalysts for the oxidation of terpene derivatives: A comparative study
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A comparative study involving four manganese(III) porphyrin catalysts combined with two different oxidants (sodium hypochlorite and potassium monopersulfate) has been performed in the epoxidation of three terpene derivatives. The catalytic oxidation of α-pinene produces selectively 100% of the epoxide or 65% of allylic oxidation products, only by modification of the substituents on the meso-positions of the metalloporphyrin catalyst. The catalytic oxidation of the 5-vinyl-2-norbornene is regio- and stereoselective, producing only the exo-2,3-epoxy-5-vinylnorbornane. With α-terpinene, a conjugated di-olefin, an oxidative dehydrogenation reaction was surprisingly observed, producing p-cymene as a major compound.
- Maraval, Valerie,Ancel, Jean-Erick,Meunier, Bernard
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p. 349 - 357
(2007/10/03)
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- Base-catalysed rearrangement of p-menth-1-en-4(8)-oxide
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p-Menth-1-en-4(8)-oxide (1), a tetrasubstituted spiro epoxide is normally resistant towards bases but under forcing condition with AIP rearranges to p-mentha-1,8-dien-4-ol (2).On the other hand, with t-BuOK, p-mentha-1,3-dien-8-ol (3) and p-mentha-1,4-dien-8-ol (4) are formed as the major products.These compounds readily get oxidised to p-cymen-8-ol (5), as seen in the reaction of 1 with N-LiEDA.
- Roy, Animesh,Gurudutt, K. N.,Rao, Sanjay
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p. 636 - 638
(2007/10/03)
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- Structure Elucidation of C10H14-Dehydroterpenes by Reaction Gas-Chromatography. - Identification of New Terpene Constituents in Essential Oils
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Alumina-catalyzed dehydration of C10H16O-monoterpene alcohols and elimination of acetic acid from C10H15OCOCH3-monoterpene acetates were carried out in the injection port of a gas chromatograph.The C10H14-monoterpene hydrocarbons formed were analyzed by gas chromatography and mass spectrometry.By means of this reaction gas chromatographic technique, verbenene (7) and 1,5,8-p-menthatriene (13) were identified unequivocally, for the first time, as constituents of essential oils.
- Kobold, Uwe,Vostrowsky, Otto,Bestmann, Hans Juergen,Kubeczka, Karl Heinz
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p. 557 - 560
(2007/10/02)
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