- A potential “green” organotin: Bis-(methylthiopropyl)tin dichloride, [MeS (CH2)3]2SnCl2
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The tetravalent organotin compound [MeS(CH2)3]2SnCl2, 1, has been synthesized in high yield and structurally characterized as being hexa-coordinate at tin with two intramolecular Sn-S bonds. The specific structure has been shown by theoretical calculations to be the low energy geometric structure available, and the differences associated with the experimental and calculated Sn-S bond lengths ascribed to crystal packing issues. The intramolecular Sn-S bonding produces a benign organotin compound with respect to its interactions with human natural killer cells; however, this blocking of coordination sites at Sn does not reduce its capacity to act as an efficient esterification catalyst.
- Vargas, Diana Gabriela,Metta-Maga?a, Alejandro,Sharma, Hemant K.,Whalen, Margaret M.,Gilbert, Thomas M.,Pannell, Keith H.
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p. 125 - 130
(2017/09/30)
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- Deep eutectic solvent choline chloride·2CrCl3·6H2O: An efficient catalyst for esterification of formic and acetic acid at room temperature
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A highly efficient and selective method for esterification of formic and acetic acid with alcohols has been achieved at room temperature, with the choline chloride (ChCl)/chromium(iii) chloride hexahydrate (CrCl3·6H2O) deep eutectic solvent as a catalyst. High yields and good selectivities of organic esters are obtained using DES [ChCl][CrCl3·6H2O]2 with the molar ratio 5:1 (carboxylic acids:alcohols) at room temperature in 24 h. The ease of recovery and reusability of DES with high catalytic activity makes this method efficient and practical.
- Cao, Jin,Qi, Bin,Liu, Jun,Shang, Yuhan,Liu, Huiwen,Wang, Wenjing,Lv, Jia,Chen, Zhiyan,Zhang, Haibo,Zhou, Xiaohai
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p. 21612 - 21616
(2016/03/08)
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- A method for esterification reaction rate prediction of aliphatic monocarboxylic acids with primary alcohols in 1,4-dioxane based on two parametrical taft equation
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Esterification reaction rates of aliphatic monocarboxylic acids with primary alcohols in 1,4-dioxane as inert solvent were investigated. Acids were esterified with 1-propanol and alcohols with acetic acid as model reactants at a constant temperature of 60°C, at a fixed ionic strength and pH in a batch reactor with a constant volume. For evaluation of reaction rates, an exact kinetic equation for the equilibrium reaction was applied. Under these conditions and for low reactants, concentrations reaction rate depends only on the structure of reactants and, therefore, can be predicted by a correlation equation with two Taft coefficients (inductive and steric effects). From these equations, it is possible to estimate the esterification reaction rate constant for other acid-alcohol pairs. This methodology may also be suitable for other kinetic systems measured under comparable experimental conditions.
- Vojtko, Jan,Tomcik, Peter
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p. 189 - 196
(2014/02/14)
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- Chemoselective palladium-catalyzed oxidation of vinyl ether to acetate using hydrogen peroxide
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A practical and environmental-friendly method was developed to convert vinyl ether into acetate by using a palladium complex with phosphine ligand and hydrogen peroxide. The only by-product is water. Chemoselective oxidation of vinyl ether and tert-enamides to form acetate and N-acetyl amide with hydrogen peroxide in the presence of palladium complex having phosphine ligand was developed under mild reaction conditions. This process is environmentally friendly because it uses hydrogen peroxide as a clean oxidant, with water being the only byprocuct.
- Kon, Yoshihiro,Tanaka, Shinji,Nakashima, Takuya,Sato, Kazuhiko,Shimada, Hiromichi
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p. 749 - 756
(2014/07/22)
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- Synthesis of acyloxyalkyl esters of thiocarbonic and dithiocarbamic acids
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Reactions of acyloxyalkyl chloride with alkaline salts of alkylxanthic, butyltrithiocarbonic, and diethyldithiocarbamic acids afforded a series of acyloxyalkyl esters of various nature and positions of the acyl groups in the molecule.
- Mustafaev,Kulieva,Mustafaev,Kulibekova,Kakhramanova,Safarova,Novotorzhina
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p. 198 - 203
(2013/07/25)
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- Palladium-catalyzed oxidation of vinyl ether to acetate with hydrogen peroxide
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The selective hydrogen peroxide oxidation of vinyl ethers to give acetates was developed using triphenylphosphine palladium and triethyl amine catalysts under mild reaction conditions.
- Kon, Yoshihiro,Chishiro, Takefumi,Imao, Daisuke,Nakashima, Takuya,Nagamine, Takashi,Hachiya, Houjin,Sato, Kazuhiko
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supporting information; experimental part
p. 6739 - 6742
(2011/12/22)
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- Hydrogen-bond interactions of nicotine and acetylcholine salts: A combined crystallographic, spectroscopic, thermodynamic and theoretical study
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The hydrogen-bond (HB) interactions of the monocharged active forms of nicotine and acetylcholine (ACh) have been compared theoretically by using density functional theory (DFT) calculations and experimentally on the basis of crystallographic observations and the measurement of equilibrium constants in solution. The 2,4,6-trinitrophenolate (picrate) counterion was used to determine the experimental HB basicity of the cations despite its potential multisite HB acceptor properties. The preferred HB interaction site of the ammonium picrate salts was determined from a survey of crystallographic data found in the Cambridge Structural Database (CSD) and is supported by theoretical calculations. Two distinct classes of ammonium groups were characterised depending on the absence (quaternary ammonium) or presence (tertiary, secondary and primary ammoniums) of an N+ H...O hydrogen bond linking the two ions. The crystal structure of nicotinium picrate was determined and compared with that of ACh. This analysis revealed the peculiar behaviour of the ammonium moiety of nicotinic acetylcholine receptor (nAChR) ligands towards the picrate anion. Dedicated methods have been developed to separate the individual contributions of the anion and cation accepting sites to the overall HB basicity of the ion pairs measured in solution. The HB basicities of the picrate anions associated with the two different ammonium classes were determined in dichloromethane solution by using several model ion pairs with non-basic ammonium cations. The experimental and theoretical studies performed on the nicotine and ACh cations consistently show the significant HB ability of the acceptor site of nAChR agonists in their charged form. Both the greater HB basicity of the pyridinic nitrogen over the carbonyl oxygen and the greater HB acidity of the N+H unit relative to N+CH could contribute to the higher affinity for nAChRs of nicotine-like ligands relative to ACh-like ligands.
- Arnaud, Virginie,Berthelot, Michel,Evain, Michel,Graton, Jerome,Questel, Jean-Yves Le
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p. 1499 - 1510
(2008/02/04)
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- Compound, retardation plate and method for forming optically anisotropic layer
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A retardation plate having a high film strength and having an optical property is provided by using a biaxial liquid crystal compound, in which the direction having a minimum refractive index of the optically anisotropic thin layer almost coincides with the normal direction in the film plane of the retardation plate, and the retardation plate comprises a transparent support and at least one optically anisotropic layer containing a liquid crystal compound capable of expressing a biaxial liquid crystal phase, wherein the liquid crystal compound is a polymerizable compound and/or a polymer compound.
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- CONVERSION OF A MULTIHYDROXYLATED-ALIPHATIC HYDROCARBON OR ESTER THEREOF TO A CHLOROHYDRIN
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The present invention relates to a process for converting a multihydroxylated-aliphatic hydrocarbon or ester thereof to a chlorohydrin, by contacting the multihydroxylated-aliphatic hydrocarbon or ester thereof starting material with a source of a superatmospheric partial pressure of hydrogen chloride for a sufficient time and at a sufficient temperature, and wherein such contracting step is carried out without substantial removal of water, to produce the desired chlorohydrin product; wherein the desired product or products can be made in high yield without substantial formation of undesired overchlorinated byproducts. In addition, certain catalysts of the present invention may be used in the present process at superatmospheric, atmospheric and subatmospheric pressure conditions with improved results.
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Page/Page column 37-38
(2008/06/13)
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- P2O5 / SiO2 as a mild and efficient reagent for acylation of alcohols, phenols and amines under solvent-free conditions
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P2O5 / SiO2 is a highly efficient reagent for the acetylations of a variety of alcohols, phenols and amines with acetic anhydride under solvent-free conditions. Primary, secondary, allylic and benzylic alcohols, diols and phenols with electron-donating or withdrawing substituents can be easily acetylated in good to excellent yield.
- Eshghi, Hossein,Shafieyoon, Parvaneh
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p. 802 - 805
(2007/10/03)
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- Acyl iodides in organic synthesis: I. Reactions with alcohols
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Reaction of acyl iodides RC(O)I (R = Me, Ph) with alcohols R′OH (R′ = Me, Et, i-Pr, t-Bu, CH2= CHCH2, HC≡CCH2) provides in the corresponding organyl iodides R′I. Unlike that 2-chloroethanol and phenol (R′ = CH 2CH2Cl, Ph) react with RC(O)I in the same way as with acyl chlorides yielding esters RCO2R′. This reaction path occurs partially also with methanol and ethanol.
- Voronkov,Trukhina,Vlasova
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p. 1576 - 1578
(2007/10/03)
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- FeCl3-adsorbed on montmorillonite K-10: An efficient catalyst for one-pot dealkylation-acetylation of ethers
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Direct conversion of ethers into acetates is achieved by treatment of ethers with acetic anhydride in the presence of FeCl3-adsorbed on montmorillonite K-10.
- Lakouraj, Mansour,Movassagh, B.,Fasihi, J.
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p. 378 - 379
(2007/10/03)
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- Indium triiodide catalysed one-step conversion of tetrahydropyranyl ethers to acetates with high selectivity
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Chemoselective one-step conversion of tetrahydropyranyl ethers of primary alcohols to corresponding acetates was carried out. The reaction occurred through an indium triiodide catalyzed transesterification process in ethyl acetate. The method provided advantages such as operational simplicity, acceptable reaction conditions to acid-sensitive functional groups and good yield.
- Ranu, Brindaban C.,Hajra, Alakananda
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p. 355 - 357
(2007/10/03)
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- Highly selective one-pot conversion of THP and MOM ethers to acetates by indium triiodide-catalysed deprotection and subsequent transesterification by ethyl acetate
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The chemoselective one-pot conversion of tetrahydropyranyl (THP) and methoxymethyl (MOM) ethers of primary alcohols to the corresponding acetates was presented. It was done using indium triiodide-catalysed deprotection and subsequent acetylation by ethyl acetate through a transesterification process. The advantages offered by the method included operational simplicity, 'green' methodology involving no toxic or hazardous chemicals and high yield.
- Ranu, Brindaban C.,Hajra, Alakananda
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p. 2262 - 2265
(2007/10/03)
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- Kinetics and mechanism of oxidation of aliphatic acetals with peroxomonosulphate
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The oxidation of fifteen aliphatic acetals of normal aliphatic aldehydes and substituted aliphatic aldehydes with aliphatic and substituted aliphatic as well as with aromatic alcohols by peroxomonosulphate in aqueous acetic acid medium is first order each in [oxidant] and [acetal] and yields the corresponding esters as the main product. The oxidation reaction is independent of change in dielectric constant of the medium. The activation enthalpies and entropies of the reactions are linearly related. A mechanism involving hydride ion shift is proposed.
- Janakiram,Venkataraman,Basheer Ahamed
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p. 339 - 341
(2007/10/03)
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- Reactions of 1,3-dioxolanes with Iodine Monochloride: Formation of Chlorohydrin Esters and Diol Monoesters
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2-Mono-substituted 1,3-dioxolanes are oxidised by iodine monochloride to the appropriate 2-substituted 1,3-dioxolan-2-ylium ions, whose stability is dependent upon the presence and nature of substituents on C-4 and C-5.Some dioxolanylium ions are labile and under the reaction conditions afford chlorohydrin esters, with inversion of configuration taking place at the ring carbon attacked by chloride.Others are stable under the reaction conditions and may be converted on aqueous workup to diol monoesters with retention of configuration at C-4 and C-5.The effect of substituents and reaction conditions on these competing reactions are described.The stereo- and regio-chemistry of both hydroxy- and chloro-ester formation was confirmed through NMR studies, which necessitated the prior detailed analysis of the 1H and 13C spectra associated with the acyloxy sidechains of the relevant esters.
- Glass, Beverley D.,Goosen, Andre,McCleland, Cedric W.
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p. 2175 - 2182
(2007/10/02)
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- Experimental evidence for AcO-7 neighboring group participation
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The reaction of diol diacetates with anhydrous aluminium chloride at ca 100° leads to displacement of only one of the acetoxy groups by chlorine. An oxygen-18 label study has shown that these displacements take place via acetoxonium intermediates and has provided direct evidence for the intervention of a seven-membered ring acetoxonium ion in the displacement of acetate by chlorine in 1,4-butanediol diacetate.
- Wilen, Samuel H.,Delguzzo, Luciano,Saferstein, Richard
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p. 5089 - 5094
(2007/10/02)
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- Novel omega-(N-imidazolyl)alkyl ethers of 1,2,3,5-tetrahydroimidazo[2,1-b]quinazolin-2-ones
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Novel compound wherein n is an integer of 1 to 8; R1 is hydrogen or alkyl of 1-6 carbons; R2 is hydrogen; R3 is hydrogen, alkyl of 1-6 carbons, phenyl, benzyl, hydroxy lower alkyl, carbamoyl alkyl, carboxyalkyl, alkoxycarbonylalkyl; R4 is hydrogen, alkyl of 1-6 carbons, benzyl, or hydroxy lower alkyl; Y is hydrogen, alkyl of 1 to 4 carbon atoms, halo or lower alkoxy; any of its optical isomers, the mixture thereof, or the pharmaceutically acceptable acid addition salt. These compounds are inhibitors of thromboxane synthetase and cyclic AMP phosphodiesterase and are therefore potential cardiovascular agents particularly useful as platelet aggregation inhibitors and anti-thrombotic agents. Accordingly, these compounds will preferably be useful in treating cardiovascular disorders with thrombotic complications. However, they also possess vasodilatory, antisecretory, antihypertensive, inotropic and antimetastatic activities.
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- Effects of Volume and Surface Property in Hydrolysis by Acetylcholinesterase. The Trimethyl Site
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β-Substituted ethyl acetates, XCH2CH2OCOCH3, have been prepared, and their hydrolysis by acetylcholinesterase has been studied.Log of enzymic reactivity, normalized for intrinsic reactivity in hydrolysis by hydroxide, log(kcat/Km)n, rises linearly with increasing refraction volume, MR (or RD25), for substrates with β-X = H, Cl, Br, CH3CH2, (CH3)2CH, (CH3)2S+, (CH3)3N+, and (CH3)3C.Larger substituents may by accommodated, (CH3)3Si and (CH3CH2)3N+, with no further increase in rate.Substrates with β-substituents CH3S, CH3S(O), (CH3)3N+(OH), and CH3S(O2) are less reactive than consistent with the relation with MR by factors of 5-40, indicating that hydrophobic surface and desolvation of the substrate-enzyme interface may be necessary for maximum reactivity correlated with MR.Values of log (kcat/Km)n for substrates with β-substituents X = CH3S, Cl, Br, CH3CH2, (CH3)2CH, (CH3)3C, and (CH3)3Si rise linearly with increasing hydrophobicity, ?, but reactivity of substrates with X = (CH3)3N+ and (CH3)2S+ are more reactive than consistent with a relation to ? by factors of 300 and 40 and with X = CH3S(O2), CH3S(O), and (CH3)2N+(OH), by factors of 7-100.Reactivity appears related to (i) volume of the β-substituent and its fit in its subsite, which is trimethyl rather than anionic, and (ii) the hydrophobicity of its surface.
- Cohen, Saul G.,Elkind, Jerome L.,Chishti, S. Bano,Giner, Jose-L. P.,Reese, Heide,Cohen, Jonathan B.
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p. 1643 - 1647
(2007/10/02)
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- Chlorination of Carboxylic Acid Derivatives. IX. Liquid Phase Chlorination of Aliphatic C2-C8 Alkyl Acetates. EI Mass Spectra of Monochlorinated Esters
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A series of aliphatic alkyl acetates from ethyl to octyl acetate was chlorinated in the liquid phase in order to obtain monochlorinated products.The chlorination of esters was carried out with chlorine in the liquid phase in the absence and in the presence of benzene and with sulfuryl chloride in the presence of Bz2O2.The products were determined by gas-liquid chromatography and gas-liquid chromatography-mass spectrometry.Chlorination is appreciably deactivated at the 1-position, particularly with SO2Cl2, the deactivation at the 2-position being strongest with Cl2 in the presence of benzene.The amounts of 1-chloro and ω-chloro isomers constituted the greatest disparity between the chlorination methods.The most characteristic mass spectral fragment ions of the 35 chlorinated alkyl acetates are given.
- Korhonen, Ilpo O. O.
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- HOMOGENEOUS-CATALYTIC REACTIONS OF ALKENES. INVESTIGATION OF THE MECHANISM OF ACETOXYLATION OF ETHYLENE
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The formation of ethylene glycol monoacetate in acetic acid containing PdCl4(2-) ions takes place through catalytic acetoxylation of ethylene.A binuclear ? complex of the olefin and palladium is formed preferentially in the initial chemical event and then isomerizes under the influence of the nucleophile (O2, ONO-) to a ?-organometallic compound.In the latter the Pd-C bond undergoes heterolytic cleavage, and the final product is formed with the participation of water molecules.The ethylene glycol and its diacetate obtained in the reaction are the products from secondary transformations of ethylene glycol monoacetate.Acyloxylation a lso occurs when other alkenes and carboxylic acids are used.The reduction in the rate and the cessation of the oxidation of the olefins are due accordingly to the screening of the coordination sphere of palladium in the intermediate compounds by the glycol esters with subsequent displacement of the alkene from the ? complex.
- Devekki, A. V.,Koshelev, Yu. N.,Mushenko, D. V.
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p. 2148 - 2154
(2007/10/02)
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