cas 539-82-2, Ethyl valerate | Articles data

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Synthesis of the 'green apple ester' ethyl valerate in organic solvents by Candida rugosa lipase immobilized in MBGs in organic solvents: Effects of immobilization and reaction parameters
Ethyl valerate, also known as the green apple flavor is well known for its wide applications in the areas of food, pharmaceuticals and cosmetics industries. Candida rugosa lipase was immobilized in microemulsion based organogels (MBGs) and used for ethyl valerate synthesis in organic solvents. Various immobilization and reaction parameters were scrutinized for enhancement of ester production. Among the immobilization parameters, sodium bis-2-(ethylhexyl) sulfosuccinate (AOT), n-heptane and gelatin were found to be the highest yielding combination. Cyclohexane was found to be the solvent of choice as the reaction medium while pH 7, 40 °C and 1:1.6 ratio of valeric acid to ethanol were the reaction parameters exhibiting highest ester formation. The organogels were highly stable in the solvents and were reused for nine cycles with meager loss of activity. Also, immobilized enzyme was thermostable at 50-70 °C for ten hours. Hence, MBGs verify to be a promising enzyme immobilization system for ester synthesis in organic solvents.
Raghavendra, Tripti,Sayania, Divya,Madamwar, Datta
p. 31 - 38
(2010)
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Thermoalkalophilic lipase from an extremely halophilic bacterial strain Bacillus atrophaeus FSHM2: Purification, biochemical characterization and application
The present study was designed to isolate and identify an extremely halophilic lipase-producing bacterial strain, purify and characterize the related enzyme and evaluate its application for ethyl and methyl valerate synthesis. Among four halophilic isolates, the lipolytic ability of one isolate (identified as Bacillus atrophaeus FSHM2) was confirmed. The enzyme (designated as BaL) was purified using three sequential steps of ethanol precipitation and dialysis, Q-Sepharose XL anion-exchange chromatography and SP Sepharose cation-exchange chromatography with a final yield of 9.9% and a purification factor of 31.8. The purified BaL (Mw～85 kDa) was most active at 70 °C and pH 9 in the presence of 4?M NaCl and retained 58.7% of its initial activity after 150 min of incubation at 80 °C. The enzyme was inhibited by Cd2+ (35.6 ± 1.7%) but activated by Ca2+ (132.4 ± 2.2%). Evaluation of BaL's stability in the presence of organic solvents showed that xylene (25%) enhanced the relative activity of the enzyme to 334.2 ± 0.6% after 1 h of incubation. The results of esterification studies using the purified BaL revealed that maximum ethyl valerate (88.5%) and methyl valerate (67.5%) synthesis occurred in the organic solvent medium (xylene) after 48 h of incubation at 50 °C.
Ameri, Atefeh,Shakibaie, Mojtaba,Faramarzi, Mohammad Ali,Ameri, Alieh,Amirpour-Rostami, Sahar,Rahimi, Hamid Reza,Forootanfar, Hamid
p. 151 - 160
(2017)
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High yield of ethyl valerate from the esterification of renewable valeric acid catalyzed by amino acid ionic liquids
Ethyl valerate (EV) as a promising fuel additive was produced by esterification of valeric acid with ethanol over Bronsted acidic amino acid ionic liquids. Hammett method and density functional theory (DFT) calculations were preformed to evaluate the acidities of the catalysts. The composition of catalyst, reaction temperature, reaction time, molar ratio of reactants, amount of catalyst, and recycling ability of the catalyst were investigated. Proline bisulfate (ProHSO4) ionic liquid has the highest catalytic activity and the best recyclability under the optimized esterification conditions. A high conversion of valeric acid (>99.9%) was obtained for 7 h at 80 °C, with 100% selectivity of EV. The density, viscosity, melting point, boiling point, elemental analysis and heat of combustion of the EV product were measured. The density of EV is 0.896 g cm -3. The viscosity of EV was 1.7 cP at room temperature. The heating values of EV are 4158.1 kJ mol-1 and 31.9 kJ g-1. EV obtained from esterification has higher energy density than methanol, ethanol, γ-valerolactone, and valeric acid, which illustrates that EV is a promising biofuel candidate.
Dong, Lin-Lin,He, Ling,Tao, Guo-Hong,Hu, Changwei
p. 4806 - 4813
(2013)
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Zeolite-Tailored Active Site Proximity for the Efficient Production of Pentanoic Biofuels
Biofuel production can alleviate reliance on fossil resources and thus carbon dioxide emission. Hydrodeoxygenation (HDO) refers collectively to a series of important biorefinery processes to produce biofuels. Here, well-dispersed and ultra-small Ru metal nanoclusters (ca. 1 nm), confined within the micropores of zeolite Y, provide the required active site intimacy, which significantly boosts the chemoselectivity towards the production of pentanoic biofuels in the direct, one-pot HDO of neat ethyl levulinate. Crucial for improving catalyst stability is the addition of La, which upholds the confined proximity by preventing zeolite lattice deconstruction during catalysis. We have established and extended an understanding of the “intimacy criterion” in catalytic biomass valorization. These findings bring new understanding of HDO reactions over confined proximity sites, leading to potential application for pentanoic biofuels in biomass conversion.
Chen, Shaohua,Chen, Tiehong,Chu, Shengqi,Gu, Qingqing,He, Jiang,Liu, Yuanshuai,Luo, Wenhao,Wang, Aiqin,Weckhuysen, Bert M.,Wu, Zhijie,Yang, Bing,Zhang, Tao,Zhang, Yafeng
supporting information
p. 23713 - 23721
(2021/09/22)

Catalytic transfer hydrogenation of ethyl levulinate to γ-valerolactone over supported MoS2catalysts
The hydrogenation of levulinate esters to γ-valerolactone (GVL) is an important step in the transformation of biomass into biofuels. It is attractive to develop new efficient systems for the catalytic transfer hydrogenation (CTH) of levulinate esters to value-added GVL. In this work, a series of MoS2-based supported catalysts were prepared via an impregnation method for the CTH of biomass-derived ethyl levulinate (EL) to GVL. By comprehensive characterization and catalytic measurements, we found that the CTH activity of EL to GVL is closely related to the MoS2 morphology and acid distribution on the support. Among the catalysts with different supports, the AC support with abundant Lewis acid sites and large surface area facilitated the high dispersion of low stacked MoS2 slabs, and the MoS2-acid synergistic catalysis contributed to the superior activity and selectivity. The conversion of EL and the selectivity of GVL reached 97.2% and 91.2% under optimized conditions over the MoS2/AC catalyst (230 °C, 1 MPa H2, 1.5 h), respectively. We also conducted reaction kinetic experiments to reveal the relationship between the active site of the MoS2/AC catalyst and its catalytic performance, and the plausible reaction pathway and mechanism over MoS2/AC was proposed. The catalytic performance gradually declined during recycling tests due to the oxidation of MoS2 and can be easily recovered by resulfuration.
Diao, Xinyong,Ji, Na,Jiang, Sinan,Liu, Caixia,Liu, Qingling,Liu, Zhenyu,Lu, Xuebin,Ma, Degang,Song, Chunfeng,Yu, Zhihao
p. 5062 - 5076
(2021/08/16)

The relevance of Lewis acid sites on the gas phase reaction of levulinic acid into ethyl valerate using CoSBA-xAl bifunctional catalysts
A series of Co supported on Al-modified SBA-15 catalysts has been studied in the gas phase direct transformation of levulinic acid (LA) into ethyl valerate (EV) using a continuous fixed-bed reactor and ethanol as solvent. It was observed that once the intermediate product gamma-valerolactone (GVL) has been formed, the presence of aluminum is required for the selective transformation to EV. Three Lewis acid sites (LAS) are identified (from highest to lowest acid strength): aluminum ions in tetrahedral and octahedral coordination and Co2+sites. The intrinsic activity of these LAS for the key reaction, the GVL ring opening, decreases with the strength of these acid sites, but so does the undesirable formation of coke, also catalyzed by these centers. The best catalyst was that with the highest Al content, CoSBA-2.5Al, that reached an EV yield of up to 70%. This result is associated with the presence of LAS attributed to the presence of Co2+surface species that, although having low intrinsic activity in the selective GVL ring-opening reaction, are highly concentrated in this sample and also possess less activity in the undesirable and deactivating formation of coke. These Co2+LAS have been stabilized by incorporation of aluminum into the support, modifying the reducibility and dispersion of cobalt species. Additionally, the lower proportion of metallic Co species decreases the hydrogenating capacity of this catalyst. This decrease is a positive result because it prevents GVL hydrogenation to undesired products. This catalyst also showed promising stability in a 140 h on-stream run.
Cecilia, J. A.,Dumesic, J. A.,Jiménez-Gómez, C. P.,López Granados, M.,Maireles-Torres, P.,Mariscal, R.,Mu?oz-Olasagasti, M.
p. 4280 - 4293
(2021/06/30)

Design, Synthesis, and Study of the Insecticidal Activity of Novel Steroidal 1,3,4-Oxadiazoles
A series of novel steroidal derivatives with a substituted 1,3,4-oxadiazole structure was designed and synthesized, and the target compounds were evaluated for their insecticidal activity against five aphid species. Most of the tested compounds exhibited potent insecticidal activity against Eriosoma lanigerum (Hausmann), Myzus persicae, and Aphis citricola. Compounds 20g and 24g displayed the highest activity against E. lanigerum, showing LC50 values of 27.6 and 30.4 μg/mL, respectively. Ultrastructural changes in the midgut cells of E. lanigerum were detected by transmission electron microscopy, indicating that these steroidal oxazole derivatives might exert their insecticidal activity by destroying the mitochondria and nuclear membranes in insect midgut cells. Furthermore, a field trial showed that compound 20g exhibited effects similar to those of the positive controls chlorpyrifos and thiamethoxam against E. lanigerum, reaching a control rate of 89.5% at a dose of 200 μg/mL after 21 days. We also investigated the hydrolysis and metabolism of the target compounds in E. lanigerum by assaying the activities of three insecticide-detoxifying enzymes. Compound 20g at 50 μg/mL exhibited inhibitory action on carboxylesterase similar to the known inhibitor triphenyl phosphate. The above results demonstrate the potential of these steroidal oxazole derivatives to be developed as novel pesticides.
Bai, Hangyu,Jiang, Weiqi,Li, Qi,Li, Tian,Ma, Shichuang,Shi, Baojun,Wu, Wenjun
p. 11572 - 11581
(2021/10/12)

Selective production of γ-valerolactone and ethyl valerate from ethyl levulinate using unsupported nickel phosphide
Unsupported nickel phosphide catalyst containing Ni2P phase was applied in the hydrodeoxygenation of ethyl levulinate in ethanol medium for the first time. The obtained catalyst was investigated by XRF, XRD, NH3–TPD, XPS and TEM techniques. γ-valerolactone and ethyl valerate were obtained as the hydrodeoxygenation products. Varying the temperature and the reaction time it was possible to obtain these products with high selectivity. γ-valerolactone was selectively formed at 200–250 °C and ethyl valerate was selectively formed at temperatures of 300–350 °C. Increase in reaction time was contributed to ethyl valerate formation. The highest selectivity of ethyl valerate was 100% at full ethyl levulinate conversion at 350 °C after 6 h. 100% γ-valerolactone selectivity was reached at low conversion of ethyl levulinate. The highest yield of γ-valerolactone reached 41.7% after 6 h of the reaction at 250 °C. The selectivity of γ-valerolactone was 86.9% and the conversion of ethyl levulinate was 48.0%.
Golubeva, Maria A.,Maximov, Anton L.
(2021/11/01)

In Situ Generated Nickel Phosphide Based Catalysts for Hydroprocessing of Levulinic Acid
Abstract: This article describes the production of unsupported nickel phosphide catalysts generated in situ in а reaction mixture from water-soluble and oil-soluble precursors during the hydroconversion of levulinic acid. These catalysts contain crystalline phases, specifically Ni12P5 and Ni(PO3)2. During the hydrogenation of levulinic acid in toluene in the presence of NiP–TOP, a lower temperature and a shorter reaction time contribute to the formation of γ-valerolactone (100% selectivity). A higher temperature and a longer reaction time favor the formation of valeric acid (94% selectivity). In the hydrogenation of levulinic acid in ethanol in the presence of NiP–H3PO2, the main reaction product is ethyl levulinate (95% selectivity).
Golubeva
p. 670 - 675
(2021/03/29)

Eco-Friendly Natural Clay: Montmorillonite Modified with Nickel or Ruthenium as an Effective Catalyst in Gamma-Valerolactone Synthesis
Ni/Ru metals supported on cheap and available support montmorillonite K10 were used for the selective hydrogenation of levulinic acid to γ-valerolactone. Different loadings of the metals were applied by the impregnation method, and detailed characterization was performed (UV–VIS, XRD, TPR, TPD, particle size distribution, SEM, XRF). Metals’ homogeneous distribution on the surface was confirmed. The selectivity to the desired product was almost independent on the used material. A detailed study of the influence of solvents on the studied reaction was also performed—protic alcohol-based solvents caused the formation of levulinic and valeric acid esters in the reaction mixture. The selectivity was influenced mainly by the alcohol structure (the highest selectivity obtained using isopropyl alcohol and sec-butanol). Mainly the solvent’s donor number (except ethanol) influenced the reaction rate. The prepared catalysts are promising, available, and cheap materials for the studied reaction. Solvent may significantly influence the yield of γ-valerolactone. Graphic Abstract: [Figure not available: see fulltext.].
?erveny, Libor,Trejbal, Ji?í,Vaňková, Michaela,Vrbková, Eva,Vysko?ilová, Eli?ka
(2021/07/25)

Genome mining reveals new bacterial type I Baeyer-Villiger monooxygenases with (bio)synthetic potential
Baeyer-Villiger monooxygenases (BVMOs) are oxidorreductases that catalyze the oxidation of ketones in a very selective manner. By genome mining we detected seven putative type I BVMOs in Bradyrhizobium diazoefficiens USDA 110. As we established the phylogenetic relationships among them and with other type I BVMOs, we found out that they belong to different clades of the phylogenetic tree. Thus, we decided to clone and heterologously express five of them. Three of them, each one from a divergent phylogenetic group, were obtained as soluble proteins, allowing us to proceed with their biocatalytic assessment and enzymatic characterization. As to substrate scope and selectivity, we observed a complementary behavior among the three BVMOs. BVMO2 was the more versatile biocatalyst in whole-cell systems while BVMO4 and BVMO5 showed a narrow substrate profile with preference for linear ketones and particular regioselectivity for (±)-cis-bicyclo[3.2.0]hept-2-en-6-one.
Bianchi, Dario A.,Carabajal, María Ayelén,Ceccoli, Romina D.,Rial, Daniela V.
(2020/03/19)

Liquid phase esterification of levulinic acid into ethyl levulinate over sulphobenzylated nanoporous Al-SBA-15 catalyst
Value added chemicals, fuels, and fuel additives can be obtained from cheap bio masses such as levulinic acid. Levulinic acid is the dehydration and hydrolysis products of pentoses and hexoses. The present work deals with the synthesis of sulphobenzylated Al-SBA-15, [SO3H-Bz-Al-SBA-15], characterization by various analytical techniques such as XRD, BET, FT-IR, TGA, DTA, FE-SEM/EDS and HR-TEM/EDX techniques and evaluation of catalytic activity towards esterification of levulinic acid to ethyl levulinate under mild and non corrosive conditions. Sulphonation of the aromatic ring of the benzyl group has been done in different amounts to get nanoporous x% SO3H-Bz-Al-SBA-15 catalysts where (x = 0.02, 0.04, 0.06, 0.08 and 0.10% w/w). Among them 0.08% SO3H-Bz-Al-SBA-15 catalyst showed the highest conversion of levulinic acid (100%) with the highest selectivity towards ethyl levulinate (100%). Esterification of levulinic acid has been carried out with different primary alcohols and all of them yielded 100% selectivity towards alkyl levulinate. However conversion level of levulinic acid was found to be different with different alcohols. Reaction conditions have been optimized. The results were compared with other supported catalysts and discussed.
Kumaravel, Sakthivel,Thiripuranthagan, Sivakumar,Radhakrishnan, Ramakrishnan,Erusappan, Elangovan,Durai, Mani,Devarajan, Arulselvan,Mukannan, Arivanandhan
p. 6965 - 6977
(2019/07/10)

Conversion of γ-Valerolactone to Ethyl Valerate over Metal Promoted Ni/ZSM-5 Catalysts: Influence of Ni0/Ni2+ Heterojunctions on Activity and Product Selectivity
Promoter (Cr, Mo and W) modified Ni/ZSM-5 catalysts were explored in the vapor phase conversion of γ-valerolactone (GVL) to ethyl valerate (EV; gasoline blender) at atmospheric pressure. Among the three different promoters (Cr, Mo and W) tested the Mo-modified catalyst was found to be the best candidate. In addition, this catalyst was found to be stable up to 50 h reaction time with an insignificant decrease in activity. The good catalytic performance is related to an optimal ratio of acid and hydrogenation functions provided by Ni2+ and Ni0, respectively. In situ FTIR spectroscopic studies revealed a strong adsorption of GVL on all catalysts which quickly reacts with dosed ethanol by formation of EV, most pronounced on the Mo-modified catalyst, while VA was identified as side product. These findings suggest the preferred GVL ring opening by cracking the C?O bond on the methyl side of the GVL molecule on this type of catalysts leading to pentenoic acid as intermediate, which is quickly hydrogenated and esterified.
Akula, Venugopal,Bentrup, Ursula,Bhargava, Suresh K.,Brückner, Angelika,Gutta, Naresh,Jampaiah, Deshetti,Velisoju, Vijay Kumar
(2020/02/11)

Method for synthesizing propionate through ester-ester exchange path
The invention provides a method for synthesizing propionate through an ester-ester exchange path and relates to a method for synthesizing the propionate. According to the method, reaction raw materials include, but are not limited to ethyl formate, propyl formate, butyl formate, ethyl acetate, propyl acetate, butyl acetate and the like; the method for synthesizing the propionate through an ester exchange one-step method is adopted. A catalyst comprises alkaline materials including ionic liquid, soluble strong base, solid base and the like respectively; the catalyst has the advantages of high catalysis efficiency and no pollution. By taking methyl propionate and ethyl acetate reaction as an example, KOH is used as the catalyst, the mol ratio of the raw materials is 1 to 1, the reaction temperature is 60 DEG C and the reaction time is 5 min; the conversion ratios of the methyl propionate and the ethyl acetate can reach 70 percent or more; products comprise ethyl propionate and the methylacetate. The whole reaction path has the characteristics of short synthetic route, simple technological flow and high yield and the catalyst is stable, does not become inactive and can be repeatedlyutilized.
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Paragraph 0030-0031

(2019/04/04)

Synthesis of Ethyl-4-ethoxy Pentanoate by Reductive Etherification of Ethyl Levulinate in Ethanol on Pd/SiO2-C Catalysts
The synthesis of biomass-derived ethers to be used as biofuels or biofuel additives has attracted much attention. Following the recently reported synthesis of etherified ester ethyl-4-ethoxy pentanoate (EEP) from γ-valerolactone (GVL) in ethanol catalyzed by H-beta zeolite, an alternative route to prepare EEP in high yield has been developed by reductive etherification of ethyl levulinate (EL) in ethanol at 140 °C under 0.5 MPa H2 with a silica-modified Pd/C catalyst. The ether production likely follows a tandem acetalization–hydrogenolysis process with ethyl-4,4-diethoxy pentanoate (EDEP) as the intermediate. The acetalization step can be favored by introducing acidic materials, such as SiO2–carbon or beta zeolite, as a cocatalyst. The combination of the Pd/SiO2-C and beta zeolite mixture leads to 100 % EL conversion and 93 % EEP selectivity under optimized reaction conditions. For the first time, the standard molar combustion enthalpy of as-prepared EEP is measured by using a static oxygen bomb, and the value of which is determined to be about ?5658 kJ mol?1, which is much larger than that of GVL (?2650 kJ mol?1).
Cui, Qianqian,Long, Yinshuang,Wang, Yun,Wu, Haihong,Guan, Yejun,Wu, Peng
p. 3796 - 3802
(2018/10/24)

Preparation of valeric acid and valerate esters from biomass-derived levulinic acid using metal triflates + Pd/C
Recently, great attention has been paid to the study of the conversion of biomass-derived compounds to value-Added chemicals. Levulinic acid (LA) is a versatile and valuable chemical and its various applications have been described. The selective conversion of biomass-derived LA to produce valeric acid and valerate esters was successfully performed in the presence of H2, in which metal triflates and Pd/C were used as the catalysts. Under optimal conditions, a 99% conversion of LA and a 92% selectivity of valeric acid was obtained with Hf(OTf)4 and Pd/C as the catalysts at a relatively low temperature of 150 °C. Moreover, the metal center of the catalyst, the solvent, the reaction temperature and other reaction conditions were studied. In addition, the results of the recycling experiment exhibited that the catalysts continued to have a satisfactory activity after being reused 5 times.
Zhou, Jian,Zhu, Rui,Deng, Jin,Fu, Yao
p. 3974 - 3980
(2018/09/11)

Sol-gel immobilisation of lipases: Towards active and stable biocatalysts for the esterification of valeric acid
Alkyl esters are high added value products useful in a wide range of industrial sectors. A methodology based on a simple sol-gel approach (biosilicification) is herein proposed to encapsulate enzymes in order to design highly active and stable biocatalysts. Their performance was assessed through the optimization of valeric acid esterification evaluating the effect of different parameters (biocatalyst load, presence of water, reaction temperature and stirring rate) in different alcoholic media, and comparing two different methodologies: conventional heating and microwave irradiation. Ethyl valerate yields were in the 80–85% range under optimum conditions (15 min, 12% m/v biocatalyst, molar ratio 1:2 of valeric acid to alcohol). Comparatively, the biocatalysts were slightly deactivated under microwave irradiation due to enzyme denaturalisation. Biocatalyst reuse was attempted to prove that good reusability of these sol-gel immobilised enzymes could be achieved under conventional heating.
Cebrián-García, Soledad,Balu, Alina M.,García, Araceli,Luque, Rafael
(2018/09/12)

Unprecedented alkylation of carboxylic acids by boron trifluoride etherate
The alkylation of carboxylic acids by an ethyl moiety of boron trifluoride etherate in the absence of ethyl alcohol from the reaction system is unexpected and novel. Both aromatic and aliphatic carboxylic acids were clearly alkylated affording good yields in short reaction times with the exception of nicotinic acid that necessitated an overnight reaction. It was noted that while ortho-substituted hydroxyl groups of carboxylic acids investigated were not affected by alkylation, those of meta- and para-substituted carboxylic acids were partially etherified. Furthermore, the alkylation reaction was found to be compatible with a range of functional groups such as halogens, amino and nitro groups except for the alkene function of undecylenic acid that underwent polymerisation with concomitant alkylation of its carboxylic acid function.
Jumbam, Ndze D.,Maganga, Yamkela,Masamba, Wayiza,Mbunye, Nomthandazo I.,Mgoqi, Esethu,Mtwa, Sphumusa
p. 387 - 392
(2018/09/06)

Carboxylation of Aromatic and Aliphatic Bromides and Triflates with CO2 by Dual Visible-Light–Nickel Catalysis
We report the efficient carboxylation of bromides and triflates with K2CO3 as the source of CO2 in the presence of an organic photocatalyst in combination with a nickel complex under visible light irradiation at room temperature. The reaction is compatible with a variety of functional groups and has been successfully applied to the synthesis and derivatization of biologically active molecules. In particular, the carboxylation of unactivated cyclic alkyl bromides proceeded well with our protocol, thus extending the scope of this transformation. Spectroscopic and spectroelectrochemical investigations indicated the generation of a Ni0 species as a catalytic reactive intermediate.
Meng, Qing-Yuan,Wang, Shun,K?nig, Burkhard
supporting information
p. 13426 - 13430
(2017/10/07)

Highly efficient transformation of Γ-valerolactone to valerate esters over structure-controlled copper/zirconia catalysts prepared via a reduction-oxidation route
Design and development of novel and efficient catalysts are crucial but challenging for the catalytic conversion of biomass and derivatives to fuels and chemicals. In this paper, a novel separate nucleation and aging steps assistant reduction-oxidation strategy was developed to synthesis CuO/ZrO2 complex precursor with homogeneously distributed Cu and Zr components, which can be used as an ideal precursor for the synthesis of highly dispersed Cu/ZrO2 catalyst. Characterization results revealed that homogeneous dispersion of CuO, high surface area of ZrO2 support with controlled porous structure, and strong interaction between CuO and ZrO2 in CuO/ZrO2 precursor could lead to the enhanced Cu dispersion and the formation of Cu+ active centers. The synthesized Cu/ZrO2 catalysts exhibited excellent catalytic performance (85.4% conversion of GVL and 98.0% selectivity of pentyl valerate) in the catalytic transformation of GVL to valerate esters, more efficient than that of Cu/ZrO2-CP and Cu/ZrO2-CH catalysts prepared via co-precipitation and chemisorption hydrolysis methods, respectively. The superior catalytic performance was mainly attributed to both the cooperation of Cu0 and Cu+ species and the highly dispersed surface Cu0, thereby improving the adsorption and polarization of C[dbnd]O bond in GVL and the following dissociation of H2 to produce active hydrogen for the hydrogenation step during the catalytic transformation of GVL. Moreover, such copper-based catalysts exhibited potential applications in the exploitation and utilization of biomass resources with significantly enhanced efficiency.
Liu, Shanshan,Fan, Guoli,Yang, Lan,Li, Feng
p. 180 - 188
(2017/07/10)

USE OF DDX3 INHIBITORS AS ANTIPROLIFERATIVE AGENTS
The present invention refers to compounds of formula I or II endowed with DDX3 inhibitory activity, relative pharmaceutical compositions and their use as antihyperproliferative agents. (I) or (II)
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Page/Page column 93

(2017/10/30)

Enhanced hydrogenation of ethyl-levulinate to γ-valerolactone over Ni:δOx stabilized Cu+ surface sites
CuNiδOx/SiO2 nanocatalysts with Cu-Ni activities below 5 nm were synthesized. The catalysts showed high performance for catalytic hydrogenation of ethyl-levulinate to γ-valerolactone under mild reaction conditions. The composition and structure of these nanocatalysts were characterized. It is shown that NiδOx plays a key role in stabilizing Cu+ against inactivation. To meet the requirements for industrial application, the CuNiδOx/SiO2 nanocatalysts were tested under continuous reaction for over 2000 hours. The conversion and product selectivity were maintained at 100% and above 95%, respectively.
Zhu, Junhua,Tang, Yi,Tang, Kangjian
p. 87294 - 87298
(2016/10/06)

Supported copper catalysts for highly efficient hydrogenation of biomass-derived levulinic acid and γ-valerolactone
Levulinic acid (LA) is one of the most significant cellulose-derived compounds. γ-Valerolactone (GVL) and 1,4-pentanediol (1,4-PDO) are considered to be important chemical intermediates. Direct conversion of LA to GVL and GVL to 1,4-PDO was achieved via chemoselective hydrogenation by supported copper catalysts. We studied the transformation of LA to GVL in water and alcohol, and the pathway of the reaction was also studied. LA was converted to GVL catalyzed by the Cu (30%)-WO3 (10%)/ZrO2-CP-300 catalyst at 413 K in ethanol with 81% yield, while 84% GVL was obtained with the Cu (30%)/ZrO2-OG-300 catalyst in water at 393 K. Furthermore, 1,4-PDO was produced from GVL in excellent selectivities (>90%) using the Cu-TiO2/ZrO2-CP-600 catalyst.
Xu, Qing,Li, Xinglong,Pan, Tao,Yu, Chuguo,Deng, Jin,Guo, Qingxiang,Fu, Yao
p. 1287 - 1294
(2016/03/09)

HUMAN HELICASE DDX3 INHIBITORS AS THERAPEUTIC AGENTS
The present invention refers to compounds endowed with RNA helicase DDX3 inhibitory activity of formula I and II and their therapeutic use, in particular for the treatment of viral diseases.
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(2016/09/22)

An improved solvent-free system for the microwave-assisted decarboxylation of malonate derivatives based on the use of imidazole
A comparative study of the thermal and microwave-assisted decarboxylation of a series of mono- and disubstituted monohydrolyzed malonate derivatives has been carried out. It has been found out that in both circumstances the use of imidazole has a profound effect on the success of the reaction. In general terms the assistance of microwave irradiation accelerates the decarboxylation process significantly and, at the same time, permits the use of minored temperatures with respect to the thermal via. It has been also found that both the thermal and the microwave-assisted transformation can be developed under solvent-free conditions.
Tellitu, Imanol,Beitia, Itziar,Díaz, Marta,Alonso, Argi?e,Moreno, Isabel,Domínguez, Esther
p. 8251 - 8255
(2015/10/05)

Reactivity of mixed organozinc and mixed organocopper reagents: 12. Three component reaction of mixed (n-alkyl)(diaryl)zincates, chloroformates and phosphines for the synthesis of esters
The reaction of mixed n-butyldiphenylzincate, n-BuPh2ZnMgBr with ethyl chloroformate, ClCOOEt in the presence n-Bu3P in THF takes place with quantitative yield and phenyl group transfer to give PhCOOEt. Ethoxycarbonylation of n-BuPh2ZnMgBr is preferable to the reaction of PhMgBr forming ester and triphenylcarbinol and also to the reaction of triphenylzincate, Ph3ZnMgBr for atom economy. Group selectivity in the phosphine catalyzed C-COOR coupling of n-BuPh2ZnMgBr and n-Bu2PhZnMgBr can be controlled by changing reaction parameters. n-Bu3P catalyzed reaction of n-BuPh2ZnMgBr with ClCOOEt takes place with phenyl selectivity whereas reaction of n-Bu2PhZnMgBr with ClCOOPh results in n-butyl transfer. Catalysis by Ph3P increases n-butyl group:phenyl group transfer ratio in the ethoxycarbonylation of both zincates. Selective transfer of aryl groups in n-Bu3P catalyzed reaction of n-butyl(aryl)2ZnMgBr reagents with ClCOOEt in THF provides a new procedure for the organometallic synthesis of arenecarboxylic acid ethyl esters at room temperature.
?zkan, Duygu,Erdik, Ender
p. 75 - 81
(2015/10/05)

Transfer hydrogenation of alkenes using Ni/Ru/Pt/Au heteroquatermetallic nanoparticle catalysts: Sequential cooperation of multiple nano-metal species
Quatermetallic alloy nanoparticles of Ni/Ru/Pt/Au were prepared and found to promote the catalytic transfer hydrogenation of non-activated alkenes bearing conjugating units (e.g., 4-phenyl-1-butene) with 2-propanol, where the composition metals, Ni, Ru, Pt, and Au, act cooperatively to provide significant catalytic ability. This journal is
Ito, Yoshikazu,Ohta, Hidetoshi,Yamada, Yoichi M. A.,Enoki, Toshiaki,Uozumi, Yasuhiro
supporting information
p. 12123 - 12126
(2015/02/19)

Stabilization of cobalt catalysts by embedment for efficient production of valeric biofuel
We herein report, for the first time, a bifunctional base-metal catalyst (Co@HZSM-5) that acts as an efficient alternative to noble-metal catalysts (e.g., Pt, Ru) for the conversion of levulinic acid into valeric biofuel under batch and fixed-bed reactor conditions. The cobalt nanoparticles were embedded in HZSM-5 crystals and catalyzed the sequential hydrogenations of the ketone and alkene functional groups; meanwhile, the acidic zeolite catalyzed the ring opening of the γ-valerolactone intermediate. Although base metals (e.g., Co) are abundant and inexpensive, their sintering and/or leaching under liquid-phase conditions always lead to the irreversible deactivation of the catalyst. In this system, the embedment structure stabilizes the nanoparticles, and Co@HZSM-5 could be used up to eight times. This work provides a practical clue toward the stabilization of base-metal catalysts and will inspire the development of large-scale biorefinery.
Sun, Peng,Gao, Guang,Zhao, Zelun,Xia, Chungu,Li, Fuwei
p. 4136 - 4142
(2015/02/19)

Catalytic functionalization of methane and light alkanes in supercritical carbon dioxide
The development of catalytic methods for the effective functionalization of methane yet remains a challenge. The best system known to date is the so-called Catalytica Process based on the use of platinum catalysts to convert methane into methyl bisulfate with a TOF rate of 10-3 s. In this contribution, we report a series of silver complexes containing perfluorinated tris(indazolyl)borate ligands that catalyze the functionalization of methane into ethyl propionate upon reaction with ethyl diazoacetate (EDA) by using supercritical carbon dioxide (scCO2) as the reaction medium. The employment of this reaction medium has also allowed the functionalization of ethane, propane, butane, and isobutane.
Fuentes, M. Angeles,Olmos, Andrea,Caballero, Ana,Perez, Pedro J.,Munoz, Bianca K.,Jacob, Kane,Etienne, Michel,Gonzalez-Nunez, M. Elena,Mello, Rossella,Asensio, Gregorio
supporting information
p. 11013 - 11018,6
(2015/01/07)

Hydrogenation of γ-valerolactone in ethanol over Pd nanoparticles supported on sulfonic acid functionalized MIL-101
A ligand-based solid solution approach is employed to incorporate sulphonic acid functional groups into the porous coordination polymer Cr-MIL-101. Loaded with Pd nanoparticles these Pd/MIL-101-SO3H materials act as bifunctional catalysts for the one-pot conversion of γ-valerolactone into ethyl valerate (up to 83% yield). The catalysts were extensively characterized before and after reaction. The influence of the sulfonic acid group density and the reaction conditions on the catalytic activity was systematically investigated and the reaction network for γ-valerolactone upgrading was discussed.
Zhang, Damin,Ye, Feiyang,Guan, Yejun,Wang, Yimeng,Hensen, Emiel J. M.
p. 39558 - 39564
(2014/12/09)

Selective hydrogenation of levulinic acid to valeric acid and valeric biofuels by a Pt/HMFI catalyst
We describe one-pot high-yield catalytic pathways for the conversion of levulinic acid (LA) to valeric acid (VA) or valeric acid esters (so-called valeric biofuels) under relatively mild conditions (2 or 8 bar H2, 200 °C). A thorough screening study reveals that a HMFI zeolite-supported Pt metal cluster (Pt/HMFI) with an average cluster size of 1.9 nm shows the highest yield of VA (99%) under solvent-free conditions. The use of ethanol or methanol as solvent changes the selectivity, resulting in 81-84% yields of ethyl valerate (EV) or methyl valerate (MV). Pt/HMFI is also effective for selective formation of valeric acid esters from γVL in alcohols under H2. Kinetics, in situ infrared (IR), and acidity-activity relationship studies show a cooperative mechanism of Pt and Bronsted acid sites of HMFI. VA formation from LA can be driven by Pt-catalyzed hydrogenation of LA to γVL, which undergoes proton-assisted ring-opening by HMFI, followed by Pt-catalyzed hydrogenation. Valeric ester formation from LA is driven by esterification of LA to levulinic ester, which is hydrogenated by Pt. the Partner Organisations 2014.
Kon, Kenichi,Onodera, Wataru,Shimizu, Ken-Ichi
p. 3227 - 3234
(2014/08/18)

IMMUNOASSAY FOR CYCLOPROPYLINDOLE BASED SYNTHETIC CANNABINOIDS, METABOLITES AND DERIVATIVES THEREOF
The invention relates to the detection and quantification of cyclopropylindole based synthetic cannabinoids UR-144 and XLR-11 by providing antibodies based on novel immunogens. These antibodies can be incorporated into methods and kits for the detection of UR-144, XLR-11 and their metabolites.
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(2014/09/30)

Enhanced hydrogenation of ethyl levulinate by Pd-AC doped with Nb 2O5
Gamma-valerolactone (GVL), as sustainable feedstock for high-value chemicals and fuel, has been produced by hydrogenation of levulinic acid (LA) or ethyl levulinate (EL). In this work, Pd nanoparticles supported on Nb 2O5-doped activated carbon (AC) were prepared via wet incipient impregnation with PdCl2 followed by reduction with NaBH4. The dispersed niobia plays a bifunctional role in the catalytic process: stabilizing Pd nanoparticles and acting as an acidic co-catalyst. This synergistic effect between niobia and Pd leads to an unprecedented high activity of supported Pd catalysts in EL hydrogenation. The synergy is correlated with both the niobia loading and calcination temperature, with 10 wt% Nb2O5 calcined at 500 °C showing the best performance (EL conversion of 87% and GVL selectivity of 97%) under mild reaction conditions (100 °C and 0.5 MPa H2). This journal is the Partner Organisations 2014.
Ye, Feiyang,Zhang, Damin,Xue, Teng,Wang, Yimeng,Guan, Yejun
p. 3951 - 3957
(2014/08/05)

Catalytic conversion of biomass-derived levulinic acid to valerate esters as oxygenated fuels using supported ruthenium catalysts
The development of the catalytic conversion of biomass-based platform molecules into oxygenated fuel molecules is of great significance in order to reduce the dependence on fossil resources and to solve environmental problems. Alkyl valerate esters were proven to have the potential to be renewable additives of gasoline and diesel. In this work, we studied the hydrogenation of levulinic acid (LA) to valerate esters over supported Ru catalysts, and found that the acidity was an important factor for the catalyst performance. A bifunctional catalyst Ru/SBA-SO3H was developed as an active catalyst, and a highest yield of 94% to ethyl valerate (EV) was achieved. The catalyst was characterized by nitrogen adsorption/desorption methods, X-ray power diffraction (XRD), transmission electron spectroscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The effects of reaction conditions were comprehensively investigated and probable reaction pathways were proposed and verified. The conversion of LA to various alkyl valerate esters can also be catalyzed by the bifunctional catalyst. In addition, supported Cu and Ni catalysts were also screened under similar reaction conditions as Ru-based catalysts, and the combination of Ni/SBA-15 and SBA-SO3H exhibited activity for the conversion of LA to EV.
Pan, Tao,Deng, Jin,Xu, Qing,Xu, Yang,Guo, Qing-Xiang,Fu, Yao
p. 2967 - 2974
(2013/10/08)

VO(acac)2: An efficient catalyst for the oxidation of aldehydes to the corresponding acids in the presence of aqueous H2O2
VO(acac)2 catalyzes the oxidation of aldehydes (aromatic, aliphatic, and heterocyclic) to the corresponding acids efficiently and selectively in the presence of H2O2 as an oxidant. This method possesses functional-group compatibility, easy workup procedure, and shorter reaction time. The reaction is highly dependent on the solvent used. Performance of titania-supported VO(acac)2 in the oxidation of aldehyde was also investigated. Georg Thieme Verlag Stuttgart . New York.
Talukdar, Dhrubajyoti,Sharma, Kiran,Bharadwaj, Saitanya K.,Thakur, Ashim Jyoti
p. 963 - 966
(2013/06/27)

New generation biofuels: γ-Valerolactone into valeric esters in one pot
Ethyl valerate and pentyl valerate, suitable as a gasoline additive and diesel component respectively, can be obtained in a one pot one step reaction from γ-valerolactone, readily available from lignocellulosic biomass. The reaction takes place in ethanol under H2 through nucleophilic addition of the alcohol to the carboxylic group giving hydroxypentanoate, dehydration to pentenoate and hydrogenation to the saturated ester. The bifunctional catalyst used consists of a non noble metal, namely copper, supported on an amorphous weakly acidic material, therefore representing an interesting alternative to Pt-zeolite catalysts. Pentyl valerate can be obtained in one pot with conversions >90% and selectivity up to 83%.
Chan-Thaw, Carine E.,Marelli, Marcello,Psaro, Rinaldo,Ravasio, Nicoletta,Zaccheria, Federica
p. 1302 - 1306
(2013/03/29)

METHOD FOR CONTINUOUSLY PREPARING CARBOXYLIC ACID ESTER
A method for continuously preparing a carboxylic acid ester is disclosed. In the method of the present invention, a vertical reactor is filled with a solid catalyst, a carboxylic acid and an alcohol are introduced into a lower part of the vertical reactor, esterification is performed to form an esterized mixture, the esterized mixture is output from an upper part of the vertical reactor, and distillation is performed to isolate the carboxylic acid ester. The method of the present invention is simple, easily controlled and environmental friendly, and has significantly high conversion rate and selectivity.
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Paragraph 0024; 0026

(2013/11/19)

Etherification of 5-hydroxymethyl-2-furfural (HMF) with ethanol to biodiesel components using mesoporous solid acidic catalysts
The etherification of 5-hydroxymethyl-2-furfural (HMF) with ethanol is studied over a series of mesoporous silica catalysts (Al-MCM-41 materials with different Si/Al ratio, and zirconia or sulfated zirconia supported over SBA-15) and compared with the behavior of H2SO4 and Amberlyst15. The observed reaction products were 5-(ethoxymethyl)furan-2- carbaldehyde (EMF), 1,1-dietoxy ethane (DE) and ethyl 4-oxopentanoate (EOP). The selectivity to EMF and EOP is closely related to the presence of Lewis and/or Br?nsted acidity on the catalyst, while the formation of DE is probably related to defect sites. The latter, being less reactive, catalyze the side reaction to DE only when strong Lewis and/or Br?nsted acid sites are absent. Catalysts with only a strong Br?nsted acidity react selectively to form EOP. When strong Lewis acid sites are present in the catalyst, e.g. by introducing ZrO2 in SBA-15 or when extra-framework isolated Al 3+ sites are present in the mesoporous channels, a high selectivity to EMF was observed. The results indicate that EMF, DE or EOP can be obtained selectively by direct reaction of HMF with bioethanol by tuning the acidity of the catalyst. EMF is a value biodiesel component, but the results also evidence the possibility to obtain selectively EOP in a one-step reaction, opening interesting perspectives to produce valeric biofuels by subsequent selective hydrogenation.
Lanzafame,Temi,Perathoner,Centi,MacArio,Aloise,Giordano
p. 435 - 441
(2012/06/04)

Covalent immobilization of lipase onto amine functionalized polypropylene membrane and its application in green apple flavor (ethyl valerate) synthesis
In this study, a functionalized hydrophobic polypropylene chloride membrane (PPC) was prepared by the amination of chlorinated polypropylene with hexamethylene diamine (APP). The PPC and APP membranes were characterized using SEM, FTIR and contact angle studies. The aminated polypropylene (APP) membrane was used for covalent immobilization of Candida rugosa lipase via glutaraldehyde coupling. The retained activity of the immobilized lipase was 76%. Kinetic analysis shows that the dependence of lipolytic activity of both free and immobilized lipase on tributyrin substrate concentration can be described by Michaelis-Menten model. The estimated apparent Km values for the free and immobilized lipase were 2.9 and 8.4 mM, respectively. The Vmax values of free and immobilized enzymes were calculated as 926 and 741 U/mg enzyme, respectively. Optimal temperature was 5 °C higher for immobilized enzyme than that of the free enzyme. Thermal and storage stabilities were found to be increased upon immobilization. Finally, the immobilized lipase was used for the production of green apple flavor (i.e., ethyl valerate) in hexane medium.
Bayramo?lu, Gülay,Hazer, Baki,Altinta?, Begum,Arica, M. Yakup
experimental part
p. 372 - 378
(2011/08/09)

Synthesis of short chain alkyl esters using cutinase from Burkholderia cepacia NRRL B2320
Short chain alkyl esters are well appreciated for fruity flavors they provide. These are mainly applied to the fruit-flavored products like jam, jelly, beverages, wine and dairy. Cutinase from Burkholderia cepacia NRRL B 2320 was found to be active in catalyzing the synthesis of alkyl esters in organic solvent. The optimal temperature range for the enzyme catalyzed synthesis was found to be from 35 °C to 40 °C. The maximum conversion (%) during synthesis of ester was obtained for butyric acid (C4) and valeric acid (C5) with butanol reflecting the specificity of the enzyme for short-chain length fatty acids. In case of alcohol specificity, butanol was found to be most preferred substrate by the enzyme and conversion (%) decreased with increasing carbon chain length of alcohol used in the esterification reaction. The kinetic analysis for the synthesis of butyl butyrate by varying concentration of one substrate at a time (butanol or butyric acid), showed that Ping-Pong Bi Bi model with acid inhibition and influence of initial water is most suitable model for the prediction of the reaction kinetics.
Dutta, Kasturi,Dasu, Veeranki Venkata
experimental part
p. 150 - 156
(2012/07/01)

Production of aroma esters by immobilized Candida rugosa and porcine pancreatic lipase into calcium alginate gel
Candida rugosa lipase (CRL) and porcine pancreatic lipase (PPL) were immobilized into calcium alginate (Ca-Alg) gel beads by means of entrapment and were used to produce three industrially important flavour esters, namely isoamyl acetate (banana flavour), ethyl valerate (green apple flavour) and butyl acetate (pineapple flavour). Immobilization conditions were optimized in terms of sodium alginate (Na-Alg) and CaCl2 concentrations by determination of the entrapped enzyme amount as well as by esterification of 4-nitrophenol and acetic acid. The best results were obtained at 2.5% Na-Alg and 2.5 M CaCl2 for CRL while at 2.5% Na-Alg and 2.0 M CaCl2 for PPL. On carrying out flavour syntheses in solvent-free medium and also in hexane medium, higher ester yields were obtained in hexane medium for all esters and both types of lipases. Ester esterification efficiency increased in parallel with both enzyme concentrations at immobilization medium and the immobilized lipase amount in esterification medium. Maximum ester production was observed between 40 and 50 °C for CRL and PPL. Besides, the effect of substrate concentrations on ester conversion was remarkable. The best ester yield was obtained for isoamyl acetate when immobilized PPL was used.
Ozyilmaz, Gul,Gezer, Esra
experimental part
p. 140 - 145
(2010/11/02)

A PROCESS FOR THE HYDROGENATION OF A LACTONE OR OF A CARBOXYLIC ACID OR AN ESTER HAVING A GAMMA-CARBONYL GROUP
The invention provides a process for the hydrogenation of a reactant selected from the group consisting of : (a) a 5- or 6-membered lactone that is substituted at the ring-closing carbon atom and has a proton at a carbon atom adjacent to the ring-closing carbon atom; (b) an ester of a carboxylic acid having a gamma- carbonyl group and a proton at a carbon atom adjacent to the carbon atom of the carbonyl group; and (c) a carboxylic acid having a gamma-carbonyl group and a proton at a carbon atom adjacent to the carbon atom of the carbonyl group, wherein the reactant is contacted with a strongly acidic heterogeneous catalyst comprising a hydrogenating metal, in the presence of hydrogen, at a temperature in the range of from 100 to 350 °C and a pressure in the range of from 1 to 150 bar (absolute). The invention further provides a fuel composition, preferably a diesel composition, comprising di-alkyl 4-methylnonanedioate or di-alkyl 3-ethyl-4-methylheptanedioate.
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(2008/06/13)

Oxidative demetalation of Fischer alkoxy carbene complexes with stoichiometric pyridine N-oxide and NaBH4-promoted demetalation of Fischer iminocarbene complexes with sulfur and selenium
Oxidation of Fischer alkoxy carbene complexes were systematically investigated with stoichiometric pyridine N-oxide (PNO) under mild conditions, forming ester products in good to excellent yields from the corresponding monocarbene complexes. Fischer alkoxy biscarbene complexes efficiently underwent stepwise oxidative demetalation under controlled conditions, resulting in ester-monocarbene and diester products, respectively. This oxidation protocol has demonstrated a generally efficient method to oxidize Fischer alkoxy carbene complexes under mild conditions, providing a new route to novel monocarbene complexes from Fischer biscarbene complexes. In the presence of NaBH4, reactions of Fischer iminocarbene complexes with elemental sulfur or selenium in ethanol at ambient temperature regioselectively afforded thione or selone complexes by insertion of a sulfur or selenium atom into the M{double bond, long}C bonds in Fischer carbene complexes, and metal-free selone was also obtained. The molecular structures of the iminocarbene complexes and selone derivatives were confirmed by X-ray crystallographic study. The NaBH4-promoted demetalation protocol suggests a potential new route to demetalate Fischer aminocarbene complexes.
Zheng, Zhaoyan,Chen, Jinzhu,Yu, Zhengkun,Han, Xiuwen
p. 3679 - 3692
(2007/10/03)

Efficient method for the preparation of carboxylic acid alkyl esters or alkyl phenyl ethers by a new-type of oxidation-reduction condensation using 2,6-dimethyl-1,4-benzoquinone and alkoxydiphenylphosphines
A new-type of oxidation-reduction condensation proceeded smoothly to afford carboxylic acid alkyl esters or alkyl phenyl ethers in good to high yields by combined use of alkoxydiphenylphosphines (1) having primary, bulky secondary or tertiary alkoxy groups, a mild quinone-type oxidant such as 2,6-dimethyl-1,4-benzoquinone (DMBQ) and carboxylic acids or phenols. Generally, alkoxydiphenylphosphines were prepared easily from chlorodiphenylphosphine (2) and alcohols in the presence of pyridine, and were isolated by distillation. On the other hand, the phosphines 1 were also prepared in situ from N,N-dimethylaminodiphenylphosphine (3a) and primary or secondary alcohols while primary, bulky secondary or tertiary alkoxydiphenylphosphines were alternatively formed in situ by adding 2 to the "BuLi-treated alcohols in order to perform the above reactions by a one-pot procedure from alcohols and nucleophiles. The reaction of thus formed 1, DMBQ and carboxylic acids or phenols afforded the corresponding alkylated products, including hindered secondary and tertiary alkylated ones, in good to high yields at room temperature. In the case of using chiral secondary alcohols, the corresponding carboxylic acid alkyl esters were obtained as well in high yields with perfect inversion of stereochemistry by SN2 replacement.
Shintou, Taichi,Kikuchi, Wataru,Mukaiyama, Teruaki
p. 1645 - 1667
(2007/10/03)

Photochemistry of diethynyl sulfides: A cycloaromatization for the formation of five-membered rings
(Matrix presented) The first five-membered ring cycloaromatization reaction has been demonstrated. Photoirradiation of bis(phenylethynyl) sulfide in hexanes/1,4-cyclohexadiene produces 3,4-diphenylthiophene through the presumed intermediacy of 2,5-didehydrothiophene. In addition, phenylacetylene is produced in this reaction consistent with competing direct carbon-sulfur cleavage. For reactions in ethanol or 2-propanol production of the thiophene is accompanied by the formation of phenylacetylene and a thionoester of the corresponding alcohol. Thiophene products also result from the irradiation of other diethynyl sulfides.
Lewis, Kevin D.,Wenzler, David L.,Matzger, Adam J.
p. 2195 - 2197
(2007/10/03)

Structure-function correlation in lipase catalysed esterification reactions of short and medium carbon chain length alcohols and acids
An attempt has been made to correlate the carbon chain lengths of acids and alcohols to the extent of esterification in the Rhizomucor miehei lipase catalyzed esterification reactions involving acids of carbon chain length C2-C5 and alcohols of carbon chain length C1-C8.
Divakar, Soundar
p. 1919 - 1922
(2007/10/03)

A novel PdCl2/ZrO2-SO42- catalyst for synthesis of carbamates by oxidative carbonylation of amines
At 170°C and ca. 4.0 MPa, oxidative carbonylation of aromatic amines to synthesize corresponding carbamates over a novel PdCl2/ZrO2-SO42- catalyst could proceed with high conversion and selectivity.
Shi, Feng,Deng, Youquan,SiMa, Tianlong,Yang, Hongzhou
p. 525 - 528
(2007/10/03)

A mild method for protodesilylation of α-dimethylphenylsilyl ester substrates
Mild conditions (1.2 eq. Hg(OAc)2, 1.2 eq. TBAF in 1:1 MeOH/THF; 35 min at 0 °C) have been developed for the protodesilylation of α- dimethylphenylsilyl esters. An enolate-dependent mechanism for the reaction was supported through studies indicating the clean incorporation of deuterium. To further investigate the mechanism, the optimal conditions as well as the kinetics of the reaction were explored.
Poliskie, G. Michelle,Mader, Mary M.,Van Well, Renate
p. 589 - 592
(2007/10/03)

Mild hydrolysis or alcoholysis of amides. Ti(IV) catalyzed conversion of primary carboxamides to carboxylic acids or esters
Reaction of primary amides (e.g., 1a or 6-13) or O-methylhydroxamates (1b and 1c) with a catalytic amount of TiCI4 and one equivalent of aqueous HCI converts these compounds in good yields to carboxylic esters (when an alcohol is used as solvent) or to carboxylic acids (when 9:1 dioxane:H2O is used as solvent). These conversions are chemoselective for primary amides: mono- and dialkyl amides are not affected by the reaction conditions. The hydrolysis conditions described do not compromise the stereochemical integrity of an adjacent chiral center. This is exemplified by the hydrolysis of naproxen amide (34) to naproxen (33) without detectable racemization as determined by chiral HPLC.
Fisher,Caroon,Stabler,Lundberg,Zaidi,Sorensen,Sparacino,Muchowski
p. 142 - 145
(2007/10/02)

Mild, one-pot conversion of carboxylic acids into esters using phase transfer catalysis
One-pot conversion of carboxylic acids into esters under the influence of phase transfer catalysis is reported.The method is shown to work satisfactorily for optically active acids having epimerisable α-hydrogen.
Puntambekar, Hemalata M,Naik, D G,Kapadi, A H
p. 793 - 794
(2007/10/02)