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106-23-0 Usage

Chemical Properties

Different sources of media describe the Chemical Properties of 106-23-0 differently. You can refer to the following data:
1. clear light yellow liquid
2. Ceylon citronella (C. nardus) and Java citronella (C. winterianus) are both perennial grasses growing more than 1 m high. The herb is harvested two to three times a year in Ceylon. The freshly cut or partially dried herb is steam distilled. The plant yields the largest amount of essential oil at about its third year of growth. Citronella is also cultivated and distilled in Java, Guatemala, Taiwan, Hainan, Argentina and New Guinea. The Java-type essential oil is considered to be of superior quality over the Ceylon type. Citronella has a characteristic citronella, rose- and lemon-like odor. The Council of Europe (CoE, 2000) has described Ceylon citronella and Java Citronella separately.
3. Citronellal has an intense, lemon-, citronella-, rose-type odor.
4. (?)-Citronellal occurs in Java citronella oil at a concentration of 35%. Racemic citronellal is the main constituent of E. citriodora oil with a content of up to 85%. Pure citronellal is a colorless liquid with a refreshing odor, reminiscent of lemon balm. Upon catalytic hydrogenation, citronellal yields dihydrocitronellal, citronellol, or dihydrocitronellol, depending on the reaction conditions. Protection of the aldehyde group, followed by addition of water to the double bond in the presence of mineral acids or ion-exchange resins results in the formation of 3,7-dimethyl-7-hydroxy-octan-l-al (hydroxydihydrocitronellal). Acid-catalyzed cyclization to isopulegol is an important step in the synthesis of (?)-menthol.

Occurrence

The d-form of citronellal has been reported in the oil of citronella (Ceylon, Jammus, Kaschmis), in the oil from leaves of Barosma pulchella, in the oil from roots of Phebalium nudum and in the oils of Eucalyptus citriodora, Leptospermum citratum and Baeckea citriodora. The /-form is present in the oils of Backhousia citriodora var. A, E. citriodora, Litsea cubeba (fruits) and lemongrass. Citronellal is generally present also in the oils of lemon, mandarin, Lavandula delphinensis, Ocimum canum f. citrata and many others (Fenarolis Handbook of Flavor Ingredients, 1971).

Uses

Different sources of media describe the Uses of 106-23-0 differently. You can refer to the following data:
1. rac-Citronellal is a monoterpenoid and the major isolate in citronella oil. Citronella oil is an essential oil bearing insecticidal properties. rac-Citronellal is also often used as a fragrance ingred ient.
2. citronella is used primarily as a fragrance (perfuming and masking), it also has tonic properties. It is derived from the essential oil of the Cymbopogon nardus plant, and its constituents include geraniol (approximately 60 percent), citronellal, camphene, limonene, linalool, and borneol.
3. Citronellal is a flavoring agent that is a liquid, faintly yellow with an intense odor resembling lemon, citronella, and rose. it is soluble in alcohol and most fixed oils, slightly soluble in mineral oil and pro- pylene glycol, and insoluble in water and glycerin. it is obtained by chemical synthesis; the aldehyde may be obtained from natural oils, such as citronella oil. it is also termed 3,7-dimethyl-6-octen-1-a1.

Definition

ChEBI: A monoterpenoid, the main component of citronella oil which gives it its distinctive lemon aroma.

Preparation

Citronellal is still isolated from essential oils in considerable quantities; it is also produced synthetically. 1) Isolation from essential oils:(+)-Citronellal is obtained from citronella oils by fractional distillation. Racemic citronellal is isolated from E. citriodora oil; when necessary, it is purified by using an addition compound, for example, the bisulfite derivative. 2) Synthesis from geraniol or nerol: Racemic citronellal can be obtained by vaporphase rearrangement of geraniol or nerol in the presence of, for example, a barium-containing copper–chromium oxide catalyst. 3) Synthesis from citronellol: Racemic citronellal can also be obtained by dehydrogenation of citronellol under reduced pressure with a copper chromite catalyst. 4) Synthesis from citral: Selective hydrogenation of citral to citronellal can be accomplished in the presence of a palladium catalyst in an alkaline alcoholic reaction medium. A continuously operating process for the hydrogenation on a palladium catalyst in the presence of trimethylamine has been developed. 5) Synthesis from myrcene: (+)- and (?)-Citronellal are available from myrcene via geranyldiethylamine, which is enantioselectively isomerized to (+)- or (?)-citronellalenamine. Hydrolysis yields pure (+)- or (?)-citronellal; see monograph menthol.

Essential oil composition

Citronella oil contains a number of fragrant fractions of which citronellal, geraniol and citronellol are the major components. Ceylon citronella oil contains 55 to 65% total acetylizable alcohols (calculated as citronellol) and 7 to 15% total aldehyde (calculated as citronellal). The main constituents are geraniol (18 to 20%), citronellol (6.4 to 8.4%), citronellal (5 to 15%), geranyl acetate (2%); limonene (9 to 11%) and methyl isoeugenol (7.2 to 11.3%). Other constituents are camphene, caryophyllene, linalool, citral (neral and geranial), methylheapenone, methyleugenol, l-borneol, nerol, eugenol and farnesol.* Java citronella oil contains not less than 35% alcohols (calculated as citronellol) and not less than 35% aldehydes (calculated as citronellal). The Java type appears to have higher concentrations of citronellol (35%) and geraniol (21%) than does the Ceylon type (citronellol 10% and geraniol 18%).

Aroma threshold values

Detection: 31 to 100 ppb

Taste threshold values

Taste characteristics at 10 ppm: floral, green, rosy and citrus-lemon.

Synthesis Reference(s)

Journal of the American Chemical Society, 108, p. 7314, 1986 DOI: 10.1021/ja00283a029Tetrahedron Letters, 30, p. 5677, 1989 DOI: 10.1016/S0040-4039(00)76168-5The Journal of Organic Chemistry, 49, p. 2279, 1984 DOI: 10.1021/jo00186a038

General Description

(±)-Citronellal was studied for its fumigant antifungal activity against Pyricularia (Magnaporthe) grisea.

Flammability and Explosibility

Nonflammable

Synthesis

Can be prepared by chemical synthesis or by fractional distillation of natural oils, such as citronella. Industrially prepared by hydrogenation of β-citronellol or by catalytic hydrogenation of citral; also in the laboratory by dehydration of hydroxydihydrocitronellal.

Metabolism

Feeding 50 g citronellal to rabbits was followed by the isolation of 13 g of a crystalline glucuronide, which proved to be p-menthane-3.8-diol-D-glucuronide. The citronellal appeared to have been cyclized and the glucuronide obtained was identical with that obtained on feeding p-menthane-3,8-diol (menthoglycol) (Kühn & Low, 1938). However, evidence was produced to show that the cyclization was not, strictly speaking, a biological reaction, but a chemical one which took place in the stomach under the influence of the gastric hydrochloric acid. The conjugation of the menthoglycol with glucuronic acid was, of course, a purely biological reaction. It was found that on shaking 20 g citronellal with 200 ml 0-5% HCl for 48 hr at 37 C, 12 g menthoglycol was formed (Kühn & Low, 1938).

Check Digit Verification of cas no

The CAS Registry Mumber 106-23-0 includes 6 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 3 digits, 1,0 and 6 respectively; the second part has 2 digits, 2 and 3 respectively.
Calculate Digit Verification of CAS Registry Number 106-23:
(5*1)+(4*0)+(3*6)+(2*2)+(1*3)=30
30 % 10 = 0
So 106-23-0 is a valid CAS Registry Number.
InChI:InChI=1/C10H18O/c1-9(2)5-4-6-10(3)7-8-11/h5,8,10H,4,6-7H2,1-3H3/t10-/m1/s1

106-23-0 Well-known Company Product Price

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  • Alfa Aesar

  • (L15753)  (±)-Citronellal, 96%   

  • 106-23-0

  • 100ml

  • 300.0CNY

  • Detail
  • Alfa Aesar

  • (L15753)  (±)-Citronellal, 96%   

  • 106-23-0

  • 500ml

  • 869.0CNY

  • Detail
  • Sigma-Aldrich

  • (72638)  (±)-Citronellal  analytical standard

  • 106-23-0

  • 72638-1ML

  • 737.10CNY

  • Detail

106-23-0SDS

SAFETY DATA SHEETS

According to Globally Harmonized System of Classification and Labelling of Chemicals (GHS) - Sixth revised edition

Version: 1.0

Creation Date: Aug 12, 2017

Revision Date: Aug 12, 2017

1.Identification

1.1 GHS Product identifier

Product name citronellal

1.2 Other means of identification

Product number -
Other names Citronellal

1.3 Recommended use of the chemical and restrictions on use

Identified uses For industry use only. Fragrances
Uses advised against no data available

1.4 Supplier's details

1.5 Emergency phone number

Emergency phone number -
Service hours Monday to Friday, 9am-5pm (Standard time zone: UTC/GMT +8 hours).

More Details:106-23-0 SDS

106-23-0Relevant articles and documents

Negatively Charged N-Heterocyclic Carbene-Stabilized Pd and Au Nanoparticles and Efficient Catalysis in Water

Ferry, Angélique,Schaepe, Kira,Tegeder, Patricia,Richter, Christian,Chepiga, Kathryn M.,Ravoo, Bart Jan,Glorius, Frank

, p. 5414 - 5420 (2015)

Herein we describe the synthesis of negatively charged N-heterocyclic carbene (NHC)-functionalized palladium and gold nanoparticles (NPs), which are stable in water for over 3 months. The formation of these NHC-NPs proceeds via an efficient ligand exchange procedure. This method was successfully applied to different negatively charged NHCs bearing sulfonate and carboxylate groups. The obtained PdNPs were investigated as catalysts in hydrogenation reactions and showed high catalytic activity (TON up to 2500 and TOF up to 2000 h-1).

Quinolinium Fluorochromate (QFC), C9H7NH: An Improved Cr(VI)-Oxidant for Organic Substrates

Chaudhuri, Mihir K.,Chettri, Shiv K.,Lyndem, Synjukta,Paul, Pradip C.,Srinivas, Pendyala

, p. 1894 - 1898 (1994)

Yellow-orange crystalline quinolinium fluorochromate (QFC) is easily prepared in a nearly quantitative yield by the interaction of quinoline with CrO3 and hydrofluoric acid in 1:1.5:1 molar ratio.The reagent is stable.Compared with pyridinium fluorochromate (PFC), the new reagent is more soluble in organic solvents and less acidic.QFC in CH2Cl2 readily oxidizes primary, secondary, and allylic alcohols to the corresponding carbonyls, benzoin to benzil, and anthracene and phenanthrene to anthraquinone and 9,10-phenanthrenequinone, respectively.Oxidations work well also in a variety of sensitive environments, e.g. isopropylidene functionality and trimethylsilyl ethers.Organic sulfides are transformed to sulfoxides at room temperature.The facile oxidation of triphenylphosphine to triphenylphosphine oxide by QFC in CH2Cl2 or CH3CN provides a clear evidence for an oxygen-transfer reaction.The reduced product of QFC, isolated after such reactions, has been ascertained to be C9H7NH, a chromium(IV) species.The advantages of QFC have been highlighted.

ENHANCEMENT OF THE HYDROLYSIS OF GERANYL PYROPHOSPHATE BY BIVALENT METAL IONS. A MODEL FOR ENZYMIC BIOSYNTHESIS OF CYCLIC MONOTERPENES

Vial, M. V.,Rojas, C.,Portilla, G.,Chayet, L.,Perez,L. M.,et al.

, p. 2351 - 2358 (1981)

Hydrolysis of geranyl pyrophosphate is catalyzed by salts of Mn2+ and involves C-O bond cleavage.The first order rate constants reach limiting values with 2+> 10E-2 M, and the most reactive species is GPP (Mn2+)2 at the optimum pH of 6.5-7.The products are similar to those from acid hydrolysis except that more cyclic hydrocarbons are formed in the presence of metal ions.Hydrolysis of geranyl phosphate is inhibited, and that of citronellyl pyrophosphate is weakly catalyzed by Mn2+.Other divalent metal cations catalyze the hydrolysis of geranyl pyrophosphate and the sequence of effectiveness is Cu2+>Mn2+>Co2+>Mg2+ Ca2+.

-

Houlihan

, p. 689 (1958)

-

Oxidation of alcohols by [Cp*Rh(ppy)(OH)]+

Koelle, Ulrich,Fraenzl, Holger

, p. 1321 - 1326 (2000)

Rh(III) polypyridine complexes ([Cp*Rh(ppy)(H2O)]2+; ppy = 2,2′-bipyridine, 2,2′-bipyridine-4,4′-dicarboxylate, o-phenanthroline, tetrahydro-4,4′-dialkyl-bis-oxazole) oxidize in organic or aqueous alkaline solution primary and secondary alcohols to aldehydes or ketones and are thereby reduced to the Rh(I) complexes Cp*Rh(ppy). The Rh(III) form can be regenerated by oxidants like pyruvate or oxygen, making the reaction quasi-catalytic. The reaction follows an autocatalytic pathway; hydrogen transfer from the a-CH2 group of an alcoholate complex [Cp*Rh(ppy)(OR)]+ to Cp*Rh(I)(ppy) is suggested to yield the Rh(II) intermediate Cp*Rh(ppy)H as the key and rate determining step. The knowledge of Rh(III)/Rh(I) redox potentials allows to estimate the thermodynamic driving force of the reaction which is not more than about 300mV.

Aerobic oxidation of monoterpenic alcohols catalyzed by ruthenium hydroxide supported on silica-coated magnetic nanoparticles

Costa, Vinicius V.,Jacinto, Marcos J.,Rossi, Liane M.,Landers, Richard,Gusevskaya, Elena V.

, p. 209 - 214 (2011)

Ruthenium hydroxide supported on silica-coated magnetic nanoparticles was shown to be an efficient heterogeneous catalyst for the liquid-phase oxidation of a wide range of alcohols using molecular oxygen as a sole oxidant in the absence of co-catalysts or additives. The material was prepared through the loading of the amino modified support with ruthenium(III) ions from an aqueous solution of ruthenium(III) chloride followed by treatment with sodium hydroxide to form ruthenium hydroxide species. Characterizations suggest that ruthenium hydroxide is highly dispersed on the support surface, with no ruthenium containing crystalline phases being detected. Various carbonylic monoterpenoids important for fragrance and pharmaceutical industries can be obtained in good to excellent yields starting from biomass-based monoterpenic alcohols, such as isoborneol, perillyl alcohol, carveol, and citronellol. The catalyst undergoes no metal leaching and can be easily recovered by the application of an external magnet and re-used.

Continuous selective hydrogenation of citral in a trickle-bed reactor using ionic liquid modified catalysts

W?rz, Nicolai,Arras, Jürgen,Claus, Peter

, p. 319 - 324 (2011)

The influence of the ionic liquid [BMIM][N(CN)2] on the palladium catalyzed hydrogenation of citral in a trickle-bed reactor has been investigated. Applying the SCILL concept (solid catalyst with ionic liquid layer), it was possible to attain citronellal selectivities close to 100% at the cost of catalyst activity. However, the yield of this intermediate was approximately four times higher compared to the neat palladium catalyst. The latter and its SCILL counterpart both seem to have long-term stability, which is relevant for any future industrial application. This is the first time that SCILL systems have been compared directly to their IL-free equivalents in continuous mode.

Iron-iron oxide core-shell nanoparticles are active and magnetically recyclable olefin and alkyne hydrogenation catalysts in protic and aqueous media

Hudson, Reuben,Riviere, Antoine,Cirtiu, Ciprian M.,Luska, Kylie L.,Moores, Audrey

, p. 3360 - 3362 (2012)

We report for the first time the use of iron-iron oxide core-shell nanoparticles for the hydrogenation of olefins and alkynes under mild conditions in ethanol and in an aqueous medium. This catalyst proves robust towards the presence of oxidants, such as oxygen and water, is magnetically recoverable and shows selectivity towards the less activated double bonds. The Royal Society of Chemistry 2012.

Effect of the acid-base properties of the support on the performance of Pt catalysts in the partial hydrogenation of citral

Santiago-Pedro, Smid,Tamayo-Galván, Victoria,Viveros-García, Tomas

, p. 101 - 108 (2013)

In this work, the effect that mesoporous solid materials, with different acid-base properties (Pt-1 wt%/acid or base) have over the product distribution during the partial hydrogenation of citral was evaluated. It was found that basic materials were the most active catalysts reaching a 100% citral conversion after 1 h of reaction. Regarding selectivity, in basic materials (Pt/MgAl-c and Pt/MgAl-r) citronellal was the main product, while nerol and geraniol were produced in acid solids (Pt/SiO2; Pt/SiO2-TiO2 and Pt/SiO2-ZrO2). The formation of unsaturated alcohols is related to the strength and density of the acid sites of the catalyst and in this sense the Pt/SiO2-ZrO2 gave a yield of 80%. The acidity trend is: Pt/SiO2-ZrO2 > Pt/SiO 2-TiO2 > Pt/SiO2 > Pt/MgAl-c.

Catalytic activity of nanoscale borides: Co2B and Ni7B3 in the liquid-phase hydrogenation of citral

Kalyon,Hofmann,Malter,Lucas,Claus,Albert

, p. 436 - 441 (2017)

Metal borides are unconventional heterogeneous catalysts. Now, two compounds – the new phase Ni7B3 and well-known Co2B – were synthesized as well-defined, nanoscale material. After characterization (X-ray diffraction, scanning electron microscopy, nitrogen physisorption) they were tested for the liquid phase hydrogenation of citral (3,7-dimethyl-2,6-octadienal) in n-hexane at different temperatures. Hydrogenation products such as geraniol, nerol, citronellal and citronellol were analyzed. The Ni-free catalyst Co2B results in the formation of nerol and geraniol or citronellol selectively, depending on the reaction time. The new compound Ni7B3 yields citronellal or citronellol, depending on the temperature. Thus, the hydrogenation potential of borides – obtained as well-characterized, unsupported heterogeneous catalysts by a one-pot synthesis procedure and post-synthetic annealing – is demonstrated. The cobalt boride preferentially hydrogenates C[dbnd]O bonds, while the nickel boride is selective for C[dbnd]C double bonds.

Pd nanoparticles immobilized on graphite oxide modified with a base: Highly efficient catalysts for selective hydrogenation of citral

Zhao, Yanfei,Zhang, Hongye,Huang, Changliang,Chen, Sha,Yu, Bo,Xu, Jilei,Liu, Zhimin

, p. 203 - 209 (2013)

In this work, the Pd-based catalysts were designed via immobilizing Pd nanoparticles on graphite oxide (GO) modified with organic base, 1,1,3,3-tetramethylguanidine (TMG), which was used for the selective hydrogenation of citral. These catalysts were characterized by various techniques including IR, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. It was demonstrated that the Pd particles with size less than 5 nm were uniformly distributed throughout the support, and they were in the electron-deficient state due to the strong interactions with the modified support. The resultant Pd-TMG/GO catalyst displayed high efficiency for the selective hydrogenation of citral with a turnover frequency of 7100 h-1 as well as superior selectivity to citronellal of 89.6%. Moreover, the catalyst can be reused for five times without obvious activity loss, which may result from its stable structure.

Room-temperature hydrogenation of citral catalyzed by palladium-silver nanocrystals supported on SnO2

Wang, Shuo,Shen, Rongan,Chen, Zheng,Wang, Jiaxi,Wang, Dingsheng,Li, Yadong

, p. 2120 - 2124 (2015)

We have developed two strategies to optimize Pd catalysts. On one hand, Ag was introduced into Pd and then they were applied to the selective hydrogenation of citral under mild conditions. The addition of metallic Ag could tune the selectivity of Pd and made it suitable for the selective hydrogenation of the conjugated double bond. The selectivity of citronellal increased from 0 (for Pd/C and Pd0.7Ag0.3/C) to 96% (for Pd0.4Ag0.6/C) as the Ag content increased. On the other hand, the addition of SnO2 made the Pd catalysts more inclined to activate the C=O bond and gave better performance for the hydrogenation of the conjugated double bond compared with the corresponding Pd-Ag catalysts. The selectivity of citronellal increased from 0 (for Pd0.7Ag0.3/C) to 76% (for Pd0.7Ag0.3-SnO2/C was used) after the addition of SnO2. On the basis of these results, we developed a catalyst (Pd0.6Ag0.4-SnO2/C) with the best catalytic performance for the selective hydrogenation of citral (the conversion of citral reached 99%, and the selectivity was up to 96%). We have developed two strategies to optimize Pd catalysts for the selective hydrogenation of citral and exploited a catalyst (Pd0.6Ag0.4-SnO2/C) with the best catalytic performance (the conversion of citral reached 99%, and the selectivity was up to 96%).

The TEMPO/copper catalyzed oxidation of primary alcohols to aldehydes using oxygen as stoichiometric oxidant

Geisslmeir, David,Jary, Walther G.,Falk, Heinz

, p. 1591 - 1599 (2005)

A catalytic system for the selective oxidation of primary alcohols to aldehydes under very mild conditions was developed. The catalytic system is based on TEMPO and Cu(II), which is generated in situ by oxidation of elemental copper and chelated by means of 2,2′-bipyridine. Compared to existing Cu/TEMPO oxidation methods we substantially lowered the amount of copper necessary and discovered that the reaction is dependent on pH. The catalytic system was also tested with polymer-bound TEMPO and new insights into the currently discussed mechanism were derived. Springer-Verlag 2005.

PHOTO-OXIDATION OF ALCOHOLS CATALYSED BY PLATINISED TITANIUM DIOXIDE

Hussein, Falah H.,Pattenden, Gerald,Rudham, Robert,Russell, James J.

, p. 3363 - 3364 (1984)

Irradiation of alcohols in benzene in the presence of platinised titanium dioxide provides a clean and convenient procedure for the synthesis of aldehydes and ketones on preparative scale.

Synthesis and Comparative Catalytic Study of Zirconia–MnCO3 or –Mn2O3 for the Oxidation of Benzylic Alcohols

Assal, Mohamed E.,Kuniyil, Mufsir,Khan, Mujeeb,Al-Warthan, Abdulrahman,Siddiqui, Mohammed Rafiq H.,Tremel, Wolfgang,Nawaz Tahir, Muhammad,Adil, Syed Farooq

, p. 112 - 120 (2017)

We report on the synthesis of the zirconia–manganese carbonate ZrOx(x %)–MnCO3 catalyst (where x=1–7) that, upon calcination at 500 °C, is converted to zirconia–manganese oxide ZrOx(x %)–Mn2O3. We also present a comparative study of the catalytic performance of the both catalysts for the oxidation of benzylic alcohol to corresponding aldehydes by using molecular oxygen as the oxidizing agent. ZrOx(x %)–MnCO3 was prepared through co-precipitation by varying the amounts of Zr(NO3)4 (w/w %) in Mn(NO3)2. The morphology, composition, and crystallinity of the as-synthesized product and the catalysts prepared upon calcination were studied by using scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and powder X-ray diffraction. The surface areas of the catalysts [133.58 m2 g?1 for ZrOx(1 %)–MnCO3 and 17.48 m2 g?1 for ZrOx(1 %)–Mn2O3] were determined by using the Brunauer–Emmett–Teller method, and the thermal stability was assessed by using thermal gravimetric analysis. The catalyst with composition ZrOx(1 %)–MnCO3 pre-calcined at 300 °C exhibited excellent specific activity (48.00 mmolg?1 h?1) with complete conversion within approximately 5 min and catalyst cyclability up to six times without any significant loss in activity. The specific activity, turnover number and turnover frequency achieved is the highest so far (to the best of our knowledge) compared to the previously reported catalysts used for the oxidation of benzyl alcohol. The catalyst showed selectivity for aromatic alcohols over aliphatic alcohols.

Kinetic influences on enantioselectivity in asymmetric catalytic hydrogenation

Sun, Yongkui,Wang, Jian,LeBlond, Carl,Reamer, Robert A.,Laquidara, Joseph,Sowa Jr., John R.,Blackmond, Donna G.

, p. 65 - 72 (1997)

The influence of reaction conditions on enantioselectivity in the RuII-(binap)-catalyzed asymmetric hydrogenation of allylic alcohols is discussed. This work highlights the importance of considering kinetic influences in addition to the stereochemical aspects of the chiral catalytic environment in interpreting catalytic behavior in asymmetric hydrogenation reactions.

A remarkably simple α-oximation of aldehydes via organo-SOMO catalysis

Gentili, Patrizia,Pedetti, Silvia

, p. 5358 - 5360 (2012)

A novel α-oximation reaction of unactivated aldehydes has been achieved in excellent yields by reaction with NaNO2-FeCl3 couple and in the presence of pyrrolidine as organocatalyst.

Catalytic activity dependency on catalyst components in aerobic copper-TEMPO oxidation

Kumpulainen, Esa T. T.,Koskinen, Ari M. P.

, p. 10901 - 10911 (2009)

The influence of catalyst components in the copper-TEMPO (2,2,6,6-tetramethylpiperidine N-oxide) catalysed aerobic oxidation of alcohols was investigated. The type and amount of base greatly influences reactivity. The bipyridyl ligand concentration had no major influence on catalysis, but ex-cessive amounts led to a decrease in activity for longer reaction times. The kinetic dependency for TEMPO was found to be 1.15, and for copper 2.25, which is an indication of a binuclear catalytic system. Optimised conditions with various allylic and aliphatic alcohols give good to excellent rapid oxidations.

Metals in Biotechnology: Cr-Driven Stereoselective Reduction of Conjugated C=C Double Bonds

Rauch, Marine C. R.,Gallou, Yann,Delorme, Léna,Paul, Caroline E.,Arends, Isabel W. C. E.,Hollmann, Frank

, p. 1112 - 1115 (2020)

Elemental metals are shown to be suitable sacrificial electron donors to drive the stereoselective reduction of conjugated C=C double bonds using Old Yellow Enzymes as catalysts. Both direct electron transfer from the metal to the enzyme as well as mediated electron transfer is feasible, although the latter excels by higher reaction rates. The general applicability of this new chemoenzymatic reduction method is demonstrated, and current limitations are outlined.

Zr-CATALYZED OXIDATION OF ALCOHOLS TO ALDEHYDES IN THE PRESENCE OF t-BuOOH. HIGH REACTIVITY FOR PRIMARY AND ALLYLIC HYDROXYL FUNCTIONS

Kaneda, Kiyotomi,Kawanishi, Yasuyuki,Teranishi, Shiichiro

, p. 1481 - 1482 (1984)

ZrO(OAc)2 catalyzes selective oxidation of primary alcohols to aldehydes without formation of carboxylic acids and also chemoselective oxidation of allylic alcohols to α,β-unsaturated aldehydes in the presence of t-BuOOH.

Kogami,Kumanotani

, p. 2508 (1968)

Oxoammonium resins as metal-free, highly reactive, versatile polymeric oxidation reagents

Weik, Steffen,Nicholson, Graeme,Jung, Gnther,Rademann, Jrg

, p. 1436 - 1439 (2001)

Polymer-supported oxidation of alcohols was conducted very efficiently by employing oxoammonium salts, the reactive intermediates in TEMPO oxidations (TEMPO = 2,2,6,6-tetramethylpiperidinoxyl). These highly reactive salts (see scheme; X = Br, C1) could be prepared and isolated on the polymeric support, and were used for the conversion of single compounds as well as of complex mixtures of alcohols.

3,5-dimethylpyrazolium chlorochromate(VI): An efficient reagent for solvent-free oxidation of organic substrates

Canbulat, Melek,Oezguen, Beytiye

, p. 634 - 637 (2012)

A new chromium(VI) reagent 3,5-dimethylpyrazolium chlorochromate, C 5H8N2H[CrO3Cl] (DmpzHCC), was synthesized and used for the selective oxidation of various organic compounds under solvent-free conditions with high efficiency. This new compound has certain advantages over its companion analogues in terms of controlled acidity, amount of oxidant, lack of solvent, short reaction times, and high yields.

Carbon-carbon double bond versus carbonyl group hydrogenation: Controlling the intramolecular selectivity with polyaniline-supported platinum catalysts

Steffan, Martin,Klasovsky, Florian,Arras, Juergen,Roth, Christina,Radnik, Joerg,Hofmeister, Herbert,Claus, Peter

, p. 1337 - 1348 (2008)

The use of polyaniline (PANI) as catalyst support for heterogeneous catalysts and their application in chemical catalysis is hitherto rather poorly known. We report the successful synthesis of highly dispersed PANI-supported platinum catalysts (particle sizes between 1.7 and 3.7 nm as revealed by transmission electron microscopy, TEM) choosing two different approaches, namely (i) deposition-precipitation of H2PtCl6 onto polyaniline, suspended in basic medium (DP method) and, (ii) immobilization of a preformed nanoscale platinum colloid on polyaniline (sol-method). The PANI-supported platinum catalysts were applied in the selective hydrogenation of the α,β-unsaturated aldehyde citral. In order to benchmark their catalytic performance, citral hydrogenation was also carried out by using platinum supported on the classical support materials silica (SiO2), alumina (Al2O3), active carbon and graphite. The relations of the structural characteristics and surface state of the catalysts with respect to their hydrogenation properties have been probed by EXAFS and XPS. It is found that the DP method yields chemically prepared PtO2 on polyaniline and, thus, produces a highly dispersed and immobilized Adams catalyst (in the β-PtO2 form) which is able to efficiently hydrogenate the conjugated C=C bond of citral (selectivity to citronellal=87%), whereas reduction of the C=O group occurs with polyanilinesupported platinum (selectivity to geraniol/nerol=78%) prepared via the sol-method. The complete reversal of the selectivity between the preferred hydrogenation of the conjugated C=C or C=O group is not only particularly useful for the selective hydrogenation of α,β-unsaturated aldehydes but also unveils the great potential of conducting polymer-supported precious metals in the field of hitherto barely investigated chemical catalysis.

Selective hydrogenation of citral catalyzed with palladium nanoparticles in CO2-in-water emulsion

Liu, Ruixia,Wu, Chaoyong,Wang, Qiang,Ming, Jun,Hao, Yufen,Yu, Yancun,Zhao, Fengyu

, p. 979 - 985 (2009)

CO2-in-Water (C/W) emulsion was formed by using a nonionic surfactant of poly (ethylene oxide)-poly (propylene oxide)-poly (ethylene oxide) (P123), and palladium nanoparticles were synthesized in situ in the present work. The catalytic performa

Continuous synthesis of menthol from citronellal and citral over Ni-beta-zeolite-sepiolite composite catalyst

Er?nen, Kari,M?ki-Arvela, P?ivi,Martinez-Klimov, Mark,Muller, Joseph,Murzin, Dmitry Yu.,Peurla, Markus,Simakova, Irina,Vajglova, Zuzana

, (2022/04/03)

One-pot continuous synthesis of menthols both from citronellal and citral was investigated over 5 wt% Ni supported on H-Beta-38-sepiolite composite catalyst at 60–70 °C under 10–29 bar hydrogen pressure. A relatively high menthols yield of 53% and 49% and stereoselectivity to menthol of 71–76% and 72–74% were obtained from citronellal and citral respectively at the contact time 4.2 min, 70 °C and 20 bar. Citral conversion noticeably decreased with time-on-stream under 10 and 15 bar of hydrogen pressure accompanied by accumulation of citronellal, the primary hydrogenation product of citral, practically not affecting selectivity to menthol. A substantial amount of defuctionalization products observed during citral conversion, especially at the beginning of the reaction (ca. 1 h), indicated that all intermediates could contribute to formation of menthanes. Ni/H-Beta-38-sepiolite composite material prepared by extrusion was characterized by TEM, SEM, XPS, XRD, ICP-OES, N2 physisorption and FTIR techniques to perceive the interrelation between the physico-chemical and catalytic properties.

B(C6F5)3-catalyzed tandem protonation/deuteration and reduction of: In situ -formed enamines

Wu, Rongpei,Gao, Ke

supporting information, p. 4032 - 4036 (2021/05/19)

A highly efficient B(C6F5)3-catalyzed tandem protonation/deuteration and reduction of in situ-formed enamines in the presence of water and pinacolborane was developed. Regioselective β-deuteration of tertiary amines was achieved with high chemo- and regioselectivity. D2O was used as a readily available and cheap source of deuterium. Mechanistic studies indicated that B(C6F5)3 could activate water to promote the protonation and reduction of enamines. This journal is

Novel nickel nanoparticles stabilized by imidazolium-amidinate ligands for selective hydrogenation of alkynes

López-Vinasco, Angela M.,Martínez-Prieto, Luis M.,Asensio, Juan M.,Lecante, Pierre,Chaudret, Bruno,Cámpora, Juan,Van Leeuwen, Piet W. N. M.

, p. 342 - 350 (2020/02/04)

The main challenge in the hydrogenation of alkynes into (E)- or (Z)-alkenes is to control the selective formation of the alkene, avoiding the over-reduction to the corresponding alkane. In addition, the preparation of recoverable and reusable catalysts is of high interest. In this work, we report novel nickel nanoparticles (Ni NPs) stabilized by three different imidazolium-amidinate ligands (ICy·(Ar)NCN; L1: Ar = p-tol, L2: Ar = p-anisyl and L3: Ar = p-ClC6H4). The as-prepared Ni NPs were fully characterized by (HR)-TEM, XRD, WASX, XPS and VSM. The nanocatalysts are active in the hydrogenation of various substrates. They present a remarkable selectivity in the hydrogenation of alkynes towards (Z)-alkenes, particularly in the hydrogenation of 3-hexyne into (Z)-3-hexene under mild reaction conditions (room temperature, 3% mol Ni and 1 bar H2). The catalytic behaviour of Ni NPs was influenced by the electron donor/acceptor groups (-Me, -OMe, -Cl) in the N-aryl substituents of the amidinate moiety of the ligands. Due to the magnetic character of the Ni NPs, recycling experiments were successfully performed after decantation in the presence of an external magnet, which allowed us to recover and reuse these catalysts at least 3 times preserving both activity and chemoselectivity.

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