cas 95-77-2, 3,4-Dichlorophenol | Articles data

Articles about 95-77-2Total 34 be found

Article title
Article abstract
Author
Journal number and time
Download

Electrophotocatalytic C?H Heterofunctionalization of Arenes
The electrophotocatalytic heterofunctionalization of arenes is described. Using 2,3-dichloro-5,6-dicyanoquinone (DDQ) under a mild electrochemical potential with visible-light irradiation, arenes undergo oxidant-free hydroxylation, alkoxylation, and amination with high chemoselectivity. In addition to batch reactions, an electrophotocatalytic recirculating flow process is demonstrated, enabling the conversion of benzene to phenol on a gram scale.
Huang, He,Lambert, Tristan H.
supporting information
p. 11163 - 11167
(2021/04/19)

A dichlorophenol synthesis method (by machine translation)
The present invention provides a kind of dichlorophenol synthetic method, comprises the following steps: S1, will be 1, 4 - dichlorobenzene alkylation reaction, to obtain the 1, 4 - dichloro - 2 - isopropyl benzene; or the 1, 3 - dichlorobenzene alkylation reaction, to obtain the 1, 3 - dichloro - 4 - cumene; or the 1, 2 - dichlorobenzene alkylation reaction, to obtain 1, 2 - dichloro - 4 - cumene; S2, to the 1, 4 - dichloro - 2 - cumene in alkyl, 1, 3 - dichloro - 4 - cumene in alkyl or 1, 2 - dichloro - 4 - alkyl in the cumene, through oxidation, the formula x structure obtained dichloro peroxide; S3, will the catalytic decomposition of the peroxide states two chlorine respectively, to obtain the dichlorophenol and acetone. The present invention provides a method for synthesizing of the dichlorophenol obtained the product content is high, the three waste less generation, mild reaction conditions, easy operation, low production cost. (by machine translation)
-
Paragraph 0033; 0054; 0056

(2019/06/05)

A new process to prepare 3,6-dichloro-2-hydroxybenzoic acid, the penultimate intermediate in the synthesis of herbicide dicamba
Glyphosate [N-(phosphonomethyl)glycine] is a broad spectrum, post-emergent herbicide that is among the most widely used agrochemicals globally. Over the past 30 years, there has been a development of glyphosate-resistant weeds, which pose a significant challenge to growers and crop scientists, resulting in lower crop yields and increased costs. 3,6-Dichloro-2-methoxybenzoic acid (dicamba) is the active ingredient in XtendiMax a standalone herbicide developed by Bayer Crop Science to control broadleaf weeds, including glyphosate-resistant species. 3,6-Dichloro-2-hydroxybenzoic acid (3,6-DCSA) is the penultimate intermediate in the synthesis of dicamba. Existing dicamba manufacturing routes utilize a high temperature, high pressure Kolbe-Schmitt carboxylation to prepare 3,6-DCSA. Described in this Letter is a new, non-Kolbe-Schmitt process to prepare 3,6-DCSA from salicylic acid in four chemical steps.
Walker, Daniel P.,Harris, G. Davis,Carroll, Jeffery N.,Boehm, Terri L.,McReynolds, Matthew D.,Struble, Justin R.,van Herpt, Jochem,van Zwieten, Don,Koeller, Kevin J.,Bore, Mangesh
p. 1032 - 1036
(2019/03/17)

Ammonium Salt-Catalyzed Highly Practical Ortho-Selective Monohalogenation and Phenylselenation of Phenols: Scope and Applications
An ortho-selective ammonium chloride salt-catalyzed direct C-H monohalogenation of phenols and 1,1′-bi-2-naphthol (BINOL) with 1,3-dichloro-5,5-dimethylhydantoin (DCDMH) as the chlorinating agent has been developed. The catalyst loading was low (down to 0.01 mol %) and the reaction conditions were very mild. A wide range of substrates including BINOLs were compatible with this catalytic protocol. Chlorinated BINOLs are useful synthons for the synthesis of a wide range of unsymmetrical 3-aryl BINOLs that are not easily accessible. In addition, the same catalytic system can facilitate the ortho-selective selenylation of phenols.
Xiong, Xiaodong,Yeung, Ying-Yeung
p. 4033 - 4043
(2018/05/22)

Electrochemical Hydroxylation of Arenes Catalyzed by a Keggin Polyoxometalate with a Cobalt(IV) Heteroatom
The sustainable, selective direct hydroxylation of arenes, such as benzene to phenol, is an important research challenge. An electrocatalytic transformation using formic acid to oxidize benzene and its halogenated derivatives to selectively yield aryl formates, which are easily hydrolyzed by water to yield the corresponding phenols, is presented. The formylation reaction occurs on a Pt anode in the presence of [CoIIIW12O40]5? as a catalyst and lithium formate as an electrolyte via formation of a formyloxyl radical as the reactive species, which was trapped by a BMPO spin trap and identified by EPR. Hydrogen was formed at the Pt cathode. The sum transformation is ArH+H2O→ArOH+H2. Non-optimized reaction conditions showed a Faradaic efficiency of 75 % and selective formation of the mono-oxidized product in a 35 % yield. Decomposition of formic acid into CO2 and H2 is a side-reaction.
Khenkin, Alexander M.,Somekh, Miriam,Carmieli, Raanan,Neumann, Ronny
supporting information
p. 5403 - 5407
(2018/04/19)

Photocatalytic benzene and benzene derivative direct hydroxylation or amination method
The invention discloses a photocatalytic benzene and benzene derivative direct hydroxylation or amination method. The method is characterized by comprising the following steps: (1) adding a photo-sensitizer and a cobalt catalyst into a solvent to obtain a solution (A); (2) adding benzene (or benzene derivatives), water, ammonia gas, and amide derivatives (or sulfonamide derivatives) into the solution (A) to obtain a solution (B); and (3) in a N2 (or Ar) environment, radiating the solution (B) by a medium pressure mercury lamp, a high pressure mercury lamp, a xenon lamp, or an LED lamp to obtain phenols or amines and H2. For the first time, a photo-sensitizer and a cobalt catalyst are combined and applied to photocatalytic hydroxylation and amination of benzene. The conditions of the method are mild, light is taken as the driving energy, no oxidant is added, the only byproduct is H2, and the whole process is green, concise, and efficient. High selective benzene one-step hydroxylation to generate phenol or high selective phenol/benzene one-step amination to generate aniline is realized, and the method can be applied to the production of phenol and aniline.
-
Paragraph 0122-0123

(2017/11/29)

The Catalyst-Controlled Regiodivergent Chlorination of Phenols
Different catalysts are demonstrated to overcome or augment a substrate's innate regioselectivity. Nagasawa's bis-thiourea catalyst was found to overcome the innate para-selectivity of electrophilic phenol chlorination, yielding ortho-chlorinated phenols that are not readily obtainable via canonical electrophilic chlorinations. Conversely, a phosphine sulfide derived from 2,2′-Bis(diphenylphosphino)-1,1′-binaphthyl (BINAP) was found to enhance the innate para-preference of phenol chlorination.
Maddox, Sean M.,Dinh, Andrew N.,Armenta, Felipe,Um, Joann,Gustafson, Jeffrey L.
supporting information
p. 5476 - 5479
(2016/11/17)

Photocatalytic Hydrogen-Evolution Cross-Couplings: Benzene C-H Amination and Hydroxylation
We present a blueprint for aromatic C-H functionalization via a combination of photocatalysis and cobalt catalysis and describe the utility of this strategy for benzene amination and hydroxylation. Without any sacrificial oxidant, we could use the dual catalyst system to produce aniline directly from benzene and ammonia, and phenol from benzene and water, both with evolution of hydrogen gas under unusually mild conditions in excellent yields and selectivities.
Zheng, Yi-Wen,Chen, Bin,Ye, Pan,Feng, Ke,Wang, Wenguang,Meng, Qing-Yuan,Wu, Li-Zhu,Tung, Chen-Ho
supporting information
p. 10080 - 10083
(2016/09/04)

SELECTIVE HYDROLYSIS AND ALCOHOLYSIS OF CHLORINATED BENZENES
The present invention relates to a process for providing a compound of formula (I):, wherein R is hydrogen or R', wherein R' is –(C1-C4)alkyl, and Hal is a halogen, the process comprising the step of: reacting a compound of formula (II) wherein Hal is defined as above, with an alkali metal alkoxide of the formula XOR', wherein X is an alkali metal, and R' is defined as above.
-
Page/Page column 15

(2015/04/22)

PROCESS FOR HYDROLYZING 1,2,4-TRIHALOBENZENE
The present invention relates to a process for providing a compound of formula (I): wherein Hal is a halogen, the process comprising the step of: reacting a compound of formula (II) wherein Hal is defined as above, with an alkali metal sulfite of the formula X2SO3 and an alkali metal hydroxide of the formula YOH, wherein X and Y are independently selected from an alkali metal.
-
Page/Page column 11

(2015/04/22)

Acceleration of the Dakin reaction by trifluoroacetic acid
An acceleration of the Dakin reaction caused by addition of trifluoroacetic acid is described. The modified protocol converts aromatic aldehydes to the corresponding phenols within 4 hours at room temperature by means of hydrogen peroxide in acidic medium. This acceleration is attributed to the stability of hydrogen peroxide in an acidic medium. This modified protocol provides alternative and easy access to important phenolic precursors that have been used in the synthesis of various natural products.
Natu, Arun D.,Burde, Ameya S.,Limaye, Rohan A.,Paradkar, Madhusudan V.
p. 381 - 382
(2014/07/08)

A quantitative assessment of the production of OH and additional oxidants in the dark Fenton reaction: Fenton degradation of aromatic amines
This paper reports the results of a kinetic study into the transformation of 2,4- and 3,4-dichloroaniline (2,4-DCA, 3,4-DCA) and of methyl yellow (MY) with the Fenton reagent in aqueous solution. All the substrates can be degraded in the presence of Fe(II) + H2O2, but the reaction between Fe(II) and H2O2 causes substrate degradation and Fe(II) oxidation within seconds under the adopted conditions. The HPLC, GC-MS and IC analyses only allow the monitoring of the reaction after all Fe(II) has been consumed, when degradation proceeds more slowly via Fe(III) reduction to Fe(II). Substrate degradation in the first part of the reaction was studied by stopped-flow spectrophotometry, using MY as substrate. The results are consistent with a reaction involving OH, where both Fe(II) and H 2O2 compete with MY for the hydroxyl radical. However, the experimental data indicate that OH is unlikely to be the only product of the reaction between Fe(II) and H2O2. Another species, possibly the ferryl ion (FeO2+), is formed as well but has a negligible role in MY degradation. The Fenton reaction would thus yield both OH (about 60% at pH 2) and ferryl (about 40%), and the 60:40 branching ratio between OH and the other species is compatible with additional data here reported concerning the degradation of 2,4-DCA and 3,4-DCA in the first ferrous step of the Fenton reaction. The reported findings will hopefully indicate a way out of a long-lasting controversy concerning the mechanism of the Fenton process, also suggesting an approach to quantitatively determine the formation yields of the reactive species as well as a strategy to identify the reactant that is actually involved in substrate transformation.
Minero, Claudio,Lucchiari, Mirco,Maurino, Valter,Vione, Davide
p. 26443 - 26450
(2013/12/04)

2-(Trimethylsilyl)ethanol as a new alcohol equivalent for copper-catalyzed coupling of aryl iodides
2-(Trimethylsilyl)ethanol as a new alcohol equivalent has been employed for copper-catalyzed coupling of aryl iodides. Using mild reaction conditions, it has been observed that substituted phenols and phenols with sensitive functional groups can be readily prepared.
Dibakar, Mullick,Prakash, Anjanappa,Selvakumar, Kumaravel,Ruckmani, Kandasamy,Sivakumar, Manickam
p. 5338 - 5341
(2011/10/19)

SYNTHESIS OF CLAY-TEMPLATED SUBNANO-SIZED ZERO VALENT IRON (ZVI) PARTICLES, CLAYS CONTAINING SAME, AND USE OF BOTH IN CONTAMINANT TREATMENTS
A clay comprising a 2:1 aluminosilicate clay having negative charge sites, the 2:1 aluminosilicate clay containing subnano-sized zero valent iron (ZVI) particles distributed on clay surfaces is provided. In one embodiment, at least some or all of the particles have a cross-section of five (5) angstroms or less. Methods of synthesizing and the novel clays and the clay-templated subnano-scale ZVI particles themselves are also described. Such novel products are useful in a variety of remediation applications, including for reduction and dechlorination reactions.
-
Page/Page column 7-8

(2011/06/23)

Expedient synthesis of 3-alkoxymethyl- And 3-aminomethyl-pyrazolo[3,4-b] pyridines
An effective strategy has been developed for the preparation of 3-alkoxymethyl-pyrazolo[3,4-b]pyridines, compounds that are currently not readily accessible by existing synthetic methods. Further manipulation of these compounds allows for access to 3-alkoxymethyl-pyrazolo[3,4-b]pyridines with a variety of substitution patterns as well as 3-aminomethyl-pyrazolo[3,4-b] pyridines.
Beutner, Gregory L.,Kuethe, Jeffrey T.,Kim, Mary M.,Yasuda, Nobuyoshi
supporting information; experimental part
p. 789 - 794
(2009/06/20)

New metabolites in the degradation of α- and γ- hexachlorocyclohexane (HCH): Pentachlorocyclohexenes are hydroxylated to cyclohexenols and cyclohexenediols by the haloalkane dehalogenase LinB from Sphingobium indicum B90A
Technical hexachlorocyclohexane (HCH) and lindane are obsolete pesticides whose former production and use led to widespread contaminations posing serious and lasting health and environmental risks. Out of nine possible stereoisomers, α-, β-, γ-, and -HCH are usually present at contaminated sites, and research for a better understanding of their biodegradation has become essential for the development of appropriate remediation technologies. Because haloalkane dehalogenase LinB was recently found responsible for the hydroxylation of β-HCH, δ-HCH, and δ-pentachlorocyclohexene (δ-PCCH), we decided to examine whether β- and γ-PCCH, which can be formed by LinA from α-and γ-HCH, respectively, were also converted by LinB. Incubation of such substrates with Escherichia coli BL21 expressing functional LinB originating from Sphingobium indicum B90A showed that both β-PCCH and γ-PCCH were direct substrates of LinB. Furthermore, we identified the main metabolites as 3,4,5,6-tetrachloro-2-cyclohexene-1-ols and 2,5,6-trichloro-2-cyclohexene-1,4-diols by nuclear magnetic resonance spectroscopy and gas chromatography-mass spectrometry. In contrast to α-HCH, γ-HCH was not a substrate for LinB. On the basis of our data, we propose a modified γ-HCH degradation pathway in which γ-PCCH is converted to 2,5-cyclohexadiene-1,4-diol via 3,4,5,6-tetrachloro-2-cyclohexene- 1-ol and 2,5,6-trichloro-2-cyclohexene-1,4-diol.
Raina, Vishakha,Rentsch, Daniel,Geiger, Thomas,Sharma, Poonam,Buser, Hans Rudolf,Holliger, Christof,Lal, Rup,Kohler, Hans-Peter E.
experimental part
p. 6594 - 6603
(2010/04/06)

Formation of chlorinated phenols, dibenzo-p-dioxins, dibenzofurans, benzenes, benzoquinnones and perchloroethylenes from phenols in oxidative and copper (II) chloride-catalyzed thermal process
Formation of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and chlorinated phenols on CuCl2 from unsubstituted phenol and three monochlorophenols was studied in a flow reactor over a temperature range of 100-425 °C. Heated nitrogen gas streams containing 8.0% oxygen were used as carrier gas. The 0.00024 mol of unsubstituted phenol and 0.00039 mol of each monochlorophenol were passed through a 1 g and 1 cm SiO2 particle containing 0.5% (Cu by mass) CuCl2. Chlorination preferentially occurred on ortho-(2, 6) and para-(4) positions. Chlorination increased up to 200 °C, and thereafter decreased as temperature increased. Chlorination of phenols plays an important role in the formation of the more chlorinated PCDD/Fs. Chlorinated benzenes are formed possibly from both chlorination of benzene and chlorodehydroxylation of phenols. Chlorinated phenols with ortho chlorine formed PCDD products, and major PCDD products were produced via loss of one chlorine. For PCDF formation, at least one unchlorinated ortho carbon was required.
Ryu, Jae-Yong
p. 1100 - 1109
(2008/12/21)

Process for the synthesis of phenols from arenes
A process to synthesize substituted phenols such as those of the general formula RR′R″Ar(OH) wherein R, R′, and R″ are each independently hydrogen or any group which does not interfere in the process for synthesizing the substituted phenol including, but not limited to, halo, alkyl, alkoxy, carboxylic ester, amine, amide; and Ar is any variety of aryl or hetroaryl by means of oxidation of substituted arylboronic esters is described. In particular, a metal-catalyzed C—H activation/borylation reaction is described, which when followed by direct oxidation in a single or separate reaction vessel affords phenols without the need for any intermediate manipulations. More particularly, a process wherein Ir-catalyzed borylation of arenes using pinacolborane (HBPin) followed by oxidation of the intermediate arylboronic ester by OXONE is described.
-
Page 22

(2008/06/13)

Kinetics of chlorination of phenol and monosubstituted phenols by t-butyl hypochlorite in aqueous alkaline medium
The kinetics of chlorination of the parent and sixteen monosubstituted phenols (2-chloro, 2-methyl, 2-carboxy, 2-nitro, 3-chloro, 3-methyl, 3-carboxy, 4-fluoro, 4-chloro, 4-bromo, 4-methyl, 4-ethyl, 4-methoxy, 4-carboxy, 4-acetyl and 4-nitro) by t-BuOCl have been studied in aqueous alkaline medium. The rates of reactions show first order kinetics each in |t-BuOCl| and |XC 6H4OH| and inverse first order in |OH-|. Variation in either ionic strength or addition of reaction product has no significant effect on the rates of reactions, while lowering of the dielectric constant of the medium increases the rate. The rates are measured at different temperatures and the activation parameters for all the phenols computed. A mechanism involving the electrophilic attack of phenoxide ions by HOCl in the rate determining step is suggested. The rates decrease in the order: 3-CH 3 > 2-CH3 > 4-OCH3 > 4-CH3 > 4-C2H5 > H > 3-Cl > 3-COO- > 4-F > 2-COO- > 4-Br > 2-Cl > 4-Cl > 4-COO- > 4-COCH3 > 2-NO2 > 4-NO2. Hammett equation of the type, log k = -3.44 - 2.35 ρ is found to be valid for substituent effects. The enthalpy and entropy of activation are correlated.
Moodithaya,Gowda, B. Thimme
p. 420 - 425
(2007/10/03)

Kinetics and mechanism of chlorination of phenol and substituted phenols by sodium hypochlorite in aqueous alkaline medium
The kinetics of chlorination of the parent and thirteen substituted phenols (2-methyl, 2-chloro, 2-carboxy, 3-methyl, 3-chloro, 3-carboxy, 4-methyl, 4-ethyl, 4-chloro, 4-bromo, 4-carboxy, 4-acetyl and 4-nitro phenols) by NaOCl have been studied in aqueous alkaline medium under varying conditions. The rates show first order kinetics each in [NaOCl] and [(X)C6H4(OH)] and inverse first order in [OH-]. Variation in ionic strength of the medium and addition of Cl have no significant effect on the rates of reactions. The rates of the reactions are measured at different temperatures and the activation parameters for all the phenols computed. A mechanism involving the electrophilic attack of the phenoxide ions by NaOCl in the rate determining step has been considered. The values of the pre-equilibrium and the rate determining steps have been calculated for all the phenols. The rates decrease in the order: 3-CH3 >2-CH3 >4-C2H5 = 4-CH3 >phenol >3-COO = 3-Cl > 2-COO >4-COO >2-Cl ? 4-Cl ? 4-Br > 4-COCH3 >4-NO2. Hammett plot of the type, log kobs = -2.88 -3.2980σ is found to be valid. The correlation between the enthalpies and the free energies of activations is reasonably linear with an isokinetic temperature of 300 K. Further, the energies of activation of all the phenols are optimised corresponding to the log A of the parent phenol through the equation, Ea = 2.303 RT (log A - log kobs). Similarly log A values of all the phenols are optimised corresponding to the Ea of PhOH through the equation, log A = log kobs + Ea/2.303RT. Ea increases with the introduction of electron-withdrawing groups into the benzene ring, while the introduction of the electron-releasing groups lowers Ea for the reaction. Similarly log A decreases with the substitution of electron-withdrawing groups, while log A increases on substitution with the electron-releasing groups.
Gowda,Mary
p. 1196 - 1202
(2007/10/03)

Identification of surrogate compounds for the emission of PCDD/F (I-TEQ value) and evaluation of their on-line realtime detectability in flue gases of waste incineration plants by REMPI-TOFMS mass spectrometry
Correlations between products of incomplete combustion (PIC), e.g., chloroaromatic compounds, can be used to characterise the emissions from combustion processes, like municipal or hazardous waste incineration. A possible application of such relationships may be the on-line real-time monitoring of a characteristic surrogate, e.g., with Resonance-Enhanced Multiphoton Ionization-Time-of-Flight Mass Spectrometry (REMPI-TOFMS). In this paper, we report the relationships of homologues and individual congeners of chlorinated benzenes (PCBz), dibenzo-p-dioxins (PCDD), dibenzofurans (PCDF) and phenols (PCPh) to the International Toxicity Equivalent (I-TEQ) of the PCDD/F (I-TEQ value) in the flue gas and stack gas of a 22 MW hazardous waste incinerator (HWI). As the REMPI detection sensitivity is decreasing with the increase of the degree of chlorination, this study focuses on the lower chlorinated species of the compounds mentioned above. Lower chlorinated species, e.g., chlorobenzene (MCBz), 1,4-dichlorobenzene, 2,4,6-trichlorodibenzofuran or 2,4-dichlorophenol, were identified as I-TEQ surrogates in the flue gas. In contrast to the higher chlorinated phenols, the lower chlorinated phenols (degree of chlorination 4) were not reliable as surrogates in the stack gas. The identified surrogates are evaluated in terms of their detectability by REMPI-TOFMS laser mass spectrometry. The outcome is that MCBz is the best suited surrogate for (indirect) on-line measuring of the I-TEQ value in the flue gas by REMPI-TOFMS. The correlation coefficient r of the MCBz concentration to the I-TEQ in the flue gas was 0.85.
Blumenstock,Zimmermann,Schramm,Kettrup
p. 507 - 518
(2007/10/03)

Investigation of the photocatalytic activity of TiO2-polyoxometalate systems
The present study reports the investigation of polyoxometalate catalyzed electron transfer from the conduction band of photoexcited TiO2 to molecular oxygen. The oxidation of 1,2-dichlorobenzene (DCB) was used as an index reaction for evaluating the photocatalyst systems TiO2-PW12O403-, TiO2-SiW12O40,4- and TiO2-W10O324- in oxygenated aqueous solution. Addition of these polyoxometalate (POM) anions to TiO2 suspensions resulted in significant rate enhancement for DCB oxidation. Photodegradation kinetics exhibited [POM] dependence, experiencing different maximum (k = 0.0318 min-1, 0.0108 min-1, and 0.0066 min-1) for each POM at different [POM] (0.1 mM PW12O403-, 0.07 mM SiW12O40,4- and 1 mM W10O32,4- respectively). The probability that the difference in the adsorption affinity of POMs on TiO2 surface could account for the observed ranking of photodegradation rates was ruled out by adsorption isotherm experiments that revealed similar binding constants for each POM (467 M-1, 459 M-1, and 417 M-1 for PW12O403-, SiW12O404-, and W10O324-, respectively). DCB degradation over TiO2 with O2 or POM+O2 systems can be modeled by the Langmuir-Hinshelwood (saturation kinetics) model. The concentration-independent rate constants (kL-H) for TiO2-O2, TiO2-W10O324-, TiO2-SiW12O404-, and TiO2-PW12O403- were 0.0818, 0.152, 0.421, and 0.638 min-1, respectively. An analysis of ΔG for electron transfer from the conduction band of TiO2 to POMs in this study shows that the electron transfer takes place even when it is endothermic.
Ozer, Ruya R.,Ferry, John L.
p. 3242 - 3246
(2007/10/03)

Reactions within Association Complexes: The Reaction of Imidazole with Substituted Phenyl Acetates in the Presence of Detergents in Aqueous Solution
The bimolecular rate constants for reaction of imidazole with phenyl acetates complexed with sodium dodecyl sulfate (SDS) or cetyltrimethylammonium bromide (CTAB) micelles obey Bronsted equations with βlg similar to that of the reaction in aqueous solution. The dissociation constants of ester (KS) and the hypothetical dissociation constant (KTS) of the transition state of the micelle complexes obey Hansch equations with similar sensitivities (p) to π (-0.66 and -0.589 for KS and -0.735 and -0.495 for KTS, respectively). The slopes also indicate that the microsolvation environments associated with the transition state and the complexed ester have aqueous character. The relative values of KTS and KS indicate that the transition state of the reaction of imidazole with ester is more weakly complexed to both micelles than is the reactant ester. Log KTS values are linear functions of log KS for reactions with both CTAB and SDS; the slopes are, respectively, -0.893 and -1.19 consistent with a slightly more "water-like" medium for the transition state than for the site of binding of ester with CTAB-micelle and slightly less for the SDS-micelle. The results for ester and transition state are consistent with the location of the phenyl residue in a hydrophobic region that possesses water molecules. It is concluded that the acetyl group in the complexed transition state is located in an aqueous part of the Stern region, whereas the phenyl residue is in a part of the Stern region that possesses alkane components. The derived kinetic and complexation parameters in these experiments refer to micelles with Stern regions that have been maintained at constant ionic compositions.
Pirinccioglu, Necmettin,Zaman, Flora,Williams, Andrew
p. 2537 - 2543
(2007/10/03)

The oxidation of polychlorinated benzenes by genetically engineered cytochrome P450(cam): Potential applications in bioremediation
Polychlorinated aromatic compounds are persistent environmental contaminants; we describe here the redesign and engineering of the haem monooxygenase cytochrome P450(cam) to oxidise these compounds efficiently to the chlorinated phenols which are readily degraded by many micro-organisms, thus providing a basis for novel systems for biological clean-up of these inert compounds.
Jones, Jonathan P.,O'Hare, Ellen J.,Wong, Luet-Lok
p. 247 - 248
(2007/10/03)

Catalysis by two sialidases with the same protein fold but different stereochemical courses: A mechanistic comparison of the enzymes from influenza A virus and Salmonella typhimurium
-
Guo Xumin,Laver,Vimr,Sinnott
p. 5572 - 5578
(2007/10/02)

Thermolysis of phenoxyaluminum compounds and formation of PCDD/F and their precursors
Within the study of the formation of chlorinated dioxins and dibenzofurans and their precursors the thermolysis of hexachloroethane over the aluminum melt was investigated. "De novo" synthesis of precursors of PCDD/F was studied in the model system AlCl3/elemental carbon. Totally chlorinated heterocyclic compounds have been detected parallel with the formation of organochlorine compounds. The possibility of inserting oxygen to aluminum organyls was presented. In order to gain more detailed knowledge of the catalytic behaviour of fly ash the chemistry of thermolysis of phenoxy- and chlorophenoxy aluminum compounds at 300°C with the presence and absence of Al2O3 was investigated. Reagent compounds and products of thermolysis were followed by mass spectrometry.
Voncina,Medved,Zerjal
p. 2029 - 2038
(2007/10/03)

Pathways for the hydrolysis of glycosides of N-acetylneuraminic acid
-
Ashwell,Guo,Sinnott
p. 10158 - 10166
(2007/10/02)

Primaerschritte der Umwandlung von Chlorbenzol-Derivaten durch Pseudomonas putida
-
Ballschmiter, Karlheinz,Scholz, Charlotte
p. 1026 - 1027
(2007/10/02)

Process for the production of 2-aryl-2H-benzotriazoles
A process for the production of 2-aryl-2H-benzotriazoles comprises reducing and cyclizing the corresponding o-nitroazobenzenes with hydrogen at a temperature in the range of about 20° C. to about 100° C. and at a pressure in the range of about 15 psia (1 atmosphere) to about 1000 psia (66 atmospheres) in an alkaline medium at a pH over 10 in the presence of a nickel catalyst, preferably molybdenum-promoted Raney nickel. High yields of pure product are obtained directly with a concomitant reduction of undesired by-product and a reduction in effluent pollution problems.
-
(2008/06/13)

Derivatives of perhydro-aza-heterocycles
The present invention provides new derivatives of perhydro-aza-heterocycles of the formula STR1 in which X is the oxo radical or hydrogen and the radical OR1, in which R1 is hydrogen or a substituted or unsubstituted aliphatic hydrocarbon radical, a substituted or unsubstituted araliphatic hydrocarbon radical or a substituted or unsubstituted aromatic hydrocarbon radical or an acyl radical, R2 is hydrogen or a substituted or unsubstituted aliphatic hydrocarbon radical, Y is oxygen or sulphur, n1 and n2 each are values of 1 to 3, n1 +n2 being at most four, and Ar is a substituted or unsubstituted aromatic hydrocarbon radical, and the acid addition salts, in particular the pharmaceutically acceptable acid addition salts thereof. These new substances possess valuable pharmacological properties, in particular antidepressant activity, and can be used for the treatment of mental depressions. Specific embodiments are trans- and cis-3-hydroxy-4-(3,4-dimethyl-phenoxy)-piperidine, trans- and cis-3-hydroxy-4-(2,3-dimethyl-phenoxy)-piperidine, their 1-methyl derivatives and the pharmaceutically acceptable salts of these substances.
-
(2008/06/13)

Process for the production of 2-aryl-2H-benzotriazoles
A process for the production of 2-aryl-2H-benzotriazoles comprises reducing and cyclizing the corresponding o-nitroazobenzenes with carbon monoxide at a temperature in the range of about 20° C. to about 150° C. and at a pressure in the range of about 15 psia (1 atmosphere) to about 1000 psia (66 atmospheres) in an alkaline medium at a pH over 10 in the presence of a copper-amine complex catalyst. High yields of pure product are obtained with a concomitant reduction of undesired by-products and a reduction in effluent pollution problems.
-
(2008/06/13)

Process for the production of 2,5-dichloro-4-bromophenol
This invention discloses a process for the preparation of 2,5-dichloro-4-bromophenol which comprises reacting a mixture of 2,5-dichlorophenol and 2,4-dichlorophenol with about 0.9 to about 1.2 molar amounts of bromine per mole of 2,5-dichlorophenol and thereafter recovering the 2,5-dichloro-4-bromophenol.
-
(2008/06/13)

Process for producing polyhalogenated phenols
A process for producing polyhalogenated phenol by mixing a polyhalogenated aniline with an aqueous sulfuric acid solution to obtain a suspension of fine particles of polyhalogenated aniline sulfate having the particle size of 50 μ or less, diazotizing the polyhalogenated aniline sulfate to obtain polyhalogenate benzenediazonium sulfate, hydrolyzing the resulting benzenediazonium sulfate by heating it as such, recycling to the diazotization step the aqueous sulfuric acid solution from which the desired polyhalogenated phenol has been separated.
-
(2008/06/13)

Process for the production of 2-aryl-2H-benzotriazoles
An improved process for the production of 2-aryl-2H-benzotriazoles by the reduction of o-nitroazobenzene intermediates with zinc in alkaline medium comprises employing a ratio of moles of alkali to moles of o-nitroazobenzene intermediate in the range of 0.2-1.7/1 in the presence of less than 150 ppm of iron based on zinc used. The improved process results in higher yields of high purity products with a concomitant reduction in the amount of undesired cleavage amine by-products and a reduction in effluent pollution problems. The process is carried out in a polar/non-polar solvent mixture.
-
(2008/06/13)