6976-72-3Relevant academic research and scientific papers
Aerobic Self-Esterification of Alcohols Assisted by Mesoporous Manganese and Cobalt Oxide
Moharreri, Ehsan,Biswas, Sourav,Deljoo, Bahareh,Kriz, David,Lim, Seyoung,Elliott, Sarah,Dissanayake, Shanka,Dabaghian, Marina,Aindow, Mark,Suib, Steven L.
, p. 3413 - 3422 (2019/08/01)
Aerobic self-esterification of primary alcohols catalyzed by mesoporous metal oxides (manganese and cobalt oxides) is reported under base and solvent free conditions. For a range of aliphatic alcohols, up to 90 % conversions to esters was achieved. The catalytic reaction is likewise applicable to neat aldehydes as substrates with yields of up to 86 %. High pressure batch reaction for ethanol to ethyl acetate led to 22 % yield. Isotope labeling studies indicated decarboxylation on the catalyst surface. Mechanistic and kinetic experiments implicate oxygen rebound and α-carbon removal as intermediate steps. Mesoporous cobalt oxide showed about 20 % higher catalytic activity compared to mesoporous manganese oxide.
Ester Hydrogenation Catalyzed by CNN-Pincer Complexes of Ruthenium
Kim, Daniel,Le, Linh,Drance, Myles J.,Jensen, Kelsey H.,Bogdanovski, Kristijan,Cervarich, Tia N.,Barnard, Melissa G.,Pudalov, Natalie J.,Knapp, Spring Melody M.,Chianese, Anthony R.
, p. 982 - 989 (2016/05/09)
Ruthenium complexes supported by two new CNN-pincer ligands were synthesized. Both were tested as catalysts for the hydrogenation of esters under mild conditions (105 °C, 6 bar H2). A striking dependence on ligand structure was observed, as a dimethylamino-substituted ligand gave a nearly inactive catalyst, while a diethylamino-substituted variant gave up to 980 catalytic turnovers for the hydrogenation of benzyl benzoate. This system catalyzes the hydrogenation of various substrates including ethyl, benzyl, and hexyl esters, but is surprisingly unreactive toward methyl esters. Experiments demonstrate that base-catalyzed transesterification is rapid under the reaction conditions and that methyl esters are effectively hydrogenated when benzyl alcohol is added to the reaction mixture. The reverse reaction, dehydrogenation of primary alcohols to give esters, was tested as well; up to 920 catalytic turnovers were observed for the dehydrogenation of 1-hexanol to hexyl hexanoate.
Fractional distribution of graphene oxide and its potential as an efficient and reusable solid catalyst for esterification reactions
Mungse, Harshal P.,Bhakuni, Niharika,Tripathi, Deependra,Sharma, Om P.,Sain, Bir,Khatri, Om P.
, p. 944 - 951 (2015/02/02)
Graphene oxide (GrO) prepared by the Hummers method was separated into three different fractions (GrO5000, GrO2000, and GrOres) on the basis of their dispersion stability in the water. Infrared, nuclear magnetic resonance, X-ray photoelectron spectroscopy, and elemental analyses revealed that GrO5000 possesses a high degree of oxygen functionalities including phenolic, carboxylic, and -OSO2H groups, compared with the other fractions. The GrO5000 was found to be a highly efficient and reusable solid catalyst for the esterification of various carboxylic acids with a variety of alcohols to furnish corresponding esters in high to excellent yields. The catalytic activity of the GrO5000 was attributed to the ability of highly polar GrO5000 scaffold to adsorb/attract reactants, where the acid functionalities of GrO5000 facilitated the esterification process efficiently. The chemical and structural features of GrO5000 were discussed to understand the improved catalytic activity compared with GrO2000 and conventional solid acid catalysts.
Fractional distribution of graphene oxide and its potential as an efficient and reusable solid catalyst for esterification reactions
Mungse, Harshal P.,Bhakuni, Niharika,Tripathi, Deependra,Sharma, Om P.,Sain, Bir,Khatri, Om P.
, p. 944 - 951 (2015/08/25)
Graphene oxide (GrO) prepared by the Hummers method was separated into three different fractions (GrO5000, GrO2000, and GrOres) on the basis of their dispersion stability in the water. Infrared, nuclear magnetic resonance, X-ray photoelectron spectroscopy, and elemental analyses revealed that GrO5000 possesses a high degree of oxygen functionalities including phenolic, carboxylic, and -OSO2H groups, compared with the other fractions. The GrO5000 was found to be a highly efficient and reusable solid catalyst for the esterification of various carboxylic acids with a variety of alcohols to furnish corresponding esters in high to excellent yields. The catalytic activity of the GrO5000 was attributed to the ability of highly polar GrO5000 scaffold to adsorb/attract reactants, where the acid functionalities of GrO5000 facilitated the esterification process efficiently. The chemical and structural features of GrO5000 were discussed to understand the improved catalytic activity compared with GrO2000 and conventional solid acid catalysts.
Optimized synthesis of (Z)-3-hexen-1-yl caproate using germinated rapeseed lipase in organic solvent
Liaquat, Muhammad
scheme or table, p. 59 - 65 (2011/07/31)
(Z)-3-hexen-1-yl esters are important green top-note components of food flavors and fragrances. Effects of various process conditions on (Z)-3-hexen-1-yl caproate synthesis employing germinated rapeseed lipase acetone powder in organic solvent were investigated. Rapeseed lipase catalyzed ester formation more efficiently with non-polar compared to polar solvents despite high enzyme stability in both types of solvents. Maximum ester yield (90%) was obtained when 0.125 M (Z)-3-hexen-1-ol and caproic acid were reacted at 25 °C for 48 h in the presence of 50 g/L enzyme in heptane. Enzyme showed little sensitivity towards aw with optimum yield at 0.45, while added water did not affect ester yield. Esterification reduced by increasing molecular sieves (>0.0125%, w/v). The highest yields of caproic acid were obtained with isoamyl alcohol (93%) followed by butanol and (Z)-3-hexen-1-o1 (88%) respectively reflecting the enzyme specificity for straight and branched chain alcohols. Secondary alcohols showed low reactivity, while tertiary alcohol had either very low reactivity or not esterified at all. A good relationship has been found between ester synthesis and the solvent polarity (log P value); while no correlation for the effect of solvents on residual enzyme activity was observed. It may be concluded that germinated rapeseed lipase is a promising biocatalyst for the synthesis of valuable green flavor note compound. The enzyme also showed a wide range of temperature stability (5-50 °C).
Characterization of aroma compounds of Chinese "Wuliangye" and "Jiannanchun" liquors by aroma extract dilution analysis
Fan, Wenlai,Qian, Michael C.
, p. 2695 - 2704 (2007/10/03)
Aroma compounds in Chinese "Wuliangye" liquor were identified by gas chromatography-olfactometry (GC-O) after fractionation. A total of 132 odorants were detected by GC-O in Wuliangye liquor on DB-wax and DB-5 columns. Of these, 126 aromas were identified by GC-mass spectrometry (MS). Aroma extract dilution analysis (AEDA) was further employed to identify the most important aroma compounds in "Wuliangye" and "Jiannanchun" liquors. The results showed that esters could be the most important class, especially ethyl esters. Various alcohols, aldehydes, acetals, alkylpyrazines, furan derivatives, lactones, and sulfur-containing and phenolic compounds were also found to be important. On the basis of flavor dilution (FD) values, the most important aroma compounds in Wuliangye and Jiannanchun liquors could be ethyl butanoate, ethyl pentanoate, ethyl hexanoate, ethyl octanoate, butyl hexanoate, ethyl 3-methylbutanoate, hexanoic acid, and 1,1-diethoxy-3-methylbutane (FD ≥ 1024). These compounds contributed to fruity, floral, and apple- and pineapple-like aromas with the exception of hexanoic acid, which imparts a sweaty note. Several pyrazines, including 2,5-dimethyl-3-ethylpyrazine, 2-ethyl-6-methylpyrazine, 2,6-dimethylpyrazine, 2,3,5-tri-methylpyrazine, and 3,5-dimethyl-2-pentylpyrazine, were identified in these two liquors. Although further quantitative analysis is required, it seems that most of these pyrazine compounds had higher FD values in Wuliangye than in Jiannanchun liquor, thus imparting stronger nutty, baked, and roasted notes in Wuliangye liquor.
