- Synthesis of: P-menthane-3,8-diol from citronellal over lignin-derived carbon acid catalysts
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p-Menthane-3,8-diol (PMD) is receiving growing attention as a natural mosquito repellent with lower toxicity compared to the widely-used N,N-diethyl m-toluamide (DEET). In this study, sustainable carbon acid catalysts derived from alkaline lignin (AL) were prepared for synthesizing PMD from a popular chemical (±)-citronellal in an environmentally friendly solvent of water. The catalytic performances of the AL-derived carbon acid catalysts prepared at different pyrolysis temperatures were better than those of other catalysts such as carbon black and H-USY. In particular, when the AL pyrolyzed at 500 °C was used as the carbon acid catalyst, the conversion of (±)-citronellal was as high as 97% with a high PMD yield of 86%, indicating that waste alkaline lignin from pulp and paper industries can be used as a source of acid catalysts. It is found that the formation of PMD is preferred over catalysts with weaker acid sites, whereas isopulegol was more easily formed over stronger acid sites. Moreover, the reaction route of the citronellal cyclization-hydration reaction was more dominant via the carbocation-hydration pathway rather than the isopulegol hydration route on the weaker carbon acid catalyst. This journal is
- Abudula, Abuliti,Chaihad, Nichaboon,Du, Xiao,Guan, Guoqing,Hao, Xiaogang,Kurnia, Irwan,Li, Shasha,Prakoso, Tirto,Yoshida, Akihiro
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- Effect of the Stereoselectivity of para-Menthane-3,8-diol Isomers on Repulsion toward Aedes albopictus
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Vector-borne diseases cause around 700,000 deaths every year. Insect repellents are one of the strategies to limit them. Para-menthane-3,8-diol (PMD), a natural compound, is one of the most promising alternatives to conventional synthetic repellents. This work describes a diastereodivergent method to synthesize each diastereoisomer of PMD from enantiopure citronellal and studies their repellence activity against Aedes albopictus. We found that cis-PMD is the kinetic control product of the cyclization of citronellal, while trans-PMD is the thermodynamic control product. X-ray diffraction analysis of crystals highlighted some differences in hydrogen-bond patterns between cis or trans isomers. The present paper demonstrates that (1R)-(+)-cis-PMD has the highest repellency index using a new evaluation system for 24 h. (1S)-(-)-cis-PMD has somewhat lower and (1S)-(+)-trans-PMD and (1R)-(-)-trans-PMD have a slight effect. Volunteer tests show that (1R)-(+)-cis-PMD is the most efficient. This effect could be ascribed to the interaction of PMD/insect odorant receptors and their physical properties, that is, the evaporation rate.
- Andrianjafy, Mbolatiana T.,Borrego, Lorenzo G.,Jeanneau, Erwann,Lemaire, Marc,Métay, Estelle,Ramanandraibe, Voahangy V.,Ramarosandratana, Niryhasinandrianina
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- Selective C-H bond hydroxylation of cyclohexanes in water by supramolecular control
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A new approach for selective hydroxylation of non-activated cyclohexanes using dioxirane generated in situ in water through supramolecular control has been developed. Using β-CD and γ-CD as the supramolecular hosts, selective hydroxylation of cyclohexane substrates, including trans/cis-1,4-, 1,3-and 1,2-dimethylcyclohexanes and trans/cis-decahydronaphthalene, was achieved in up to 54% yield in water. Furthermore, site-selective C-H bond hydroxylation of (+)-menthol was achieved by obstructing the approach of dioxirane to the C-H bond with higher steric hindrance through inclusion complexation with β-CD and γ-CD in water.
- Yang, Bin,Cui, Jian-Fang,Wong, Man Kin
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p. 30886 - 30893
(2017/07/07)
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- P-MENTHANE-3,8-DIOL ISOMER MIXTURE, COOLING SENSATION COMPOSITION COMPRISING THE SAME, AND PRODUCT COMPRISING THE COOLING SENSATION COMPOSITION
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The present invention relates to a p-menthane-3,8-diol isomer mixture 50% by mass or more of which is constituted of (1S)-isomers and a cooling sensation composition containing this mixture. The present invention also relates to a flavor and/or fragrance composition, food, beverage, cosmetic, daily use product, oral cavity composition, or pharmaceutical containing the p-menthane-3,8-diol isomer mixture in an amount of 0.0001 to 90% by mass.
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Paragraph 0073-0075
(2014/08/19)
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- Biotransformations of terpenes by fungi from amazonian Citrus plants
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The biotransformations of (RS)-linalool (1), (S)-citronellal (2), and sabinene (3) with fungi isolated from the epicarp of fruits of Citrus genus of the Amazonian forest (i.e., C. limon, C. aurantifolia, C. aurantium, and C. paradisiaca) are reported. The
- Moreno Rueda, Maria Gabriela,Guerrini, Alessandra,Giovannini, Pier Paolo,Medici, Alessandro,Grandini, Alessandro,Sacchetti, Gianni,Pedrini, Paola
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p. 1909 - 1919
(2013/11/06)
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- Hydroxylation of (+)-menthol by Macrophomina phaseolina
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Biotransformation of (+)-menthol with Macrophomina phaseolina led to hydroxylations at C-1, C-2, C-6, C-7, C-8 and C-9, with the C-8 position being preferentially oxidized. The resulting metabolites were identified as 8-hydroxymenthol (2), 6R-hydroxymenthol (3), 1R-hydroxymenthol (4), 9-hydroxymenthol (5), 2R,8-dihydroxymenthol (6), 8S,9-dihydroxymenthol (7), 6R,8-dihydroxymenthol (8), 1R,8-dihydroxymenthol (9) and 7,8-dihydroxymenthol (10). Metabolites 6-10 are described here for the first time. Their structures were characterized by spectroscopic analysis.
- Musharraf, Syed Ghulam,Ahmed, Muhammad Arif,Ali, Rahat Azher,Choudhary, Muhammad Iqbal
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experimental part
p. 77 - 82
(2012/04/11)
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- New Lewis-acidic molybdenum(II) and tungsten(II) catalysts for intramolecular carbonyl erie and prins reactions. Reversal of the stereoselectivity of cyclization of citronellal
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New Mo(II) complexes BnEt3N+[Mo(CO)4ClBr2]- (A) and Mo(CO)5(OTf)2 (B) and their W(II) congeners D and E have been developed as catalysts for the title reactions. Unlike other Lewis acids, the latter catalysts exhibit cis-stereoselectivity in the cyclization of citronellal (1 → 3 with A and 1 → 5 with B). Isotopic labeling allowed formulation of the reaction mechanism, according to which these complexes act as bulky Lewis acids, η1- coordinated to the carbonyl oxygen. The stereochemistry appears to be controlled by the protruding ligand L(p), which dictates the boatlike transition state III. The kinetically formed cis-alkenol 3 can be equilibrated by [Mo(CO)4Br2]2 (C) or ZnCl2 to its trans-epimer 2 via a retro-ene reaction.
- Kocovsky, Pavel,Ahmed, Ghafoor,Srogl, Jiri,Malkov, Andrei V.,Steele, John
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p. 2765 - 2775
(2007/10/03)
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- Selective oxidation of terminal isopropyl groups to tertiary alcohols by electrochemical methodology
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Selective oxidation of terminal isopropyl groups to the corresponding tertiary alcohols by an electrochemical method is described. Under the conditions using the TI(TFA)3-hematoporphyrin-O2- cathode reduction system, several substrates such as cholesterol (1) and Grundmann's alcohol (3) gave the corresponding tertiary alcohols 2 and 4, respectively, in reasonable yield.
- Maki, Shojiro,Konno, Katsuhiro,Takayama, Hiroaki
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p. 7067 - 7070
(2007/10/03)
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- Heterolytic Cleavage of Homoallylic Alcohols: Part V - Stereoelectronic and Ring-Strain Factors Governing Fragmentation
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Some aspects of stereoelectronic factors governing the cleavage of hydroxycamphene derivatives with electrophiles, have been studied by the attempted fragmentation of epoxides (7, 9, 10, 12 and 14).To assess the role of ring-strain in this fragmentation, bicyclooctane derivative (28) and isopulegol (31) have been subjected to fragmentation conditions.Their failure to readily undergo fragmentation emphasises the contribution of ring-strain in providing driving force for this reaction.
- Patil, Dilip G.,Chawla, H. P. S.,Dev, Sukh
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p. 206 - 211
(2007/10/02)
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