- Scalable green approach toward fragrant acetates
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The advantageous properties of ethylene glycol diacetate (EGDA) qualify it as a useful substitute for glycerol triacetate (GTA) for various green applications. We scrutinised the lipase-mediated acetylation of structurally diverse alcohols in neat EGDA furnishing the range of naturally occurring fragrant acetates. We found that such enzymatic system exhibits high reactivity and selectivity towards activated (homo) allylic and non-activated primary/secondary alcohols. This feature was utilised in the scalable multigram synthesis of fragrant (Z)-hex-3-en-1-yl acetate in 70percent yield. In addition, the Lipozyme 435/EGDA system was also found to be applicable for the chemo-selective acetylation of (hydroxyalkyl) phenols as well as for the kinetic resolution of chiral secondary alcohols. Lastly, its discrimination power was demonstrated in competitive experiments of equimolar mixtures of two isomeric alcohols. This enabled the practical synthesis of 1-pentyl acetate isolated as a single product in 68percent yield from the equimolar mixture of 1-pentanol and 3-pentanol.
- Puchl'Ová, Eva,Szolcsányi, Peter
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supporting information
(2020/08/07)
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- Preparing method and application of aminopyridine derivative
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The invention provides an aminopyridine derivative and a preparing method and application thereof. The structural formula of the aminopyridine derivative is shown in the description, wherein R represents substitute groups and is selected from one or more of alkyl groups of C1-C20, phenyl groups, naphthyls, methoxy groups, benzyloxy groups, fluorine, chlorine, bromine, trifluoromethyl, methoxycarbonyl groups. The preparing method comprises the steps of conducting benzylation on 4-aminopyridine and benzylic halides under action of an alkaline reagent. The aminopyridine derivative is used for catalyzing esterification reaction, and is especially suitable for catalyzing acetic acid esterification reaction with alcohol as the substrate; the reaction speed is high, the yield is high, and the reaction effect and the reaction speed are almost equal to those of 4-dimethylamino pyridine. The aminopyridine derivative has large molecular weight and a high boiling point and accordingly can be separated from primary products and auxiliary products through distillation or rectification and can be reused cyclically ten times or more, the cost of the catalyst is greatly reduced, and the aminopyridine derivative has good industrial application prospects.
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Paragraph 0101-0103; 0108; 0109; 0113
(2019/07/16)
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- Identification of (Z)-3:(E)-2-Hexenal isomerases essential to the production of the leaf aldehyde in plants
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The green odor of plants is characterized by green leaf volatiles (GLVs) composed of C6 compounds. GLVs are biosynthesized from polyunsaturated fatty acids in thylakoid membranes by a series of enzymes. A representative member of GLVs (E)-2-hexenal, known as the leaf aldehyde, has been assumed to be produced by isomerization from (Z)-3-hexenal in the biosynthesis pathway; however, the enzyme has not yet been identified. In this study, we purified the (Z)-3:(E)-2-hexenal isomerase (HI) from paprika fruits and showed that various plant species have homologous HIs. Purified HI is a homotrimeric protein of 110 kDa composed of 35-kDa subunits and shows high activity at acidic and neutral pH values. Phylogenetic analysis showed that HIs belong to the cupin superfamily, and at least three catalytic amino acids (His, Lys, Tyr) are conserved in HIs of various plant species. Enzymatic isomerization of (Z)-3-hexenal in the presence of deuterium oxide resulted in the introduction of deuterium at the C4 position of (E)-2-hexenal, and a suicide substrate 3-hexyn-1-al inhibited HI irreversibly, suggesting that the catalytic mode of HI is a keto-enol tautomerism reaction mode mediated by a catalytic His residue. The gene expression of HIs in Solanaceae plants was enhanced in specific developmental stages and by wounding treatment. Transgenic tomato plants overexpressing paprika HI accumulated (E)-2-hexenal in contrast to wild-type tomato plants mainly accumulating (Z)-3-hexenal, suggesting that HI plays a key role in the production of (E)-2-hexenal in planta.
- Kunishima, Mikiko,Yamauchi, Yasuo,Mizutani, Masaharu,Kuse, Masaki,Takikawa, Hirosato,Sugimoto, Yukihiro
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p. 14023 - 14033
(2016/07/11)
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- Parameters affecting the synthesis of (Z)-3-hexen-1-yl acetate by transesterifacation in organic solvent
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Summary: (Z)-3-hexen-1-yl esters are important green top-note components of food flavors and fragrances. Crude acetone powders extracted lipases from five plant seedlings of rapeseed, wheat, barley, linseed and maize were investigated for their use in the synthesis of flavor esters with vinyl acetate by transesterification in organic solvents. Rape seedlings showed the highest degree of (Z)-3-hexen-1-yl acetate synthesis with a yield of 76% in 72 h. Rape seedling was chosen as promising biocatalyst to evaluate the effects of some of reaction parameters on (Z)-3-hexen-1-yl acetate synthesis using vinyl acetate and (Z)-3-hexen-1-ol at 40 °C in n-hexane with 50 g/L enzyme as catalyst. Acetonitrile proved distinctly superior solvent. The percent remaining activity relative to fresh seedlings powders was highest in wheat and barley. Highest ester yield of 80% was obtained with 0.8 M of substrate concentrations within 48 h. Crude rapeseed lipase afforded a conversion 93% of ethyl alcohol. Higher ester yield was achieved within first 24 h with added molecular. The crude rape seedlings lipase is low cost yet effective, showed potential for the production of green note esters industrially.
- Liaquat, Muhammad,Mehmood, Talat,Khan, Sami-Ullah,Ahmed, Zahoor,Saeed, Muhammad,Aslam, Sher,Khan, Junaid,Ali, Naushad,Nawaz, Mohsan,Jahangir, Muhammad
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p. 323 - 334
(2015/05/27)
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- Effective synthesis of cis-3-hexen-1-yl acetate via transesterification over KOH/γ-Al2O3: Structure and catalytic performance
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Cis-3-hexen-1-yl acetate is a significant green note flavor compound and widely used in the food and cosmetic industry. In this research, a series of solid base KOH/γ-Al2O3 have been prepared and been utilized for the synthesis of cis-3-hexen-1-yl acetate via transesterification from cis-3-hexen-1-yl and ethyl acetate. The catalysts were also characterized by several physic-chemical techniques such as X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, N2 adsorption, CO 2-temperature-programmed desorption (CO2-TPD), and X-ray fluorescence (XRF). 30%KOH/Al2O3 was suggested to be the best conversion due to the cis-3-hexen-1-ol conversion of 59.3% at a temperature 88 °C within 2 h. Characterization results showed that KOH transformed into Al-O-K and K2O·CO2 species during the calcination process. It was confirmed that K2O·CO2 disappeared and Al-O-K groups existed on the surface of the water-washing 30%KOH/Al 2O3 which was inactive for transesterification. K 2O·CO2 species might be the major active species on KOH/Al2O3, and Al-O-K groups was inactive for cis-3-hexen-yl acetate synthesis.
- Li, Xiaoshuan,Yu, Dinghua,Zhang, Wengui,Li, Zhengwen,Zhang, Xiaowei,Huang, He
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- Rape seedling lipase catalyzed synthesis of flavor esters through transesterification in hexane
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Butyl butyrate, a short-chain ester with fruity pineapple odor, is a significant flavor compound that is widely used in the food industry. Enzymatic synthesis of butyl butyrate by crude rape seedlings lipase has been investigated in n-hexane using 50 g/L of enzyme at 40 °C through alcoholysis of ethyl butyrate with butanol. The influence of reaction parameters such aswater content, water activity, substrate concentrations and reaction time were also studied. Ester yield of 60% after 96 h has been obtained with 0.5% (v/v) of added water using reversible reaction or activated ester. A concentration of 0.1M of butanol while 0.6 M of ethyl butyrate was found optimal for butyl butyrate synthesis. The esterification catalyzed by lipase was inhibited by increasing the butanol concentration beyond 0.10 M while no inhibition of enzyme was observed with ethyl butyrate. (Z)-3-hexen-1-ol (cis-3-hexen-1-ol) esters posses the odour of freshly cut grass and are used to obtain natural green top notes in food flavours. Two different approaches for rapeseed lipase catalyzed synthesis of these flavour esters were also studied. Acylation of (Z)-3-hexen-1-ol with vinyl acetate (irreversible acyl donor) and butyl caproate (reversible acyl donor) was evaluated. Ester yield of 99 % after 24 h was obtained for (Z)-3-hexen-1-yl acetate with vinyl acetate as acyl donor. Crude rape seedlings lipase has proved to be an efficient catalyst to obtain (Z)-3-hexen-1-ol esters using irreversible acyl donor such as vinyl ester in hexane. Crude lipase also works well at ambient temperature without need of immobilization.
- Liaquat, Muhammad,Khan, Saeed,Aslam, Sher,Khan, Ayub,Khan, Hakim,Khan, Shah Masaud,Ali, Sardar,Wahab, Said,Bhatti, Haq Nawaz
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scheme or table
p. 144 - 150
(2012/05/19)
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- Highly active and selective semihydrogenation of alkynes with the palladium nanoparticles-tetrabutylammonium borohydride catalyst system
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Palladium nanoparticles are prepared from palladium(II) acetate and 2 equivalents of potassium tert-butoxide in the presence of 4-octyne. The palladium nanoparticles-tetrabutylammonium borohydride system shows excellent catalytic activity and selectivity in the semihydrogenation of alkynes to the [(Z)-]alkenes. The hydrogenation of 4-octyne is conducted with the catalyst system at a substrate-to-palladium molar ratio of 10,000-200,000 under 8 atm of hydrogen to give (Z)-4-octene in > 99% yield. Isomerization and over-reduction of the Z-alkene are very slow even after consumption of the alkyne.
- Hori, Junichi,Murata, Kunihiko,Sugai, Toshiki,Shinohara, Hisanori,Noyori, Ryoji,Arai, Noriyoshi,Kurono, Nobuhito,Ohkuma, Takeshi
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supporting information; experimental part
p. 3143 - 3149
(2010/04/06)
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- 1,4-HYDROGENATION OF DIENES WITH RU COMPLEXES
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The present invention relates to the use of Ru complexes, having a cyclopentadienyl derivatives and a diene as ligands, together with some acidic additives for improving the selectivity in the 1,4-hydrogenation of conjugated dienes into the corresponding "cis "-alkene as major product, i.e. wherein the two substituents in position 2,3 of said diene are in a cis configuration in the corresponding alkene.
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Page/Page column 19; 21-22
(2008/12/04)
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- Cobalt(II)-catalyzed direct acetylation of alcohols with acetic acid
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Cobalt(II) chloride hexahydrate (CoCl2·6H2O) efficiently catalyzes the acetylation of alcohols with AcOH in high yields. This protocol is also effective with other carboxylic acids, trifluoroacetic acid, propanoic acid, phenylacetic acid and benzoic acid, affording the corresponding acylated products in moderate to good yields. Removal of water is not necessary in these reactions. The catalyst can be filtered and recycled without loss of activity.
- Velusamy, Subbarayan,Borpuzari, Sarbani,Punniyamurthy
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p. 2011 - 2015
(2007/10/03)
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- Zn(ClO4)2·6H2O as a Powerful Catalyst for a Practical Acylation of Alcohols with Acid Anhydrides
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A new protocol for the acylation of alcohols with anhydrides in the presence of Zn(ClO4)2·6H2O as the catalyst is reported. The activity of Zn(ClO4)2· 6H2O has been proven to be superior to that exerted by dry Mg(ClO4)2 and by metal triflates. Its efficiency allows reactions between poorly reactive substrates, such as sterically hindered tertiary alcohols and aromatic anhydrides, All of the reactions were carried out at a 1:1.05 alcohol/anhydride ratio. These conditions are extremely convenient from a practical and economic point of view, since they avoid wasting reagents and allow a simple workup procedure. The catalytic action of Zn(ClO4)2·6H2O is so specific for the activation of the anhydrides, that acid-sensitive functionalities and the stereochemical configuration of the starting materials remain unaltered in the esterification process. In all cases, the acylated products are quantitatively obtained in pure form. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
- Bartoli, Giuseppe,Bosco, Marcella,Dalpozzo, Renato,Marcantoni, Enrico,Massaccesi, Massimo,Sambri, Letizia
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p. 4611 - 4617
(2007/10/03)
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- SmI2-Induced Deoxygenation of Epoxides and Its Application to Carbonyl Methylenation in Combination with Iodomethylation
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Deoxygenation of epoxides to olefins was effected by an efficient electron transfer system of SmI2-THF-HMPA in the presence of N,N-dimethylaminoethanol (DMAE) or glutaric anhydride.This procedure, in combination with the SmI2-induced iodomethylation, afforded a new, rapid and mild one-pot carbonyl methylenation method.
- Matsukawa, Mihaya,Tabuchi, Takanori,Inanaga, Junji,Yamaguchi, Masaru
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p. 2101 - 2102
(2007/10/02)
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- Vakuum UV Photolyses of Some Bichromophoric Alkenes Possesing Hydroxyl or Methoxycarbonyl Group
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The direct photolyses at 185 nm of some naturally occuring and related bichromophoric alkenes possesing hydroxyl or methoxycarbonyl group at an allylic, homoallylic, or remote position gave the geometrical isomers as the major photoproducts detectable on gas chromatography.The isomerization yield was highly sensitive to the functional group introduced and its position; allylic alkenols gave poor yields, while both functionalization at a remote position and esterification of the hydroxyl group improve the photoisomerization yield.
- Inoue, Yoshihisa,Goan, Kazuyoshi,Hakushi, Tadao
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p. 2217 - 2220
(2007/10/02)
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