- Study on Gas-phase mechanism of chloroacetic acid synthesis by catalysis and chlorination of acetic acid
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The process of acetic acid catalysis and chlorination for synthesizing chloroacetic acid can exist in not only gas phase but also liquid phase. In this paper, the gas-phase reaction mechanism of the synthesis of chloroacetic acid was studied. Due to the high concentration of acetic acid and the better reaction mass transfer in the liquid-phase reaction, the generation amount of the dichloroacetic acid was higher than that in the gas-phase reaction. Under the solution distillation, the concentration of acetyl chloride, whose boiling point is very low, was very high in the gas phase, sometimes even up to 99 %, which would cause the acetyl chloride to escape rapidly with the hydrogen chloride exhaust, so that the reaction slowed down. Therefore, series reactions occured easily in the gas-phase reaction causing the amount of the dichloroacetic acid to increase.
- Xue, Jian-Wei,Zhang, Jian-Peng,Wu, Bo,Li, Fu-Xiang,Lv, Zhi-Ping
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Read Online
- Synthesis of monochloroacetic acid from ethylene chlorohydrin
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The possibility of preparing monochloroacetic acid by oxidation of ethylene chlorohydrin with nitric acid was examined.
- Svetlakov,Nikitin,Nikolaeva
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Read Online
- Microwave synthesis of chloroacetic acid with various cocatalysts in acetic anhydride catalyzing method
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In this paper, we introduce a method of synthesizing chloroacetic acid using acetyl chloride as catalyst and anhydrous ferric chloride, ferric chloride hexahydrate, zinc chloride and concentrated sulfuric acid (98 % H 2SO4) as cocatalysts respectively with a variable frequency microwave oven as heater. From investigating the influences of cocatalysts in reaction, we draw a optimal condition that the yield and selectivity of chloroacetic acid are 98.11 and 98.58 % respectively when adding 0.4 g FeCl3 in mixture after reacting 3.5 h and in comparable with the corresponding percentages, 96.9 and 96.87 %, with 0.7 g ZnCl2 adding, the adding amount of 1.5 g 98 % H2SO4 result in a little lower percentages of 95.71 and 95.61 % correspondingly. We have speculated the cocatalytic mechanisms in chlorination.
- Song, Guo-Qiang,Wang, Li-Sheng,Li, Fu-Xiang
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- Reductive dechlorination of trichloroacetic acid (TCAA) by electrochemical process over Pd-In/Al2O3 catalyst
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Electrochemical reduction treatment was found to be a promising method for dechlorination of Trichloroacetic acid (TCAA), and acceleration of electron transfer or enhancement of the concentration of atomic H* significantly improve the electrochemical dechlorination process. Bimetallic Pd-based catalysts have the unique property of simultaneously catalyzing the production of atomic H* and reducing target pollutants. Herein, a bimetallic Pd–In electrocatalyst with atomic ratio of 1:1 was evenly deposited on an Al2O3 substrate, and the bimetallic Pd-In structure was confirmed via X-ray photoelectron spectroscopy (XPS). Electrochemical removal of trichloroacetic acid (TCAA) by the Pd-In/Al2O3 catalyst was performed in a three-dimensional reactor. 94% of TCAA with the initial concentration of 500?μg?L?1 could be degraded within 30?min under a relatively low current density (0.9?mA?cm?2). In contrast to the presence of refractory intermediates (dichloroacetic acid (DCAA)) found in the Pd/Al2O3 system, TCAA could be thoroughly reduced to monochloroacetic acid (MCAA) using Pd-In/Al2O3 catalysts. According to scavenger experiments, an electron transfer process and atomic H* formation function both existed in the TCAA reduction process, and the enhanced indirect atomic H* reduction process (confirmed by ESR signals) played a chief role in the TCAA removal. Moreover, the synergistic effects of Pd and In were proven to be able to enhance both direct electron transfer and indirect atomic H* formation, indicating a promising prospect for bimetallic electrochemical reduction treatment.
- Liu, Yanzhen,Mao, Ran,Tong, Yating,Lan, Huachun,Zhang, Gong,Liu, Huijuan,Qu, Jiuhui
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Read Online
- Solution Dynamics of Hybrid Anderson-Evans Polyoxometalates
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Understanding the stability and speciation of metal-oxo clusters in solution is essential for many of their applications in different areas. In particular, hybrid organic-inorganic polyoxometalates (HPOMs) have been attracting increasing attention as they combine the complementary properties of organic ligands and metal-oxygen nanoclusters. Nevertheless, the speciation and solution behavior of HPOMs have been scarcely investigated. Hence, in this work, a series of HPOMs based on the archetypical Anderson-Evans structure, δ-[MnMo6O18{(OCH2)3C-R}2]3-, with different functional groups (R = -NH2, -CH3, -NHCOCH2Cl, -NCH(2-C5H4N) {pyridine; -Pyr}, and -NHCOC9H15N2OS {biotin; -Biot}) and countercations (tetrabutylammonium {TBA}, Li, Na, and K) were synthesized, and their solution behavior was studied in detail. In aqueous solutions, decomposition of HPOMs into the free organic ligand, [MoO4]2-, and free Mn3+ was observed over time and was shown to be highly dependent on the pH, temperature, and nature of the ligand functional group but largely independent of ionic strength or the nature of the countercation. Furthermore, hydrolysis of the amide and imine bonds often present in postfunctionalized HPOMs was also observed. Hence, HPOMs were shown to exhibit highly dynamic behavior in solution, which needs to be carefully considered when designing HPOMs, particularly for biological applications.
- Salazar Marcano, David E.,Lentink, Sarah,Moussawi, Mhamad A.,Parac-Vogt, Tatjana N.
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supporting information
p. 10215 - 10226
(2021/05/31)
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- Reaction of Lithium Acylate α-Carbanions with Carbon Tetrachloride
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Metalation of acetic, butanoic, or 2-methylpropanoic acid with lithium diisopropylamide in tetrahydrofuran under argon gave the corresponding lithium acylate α-carbanions which reacted with carbon tetrachloride at 20–25°C for 2 h to afford butanedioic acid or its 2,3-diethyl and 2,2,3,3-tetramethyl derivatives, as well as the corresponding α-chlorocarboxylic acids and chloroform. A radical mechanism was proposed for the formation of dicarboxylic and α-chlorocarboxylic acids.
- Zorin,Zaynashev,Zorin
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- Catalytic Oxidative Cracking of Benzene Rings in Water
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Efficient degradation of harmful benzene rings in water is indispensable for achieving a clean water environment. We report herein unprecedented catalytic oxidative benzene cracking (OBC) in water using a ruthenium(II)-aqua complex having an N-heterocyclic carbene ligand as a catalyst and a cerium(IV) salt as a sacrificial oxidant under mild conditions. The OBC reactions produced carboxylic acids such as formic acid, which can be converted to dihydrogen directly from the OBC solution using a rhodium(III) catalyst with adjustment of the solution pH to 3.3. The OBC reactions can be applied to monosubstituted benzene derivatives such as ethylbenzene, chlorobenzene, and benzoic acid. Initial rates of the OBC reactions showed a linear relationship in the Hammett plot with a negative slope, indicating the electrophilicity of a Ru(III)-oxyl complex as the reactive species in the catalytic OBC reaction. Also, we discuss a plausible mechanism of the catalytic OBC reactions based on the kinetic analysis and the product stoichiometry for the OBC reaction of nonvolatile sodium m-xylene sulfonate. The addition of an electrophilic radical to the aromatic ring to form arene oxide/oxepin is proposed as the initial step of the OBC reaction.
- Shimoyama, Yoshihiro,Ishizuka, Tomoya,Kotani, Hiroaki,Kojima, Takahiko
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p. 671 - 678
(2019/01/08)
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- A Straightforward Homologation of Carbon Dioxide with Magnesium Carbenoids en Route to α-Halocarboxylic Acids
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The homologation of carbon dioxide with stable, (enantiopure) magnesium carbenoids constitutes a valuable method for preparing α-halo acid derivatives. The tactic features a high level of chemocontrol, thus enabling the synthesis of variously functionalized analogues. The flexibility to generate magnesium carbenoids through sulfoxide-, halogen- or proton- Mg exchange accounts for the wide scope of the reaction. (Figure presented.).
- Monticelli, Serena,Urban, Ernst,Langer, Thierry,Holzer, Wolfgang,Pace, Vittorio
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supporting information
p. 1001 - 1006
(2019/01/30)
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- Preparation method of alpha-chloro carboxylic acid
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The invention discloses a preparation method of alpha-chloro carboxylic acid. According to the preparation method, amino acids are dissolved into hydrochloric acid to form a homogeneous solution; thenobtained homogeneous solution and a sodium nitrite water solution are simultaneously pumped into a mixing valve through an injection pump A and an injection pump B of a micro-channel reaction apparatus; after the solutions are fully mixed, the mixed solution is pumped into a micro reactor of the micro-channel reaction apparatus to carry out reactions at a constant flowing speed, and the flow-outliquid namely alpha-chloro carboxylic acid is collected. The provided method realizes the continuous production of alpha-chloro carboxylic acid; furthermore, the product quality is good, the operationis simple, the using amount of raw materials is little, the process is safe, the method is green and environmentally friendly, energy is saved, the efficiency is high, and thus the method is suitablefor industrial production.
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Paragraph 0058; 0059
(2018/04/26)
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- METHOD OF INDUSTRIALLY PRODUCING MONOCHLOROACETIC ACID
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A method of producing monochloroacetic acid (MCAA) has been disclosed encompassing (a) a stage of the direct chlorination of acetic acid with chlorine and (b) a stage of recovery of the catalyst in the form of acid chlorides from the reaction mixture before (c) a hydrodehalogenation stage characterized by the fact that the chlorination process (a) is conducted at the boiling temperature of the mixture under a pressure of 0 - 1.0 barg, in an excess of acetic acid with respect to the dosed chlorine gas, while the heat from the reaction is taken off mainly through the evaporation of volatile components of the mixture, followed by their condensation in the reflux condenser above the reactor and the return to the chlorination reaction, after which the reaction mixture containing monochloroacetic acid, acetic acid, dichloroacetic acid and optionally acid chlorides which are present in the mixture and, optionally, anhydrides of these acids, is feed to the vacuum distillation process (b), which is conducted continuously in the distillation column in a vacuum of 0 to 500 mbar from which volatile components of the mixture, mainly acid chlorides, as well as some acetic acid and some monochloroacetic acid are taken off as distillate and returned to the chlorination process as a result of which the catalyst of the chlorination is almost completely recovered.
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Page/Page column 12-14
(2018/02/03)
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- Prebiotic synthesis of phosphoenol pyruvate by α-phosphorylation-controlled triose glycolysis
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Phosphoenol pyruvate is the highest-energy phosphate found in living organisms and is one of the most versatile molecules in metabolism. Consequently, it is an essential intermediate in a wide variety of biochemical pathways, including carbon fixation, the shikimate pathway, substrate-level phosphorylation, gluconeogenesis and glycolysis. Triose glycolysis (generation of ATP from glyceraldehyde 3-phosphate via phosphoenol pyruvate) is among the most central and highly conserved pathways in metabolism. Here, we demonstrate the efficient and robust synthesis of phosphoenol pyruvate from prebiotic nucleotide precursors, glycolaldehyde and glyceraldehyde. Furthermore, phosphoenol pyruvate is derived within an α-phosphorylation controlled reaction network that gives access to glyceric acid 2-phosphate, glyceric acid 3-phosphate, phosphoserine and pyruvate. Our results demonstrate that the key components of a core metabolic pathway central to energy transduction and amino acid, sugar, nucleotide and lipid biosyntheses can be reconstituted in high yield under mild, prebiotically plausible conditions.
- Coggins, Adam J.,Powner, Matthew W.
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p. 310 - 317
(2017/04/03)
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- A method for producing sodium monochloroacetate and chlorination reactor
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The invention provides a chloroacetic acid production method and a chlorination reactor. The chloroacetic acid production method comprises the following steps: primarily mixing acetic acid, liquid chlorine and acetic anhydride according to a ratio, feeding a mixture obtained from the former step into the chlorination reactor, keeping a certain reaction temperature and a certain reaction pressure, completing chlorination reaction in a gravity field of 100-1000g, and performing separation purification on the product by using a continuous method production process after the reaction is completed, thereby obtaining a product finally. The chlorination reactor mainly comprises a reaction kettle, a cooling half-tube, a supergravity bucket, a driving motor and a mixer. By adopting the chloroacetic acid production method and the chlorination reactor provided by the invention, the macroscopic and microcosmic distribution of components in a reaction system can be improved, the side effect is reduced, the internal mass transfer velocity of the liquid phase is reduced, the separation of the gas phase and the liquid phase is improved, the chlorination reaction velocity is increased, the reaction retention time is shortened, the heat radiation effect is improved, and the treatment capacity is much higher than that of a conventional method, and the chloroacetic acid production method is particularly applicable to a large-size chloroacetic acid device.
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Paragraph 0026-0028
(2017/01/09)
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- An intermittent chlorination method for preparing of chloroacetic acid
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The invention discloses a method for preparing monochloro acetic acid based on an intermittent catalytic chlorination process of acetic acid. The method comprises the following steps: sequentially adding acetic acid, a main catalyst which is sulphur and a cocatalyst which is chlorosulfonic acid into a reaction kettle, increasing the temperature of the reaction kettle to 70-75 DEG C, reacting for 0.5-1 hour, then increasing the temperature of the reaction kettle to 95-100 DEG C, and continuously carrying out circulation reaction on a reaction solution and chlorine gas by virtue of a tubular reactor until reaction reaches the final point, wherein the constant temperature of the reaction kettle is retained by the circulation water in the reaction process. The method has the advantages that the production efficiency is high, and the generated dichloroacetic acid is low in content.
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Paragraph 0017-0018
(2017/06/27)
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- Method for preparing chloroacetic acid through dual-additive catalytic chlorization
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The invention provides a method for preparing chloroacetic acid through dual-additive catalytic chlorization. According to the method, acetyl chloride serves as a main catalyst, a certain amount of manganese acetate/chromium acetate is added to serve as a chlorine resistance agent based on a concentrated sulfuric acid cocatalyst to obtain dual-additives for catalytic chlorization preparation of chloroacetic acid, the mass fraction of chloroacetic acid (MCA) in reaction products can reach 98.1%, and the mass fraction of dichloroacetic acid (DCA) in reaction products is 0.7%.
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Paragraph 0043
(2017/06/27)
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- A mild method for the replacement of a hydroxyl group by halogen. 1. Scope and chemoselectivity
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α-Chloro-, bromo- and iodoenamines, which are readily prepared from the corresponding isobutyramides have been found to be excellent reagents for the transformation of a wide variety of alcohols or carboxylic acids into the corresponding halides. Yields are high and conditions are very mild thus allowing for the presence of sensitive functional groups. The reagents can be easily tuned allowing therefore the selective monohalogenation of polyhydroxylated molecules. The scope and chemoselectivity of the reactions have been studied and reaction mechanisms have been proposed.
- Munyemana, Fran?ois,George, Isabelle,Devos, Alain,Colens, Alain,Badarau, Eduard,Frisque-Hesbain, Anne-Marie,Loudet, Aurore,Differding, Edmond,Damien, Jean-Marie,Rémion, Jeanine,Van Uytbergen, Jacqueline,Ghosez, Léon
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p. 420 - 430
(2015/12/31)
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- Reactions of α-carbanions of lithium acylates with N,N-diethyl-N-chloro- and N,N-diethyl-N-bromoamines
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The interaction of α-carbanions of lithium acylates (prepared via metalation of acetic, butyric, or isobutyric acid with lithium diisopropylamide in tetrahydrofuran under argon atmosphere) with N,N-diethyl-N-chloro- or N,N-diethyl-N-bromoamine has resulte
- Zorin,Zainashev,Zorin
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p. 2469 - 2472
(2016/12/24)
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- Effect of dissolved oxygen concentration on iron efficiency: Removal of three chloroacetic acids
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The monochloroacetic, dichloroacetic and trichloroacetic acid (MCAA, DCAA and TCAA) removed by metallic iron under controlled dissolved oxygen conditions (0, 0.75, 1.52, 2.59, 3.47 or 7.09mg/L DO) was investigated in well-mixed batch systems. The removal of CAAs increased first and then decreased with increasing DO concentration. Compared with anoxic condition, the reduction of MCAA and DCAA was substantially enhanced in the presence of O2, while TCAA reduction was significantly inhibited above 2.59mg/L. The 1.52mg/L DO was optimum for the formation of final product, acetic acid. Chlorine mass balances were 69-102%, and carbon mass balances were 92-105%. With sufficient mass transfer from bulk to the particle surface, the degradation of CAAs was limited by their reduction or migration rate within iron particles, which were dependent on the change of reducing agents and corrosion coatings. Under anoxic conditions, the reduction of CAAs was mainly inhibited by the available reducing agents in the conductive layer. Under low oxic conditions, the increasing reducing agents and thin lepidocrocite layer were favorable for CAA dechlorination. Under high oxic conditions, the redundant oxygen competing for reducing agents and significant lepidocrocite growth became the major restricting factors. Various CAA removal mechanisms could be potentially applied to explaining the effect of DO concentration on iron efficiency for contaminant reduction in water and wastewater treatment.
- Tang, Shun,Wang, Xiao-mao,Mao, Yu-qin,Zhao, Yu,Yang, Hong-wei,Xie, Yuefeng F.
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p. 342 - 352
(2015/03/04)
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- Thermodynamically leveraged tandem catalysis for ester RC(O)O-R′ bond hydrogenolysis. scope and mechanism
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Rapid and selective formal hydrogenolysis of aliphatic ester RC(O)O-R′ linkages is achieved by a tandem homogeneous metal triflate + supported palladium catalytic system. The triflate catalyzes the mildly exothermic, turnover-limiting O-R′ cleavage process, whereas the exothermic hydrogenation of the intermediate alkene further drives the overall reaction to completion.
- Lohr, Tracy L.,Li, Zhi,Assary, Rajeev S.,Curtiss, Larry A.,Marks, Tobin J.
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p. 3675 - 3679
(2015/06/16)
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- High-dispersive FeS2 on graphene oxide for effective degradation of 4-chlorophenol
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A high-dispersive FeS2 micro-cube crystal on graphene oxide (FeS2@GO) was fabricated by a one-pot hydrothermal method. The catalytic degradation of 4-chlorophenol (4-CP) and its mechanism in a FeS2@GO-based Fenton system was investigated. Under acidic to slight alkaline conditions, FeS2@GO demonstrated an excellent capacity to remove 4-CP. More than 97% of 4-CP was eliminated within 60 min in pH 7.0 reaction solutions initially containing 0.2 g L-1 FeS2@GO, 128.6 mg L-1 4-CP and 100 mM H2O2 at 25 ± 1°C, and the removal of 4-CP was further enhanced with increasing FeS2@GO loadings. In the meantime, the FeS2@GO also achieved lower iron leaching and a more complete TOC removal compared with pure synthetic FeS2 without graphene oxide. Furthermore, acetic acid and oxalic acid were identified as the primary products. The remarkable capacity of the FeS2@GO-based Fenton system in removing 4-CP displays its potential application in the treatment of organic compound-contaminated water.
- Liu, Wanpeng,Xu, Lili,Li, Xingfa,Shen, Chensi,Rashid, Sadia,Wen, Yuezhong,Liu, Weiping,Wu, Xiaohua
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p. 2449 - 2456
(2015/02/19)
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- An integrated platform for automatic design and screening of virtual mutants based on 3D-QSAR analysis
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An innovative application of 3D-QSAR methodology to the rational design of enzymes is here reported. The introduction of amidase activity inside the scaffold of lipase B from Candida antarctica (CaLB) was studied and 3D-QSAR models were constructed to correlate the structures of a set of CaLB mutants with their experimentally measured activities. Properties, like hydrophilicity, hydrophobicity and hydrogen bonding capability of the enzyme active site were computed by means of the GRID method and the output was used as molecular descriptors. Correlations with experimental behavior of the catalysts were calculated by means of partial least square regression (PLS). The analysis of the QSAR model fully exploits fundamental knowledge while avoiding conceptual biases. Rationales for driving enzyme engineering are disclosed and a priori evaluation of new virtual candidate mutants becomes feasible. On that respect, the whole procedure for production of virtual mutants and scoring of their activity was automated within a workflow constructed by means of the modeFRONTIER package. The method allows for the automated construction and scoring of each mutant in 2 h on a normal workstation.
- Ferrario, Valerio,Ebert, Cynthia,Svendsen, Allan,Besenmatter, Werner,Gardossi, Lucia
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- Nucleofugality of aliphatic carboxylates in mixtures of aprotic solvents and water
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The leaving group ability (nucleofugality) of fluoroacetate, chloroacetate, bromoacetate, dichloroacetate, trifluoroacetate, trichloroacetate, heptafluorobutyrate, formate, isobutyrate, and pivalate have been derived from the solvolysis rate constants of the corresponding X,Y-substituted benzhydryl carboxylates in 60 % and 80 % aqueous acetonitrile and 60 % aqueous acetone, applying the LFER equation: log k = sf(Ef + Nf). The experimental barriers (ΔG?,exp) for solvolyses of 11 reference dianisylmethyl carboxylates in these solvents correlate very well (r = 0.994 in all solvents) with ΔG?,model of the model σ-assisted heterolytic displacement reaction of cis-2,3-dihydroxycyclopropyl trans-carboxylates calculated earlier. Linear correlation observed between the log k for the reference dianisylmethyl carboxylates and the sf values enables estimation of the reaction constant (sfestim). Using the ΔG?,exp vs. ΔG?,model correlation, and taking the estimated sfestim, the nucleofugality parameters for other 34 aliphatic carboxylates have been determined in 60 % and 80 % aqueous acetonitrile and 60 % aqueous acetone. The most important variable that determines the reactivity of aliphatic carboxylates in aprotic solvent/water mixtures is the inductive effect of the group(s) attached onto the carboxylate moiety.
- Mati, Mirela,Denegri, Bernard,Kronja, Olga
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p. 375 - 384
(2015/10/12)
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- Microwave synthesis of chloroacetic acid with acetic anhydride catalyzing chlorination of acetic acid
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In this paper, the chloroacetic acid has been synthesized with the acetic anhydride catalyzing chlorination of acetic acid by microwave irradiation. The volume fraction of acetic anhydride in acetic acid, reaction time, microwave power and reaction temperature have been investigated in the self-designed experimental device. The results showed that the optimum conditions were the volume fraction of acetic anhydride in acetic acid of 20 %, reaction time of 3.5 h, microwave power of 300 W, reaction temperature of 95 °C, the yield of chloroacetic acid was 94.31 % and the selectivity was 93.01 %. Compared with ordinary heating, the selectivity and the reaction rate of using microwave irradiation were apparently improved.
- Wang, Li-Sheng,Song, Guo-Qiang,Meng, Ying,Li, Shou-Gao,Li, Fu-Xiang
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p. 8997 - 8999
(2013/11/19)
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- CHEMICALLY AMPLIFIED POSITIVE RESIST COMPOSITION FOR ArF IMMERSION LITHOGRAPHY AND PATTERN FORMING PROCESS
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A chemically amplified positive resist composition comprising (A) a sulfonium salt of 3,3,3-trifluoro-2-hydroxy-2-trifluoromethylpropionic acid, (B) an acid generator, (C) a base resin, and (D) an organic solvent is suited for ArF immersion lithography. The carboxylic acid sulfonium salt is highly hydrophobic and little leached out in immersion water. By virtue of controlled acid diffusion, a pattern profile with high resolution can be constructed.
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Page/Page column
(2013/03/26)
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- Oxidation of some aliphatic aldehydes by tetrakis (pyridine) silver dichromate: A kinetic and mechanistic study
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The oxidation of six aliphatic aldehydes by tetrakis (pyridine) silver dichromate (TPSD) in dimethyl sulfoxide (DMSO) leads to the formation of corresponding carboxylic acids. The reaction is first order each in TPSD. A Michaelis-Menten type of kinetics is observed with respect to the aldehydes. The reaction is catalysed by hydrogen ions, the hydrogen-ion dependence has the form : kobs = a + 6[H+]. The oxidation of deuteriated acetaldehyde, MeCDO, exhibited a substantial primary kinetic isotope effect (kH/kD = 5.80 at 298 K). The oxidation of acetaldehyde has been studied in nineteen different organic solvents. The solvent effect has been analysed using Taft's and Swain's multiparametric equations. The rate constants correlate well with Taft's σ*values; reaction constants being negative. A mechanism involving transfer of hydride ion has been suggested.
- Patel,Poonam,Jha,Baghmar,Kothari,Shastri,Sharma, Pradeep K.
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p. 1149 - 1154
(2013/01/14)
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- FLUOROALCOHOL, FLUORINATED MONOMER, POLYMER, RESIST COMPOSITION AND PATTERNING PROCESS
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Fluoroalcohol compounds of formula (1) are useful in producing polymers which are used as the base resin to formulate radiation-sensitive resist compositions having transparency to radiation having a wavelength of up to 500 nm and improved development characteristics. R1 is hydrogen or a monovalent C1-C20 hydrocarbon group in which any constituent —CH2— moiety may be replaced by —O— or —C(═O)—, Aa is a (k1+1)-valent C1-C20 hydrocarbon or fluorinated hydrocarbon group, and k1 is 1, 2 or 3.
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- Optimization of HNO production from N, O - Bis -acylated hydroxylamine derivatives
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A wide range of N,O-bis-acylated hydroxylamine derivatives with chloro or arenesulfonyl leaving groups, and a related set of N-hydroxy-N-acylsulfonamides, have been synthesized and evaluated for nitroxyl (HNO) production. Mechanistic studies have revealed that the observed aqueous chemistry is more complicated than originally anticipated, and have been used to develop a new series of efficient HNO precursors (4u-4x, 7c-7d) with tunable half-lives.
- Sutton, Art D.,Williamson, Morgan,Weismiller, Hilary,Toscano, John P.
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supporting information; experimental part
p. 472 - 475
(2012/03/26)
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- Photocatalytic degradation of chlorinated ethanes in the gas phase on the porous TiO2 pellets: Effect of surface acidity
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The photocatalytic degradation of chlorinated ethanes was studied in a tubular photoreactor packed with TiO2 pellets prepared by sol-gel method. The steady-state condition was not obtained, but the deterioration in the photocatalytic activity was observed during the irradiation. Effects of mole fractions of water vapor, O2, and C2H5Cl or C2H4Cl2 and reaction temperature on the photodegradation of C2H5Cl or C2H 4Cl2 were examined, and these data were compared with those obtained by the photodegradation of chlorinated ethylenes. On the basis of the products detected with and without oxygen in the reactant's gas stream, we proposed the degradation mechanism. Measurement of diffuse reflectance infrared Fourier transform spectroscopy of pyridine adsorbed on the catalysts showed that decrease in the conversion for the photodegradation of C2H 5Cl was attributable to the formation of Bronsted acid sites. Comparison of the data obtained with the TiO2 and the sulfated TiO2 (SO42-/TiO2) pellets indicated that the photodegradation of C2H5Cl was suppressed by the presence of the Bronsted sites, but that of trichloroethylene was not affected. Such a difference is attributable to the adsorption process of these reactants on the acid sites on the catalyst surface.
- Yamazaki, Suzuko,Ichikawa, Keiko,Saeki, Atsue,Tanimura, Toshifumi,Adachi, Kenta
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experimental part
p. 5092 - 5098
(2010/08/05)
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- Rotanone Analogs: Method of Preparation and Use
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The present invention provides rotenone analogs and methods of making and using them. Labeled with single photon and positron emitting isotopes, the rotenone analogs of the present invention are useful in, for example, clinical imaging applications as tracers to measure cardiac blood flow and detect regions of ischemia.
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- The Ever-surprising chemistry of boron: Enhanced acidity of phosphine·boranes
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The gas-phase acidity of a series of phosphines and their corresponding phosphine·borane derivatives was measured by FT-ICR techniques. BH 3 attachment leads to a substantial increase of the intrinsic acidity of the system (from 80 to 110 kJ mol-1). This acidity-enhancing effect of BH3 is enormous, between 13 and 18 orders of magnitude in terms of ionization constants. This indicates that the enhancement of the acidity of protic acids by Lewis acids usually observed in solution also occurs in the gas phase. High- level DFT calculations reveal that this acidity enhancement is essentially due to stronger stabilization of the anion with respect to the neutral species on BH3 association, due to a stronger electron donor ability of P in the anion and better dispersion of the negative charge in the system when the BH3 group is present. Our study also shows that deprotonation of ClCH2PH2 and ClCH 2PH2·BH3 is followed by chloride departure. For the latter compound deprotonation at the BH3 group is found to be more favorable than PH2 deprotonation, and the subsequent loss of Cl- is kinetically favored with respect to loss of Cl - in a typical SN2 process. Hence, ClCH2PH 2·BH3 is the only phosphine·borane adduct included in this study which behaves as a boron acid rather than as a phosphorus acid.
- Hurtado, Marcela,Yanez, Manuel,Herrero, Rebeca,Guerrero, Andres,Juan Z. Davalos,Jose-Luis, M. Abboud,Khater, Brahim,Guillemin, Jean-Claude
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supporting information; experimental part
p. 4622 - 4629
(2009/12/29)
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- MANUFACTURE OF SUBSTANTIALLY PURE MONOCHLOROACETIC ACID
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A process for the manufacture of substantially pure monochloroacetic acid from a liquid chloroacetic acid mixture comprising monochloroacetic acid and dichloroacetic acid, in particular in an amount of 2 to 40 percent by weight, wherein said mixture, further mixed with a suspended hydrogenation catalyst, is mixed with hydrogen gas and the resulting mixture is brought to reaction in a reactor, which is characterized in that the reactor is a loop reactor comprising a gas and liquid recirculation system coupled via an ejector mixing nozzle, in which reactor the gas and liquid are circulated in co-current flow, and the mixing intensity introduced to the liquid phase is at least 50 W/l of liquid phase.
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Page/Page column 13-16
(2008/06/13)
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- Kinetics and mechanism of oxidation of aliphatic aldehydes by morpholinium chlorochromate
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Oxidation of six aliphatic aldehydes by morpholinium chlorochromate (MCC) in dimethyl sulfoxide (DMSO) leads to the formation of corresponding carboxylic acids. The reaction is first order each in MCC and the aldehyde. The reaction is catalysed by hydrogen ions. The hydrogen-ion dependence has the form : k ods = a + b[H+]. The oxidation of deuteriated acetaldehyde, MeCDO, exhibited a substantial primary kinetic isotope effect (kH/kD = 5.95 at 298 K). The oxidation of acetaldehyde has been studied in 19 different organic solvents. The solvent effect has been analysed using Taft's and Swain's multiparametric equations. The rate constants correlate well with Taft's σ* values and reaction constants are negative. A mechanism involving transfer of hydride ion has been suggested.
- Soni, Neelam,Tiwari, Vandana,Kumbhani,Shastri,Sharma, Vinita
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experimental part
p. 857 - 861
(2009/12/01)
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- An efficient and practical system for the catalytic oxidation of alcohols, aldehydes, and α,β-unsaturated carboxylic acids
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(Chemical Equation Presented) Upon exposure to commercial bleach (～5% aqueous sodium hypochlorite), nickel(II) chloride or nickel(II) acetate is transformed quantitatively into an insoluble nickel species, nickel oxide hydroxide. This material consists of high surface area nanoparticles (ca. 4 nm) and is a useful heterogeneous catalyst for the oxidation of many organic compounds. The oxidation of primary alcohols to carboxylic acids, secondary alcohols to ketones, aldehydes to carboxylic acids, and α,β- unsaturated carboxylic acids to epoxy acids is demonstrated using 2.5 mol % of nickel catalyst and commercial bleach as the terminal oxidant. We demonstrate the controlled and selective oxidation of several organic substrates using this system affording 70-95% isolated yields and 90-100% purity. In most cases, the oxidations can be performed without an organic solvent, making this approach attractive as a "greener" alternative to conventional oxidations.
- Grill, Joseph M.,Ogle, James W.,Miller, Stephen A.
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p. 9291 - 9296
(2007/10/03)
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- The kinetics and mechanism of oxidation of aliphatic aldehydes by benzyltriethylammonium chlorochromate
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The oxidation of six aliphatic aldehydes by benzyltriethylammonium chlorochromate (BTEACC) in dimethyl sulfoxide (DMSO) leads to the formation of corresponding carboxylic acids. The reaction is first order each in BTEACC and the aldehyde. The reaction is catalysed by hydrogen ions. The hydrogen-ion dependence has the form: kobs = a + 6[H+]. The oxidation of deuteriated acetaldehyde, MeCDO, exhibited a substantial primary kinetic isotope effect (kH/ kD = 5.89 at 298 K). The oxidation of acetaldehyde has been studied in 19 different organic solvents. The solvent effect has been analysed using Taft's and Swain's multiparametric equations. The rate constants correlate well with Taft's σ* values; reaction constants being negative. A mechanism involving transfer of hydride ion has been suggested.
- Chouhan, Kavita,Rao, P.T.S.R.K. Prasad,Sharma, Pradeep K.
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p. 191 - 194
(2007/10/03)
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- Oxidation of ethers with dimethyldioxirane
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Oxidation of a series of tert-butyl ethers ButOR (R = Me, Et, CH2CH2Cl, Pri, Bui), diethyl ether, diisopropyl ether, 1,2-dimethoxyethane, diisobutoxymethane, 1,4-dioxane, and tetrahydrofuran with dimethyldioxirane (DMDO) was studied. The reaction kinetics obeys the second-order equation w = k[DMDO][ether]. The rate constants in a range of 5-50°C and the activation parameters of the reaction were determined. The solvent effect on the oxidation rate was studied. The oxidation products are the corresponding alcohols and carbonyl compounds. The competition between the nonradical (oxygen insertion) and radical mechanisms of the reaction is discussed. The reactions of the parent dioxirane and DMDO with a series of methyl ethers MeOR′ (R′ = Me, Et, CH2CH2F, Pri) were studied by the density functional theory (DFT). The (U)B3LYP-6-311G(d,p) method was employed to calculate the geometry and energies of the reactants and transition states. The data obtained indicate a possible increase in the probability of oxidation via the radical route and an increase in the activation barrier for the substrates containing electron-withdrawing substituents.
- Grabovskiy,Timerghazin,Kabal'nova
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p. 2384 - 2393
(2007/10/03)
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- Mechanisms of solvolyses of acid chlorides and chloroformates. Chloroacetyl and phenylacetyl chloride as similarity models
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Rate constants and product selectivities (S = ([ester product]/[acid product]) × ([water]/[alcohol solvent]) are reported for solvolyses of chloroacetyl chloride (3) at -10 °C and phenylacetyl chloride (4) at O °C in ethanol/and methanol/water mixtures. Additional kinetic data are reported for solvolyses in acetone/water, 2,2,2-trifluoroethanol(TFE)/water, and TFE/ethanol mixtures. Selectivities and solvent effects for 3, including the kinetic solvent isotope effect (KSIE) of 2.18 for methanol, are similar to those for solvolyses of p-nitrobenzoyl chloride (1, Z = NO2); rate constants in acetone/water are consistent with a third-order mechanism, and rates and products in ethanol/and methanol/water mixtures can be explained quantitatively by competing third-order mechanisms in which one molecule of solvent (alcohol or water) acts as a nucleophile and another acts as a general base (an addition/elimination reaction channel). Selectivities increase for 3 as water is added to alcohol. Solvent effects on rate constants for solvolyses of 3 are very similar to those of methyl chloroformate, but acetyl chloride shows a lower KSIE, and a higher sensitivity to solvent-ionizing power, explained by a change to an SN2/SN1 (ionization) reaction channel. Solvolyses of 4 undergo a change from the addition/elimination channel in ethanol to the ionization channel in aqueous ethanol (80% v/v alcohol). The reasons for change in reaction channels are discussed in terms of the gas-phase stabilities of acylium ions, calculated using Gaussian 03 (HF/6-31G(d), B3LYP/6-31G(d), and B3LYP/6-311G(d,p) MO theory).
- Bentley, T. William,Harris, H. Carl,Ryu, Zoon Ha,Lim, Gui Taek,Sung, Dae Dong,Szajda, Stanley R.
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p. 8963 - 8970
(2007/10/03)
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- Facile Hydrolysis of Esters with KOH-Methanol at Ambient Temperature
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A simple, rapid, and efficient method is reported for the hydrolysis of a variety of mono-and diesters of aromatic, aliphatic, fatty, and heterocyclic acids with potassium hydroxide in methanol at ambient temperature (～35°C).
- Khurana, Jitender M.,Chauhan, Sushma,Bansal, Geeti
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- α-Chlorination of Carboxylic Acids Using Trichloroisocyanuric Acid
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Carboxylic acids are chlorinated in the a position by heating with trichloroisocyanuric acid after formation of a small amount of the acid chloride using phosphorus trichloride.
- Hiegel, Gene A.,Faher, Diane Dutton,Lewis, Justin C.,Tran, Tan Duc,Hobson, Gregory G.,Farokhi, Farhad
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p. 889 - 893
(2007/10/03)
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- A PROCESS FOR THE PREPARATION OF MONOCHLOROACETIC ACID
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The invention pertains to a process for the production of monochloroacetic acid from chlorine and acetic acid in the presence of a catalyst by reactive distillation. The process and the required reactive distillation apparatus is much less complex than conventional reactors and yields a monochloroacetic acid product having a low content of over-chlorinated products.
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- Apoptotic compounds
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The invention provides methods and compositions for enhancing apoptosis of pathogenic cells. The general method comprises the of contacting the cells with an effective amount of an AV peptoid, wherein the AV peptoid is a peptide comprising AX1, wherein X1is V, I or L, or a peptide mimetic thereof, which interacts with an Inhibitor of Apoptosis protein (IAP) as measured by IAP binding, procaspase-3 activation or promotion of apoptosis, wherein apoptosis of the pathogenic cells is enhanced. The subject compositions encompass pharmaceutical compositions comprising a therapeutically effective amount of a subject AV peptoid in dosage form and a pharmaceutically acceptable carrier, wherein the AV peptoid is a peptide comprising AX1, wherein X1is V, I or L, or a peptide mimetic thereof, which inhibits the activity of an Inhibitor of Apoptosis protein (IAP) as measured by IAP binding, procaspase-3 activation or promotion of apoptosis. The invention also provides assays for identifying agents which modulates the interaction of an AV peptoid with an IAP, active compounds identified in such screens and their use in the foregoing compositions and therapeutic methods.
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- Hair conditioning compositions and their use in hair colouring compositions
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The present invention relates to a hair care composition comprising a aminofunctional polysiloxane having a specified average effective particle size which provides improved durable conditioning particularly when utilised in conjunction with a hair colouring composition.
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- Hair colouring and conditioning compositions
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A hair colouring and conditioning composition comprising: (a) a hair colouring agent; and (b) a hair conditioning agent; wherein the composition provides an Average Combing Index Value of greater than 1.2 as measured by the Combing Technical Test Method. The products can provide excellent hair colouring together with excellent conditioning, reduced hair damage, brittleness and dryness, and is convenient and easy to use.
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- Novel photoacid generators for photodirected oligonucleotide synthesis
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Photodirected oligonucleotide synthesis uses either direct or indirect light-dependent 5′-deprotection. Both have been reported to give lower stepwise synthetic yields than conventional methods. The deficiency appears to be due to incomplete deprotection at the oligonucleotide 5′-position and, additionally in the case where photodirection is indirect and uses photogenerated photoacid to effect 5′-detritylation, the depurinating effects of strong acid. We have developed novel photosensitive-2-nitrobenzyl esters that on irradiation with near UV light generate α-chloro-substituted acetic acids, such as trichloroacetic acid, which are widely and successfully used in conventional solid-phase oligonucleotide synthesis. α-Phenyl-4,5-dimethoxy-2-nitrobenzyltrichloroacetate and α-phenyl-4,5-dimethoxy-2,6-dinitrobenzyltrichloroacetate showed appropriate photochemical characteristics and were used for photodirected synthesis of a variety of oligonucleotides, including (T)5, TATAT, TGTGT, (T)10, (AT)5, (CT)5 (GT)5 and (TGCAT)2 on a modified Millipore Expedite DNA synthesizer. The outcomes were compared with those obtained by use of directly added trichloroacetic acid (conventional synthesis). The stepwise yields for the two methods were essentially identical.
- Serafinowski, Pawel J.,Garland, Peter B.
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p. 962 - 965
(2007/10/03)
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- HAIR COLORING COMPOSITIONS
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A hair coloring composition comprising: (a) from about 0.0003 moles (per 100 g of composition) to less than about 0.09 moles (per 100 g of composition) of an inorganic peroxygen oxidizing agent; and (b) an oxidative hair coloring agent; wherein the pH of each of (a) and (b) is in the range of from about 1 to about 6 and wherein the combined mixture of (a) and (b) has a pH in the range of from about 1 to about 6. The products can provide excellent hair coloring and in-use efficacy benefits including excellent initial color and good wash fastness in combination with reduced hair damage at low pH.
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- HAIR COLORING COMPOSITIONS
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A hair coloring composition comprising: (a) a preformed organic peroxyacid oxidising agent; and (b) an oxidative hair coloring agent; wherein the pH of each of components (a) and (b) is in the range of from about pH 1 to less than about pH 7 and wherein the pH of the composition is in the range of from about pH 1 to less than about pH 7. The products can provide excellent hair coloring and in-use efficacy benefits including excellent initial color and good wash fastness in combination with reduced hair damage at low pH.
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- Deprotection of benzylic esters catalysed by anhydrous ferric chloride and rhenium carbonyl compounds
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Anhydrous ferric chloride and [Re(CO)4Br]2 are shown to be useful reagents for the catalytic deprotection of benzylic esters. A suitable protecting group is p-MeC6H4CH2 with a working temperature of 5
- Davies, Timothy J.,Jones, Ray V.H.,Lindsell, W.Edward,Miln, Colin,Preston, Peter N.
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p. 487 - 488
(2007/10/03)
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- Reduction of haloacetic acids by Fe0: Implications for treatment and fate
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To predict the fate of haloacetic acids (HAAs) in natural or engineered systems, information is needed concerning the types of reactions that these compounds undergo, the rates of those reactions, and the products that are formed. Given that many drinking water distribution systems consist of unlined cast iron pipe, reactions of HAAs with elemental iron (Fe0) may play a role in determining the fate of HAAs in these systems. In addition, zerovalent iron may prove to be an effective treatment technology for the removal of HAAs from chlorinated drinking water and wastewater. Thus, batch experiments were used to investigate reactions of four trihaloacetic acids, trichloroacetic acid (TCAA), tribromoacetic acid (TBAA), chlorodibromoacetic acid (CDBAA), and bromodichloroacetic acid (BDCAA), with Fe0. All compounds readily reacted with Fe0, and investigation of product formation and subsequent disappearance revealed that the reactions proceeded via sequential hydrogenolysis. Bromine was preferentially removed over chlorine, and TBAA was the only compound completely dehalogenated to acetic acid. In compounds containing chlorine, the final product of reactions with Fe0 was monochloroacetic acid. Halogen mass balances were 95-112%, and carbon mass balances were 62.6-112%. The pseudo-first-order rate constants for trihaloacetic acid degradation were as follows: BDCAA (10.6 ± 3.1 h-1) > CDBAA (1.43 ± 0.32 h-1) ≈ TBAA (1.41 ± 0.28 h--1) ? TCAA (0.08 ± 0.02 h-1).
- Hozalski, Raymond M.,Zhang, Li,Arnold, William A.
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p. 2258 - 2263
(2007/10/03)
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- Hydrolytic removal of the chlorinated products from the oxidative free-radical-induced degradation of chloroethylenes: Acid chlorides and chlorinated acetic acids
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Progressive hydrolytic decomposition of acyl chlorides, among them the chlorinated acetyl chlorides, which are produced in the gas-phase oxidation of chlorinated ethylenes, permits the complete mineralization of organically bound chlorine to chloride anion. Hydrolysis rate constants (100% water) have been determined for the following acyl chlorides: acetyl (350 s-1), chloroacetyl (5.5 s-1), dichloroacetyl (300 s-1), trichloroacetyl (>350 s-1), and oxalyl dichloride (>350 s-1). The chlorinated acetyl chlorides thereby give rise to the chloroacetates whose decomposition has also been studied and the kinetic parameters determined. Mono- and dichloroacetate anion undergo hydrolytic dechlorination (kobs = ko + kOH- × [OH-]; ClCH2C(O)O-: Ao 6.4 × 1015 s-1, Eo 148 kJ mol-1, AOH- 1.6 × 109 dm3 mol-1 s-1, EOH- 86 kJ mol-1. Cl2CHC(O)O-: Ao 3.2 × 1016 s-1, Eo 156 kJ mol-1, AOH- 3.2 × 1010 dm3 mol-1 s-1, EOH- 104 kJ mol-1). Trichloroacetate anion decomposes by another mechanism, undergoing decarboxylation which is base-uncatalyzed: Ao 2.1 × 1017 s-1, Eo 146 kJ mol-1. Procedures on a pilot-plant scale are pointed out that allow the elimination of these compounds upon oxidation of the strip-gas produced when contaminated water is freed from chlorinated ethylenes by air-stripping.
- Prager, Lutz,Dowideit, Peter,Langguth, Helmut,Schuchmann, Heinz-Peter,Von Sonntag, Clemens
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p. 1641 - 1647
(2007/10/03)
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- Oxidation of alcohols by dimethyldioxirane
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The kinetics of oxidation of a series of monoalomic alcohols (methanol, 2-propanol, 2-butanol, 2-methyl-1-propanol, 2-chloroethanol, 1,3-dichloro-2-propanol, benzyl alcohol), hydroxyacetic acid, and 1,3-butandiol (ROH) by dimethyldioxirane (1) was studied. The reaction kinetics obeys the second order equation w = k[ROH][1]. The rate constants were measured in the range of 7 - 50 C, and the activation parameters were found. To describe the reaction rate constants as a function of the ROH structure, the two-parametric Taft equation was used, which takes into account both the polar and resonance substituent effects. Alcohol oxidation produces the corresponding carbonyl compounds, viz., ketones from secondary alcohols and aldehydes from primary alcohols, in yields of at least 80%. The results were explained by the competition of the molecular (oxenoid) and radical mechanisms. The introduction of electron-withdrawing substituents into the alcohol molecule increases the contribution of the radical channel of the reaction.
- Grabovskii,Suvorkina,Kabal'nova,Khursan,Shereshovets
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p. 1332 - 1337
(2007/10/03)
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- Kinetics and mechanism of oxidation of aliphatic aldehydes by 2,2′-bipyridinium chlorochromate
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Oxidation of six aliphatic aldehydes by 2,2′-bipyridinium chlorochromate (BPCC) in dimethyl sulphoxide (DMSO) leads to the formation of corresponding carboxylic acids. The reaction is first order each in BPCC and the aldehyde. The reaction is catalysed by hydrogen ions. The hydrogen-ion dependence has the form: kobs = a + b[H+]. The oxidation of deuteriated acetaldehyde, MeCDO, exhibits a substantial primary kinetic isotope effect (kH/kD = 5.90 at 298K). The oxidation of acetaldehyde has been studied in nineteen different organic solvents. The solvent effect has been analysed using Taft's and Swain's multiparametric equations. The rate constants correlate well with Taft's σ* values; reaction constants being negative. A mechanism involving transfer of hydride ion has been suggested.
- Kumbhat,Sharma,Banerji
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p. 1169 - 1173
(2007/10/03)
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- Chloroacetoxylation of oleic acid - a kinetic study
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The kinetics of the addition reaction of chloroacetic acid to oleic acid (chloroacetoxylation) in the presence of sulfuric acid as a catalyst were investigated. The reactions were carried out at the same concentration of both reactants at various temperatures and catalyst content. The reaction time ranged from 30 min up to 12 h, and the reaction course was observed by determining mainly iodine value, and chlorine content of the oil samples at 30-min intervals. The experimental data fitted the reversible second-first order rate equation for bi-molecular-unimolecular type reactions. The reaction constants of the forward and reverse reactions were obtained at temperatures 70 and 80 °C. The effect of sulfuric acid content on the reaction constant was investigated at 70 and 80 °C.
- Doulia, Danae,Rigas, Fotis,Gimouhopoulos, Kostantinos
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p. 239 - 242
(2007/10/03)
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