141-14-0Relevant articles and documents
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.
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.
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