- Selective Reduction of α-Chloroketone to α-Chloroalcohol Using Hydrogen Transfer from Alcohol over Metal Oxide Catalysts
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The carbonyl group of 1,3-dichloro-2-propanone was reduced selectively through hydrogen transfer from 2-butanol over MgO, SiO2*Al2O3, Al2O3, and ZrO2. It is suggested that the reaction is promoted by either base or acid site of the catalysts.
- Gotoh, Kunihiro,Kubo, Jun,Ueda, Wataru,Mori, Tohru,Morikawa, Yutaka
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- Kinetics and mechanistic investigation into the degradation of naproxen by a UV/chlorine process
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In this study, UV irradiation combined with chlorine (UV/chlorine) was used to degrade naproxen (NPX), a typical non-steroidal anti-inflammatory drug (NSAID) widely used for the treatment of symptoms associated with inflammation, in water. Compared with UV irradiation alone and direct chlorination, the UV/chlorine process shows a synergistic effect on NPX degradation. The effects of different factors, including the chlorine dose, solution pH, and the presence of Cl-, HCO3- or humic acid (HA), on NPX degradation in the UV/chlorine process were investigated. The results indicated that the degradation of NPX followed pseudo-first-order kinetics in all cases, and the rate constant increased as the chlorine dose increased and decreased as the pH increased. The effects of the water matrix on UV/chlorine treatment were species-dependent. The NPX degradation rate was inhibited by the presence of HCO3- and HA but significantly improved by Cl-. LC/MS/MS analysis indicated that NPX decomposition in the UV/chlorine process was associated with decarboxylation, demethylation and hydroxylation. These results indicate that the UV/chlorine process is a promising technology for the treatment of water polluted by emerging contaminants, such as NPX. However, UV/chlorine can notably enhance the formation of disinfection by-products compared to direct chlorination, which should be carefully considered when integrating this process into drinking water treatment schemes.
- Gao, Yu-Qiong,Gao, Nai-Yun,Chu, Wen-Hai,Yang, Qin-Lin,Yin, Da-Qiang
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p. 33627 - 33634
(2017/07/12)
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- PROCESS FOR PREPARING 1,3-DICHLOROACETONE
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Epichlorohydrin is produced from acetone by (1) chlorinating acetone to form monochloroacetone; (2) disproportionating the monochloroacetone in the presence of a platinum catalyst, a strong acid and preferably a chloride source (for example, added as a salt or from hydrolysis of monochloroacetone) and some water to produce acetone and 1,3-dichloroacetone; (3) hydrogenating the 1,3-dichloroacetone in the presence of a catalyst to produce 1,3-dichlorohydrin; and (4) cyclizing the 1,3-dichlorohydrin with a base to produce epichlorohydrin.
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Page/Page column 7-8
(2008/06/13)
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- Esterification of carboxylic acid salts
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Mono- or polycarboxylic acid esters are prepared by reacting a salt of such carboxylic acid with an organic halocompound, e.g., a (cyclo)alkyl, (cyclo)alkenyl, aryl or aralkyl halide, in an aqueous reaction medium, in the presence of a catalytically effective amount of a phase transfer catalyst, for example an onium salt.
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- Process for the hydroxyalkylation of a carbocyclic aromatic ether
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The present invention concerns a process for the hydroxyalkylation of a carbocyclic aromatic ether. The invention preferably relates to the preparation of 3-methoxy-4-hydroxybenzyl alcohol by the hydroxymethylation of guaiacol. It also concerns the oxidation of the hydroxyalkylated ethers obtained, in particular the oxidation of 3-methoxy-4-hydroxybenzyl alcohol to 3-methoxy-4-hydroxybenzaldehyde, commonly known as "vanillin". The process for the hydroxyalkylation of a carbocyclic aromatic ether of the invention consists of reacting the aromatic ether with a carbonyl compound in the presence of a catalyst and is characterized in that the hydroxyalkylation reaction is carried out in the presence of an effective quantity of a zeolite.
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- Chemistry of the biosynthesis of halogenated methanes: C1-organohalogens as pre-industrial chemical stressors in the environment?
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We have chemical evidence that in the biosynthesis of the halomethanes C1H(4-n),X(n) (n = 1-4) three different pathways of biogenic formation have to be distinguished. The formation of methyl chloride, methyl bromide, and methyl iodide, respectively, has to be considered as a methylation of the respective halide ions. The dihalo- and trihalomethanes are formed via the haloform and/or via the sulfo-haloform reaction. The possible formation of tetrahalomethanes may involve a radical mechanism. Methionine methyl sulfonium chloride used as substrate in the incubation together with chloroperoxidase (CPO) and H2O2 gave high yields of monohalomethanes only. We were able to show that next to the CPO/H2O2 driven haloform reaction of carbonyl activated methyl groups also methyl-sulphur compounds - e.g. dimethylsulfoxide, dimethylsulfone, and the sulphur amino acid methionine - can act as precursors for the biosynthesis of di- and trihalogenated methanes. Moreover, there is some but not yet very conclusive evidence for an enzymatic production of tetrahalogenated methanes. In our experiments with chloroperoxidase involving amino acids and complex natural peptide based substrates, dihalogenated acetonitriles and several other volatile halogenated but yet unidentified compounds were formed. On the basis of these experiments we like to suggest that biosynthesis of halogenated nitriles occurs in general and therefore a natural atmospheric background should exist for halogenated acetonitriles and halogenated acetaldehydes, respectively.
- Urhahn, Thorsten,Ballschmiter, Karlheinz
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p. 1017 - 1032
(2007/10/03)
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- Para-hydroxyalkylation of hydroxylated aromatic compounds
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Hydroxylated aromatic compounds devoid of substituents in the para-position to the hydroxyl group thereof are para-hydroxyalkylated, e.g., into optionally substituted p-hydroxymandelic acid compounds, more particularly p-hydroxymandelic acid and 3-methoxy-p-hydroxymandelic acid, by condensing same with an organic carbonyl compound in the presence of a quaternary ammonium hydroxide.
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- Reactions of α-Chloro- and α,α-dichloro-β-oxoaldehydes with Anionic Nucleophiles
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The reaction of α-chloro and α,α-dichloro-β-oxoaldehydes with anionic nucleophiles (NaOH, MeONa, PhONa, MeCOOK) proceeds mainly via haloform splitting with elimination of the formyl group; only with the most nucleophilic sodium methoxide, the reaction at the β-carbon atom partially occurs.The intermediate anions react with benzaldehyde to give difficulty accessible polyfunctional compounds.
- Guseinov, F. I.,Tagiev, S. Sh.,Moskva, V. V.
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- REACTIONS OF α-CHLORO- AND α,α-DICHLORO-β-CARBONYL-SUBSTITUTED ALDEHYDES WITH AMINES
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Depending on the nature of the substrate (the chlorodicarbonyl compound) and the nature of the nucleophilic reagent (the amine), the reaction of α-chloro- and α,α-dichloro-β-carbonyl-substituted aldehydes with amines takes place mainly in three directions i.e., with the formation of enamines or imines or with cleavage of the C-CHO bond of the aldehydes.
- Guseinov, F. I.,Klimentova, G. Yu.,Moskva, V. V.
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p. 530 - 533
(2007/10/02)
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- PRODUCTION OF 1,1,1-TRIHALOGENO-2-ALKANOLS AND SOME OF THEIR PROPERTIES
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The reaction of acyclic and carbocyclic carbonyl compounds with haloforms was studied in liquid ammonia and dimethylformamide in the presence of basic catalysts (t-BuOK, KOH).As a result of the reaction 1,1,1-trihalogeno-2-alkanols were obtained.They were used for the synthesis of 1,1,1-trihalogeno-2-methoxyalkanes, 1,1-dibromoalkenes, 1,1-dichloro-2-methoxyalkenes, and alkyl mono- and dichloromethyl ketones.
- Bal'on, Ya. G.,Shul'man, M. D.,Vakulenko, L. I.
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p. 1231 - 1237
(2007/10/02)
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- 1,1,1-TRICHLOROPROPANONE: A MILD, SELECTIVE ACETYLATING AGENT
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The use of the title compound in the acetylation of primary and secondary amines is described.
- Salim, Jose Roberto,Nome, Faruk,Rezende, Marcos Caroli
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p. 1181 - 1188
(2007/10/02)
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- A Convenient Synthesis of 1-Chloro-2-alkanones
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1-Chloro-2-alkanones (α-chloromethylketones) were conveniently prepared by chlorination of methyl β-ketoesters and subsequent demethoxycarbonylation using 50percent sulfuric acid.
- Kimpe, Norbert De,Cock, Wim De,Schamp, Niceas
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p. 188 - 190
(2007/10/02)
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- The chlorination of acetone: a complex kinetic analysis
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Rate constants are reported for all of the major steps followed in the chlorination of acetone, including the chlorination of mono- and 1,1-dichloroacetone, the chlorination of hydroxyacetone, the chlorination and hydroxide-catalyzed rearrangement of 1,1-dihydroxyacetone, and the haloform cleavage of trichloroacetone. pKa values are reported for hydroxyacetone and monochloroacetone.Rate constants for the hydrolyses of chloroacetone and 1,1-dichloroacetone are reported; these reactions are probably not SN2 displacements but proceed by addition of hydroxide and intramolecular displacement.
- Guthrie, Peter J.,Cossar, John
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p. 1250 - 1266
(2007/10/02)
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- CHLORINATION OF KETONES WITH TRICHLOROISOCYANURIC ACID
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Trichloroisocyanuric acid is an effective reagent for the chlorination of ketones in the alpha position.
- Hiegel, Gene A.,Peyton, Kim B.
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p. 385 - 392
(2007/10/02)
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- Chlorination of Aliphatic Ketones in Methanol
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The chlorination of aliphatic ketones in methanol has been examined.The product distributions in methanol differ substantially from those obtained by chlorination in carbon tetrachloride.The reaction in methanol favors addition of chlorine to the least substituted carbon α to the carbonyl group.The effect is especially pronounced if an α carbon bearing two substituents is present.The distribution of products is determined by the relative stability of the enol ethers formed from the ketone under the reaction conditions.
- Gallucci, R. R.,Going, R.
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p. 2532 - 2538
(2007/10/02)
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- Halogen Epoxides, 3. Reactions of 2-Chloro- and 2,3-Dichlorooxiranes with Silver Tetrafluoroborate: Synthesis of α-Fluorinated Carbonyl Compounds
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Reactions of chlorinated oxiranes with silver tetrafluoroborate in ether have been investigated.Substituted-2-chlorooxiranes (4a - e) afforded the corresponding α-fluorocarbonyl compounds (7a - e) as major products and the isomeric α-chlorocarbonyl compounds (8a - e) as minor products.Substituted 2,3-dichlorooxiranes (10, 14, 20, 24) yielded the isomeric α,α-dichloroketones (13, 19, 22, 26b, 29b) as well as the corresponding α-chloro-α-fluoroketones (12, 17, 21, 26a, 29a) and α,β-unsaturated α-chloroketones (18, 23, 27, 30).The course of the reaction was rationalized.Similar reaction with α-chloroketones and with α,α-dichloroketones succeeded only at substrates (8b, 35) in which the chlorine substituents were in benzylic positions.
- Griesbaum, Karl,Keul, Helmut,Kibar, Riza,Pfeffer, Bernd,Spraul, Manfred
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p. 1858 - 1870
(2007/10/02)
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