141-14-0Relevant academic research and scientific papers
Bioreactors based on monolith-supported ionic liquid phase for enzyme catalysis in supercritical carbon dioxide
Lozano, Pedro,Garcia-Verdugo, Eduardo,Piamtongkam, Rungtiwa,Karbass, Naima,De Diego, Teresa,Burguete, M. Isabel,Luis, Santiago V.,Iborra, Jose L.
, p. 1077 - 1084 (2007)
Bioreactors with covalently supported ionic liquid phases (SILP) were prepared as polymeric monoliths based on styrene-divinylbenzene or 2-hydroxyethyl methacrylate-ethylene dimethacrylate, and with imidazolium units loadings ranging from 54.7 to 39.8 % wt IL per gram of polymer. The SILPs were able to absorb Candida antarctica lipase B (CALB), leading to highly efficient and robust heterogeneous biocatalysts. The bioreactors were prepared as macroporous monolithic mini-flow systems and tested for the continuous flow synthesis of citronellyl propionate in supercritical carbon dioxide (scCO 2) by transesterification. The catalytic activity of these mini-flow-bioreactors remained practically nchanged for seven operational cycles of 5 h each in different supercritical conditions. The best results were obtained when the most hydrophobic monolith, M-SILP-8-CALB, was assayed at 80°C and 10 MPa, reaching a total turnover number (TON) of 35.8 × 104 mol product/mol enzyme. The results substantially exceeded those obtained for packed-bed reactors with supported silica-CALB-Si-4 catalyst under the same experimental conditions.
Citronellol fatty acid ester derivative and application and preparation method thereof
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Paragraph 0041; 0042, (2017/12/09)
The invention relates to a citronellol fatty acid ester derivative and an application and preparation method thereof. The citronellol fatty acid ester derivative is used as a transdermal absorption penetration enhancer for application and used for preparing a transdermal drug delivery preparation so that transdermal absorption of drugs can be improved, and the accumulative penetration amount of the drugs is increased. According to the citronellol fatty acid ester derivative, after reaction with thionyl chloride, fatty acyl chloride is prepared, then the fatty acyl chloride reacts with citronellol, and the citronellol fatty acid ester derivative is obtained. The citronellol fatty acid ester derivative can be applied to the transdermal drug delivery preparation, improves the penetration ability of the drugs, and can also be used as spice to mask the objectionable odor of the preparation.
Unravelling transition metal-catalyzed terpenic alcohol esterification: A straightforward process for the synthesis of fragrances
Da Silva,Ayala
, p. 3197 - 3207 (2016/05/24)
Iron nitrate is a simple and commercially available Lewis acid and is demonstrated to be able to catalyze β-citronellol esterification with acetic acid, achieving high conversion and ester selectivity (ca. 80 and 70%, respectively), within shorter reaction times than those reported in the literature. To the best of our knowledge, this is the first report of a terpenic alcohol esterification reaction catalyzed by Fe(NO3)3. This process is an attractive alternative to the slow and expensive enzymatic processes commonly used in terpenic alcohol esterification. Moreover, it avoids the undesirable steps of neutralizing the products, which are always required in mineral acid-catalyzed reactions. We have performed a study of the activity of different metal Lewis acid catalysts, and found that their efficiency is directly linked to the ability of the metal cation to generate H+ ions from acetic acid ionization. The measurement of pH as well as the conversions achieved in the reactions allowed us to obtain the following trend: Fe(NO3)3 > Al(NO3)3 > Cu(NO3)2 > Ni(NO3)2 > Zn(NO3)2 > Mn(NO3)2 > Co(NO3)2 > LiNO3. The first three are recognized as stronger Lewis acids and they generate more acidic solutions. When we carried out reactions with different iron salts, it was possible to conclude that the type of anion affects the solubility of the catalyst, as well as the conversion and selectivity of the process. Fe2(SO4)3 and FeSO4 were insoluble and less active. Conversely, though they were equally soluble, Fe(NO3)3 was more selective for the formation of β-citronellyl acetate than FeCl3. We assessed the effects of the main reaction variables such as reactant stoichiometry, temperature, and catalyst concentration. In addition to citronellol, we investigated the efficiency of the iron(iii) catalyst in the solvent free esterification of several terpenic alcohols (geraniol, nerol, linalool, α-terpineol) as well as other carboxylic acids.
Tailor-made N-heterocyclic carbenes for nanoparticle stabilization
Richter, Christian,Schaepe, Kira,Glorius, Frank,Ravoo, Bart Jan
, p. 3204 - 3207 (2014/03/21)
N-heterocyclic carbenes (NHCs) represent a leading class of ligands in organometallic chemistry, but have been rarely exploited as stabilizers for metal nanoparticles (NPs). We report the first example of NHC stabilized Pd-NPs that demonstrate long term stability. These NHC Pd-NPs were synthesized by a facile ligand exchange protocol using rationally designed long chained NHCs (LC-NHCs). Furthermore, we demonstrate that the surface modification of Pd-NPs results in significant chemoselectivity in a model reaction. The Royal Society of Chemistry 2014.
Enzymatic modification of palmarosa essential oil: Chemical analysis and olfactory evaluation of acylated products
Ramilijaona, Jade,Raynaud, Elsa,Bouhlel, Charfeddine,Sarrazin, Elise,Fernandez, Xavier,Antoniotti, Sylvain
, p. 2291 - 2301 (2014/01/06)
We have developed an enzymatic protocol to modify the composition of palmarosa essential oil by acylation of its alcohol components by three different acyl donors at various rates. The resulting modified products were characterized by qualitative and quantitative analyses by gas chromatography, and their olfactory properties were evaluated by professional perfumers. We showed that our protocol resulted in two types of modifications of the olfactory properties. The first and most obvious effect observed was the decrease of the alcohol content, with the concomitant increase of the corresponding esters, along with their fruity notes (pear, most notably). The second and less obvious effect was the expression of notes from minor components ((E)-β-ocimene, linalool, β-caryophyllene, and farnesene), originally masked by the sweet-floral-rose odor of geraniol, present in 70% in the palmarosa essential oil used, and emergence of citrus, green, spicy and clove characters in the modified products. This methodology might be considered in the future as a sustainable route to new natural ingredients for the perfumer. Copyright
A clean enzymatic process for producing flavour esters by direct esterification in switchable ionic liquid/solid phases
Lozano, Pedro,Bernal, Juana M.,Navarro, Alicia
, p. 3026 - 3033 (2013/01/15)
A clean biocatalytic approach for producing flavour esters using switchable ionic liquid/solid phases as reaction/separation media has been developed. The phase behaviour of different IL/flavour acetyl ester (geranyl acetate, citronellyl acetate, neryl acetate and isoamyl acetate) mixtures was studied at several concentrations, resulting for all cases in fully homogeneous liquid media at 50 °C, and solid systems at room temperature. By using an iterative centrifugation protocol on the solid IL/flavour ester mixtures at controlled temperatures, the solid IL phase and the liquid flavour ester phase can be easily separated. The excellent suitability of an immobilized Candida antarctica lipase B (Novozym 435) catalyst in the esterification reaction between an aliphatic carboxylic acid (acetic, propionic, butyric or valeric) and a flavour alcohol (isoamyl alcohol, nerol, citronellol or geraniol) in N,N′,N′′,N′′′-hexadecyltrimethyl-ammonium bis(trifluoromethylsulfonyl)imide ([C16tma][NTf2])IL has been demonstrated, the product yield being improved up to 100% under appropriate reaction conditions (enzyme amount, dehydrating molecular sieves, etc.) at 50 °C. The enzymatic synthesis of sixteen different flavour esters was carried out in [C16tma][NTf2] by means of this approach, providing products of up to 0.757 g mL-1 concentration after IL separation. The residual activity of the enzyme/IL system during seven consecutive operation cycles was shown to be practically unchanged after reuse.
Preparative Production of Optically Active Esters and Alcohols Using Esterase-Catalyzed Stereospecific Transesterification in Organic Media
Cambou, Bernard,Klibanov, Alexander M.
, p. 2687 - 2692 (2007/10/02)
A novel enzymatic approach to the production of optically active alcohols and esters from racemates is developed.It involves the use of esterase catalyzed transesterifications carried out in biphasic aqueous-organic mixtures.Water-insoluble substrates constitute the organic phase, while the enzyme is located in the aqueous phase.Since the fraction of the latter phase can be made very low, such an arrangement solves the problem of both the competition of an alcohol (the nucleophile) with water in the enzymatic reaction and poor solubility of most organic esters and alcohols in water.By use of porous supports (Sepharose or Chromosorb) filled with aqueous solutions of hog liver carboxyl esterase as a stereoselective catalyst and methyl propionate as a matrix ester, the following optically active alcohols and their propionic esters were produced on a preparative scale: 3-methoxy-1-butanol, 3-methyl-1-pentanol, 3,7-dimethyl-1-octanol, and β-citronellol.To overcome a rather narrow substrate specificity of hog liver carboxyl esterase, a nonspecific lipase from yeast (Candida cylindracea) also was employed as a stereoselective transesterification catalyst.Using an aqueous solution of this enzyme confined to the pores of Chromosorb and tributyrin as a matrix ester, we have prepared gram amounts of the following optically active alcohols and their butyric esters: 2-butanol, sec-phenethyl alcohol, 2-octanol, 1-chloro-2-propanol and 2,3-dichloro-1-propanol (subsequently nonenzymatically converted to optically active propylene oxide and epichlorohydrin, respectively), 6-methyl-5-hepten-2-ol, and 1,2-butanediol.
