Showing papers on "Citral published in 1993"
TL;DR: In this article, the selective hydrogenation of citral has been studied under mild conditions over Ru catalysts supported on activated carbon, and the specific catalytic activity per Ru surface atom as well as the products distribution remains constant with changing metal particle size.
Abstract: Selective hydrogenation of citral has been studied under mild conditions over Ru catalysts supported on activated carbon. Geraniol, nerol, citronellal and isopulegol were the main reaction products. Isopulegol is obtained by isomerization of citronellal. Small amounts of citronellol are formed through the hydrogenation of citronellal. The specific catalytic activity per Ru surface atom as well as the products distribution remains constant with changing metal particle size. A comparison with results obtained on the hydrogenation of cinnamaldehyde on the same Ru/C catalysts is reported.
86 citations
TL;DR: In this article, the Ru-Sn/C system has been studied as a function of the Ru/Sn ratio under the conditions used the carbonyl group and the conjugated double bond are hydrogenated.
Abstract: Citral has been hydrogenated over Ru-Sn/C catalysts The Ru-Sn/C system has been studied as a function of the Ru/Sn ratio Under the conditions used the carbonyl group and the conjugated double bond are hydrogenated No products obtained from the hydrogenation of the isolated double bond are formed Addition of tin on the Ru/C decreases the number of Ru active sites on the surface with a corresponding increase in the specific catalytic activity A higher selectivity (>80%) to geraniol + nerol is observed on the samples with the highest Sn/Ru ratio The higher selectivity and higher specific activity are attributed to an activation of the C≐O bond by tin ions
73 citations
TL;DR: The conversion of geraniol into citral trans in Cymbopogon flexuosus leaves is catalyzed by NADP + -dependent Geraniol dehydrogenase, which showed normal Michaelis-Menten kinetics.
44 citations
TL;DR: In this paper, the authors presented a bi-metallic Rh[M'(n-C 4 H 9 ) x ] y /SiO 2 (M'=Ge, Sn, Pb) catalysts for citral (cis and trans) conversion into geraniol and nerol.
Abstract: Bi-metallic Rh[M'(n-C 4 H 9 ) x ] y /SiO 2 (M'=Ge, Sn, Pb) catalysts can be obtained by surface organometallic chemistry on metals. With Ge and Sn based complexes, stable organometallic fragment can be obtained for which x ≈ 2 and y ≥ 0.3. These catalysts exhibit increasing activities and selectivities for citral (cis and trans) conversion into geraniol (and nerol) when“y” varies from 0.3 to ca. 1. With the Rh-Pb system, no butyl groups remain on the catalyst surface when “y” increases. These catalysts exhibits a decay of activity when “y” increases.
38 citations
TL;DR: Citral gavage at doses that were equivalent to up to 10% in the diet (2280 mg/kg body weight) did not cause toxicity in rats, except for minimal hyperplasia of the squamous epithelium of the forestomach in high-dose males.
28 citations
TL;DR: In this article, it is suggested that the preferential hydrogenation of the C=O group occurs on sites associated with tin ions, and the influence of the nature of the support and salt precursors is also discussed.
Abstract: Citral and cinnamaldehyde have been hydrogenated over a series of Ru catalysts supported on carbon and alumina. In the hydrogenation of citral selectivity to unsaturated alcohols remains constant regardless of the Ru particle size. In the hydrogenation of cinnamaldehyde, cinnamyl alcohol is instead preferentially formed on the larger Ru particles. Addition of tin to ruthenium decreases the catalytic activity but increases (up to 90%) the selectivity to unsaturated alcohols. It is suggested that the preferential hydrogenation of the C=O group occurs on sites associated with tin ions. The influence of the nature of the support and salt precursors is also discussed.
28 citations
TL;DR: The results are suggestive of a strong relationship between the enzyme activity and essential oil quality in lemongrass cultivars, and a positive and significant association with citral to Geraniol, and geranial to geraniol ratios.
Abstract: Geraniol dehydrogenase, the specific enzyme involved in geraniol to citral trans (geranial) transformation, activity was monitored in various lemon-grass cultivars differing in amounts and relative percentages of citral and geraniol in their essential oils. The enzyme activity had a positive and significant association with citral to geraniol, and geranial to geraniol ratios. The results are suggestive of a strong relationship between the enzyme activity and essential oil quality in lemongrass cultivars
28 citations
TL;DR: In this article, an infrared spectrophotometric method is described to correct for interference by limonene in the determination of citral in orange and lemon essential oils by subtracting the Limonene spectrum from the essential oil spectrum, and the first derivative trough-to-peak distance between 1684 cm−1 and 1677 cm− 1 was most reliable in determining citral, parameters of the zero order absorption spectrum (net absorbance and peak area) performed poorly in comparison.
10 citations
Journal Article•
7 citations
TL;DR: In this paper, the Ni-M (M = Al, Cr, Cu, Co and Mo) catalysts supported on graphite, at low temperature, by coreduction of metal salt mixtures (NiX2, MX2) deposited on this support with sodium naphthalene as reducting agent were compared with the unsupported bimetallic catalysts, with the same atomic composition and prepared by the same procedure.
Abstract: We prepared Ni-M (M = Al, Cr, Cu, Co and Mo) catalysts supported on graphite, at low temperature, by coreduction of metal salt mixtures (NiX2, MX2) deposited on this support with sodium naphthalene as reducting agent Quantitative microanalyses performed by STEM/EDX showed that the two metals were evenly distributed over graphite leaflets The activity and the selectivity of these catalysts in the hydrogenation of citral to citronellal and citronellol have been compared with that of unsupported bimetallic catalysts, with the same atomic composition and prepared by the same procedure It appeared that the nickel surface area of the supported catalysts was notably higher than that of the unsupported ones, but the support had almost no effect on the catalytic properties
5 citations
TL;DR: A bi-metallic RhsSn(C4H9)2/SiO2 catalyst can be obtained by partial hydrogenolysis, at 373 K, of Sn(n-C4h9)4 on the surface of a Rh(0) particle supported on SiO2.
Abstract: A bi-metallic RhsSn(C4H9)2/SiO2 catalyst can be obtained by partial hydrogenolysis, at 373 K, of Sn(n-C4H9)4 on the surface of a Rh(0) particle supported on SiO2 The catalyst has been found to be extremely active and selective in the hydrogenation of citral (cis and trans) to the corresponding unsaturated alcohols (geraniol and nerol): 96% of selectivity at 100% conversion
Patent•
23 Feb 1993
TL;DR: In this paper, a lemon oil comprising a lemon essential oil, its mixture with citral, octyl aldehyde, nonyl alcohol, geraniol, linalool or methyl Nonyl ketone, or mixture with cineol or laurel essential oil is added to a sulfide compound of formula: R1-Sn-R2 (R1, R2 are 1-5C alkyl, alkenyl; n is 1-4S sulfite) and raw garlic, garlic extract or other garlic product to deodorize
Abstract: PURPOSE:To deodorize an alkyl sulfide of smelling ingredient contained in garlic by adding a lemon oil to an alkyl sulfide compound and raw garlic, a garlic product, etc. CONSTITUTION:A lemon oil comprising a lemon essential oil, its mixture with citral, octyl aldehyde, nonyl alcohol, geraniol, linalool or methyl nonyl ketone, or its mixture with cineol or laurel essential oil is added to a sulfide compound of formula: R1-Sn-R2 (R1, R2 are 1-5C alkyl, alkenyl; n is 1-4S sulfite) and raw garlic, garlic essential oil, garlic extract or other garlic product to deodorize the garlic product. The deodorized product of the alkyl sulfide and the garlic essential oil can readily and orally be administered and is useful for cerebral thrombosis, arterial sclerosis, diabete or nephreopathy-originated vascular lesion, etc. Since the, garlic odor can be deodorized, the deodorized product can be used for general foods, healthy foods, etc.
Patent•
06 Aug 1993
TL;DR: In this article, a solid detecting element capable of conducting simple measurement of a citral or a beta-ionone in water solution by an optical means was obtained, which consists of a transparent quartz substrate and a two-layered film (thin film).
Abstract: PURPOSE:To obtain a solid detecting element capable of conducting simple measurement of a citral or a beta-ionone in water solution by an optical means CONSTITUTION:The detecting element 1 of this invention consists of a transparent quartz substrate 12, and a two-layered film (thin film) 11 provided on the substrate 12, which consists of a mixture of [9-(o-carboxylphenyl)-6-(N-ethyl-N- octadecylamino)-3H-xanthene-3-ylidene]-N-ethyl-N-octadecylammonium and arachidine acid or di n-hexadecylphosphate After soaking the detecting element 1 into water solution 3 of a citral or a beta-ionone to adsorb the citral or the beta-ionone onto the two-layered film (thin film) 11, intensity change of phosphorescence that is generated by incident excitation beam into the two layers film (thin film) 11, is measured and therewith the density thereof is obtained
TL;DR: In this article, the factors affecting citral hydrogenation at an annealed copper cathode have been determined and the highest total yield (94 %) of the alcohols (nerol, geraniol, citronellol) with a considerable predominance of the latter is achieved at 40 % DMF in water, citral concentration 0.02M, and AcOH ∶ citral ratio=10∶1.
Abstract: The factors (concentration of citral, composition of the solvent, AcOH ∶ citral ratio) affecting electrochemical hydrogenation of citral at an annealed copper cathode have been determined. The highest total yield (94 %) of the alcohols (nerol, geraniol, citronellol) with a considerable predominance of the latter is achieved at 40 % DMF in water, citral concentration 0.02M, and AcOH ∶ citral ratio=10∶1. The transition to purely organic or purely aqueous media leads to a decrease in both the total yield of the alcohols and the selectivity of the process.