cas 87-65-0, 2,6-Dichlorophenol | Articles data

Articles about 87-65-0Total 59 be found

Article title
Article abstract
Author
Journal number and time
Download

The use of polymeric sulfides as catalysts for the para-regioselective chlorination of phenol and 2-chlorophenol
Various poly(alkylene sulfide)s have been synthesized and used as catalysts to enhance the para-regioselectivity in chlorination of phenol and 2-chlorophenol using freshly distilled sulfuryl chloride in the presence of AlCl3 as an activator. Poly(alkylene sulfide)s having alternating spacers, one having three methylene groups and the second having three, six or nine methylene groups were the most para-regioselective catalysts in chlorination of both phenol and 2-chlorophenol. For example, chlorination of phenol and 2-chlorophenol in the presence of optimal examples of such poly(alkylene sulfide)s gave 4-chlorophenol and 2,4-dichlorophenol as the major products in 94.8 and 95.4% yields, respectively, compared with 75.4 and 55.0% yields in the absence of catalysts. In addition, double chlorination of phenol in the presence of poly(alkylene sulfide)s gave 2,4-dichlrophenol in up to 97.1% yield compared with only 58.6% in the absence of catalysts.
Smith, Keith,Hegazy, Amany S.,El-Hiti, Gamal A.
p. 1 - 12
(2019/11/20)

Method for catalytically synthesizing dichlorophenol by adopting surfactant catalyst
The invention belongs to the field of chemical synthesis, and particularly relates to a method for dichlorinating a phenolic substance, which directionally and selectively catalyzes substitution of C-H at an ortho-position and a para-position of phenolic hydroxyl by Cl atoms. The dichlorination method comprises the following steps: adding concentrated hydrochloric acid into a reactor, then addinga catalyst and a phenolic reactant, heating in an oil bath under violent stirring, and then adding a H2O2 aqueous solution with the mass percent concentration of 30-60%, and reacting for 2-26 hours and then ending the reaction, collecting an organic phase, and diluting with acetonitrile to prepare a sample for analysis. According to the dichlorination method disclosed by the invention, water is used as a reaction medium, so that the use of a traditional VOC organic solvent and heavy metals is avoided, and the method is safer and more environment-friendly. Meanwhile, the reaction conditions aremild, the operation is simple and convenient, the product yield is high, and the atom economy is high.
-
Paragraph 0032-0033; 0040-0041

(2020/06/09)

Method for producing high purity 2, 4 - dichlorophenol
The invention provides a method for producing high purity 2, 4 - dichlorophenol, including: (1) heating and melting the raw materials, the mixed catalyst is added in the raw material, wherein the feedstock is phenol, O-phenol or [...] in at least one of, the mixed catalyst is phenyl sulfide, mixture of ferric chloride and trifluoromethanesulfonic acid; (2) to maintain the temperature of the material is 40 - 100 °C, to the material to carry out chlorination chlorinating agent is filled in the catalytic reaction to obtain 2, 4 - dichlorophenol crude product, the chlorinating agent is chlorine or sulfuryl chloride in at least one of; (3) to said 2, 4 - dichlorophenol crude melt crystallization, to obtain 2, 4 - dichlorophenol product. In this invention the states the chlorizating agent can be a chloride, can also be chlorine, the two can achieve higher conversion rate of raw materials, the application in the catalytic chlorination reaction the crude product obtained without rectification, only through the melt crystallization to obtain the purity 99% of the 2, 4 - dichlorophenol product.
-
Paragraph 0107-0115

(2019/07/04)

Reductive dehalogenation and dehalogenative sulfonation of phenols and heteroaromatics with sodium sulfite in an aqueous medium
Prototropic tautomerism was used as a tool for the reductive dehalogenation of (hetero)aryl bromides and iodides, or dehalogenative sulfonation of (hetero)aryl chlorides and fluorides, using sodium sulfite as the sole reagent in an aqueous medium. This protocol does not require a metal or phase transfer catalyst and avoids using organic solvent as the reaction medium. This method is especially suitable for substrates that readily tautomerize (such as 2-or 4-halogenated aminophenols and 4-halogenated resorcinols), for which dehalogenation or sulfonation proceeds under mild reaction conditions (≤60 °C). As sodium sulfite is an inexpensive, safe, and environmentally less hazardous reagent, this method has at least three potential applications: (i) in the deprotection of halogens as protecting groups, using sodium sulfite as a reducing agent; (ii) in the sulfonation of aromatic halides under mild reaction conditions avoiding hazardous and corrosive reagents/solvents; and (iii) in the transformation of toxic halogenated aromatics into less harmful compounds.
Tomanová, Monika,Jedinák, Luká?,Canka?, Petr
supporting information
p. 2621 - 2628
(2019/06/03)

Synthetic method of 2,6-dichlorophenol
The invention discloses a synthetic method of 2,6-dichlorophenol. The synthetic method of 2,6-dichlorophenol comprises following steps: 1, in an organic solvent, 2,2,6,6-tetrachlorocyclohexan-1-one istaken as a raw material, and is subjected to reaction with an organic base under backflow conditions so as to obtain 2,6-dichlorophenol; and 2, a reaction solution obtained in step 1 is filtered, andobtained filtrate is subjected to underpressure distillation for complete drying so as to obtain 2,6-dichlorophenol crud product. The 2,6-dichlorophenol yield of the synthetic method is 84.4%; usingof high pollution catalysts is avoided; discharge of three wastes is reduced; production cost is reduced; and high industrial application value is achieved.
-
Paragraph 0028-0054; 0058-0064

(2018/07/30)

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)

Preparation process of 2,4-dichlorophenol
The invention discloses a preparation process of 2,4-dichlorophenol. The preparation process comprises the following steps: chloridizing phenol or o-chlorophenol serving as a raw material and a mixture which is prepared from boric acid, phenyl sulfide and ferric trichloride and serves as a catalyst to generate a 2,4-dichlorophen coarse product, and rectifying the coarse product to obtain a target product. The mixed catalyst used in the reaction has a positioning effect, so that the content of p-chlorophenol in a chlorinated phenols mixture generated by the reaction is greater than 65 percent, the content of the 2,4-dichlorophenol in di-chlorophenol generated in the reaction is greater than 95 percent, the number of di-chlorophenol impurities generated in the reaction is reduced, and the 2,4-dichlorophenol with the content greater than 99.5 percent and the total yield of 95 percent or above can be obtained by rectification treatment; furthermore, the reaction yield is greatly increased, and the yield of the p-chlorophenol is also increased.
-
Paragraph 0019

(2017/09/08)

Selective water-based oxychlorination of phenol with hydrogen peroxide catalyzed by manganous sulfate
An efficient method for the selective oxychlorination of phenol to 2,4-dichlorophenol catalyzed by manganous(ii) sulfate is developed using hydrogen chloride as a chlorinating source, hydrogen peroxide as an oxidant and water as a solvent. The catalyst has high activity and selectivity under mild conditions. The products are automatically isolated from aqueous solution, which also contains the catalyst at the end of the reaction, and hence product separation and catalyst recycling are both simple in this system. The performance of manganous(ii) sulfate with the oxidative chlorinating system HCl/H2O2 indicates that this is a promising synthetic method for the manufacture of various 2,4-dichlorophenol derivatives.
Xin, Hongchuan,Yang, Shilei,An, Baigang,An, Zengjian
p. 13467 - 13472
(2017/03/11)

MCM-41-supported phosphotungstic acid-catalyzed cleavage of C-O bond in allyl aryl ethers
Removal of the protecting allyl group from allyl aryl ethers in the presence of other oxygen protecting groups was successfully achieved using a solid acid supported on the high surface area material MCM-41. The catalyst showed excellent activity in the presence of various electron withdrawing, electron donating, and oxidizable functional groups. The methodology is also very useful for the removal of protecting allyl groups of various natural products such as vanillin, isovanillin, and other oxygen functionalized aldehydes and ketones.
Sakate, Sachin S.,Kamble, Sumit B.,Chikate, Rajeev C.,Rode, Chandrashekhar V.
p. 4943 - 4949
(2017/07/12)

Preparation process of chlorinated phenol
The invention discloses a preparation process of chlorinated phenol; phenol is used as a raw material, a mixture of arbitrary one of diphenyl sulfide and dimethyl sulfide, arbitrary one of acetic acid and toluene sulfonic acid and arbitrary one of aluminum trichloride and ferric trichloride is used as a catalyst, a chlorinated phenol crude product is generated through sulfuryl chloride chlorination, and a target product is obtained by melt crystallization. The mixed catalyst used in the reaction has a positioning function, the content of p-chlorophenol in the monochlorophenol mixture generated from the reaction is greater than 83%, the content of 2,4-dichlorophenol in dichlorinated phenol generated from the reaction is greater than 98%, the amount of trichlorinated phenol impurities generated from the reaction is reduced, and 2,4,6-dichlorophenol with the content greater than 99% and the total yield more than or equal to 98% is obtained without purification treatment; moreover, energy consumption is greatly reduced, and high-content p-chlorophenol and high-quality 2,4-dichlorophenol can be produced at the same time.
-
Paragraph 0020

(2017/04/11)

Electrochemical degradation of bisphenol A in chloride electrolyte—Factor analysis and mechanisms study
Electrochemical oxidation technology is a powerful method in the degradation of recalcitrant organics, due to the high oxidizing ability of active chlorine and reactive oxygen species generated in the cell. However, influencing factor analysis and intermediates detection during the electrochemical removal of organics has not been extensively studied in the chloride electrolyte. In this study, an orthogonal test array design of L16(4)3 was carried on with Pt anode in NaCl electrolyte, using the typical endocrine disruptor bisphenol A (BPA) as the model pollutant. The influencing order of the three main factors for BPA degradation rate was current density?>?initial organic concentration?>?chloride concentration, based on the analysis of variance in this experiment. This emphasized the very significance of the active chlorine and hydroxyl radicals which were closely related with the potential of the system and the applied current density. Then both organic and inorganic Cl-byproducts were determined. The concentration of chloride decreased to 9.88?mM with an initial of 10?mM in the 480-min electrolysis and extremely low concentration of active chlorine was produced in this system (maximized at 0.037?mM) for the first set. Neither chlorate nor perchlorate was detected with the Pt anode. The factor of current density influenced greatest on the formation of chloroform due to the amount of active chlorine affected by the current density. Finally, intermediates generated in the electrolysis cell were concretely investigated. Compared with traditional chlorination, the amount of chlorinated-BPA (2, 2′-D2CBPA and T4CBPA) generated was relatively less (2.46 and 10.00?μM equiv BPA), which might be due to their fast simultaneously transformation in the electrochemical system. With the isopropylidene bridge cleavage of chlorinated-BPA, one-ring aromatic compounds (2,6-dichlorophenol, 2,6-dichloro-2,5-cyclohexadiene, 2,4,6-trichlorophenol) occurred at the same time. Finally, chlorinated-BPA was totally transformed and low molecular chlorinated compounds were detected to the end of the experiment. This is one of the very few studies dealing with chlorinated organic intermediates formed in chloride electrolyte, and thus these findings may have significant technical implications for electrochemical treatment of wastewater containing BPA.
Li, Hongna,Long, Yujiao,Wang, Yu,Zhu, Changxiong,Ni, Jinren
p. 1144 - 1152
(2017/01/06)

IPSO-hydroxylation of boronic acid via ozonolysis: A metal-, ligand-, and base-free method
Here, we have developed a simple, efficient, and metal-, ligand-, and base-free method for the synthesis of functionalized aryl and alicyclic alcohols via ozonolysis of corresponding boronic acids in aqueous ethanol. The procedure is compatible with a variety of functional groups and can be utilized as an alternative method for the synthesis of hydroxy arenes and alicyclic alcohols.
Bommegowda, Yadaganahalli K.,Mallesha, Ningegowda,Vinayaka, Ajjampura C.,Sadashiva, Maralinganadoddi P.
supporting information
p. 268 - 270
(2016/05/02)

2,2,6,6-Tetramethylpiperidine-catalyzed, ortho-selective chlorination of phenols by sulfuryl chloride
2,2,6,6-Tetramethylpiperidine (TMP)-catalyzed (1- 10%) chlorinations of phenols by SO2Cl2 in aromatic solvents are more ortho selective than with primary and less hindered secondary amine catalysts. Ortho-selective chlorination is successful even with electron deficient phenols such as 2-hydroxybenzaldehyde and 2'- hydroxyacetophenone. Notably, ortho selectivity increases with the reaction temperature. On the other hand, tetraalkylammonium chloride-catalyzed chlorinations are moderately para selective.
Saper, Noam I.,Snider, Barry B.
p. 809 - 813
(2014/04/03)

Room-temperature Pd-catalyzed C-H chlorination by weak coordination: One-pot synthesis of 2-chlorophenols with excellent regioselectivity
A room-temperature Pd(ii)-catalyzed regioselective chlorination reaction has been developed for a facile one-pot synthesis of a broad range of 2-chlorophenols. The reaction demonstrates an excellent regioselectivity and reactivity for C-H chlorination. This reaction represents one of the rare examples of mild C-H functionalization at ambient temperature.
Sun, Xiuyun,Sun, Yonghui,Zhang, Chao,Rao, Yu
p. 1262 - 1264
(2014/02/14)

Simultaneous identification of Fenton degradation by-products of diclofenac, ibuprofen and ketoprofen in aquatic media by comprehensive two-dimensional gas chromatography coupled with mass spectrometry
Diclofenac, ibuprofen and ketoprofen are anti-inflammatory drugs intensively used both in human and animal treatment. Due to their high stability these compounds are partially removed by wastewater treatment plants and from this reason the development of some alternative treatments such as advanced oxidative processes are necessary. The main problems in the optimization of an advanced oxidative process rise from the difficulties which appear in the identification of degradation by-products necessary for the establishment of degradation pathway. In this paper a developed method for the simultaneous identification of Fenton degradation by-products of the three above mentioned pharmaceuticals is presented. The obtained results show the comprehensive two-dimensional gas chromatography coupled with mass spectrometry as a proper method for the analysis of the complex mixture of compounds resulted from the Fenton degradation process. Moreover, some compounds never mentioned in the scientific literature were identified. (Chemical Equation Presented).
Beldean-Galea, Mihail Simion,Coman, Virginia,Copaciu, Florina,Thiébaut, Didier,Vial, Jér?me
p. 1021 - 1027
(2015/07/15)

Hydroxyl radical reactions with 2-chlorophenol as a model for oxidation in supercritical water
To determine the detailed mechanism of 2-chlorophenol (2-CP) oxidation in supercritical water, both the experiments and theoretical calculations were conducted in this paper. A set of experiments was performed to oxidize 2-CP in supercritical water under temperatures of 380-420 °C, pressure of 25 MPa, residence times of 0-60 s, and H2O2 as oxidant. By determining the molar yields of products, the primary single-ring products were identified as chlorohydroquinone, 2,4-dichlorophenol (2,4-DCP), 2,6-DCP, and 4-CP. The trends for the molar yields of the four products were analyzed at various temperatures and residence times. And built upon the trends, the possible reaction pathways were conjectured. Subsequently, the reaction mechanism was further verified by theoretical calculations, in which density functional theory was adopted as the computational method. The calculated results have well illustrated the experimental results and ascertained the reaction paths we proposed. Springer Science+Business Media Dordrecht 2013.
Zhang, Jiaming,Ma, Chunyuan,Sun, Youmin,Ren, Xiaohua
p. 973 - 990
(2014/05/06)

Cu-Mn spinel oxide catalyzed regioselective halogenation of phenols and N-heteroarenes
A novel simple, mild chemo- and regioselective method has been developed for the halogenation of phenols using Cu-Mn spinel oxide as a catalyst and N-halosuccinimide as halogenating agent. In the presence of Cu-Mn spinel oxide B, both electron-withdrawing and electron-donating groups bearing phenols gave monohalogenated products in good to excellent yields with highest para-selectivity. The para-substituted phenol gave monohalogenated product with good yield and ortho-selectivity. N-Heteroarenes such as indoles and imidazoles also gave monohalogenated products with high selectivity. Unlike the copper-catalyzed halogenation, the present method works well with electron-withdrawing group bearing phenols and gives comparatively better yields and selectivity. The Cu-Mn spinel catalyst is robust and reused three times under optimized conditions without any loss in catalytic activity. Nonphenolics did not undergo this transformation.
Singh, Parvinder Pal,Thatikonda, Thanusha,Kumar, K. A. Aravinda,Sawant, Sanghapal D.,Singh, Baldev,Sharma, Amit Kumar,Sharma,Singh, Deepika,Vishwakarma, Ram A.
experimental part
p. 5823 - 5828
(2012/09/05)

Electrooxidation of phenol on a Ti/RuO2 anode: Effect of some electrolysis parameters
The influences of electrolysis time, anodic area, current density and supporting electrolyte on phenol and its byproducts degradation on a Ti/RuO 2 anode were investigated. It was observed that phenol and its byproducts were rapidly broken down in the presence of chloride ions. Gas chromatography/mass spectrometry (GC/MS) data have shown that the presence of chloride ions lead to chlorophenols formation, due to reactions with Cl 2. and/or OCl generated during electrolysis. However, these intermediate products were also degraded later by the oxidizing agents. The standards established by the CONAMA (Brazilian National Council for the Environment) for phenols and chlorophenols in effluents were achieved after 360 min of electrolysis with a current density of 10 mA cm-2. Cyclic voltammograms obtained with the anodes before and after 436 h of electrolysis under severe salinity conditions (2 mol L-1) and current density (800 mA cm-2) showed that Ti/RuO2 did not lose its electrocatalytic properties. This fact indicates that Ti/RuO2 can be used for the treatment of effluents containing phenols in a chloride environment.
Dos Santos, Iranildes D.,Afonso, Ju?lio C.,Dutra, Achilles J. B.
scheme or table
p. 875 - 883
(2012/02/01)

The use of sodium chlorate/hydrochloric acid mixtures as a novel and selective chlorination agent
Sodium chlorate/hydrochloric acid mixtures were used to chlorinate activated arenes and the α-position of ketones. This chlorination method was used to produce selectively mono-, di-, and trichlorinated compounds by controlling the molarity of sodium chlorate. This reagent proved to be much more efficient and easier to handle than chlorine gas.
Moon, Byung Seok,Choi, Han Young,Koh, Hun Yeong,Chi, Dae Yoon
experimental part
p. 472 - 476
(2011/12/04)

Recyclable catalysts for palladium-catalyzed C - O coupling reactions, Buchwald-Hartwig aminations, and Sonogashira reactions
Simply reuse: Homogeneous palladium catalysts are effective and attractive tools for advanced organic synthesis (see example). Compound 1 belongs to a new class of ligands that enable recycling of the precious-metal catalyst directly from the reaction without any heterogenization.
Dumrath, Andreas,Wu, Xiao-Feng,Neumann, Helfried,Spannenberg, Anke,Jackstell, Ralf,Beller, Matthias
supporting information; experimental part
p. 8988 - 8992
(2011/02/23)

LiOAc-catalyzed chemoselective deprotection of aryl silyl ethers under mild conditions
-
Wang, Bing,Sun, Hui-Xia,Sun, Zhi-Hua
scheme or table
p. 1781 - 1784
(2009/08/07)

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)

Mechanisms of dioxin formation from the high-temperature oxidation of 2-chlorophenol
The homogeneous, gas-phase oxidative thermal degradation of 2-chlorophenol was studied in a 1 cm i.d., fused silica flow reactor at a concentration of 88 ppm, reaction time of 2.0 s, over a temperature range of 300 to 1000 °C. Observed products in order of yield were as follows: 4,6-dichlorodibenzofuran (4,6-DCDF) > dibenzo-p-dioxin (DD) > 1-monochlorodibenzo-p-dioxin (1-MCDD), 4-chlorodibenzofuran (4-MCDF), dibenzofuran (DF), naphthalene, chloronaphthalene, 2,4-dichlorophenol, 2,6-dichlorophenol, phenol, chlorobenzene, and benzene. In contrast to pyrolysis, 4,6-DCDF is the major product rather than DD, and 1-MCDD and naphthalene are formed at temperatures as low as 400 °C. Under oxidative conditions, ?OH and Cl? are the major carriers, which favors 4,6-DCDF formation over DD or 1-MCDD through abstraction of H? through diketo- and ether- intermediates. It is proposed that below 500 °C, unimolecular tautomerization/HCl elimination and CO elimination/isomerization reactions result in the formation of 1-MCDD and naphthalene, respectively.
Evans, Catherine S.,Dellinger, Barry
p. 122 - 127
(2007/10/03)

Formation and destruction of chlorinated pollutants during sewage sludge incineration
The limitations facing land filling and recycling and the planned ban on sea disposal of sludge leads to the expectation that the role of sludge incineration will increase in the future. The expected increase in sludge incineration will also increase scrutiny of the main drawback to sewage sludge incineration-the formation of hazardous air pollutants (HAPs). Despite the extensive body of knowledge available on sewage sludge combustion, very few studies have been conducted on the formation of HAPs during sludge combustion. In this work, the interactions between sewage sludge pyrolysis products and sludge ash were investigated using a dual chamber flow reactor system and a horizontal laboratory scale reactor. The results of this study shows that sludge ash can catalyze oxidation and chlorination of organics. In the absence of HCl in the gas stream, sludge ash acts as an oxidizing catalyst, but in the presence of HCl, sludge ash acts as a chlorination catalyst producing high yields of organochloride compounds.
Fullana, Andres,Conesa, Juan A.,Font, Rafael,Sidhu, Sukh
p. 2953 - 2958
(2007/10/03)

Investigations of the reactions of monochloramine and dichloramine with selected phenols: Examination of humic acid models and water contaminants
The phenols are an important area of investigation because they are substituents in the humic acids and are common contaminants in water. The reactivities and orientations of two common phenols (phenol and m-cresol), and some of their chlorinated intermediates with aqueous monochloroamine and dichloroamine were presented. m-Cresol was more reactive than phenol with both chlorinating agents. NH2Cl and NHCl2 showed extensive reactivity toward the phenols, even the partially chlorinated less reactive intermediates would be expected to fully chlorinate the activated positions in phenolic substituents in the humic acids.
Heasley, Victor L.,Fisher, Audra M.,Herman, Erica E.,Jacobsen, Faith E.,Miller, Evan W.,Ramirez, Ashley M.,Royer, Nicole R.,Whisenand, Josh M.,Zoetewey, David L.,Shellhamer, Dale F.
p. 5022 - 5029
(2008/04/18)

Selective ortho-chlorination of phenol using sulfuryl chloride in the presence of t-butylaminomethyl polystyrene as a heterogeneous amine catalyst
ortho-Chlorination of phenol with sulfuryl chloride in the presence of a t-butylaminomethyl polystyrene catalyst, proceeds in high conversion (～98%) and with high selectivity (～89%). Reaction of phenol with sulfuryl chloride in the presence of a catalytic amount of the heterogeneous amine catalyst, t-butylaminomethyl polystyrene, in a nonpolar solvent, proceeds with high conversion (～98%) and with high selectivity (～89%) to ortho-chlorophenol. The catalyst is stable under the chlorination conditions, and can easily be regenerated by filtration and reused. This method could be applicable to other phenols.
Gnaim, Jallal M.,Sheldon, Roger A.
p. 8471 - 8473
(2007/10/03)

Electroreduction of Organic Compounds, 34 [1]. Cathodic Dehalogenation of Chloroarenes with Electron-Donating Substituents
The electrochemical reduction of chlorinated arenes with electron-donating substituents, i.e. chlorotoluenes, -anisoles and -phenols, is studied. Preparative electrolyses are run in various solvent-supporting electrolytes under potentiostatic and galvanostatic conditions at lead or carbon cathodes. A partial and mostly regioselective hydrodechlorination of compounds with two or more chloro substituents is possible under suitable conditions. The replacement of one single chloro substituent, in particular in a para-position, is difficult. Highly toxic and persistent oligochloro derivatives are thus transformed into less problematic compounds with a low degree of chlorination. The chlorine content of real-life materials such as extracts of soil contaminated with chlorinated phenols and Nitrofen can also be significantly decreased by electroreduction.
Kranz, Olaf,Voss, Jürgen
p. 1187 - 1200
(2007/10/03)

Kinetics of degradation of diclofenac sodium in aqueous solution determined by a calorimetric method
An isothermal heat conduction microcalorimeter has been used to study the stability of diclofenac sodium both alone and its inclusion complex with β-cyclodextrin in aqueous solution. The rates of heat evolved during degradation of diclofenac sodium have been measured by a highly sensitive microcalorimetric technique as function of concentration, pH and temperature. The calorimetric accessible data have been incorporated in the equations for determination of rate constants, change in enthalpy and order of reaction. The decomposition of diclofenac sodium both alone and its inclusion complex with β-cyclodextrin in solution corresponds to a pseudo-first order reaction. The values of rate constants, k's at 338.15 K, (calculated from the variation of heat evolution with the time) for the degradation of diclofenac sodium at pH 5, 6, 7, 8 and its inclusion complex with β-cyclodextrin at pH 7 are found to be 4.71 × 10-4, 5.69 × 10-4, 6.12 × 10-4, 6.57 × 10-4 and 4.26 × 10-4 h-1 respectively. There is good agreement between calorimetric determined t0.5 and literature values. It has been found that β-cyclodextrin retards the degradation of diclofenac sodium. The kinetic parameters have been calculated for the reaction. The negative entropy of activation suggests the formation of an ordered transition state.
Chadha, Renu,Kashid,Jain
p. 631 - 635
(2007/10/03)

Process for functionalising a phenolic compound carrying an electron-donating group
The invention concerns a method for functionalizing a phenolic compound bearing an electron-donor group, in said group para position, inter alia a method for the amidoalkylation of a phenolic compound bearing an electron-donor group, and more particularly, a phenolic compound bearing an electron-donor group preferably, in the hydroxyl group ortho position. The method for functionalizing in para position with respect to an electron-donor group carried by a phenolic compound is characterised in that the phenolic compound bearing an electron-donor group is subjected to the following steps: a first step which consists of protecting the hydroxyl group in the form of a sulphonic ester function; a second step which consists in reacting the protected phenolic compound with an electrophilic reagent; optionally, a third step deprotecting the hydroxyl group.
-
(2008/06/13)

Role of phenoxy radicals in PCDD/F formation
In this work, the role of phenoxy radicals in polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F) formation was investigated by studying the slow oxidation of 2-chlorophenol (2-CP) and 2-chloroanisole (2-CA) at a gas-phase concentration of 4 ppm (～2.1 × 104 μg/m3) over a temperature range of 400-800°C. Residence times were maintained at 2.0 ± 0.10 s. PCDD/F reaction products were dibenzofuran, dibenzo-p-dioxin, 4-chlorodibenzofuran, 1-chlorodibenzo-p-dioxin, 4,6-dichlorodibenzofuran, and 1,6-dichlorodibenzo-p-dioxin (1,6-DCDD). Major products observed in these experiments were 2,6-dichlorophenol, 3-phenyl-2-propenal, 1-indanone, 1,3-isobenzofurandione, and 3-phenyl-2-propenoyl chloride. The 2-CP and 2-CA experiments, along with the variable concentration 2-CA experiments, showed that the concentration of radicals present in the oxidation system has a significant effect on the PCDD/F product distribution and ultimately the PCDD/PCDF ratio. Also, the observation of dichlorinated phenoxy phenol and dichlorinated dihydroxybiphenyl, the proposed intermediate species in the radical-radical mechanism, suggests that radical-radical mechanism dominates gas-phase PCDD/F formation. This information will be helpful in constructing a detailed kinetic mechanism of PCDD/F formation/destruction in combustor postcombustion zone.
Sidhu, Sukh,Edwards, Phil
p. 531 - 541
(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)

Selenium(IV) oxide catalyzed oxidation of aldehydes to carboxylic acids with hydrogen peroxide
A convenient method for oxidative transformation of aromatic, heteroaromatic and aliphatic aldehydes into carboxylic acids is presented. It is based on the oxidation of aldehydes in THF using 30% hydrogen peroxide in the presence of 5 molar % of selenium(IV) oxide. The scope and limitation of the method are discussed.
Brzaszcz,Kloc,Maposah,Mlochowski
p. 4425 - 4434
(2007/10/03)

Conjugation and proton exchange equilibria. Heteroconjugation constants in substituted phenol-piperidine systems in acetonitrile
It has been shown by mathematical transformations that the final equations and expressions required for determining equilibrium concentrations of major species in HA + B systems are analogous to those used previously for HA + A1- systems. Heteroconjugation constants K→AHB = [AHB]/([HA][B]) for eight substituted phenol (HA)-piperidine (B) systems in acetonitrile (AN) were determined from emf measurements. A fairly linear dependence between log K→AHB and ΔpKaAN = pKBH+AN - pKHAAN was observed with a slope of 0.52. The [KAHB2/(KAHA - KBHB+)]atδpKa=0 quotient appeared to be much greater than [KAHA1-2/(KAHA - KA1HA1-)]atΔpKa=0 calculated from results obtained previously for HA + A1- type systems. From this fact it has been concluded that the formation of AHB type complexes (relative to the AHA- and BHB+ type complexes) is likely to be favoured by their overall neutrality ensuring weaker peripheral interactions.
Magonski, Jozef,Rajzer, Barbara
p. 1181 - 1185
(2007/10/03)

Natural formation of chlorinated phenols, dibenzo-p-dioxins, and dibenzofurans in soil of a Douglas fir forest
The natural formation of 4-MCP, 24/25- and 26-DCP, and 245-TrCP was detected in four selected areas of a rural Douglas fir forest where the humic layer was spiked in situ with a solution of Na37Cl and covered by an enclosure, after 1 year of incubation. Chlorinated phenols (CP) can be formed naturally from organic matter and inorganic chloride by either de novo synthesis or chloroperoxidase (CPO)-catalyzed chlorination. The natural CP congeners were found to be present in high concentrations in soil compared to the other congeners, except for 245-TrCP which was present in a relatively low concentration. This study did not reveal which source, natural or anthropogenic, caused the observed concentrations. Some 20 chlorinated dibenzo-p-dioxins and dibenzofurans (CDD/F) were found to be formed naturally in soil of the Douglas fir forest; the formation of three 2,3,7,8-substituted congeners, 2378-TeCDD, 12378-PeCDD, and 123789-HxCDD, deserves special attention. A formation mechanism has been proposed which starts from naturally formed CP congeners and which probably involves peroxidase mediation. Chlorination of CDD/F congeners by the CPO-mediated reaction cannot be ruled out, but seems to be less likely due to the absence of several predicted congeners. The natural formation of 4-MCP, 24/25- and 26-DCP, and 245-TrCP was detected in four selected areas of a rural Douglas fir forest where the humic layer was spiked in situ with a solution of Na37Cl and covered by an enclosure, after 1 year of incubation. Chlorinated phenols (CP) can be formed naturally from organic matter and inorganic chloride by either de novo synthesis or chloroperoxidase (CPO)-catalyzed chlorination. The natural CP congeners were found to be present in high concentrations in soil compared to the other congeners, except for 245-TrCP which was present in a relatively low concentration. This study did not reveal which source, natural or anthropogenic, caused the observed concentrations. Some 20 chlorinated dibenzo-p-dioxins and dibenzofurans (CDD/F) were found to be formed naturally in soil of the Douglas fir forest; the formation of three 2,3,7,8-substituted congeners, 2378-TeCDD, 12378-PeCDD, and 123789-HxCDD, deserves special attention. A formation mechanism has been proposed which starts from naturally formed CP congeners and which probably involves peroxidase mediation. Chlorination of CDD/F congeners by the CPO-mediated reaction cannot be ruled out, but seems to be less likely due to the absence of several predicted congeners.
Hoekstra, Eddo J.,De Weerd, Henk,De Leer, Ed W. B.,Brinkman, Udo A.Th.
p. 2543 - 2549
(2007/10/03)

Oxidative chlorination, desulphonation, or decarboxylation to synthesize pharmaceutical intermediates: 2,6-Dichlorotoluene, 2,6-dichloroaniline, and 2,6-dichlorophenol
An alternative manufacturing process scheme was developed for 2,6-dichlorotoluene, 2,6-dichloroaniline, and 2,6-dichlorophenol, involving oxidative chlorination after protection of the starting material in the para position followed by deprotection involving desulphonation or decarboxylation. Oxidative chlorination of 4-methylbenzenesulphonic acid, 4-methylbenzoic acid, 4-aminobenzoic acid, and 4-hydroxybenzoic acid by using HCl-H2O2, and their subsequent desulphonation or decarboxylation, gave a 60-75% yield of the desired product.
Mukhopadhyay,Chandalia
p. 10 - 16
(2013/09/08)

An advanced method for the preparation of 2,6-dichlorodiphenylamine and its N-chloroacetyl derivative - Intermediates in the synthesis of antiinflammatory drug ortophenum
-
Ryabova,Bokanov,Isakovich,Kuzovkin,Grigor'ev,Levina,Shvedov,Granik
p. 38 - 40
(2007/10/03)

Reaction of Aromatic and Unsaturated Compounds with the Potassium Permanganate/HCI (HBr) Acetonitrile Reagent
Addition of hydrochloric or hydrobromic acid to a solution of potassium permanganate in acetonitrile produced a homogeneous mixture, which is suitable for laboratory chlorination or bromination, respectively. Aromatic compounds more reactive than alkylbenzenes can be chlorinated or brominated without additional catalyst. Alkenes and alkynes give the corresponding vicinal dihaloalkanes and vinyl halides. All reactions complete within two hours under mild condition (25-60 °C) with excellent to moderate yields.
Liu, Lilian Kao,Lin, Ching-Shan
p. 61 - 66
(2007/10/03)

Highly regioselective ortho-chlorination of phenol with sulfuryl chloride in the presence of amines
Chlorination of phenol with sulfuryl chloride catalyzed by amines in non-polar solvents is fast, and specific for monochlorination and highly regioselective for ortho-substitution. Under optimal conditions, phenol was chlorinated with an equimolar quantity of sulfuryl chloride in the presence of di-s-butylamine (0.8 mole% relative to phenol) to give after 1 h of reaction at 70°C a 90.1% yield of ortho-chlorophenol with an ortho/para ratio of 22.0.
Gnaim,Sheldon
p. 3893 - 3892
(2007/10/02)

Chlorination of ortho-chlorophenol
The polychlorophenols, e.g., 2,6-dichlorophenol (a known agrochemical intermediate), are effectively prepared by chlorinating ortho-chlorophenol with gaseous chlorine, optionally in the presence of other chlorophenols, characteristically in the molten state, and in the presence of a catalytically effective amount of a primary, secondary or tertiary amine.
-
(2008/06/13)

HIGH ORTHO-SELECTIVITY IN THE CHLORINATION OF PHENOLS WITH N-CHLORODIALKYLAMINES IN THE PRESENCE OF SILICA.
Phenols are readily chlorinated by N-chlorodialkylamines in the presence of silica.Furthermore, this approach allows greater selectivity for mono:di and ortho: para chlorination than is possible with many other approaches.
Smith, Keith,Butters, Michael,Nay, Barry
p. 1319 - 1322
(2007/10/02)

Chemical composition and use thereof
This invention relates to novel compositions comprising a N-halodialkylamine as defined in the specification and an inorganic oxide. The compositions are useful as halogenating agents for phenolic compounds. The compositions have the advantage that they are milder halogenating agents than halogens or hydrogen halides.
-
(2008/06/13)

Regioselective Para Chlorination of Activated Aromatic Compounds
A series of 2-alkylphenols were chlorinated with chlorine, sulfuryl chloride, and sulfuryl chloride catalyzed with a divalent sulfur compound a metal halide.The latter chlorinating system is the most regioselective for both para chlorination and for the degree of chlorination, i.e.,monochlorination.The selectivity is also demonstrated for 2-halophenols, 3-substituted phenols, and aromatic ethers.The reactive intermediate is proposed to be +>-> which explains the selectivity to the para isomer due to the bulkiness of the chlorinating agent.The observed differences in isomer distribution with the studied phenols are explained by the degree of hydrogen bonding of the phenol as seen in the IR and NMR as well as the differences in reactivity.
Watson, William David
p. 2145 - 2148
(2007/10/02)

SELECTIVE FUNCTIONALISATION. PART 8: SYNTHESES OF SOME NOVEL TENTACLE MOLECULES AND THEIR EFFECT UPON THE CHLORINATION OF PHENOL IN AQUEOUS AND METHANOLIC SOLUTION
-
Robinson, Derek I.,Sherrington David C.,Suckling, Colin J.
p. 1701 - 1728
(2007/10/02)

Tris(polyoxaalkyl)amines (Trident), a New Class of Solid-Liquid Phase-Transfer Catalysts
A new class of solid-liquid phase-transfer catalysts has been prepared.These tris(polyoxaalkyl)amines (I) are designed to obtain the best balance between straightforward synthesis (cheap starting materials), high activity, easy recovery, and low toxicity.The catalysts are synthesized from ethylene glycols by a simple one-step method in yields in the range of 65-81percent.They show high catalytic effects in aliphatic nucleophic substitutions and aromatic nucleophilic substitutions on activated and unactivated molecules.In the Ullman synthesis (a new PTC reaction) there is a synergic effect of anionic activation by tridents and by copper salts.Reactions have been carried out at temperatures up to 180 deg C without evidence of decomposition of the tris(polyoxaalkyl)amines. The behavior and catalytic activity of these catalysts are discussed.
Soula, Gerard
p. 3717 - 3721
(2007/10/02)

Vapour-phase Chemistry of Arenes. Part 10. Formation of Phenols in Air Oxidation of Benzene, Chlorobenzene, m-Dichlorobenzene, and Benzonitrile in the Presence of Cyclohexa-1,3-diene at ca. 600 K
In a flow reactor at 573-623 K, flow time ca. 2 min, vapours of benzene and derivatives, e.g. chlorobenzene and benzonitrile, are not measurably oxidized by air.In the presence of small amounts of cyclohexa-1,3-diene (1), however, substantial conversion of (1) is accompanied by formation of phenols from arenes.The main oxidation product of (1) is benzene, but some phenol, and cyclohex-3-enone (2) is also formed.Conversion of (1) is largely due to hydrogen abstraction by O2, log(A2/l mol-1 s-1)=8.9, E2 ca. 104 kJ mol-1.The resulting cyclohexadienyl radicalgives benzene by disproportionation with O2.Formation of phenol is explained by addition of O2 to cyclohexadienyl radical, followed by rearrangement and reaction with O2.Addition of HO2 to (1) is shown to be the likely first step in forming non-aromatic oxygenated products such as (2).This slow combustion of (1) leads to OH radicals which must be responsible for conversion of arene.Product data, especially isomeric composition of substituted phenols, as well as thermochemical-kinetic analysis indicate that, at ca. 600 K, a mechanistic transition occurs, from addition of OH (prevailing at lower temperatures) to hydrogen abstraction to give aryl radicals, which lead to phenol via ArO2 and ArO.
Mulder, Peter,Louw, Robert
p. 1135 - 1142
(2007/10/02)

CATALYTIC REARRANGEMENT OF THE γ-CHLOROALLYL ETHERS OF PHENOLS
The catalytic rearrangement of the γ-chloroallyl ethers of phenol, p- and o-cresol, p- and o-chlorophenol, and 2,4-dichlorophenol takes place by an intermolecular mechanism with the formation of alkenylphenols without inversion of the allylic unit.The transformation of the ethers with a CH3 group (ortho or para) in the benzene ring takes place under milder conditions than that of ethers with a chlorine atom at the same positions.
Andreev, N. A.,Bunina-Krivorukova, L. I.,Levashova, V. I.,Aleksandrova, E. K.
p. 1398 - 1402
(2007/10/02)

APPLICATIONS OF AMMONIUM FORMATE CATALYTIC TRANSFER HYDROGENOLYSIS--IV: A FACILE METHOD FOR DEHALOGENATION OF AROMATIC CHLOROCARBONS
Ammonium formate catalytic transfer hydrogenolysis, in the presence of palladium on carbon, has shown utility for the rapid dehalogenation of mono-or polychlorinated aromatic compounds in neutral media under ambient conditions of temperature and pressure.
Anwer, Mohmed K.,Spatola, Arno F.
p. 1381 - 1384
(2007/10/02)

Ortho-Specific Bromination of Phenols
Phenol as well as 3-substituted phenols are brominated exclusively in the ortho positions by N.N-dibromomethylamine, yielding 2.6-dibrominated phenols in excellent yields.Phenols bearing an ortho-substituent need N-bromomethylamine as the brominating agent to take up one bromine atom into the free ortho-position. para-Bromination is not observed in either case. 1-Naphthol gives 2-bromo-1-naphthol, 8-hydroxyquinoline gives 7-bromo-8-hydroxyquinoline with 80percent and 98percent yield respectively. ortho-Specific chlorination of phenols was carried out in some cases using N-chloro-alkylamines.
Schmitz, Ernst,Pagenkopf, Ingeborg
p. 998 - 1006
(2007/10/02)

SELECTIVE FUNCTIONALISATION-7; CHLORINATION OF AROMATIC COMPOUNDS IN THE PRESENCE OF TENTACLE MOLECULES WITH PYRIDINIUM HEAD GROUPS
tris-Pyridiniumalkyl triesters of benzene-1,3,5-tricarboxylic acid 3,6 and 11 carbon atoms in the alkyl chain interact with aromatic substrates, phenol, anisole, diphenyl ether and naphthalene in a manner dependent upon the struture of the substrate.Thus all three tentacle molecules interact with phenol through the pyridinium head group as shown by (1)H NMR (250 MHz) and confirmed by inhibition of chlorination of the bound phenol.The remaining substrates interact but away from the head group; chlorination is also inhibited.In these cases, a contributor to the low reactivity of the substrates to chlorination in the presence of the tentacle molecules is shown to be the unexpected inactivation of the chlorinating agent, t-butyl hypochlorite, by the tentacle molecules.
Robinson, D. I.,Sherrington, D. C.,Suckling, C. J.
p. 785 - 792
(2007/10/02)