- Nature's hydrides: rapid reduction of halocarbons by folate model compounds
-
Halocarbons R-X are reduced to hydrocarbons R-H by folate model compounds under biomimetic conditions. The reactions correspond to a halide-hydride exchange with the methylenetetrahydrofolate (MTHF) models acting as hydride donors. The MTHF models are also functional equivalents of dehalohydrogenases but, unlike these enzymes, do not require a metal cofactor. The reactions suggest that halocarbons have the potential to act as endocrinological disruptors of biochemical pathways involving MTHF. As a case in point, we observe the rapid reaction of the MTHF models with the inhalation anaesthetic halothane. The ready synthetic accessibility of the MTHF models as well as their dehalogenation activity in the presence of air and moisture allow for the remediation of toxic, halogenated hydrocarbons.
- Denk, Michael K.,Milutinovi?, Nicholas S.,Marczenko, Katherine M.,Sadowski, Natalie M.,Paschos, Athanasios
-
-
Read Online
- Tailorable carbazolyl cyanobenzene-based photocatalysts for visible light-induced reduction of aryl halides
-
Herein, a series of carbazolyl cyanobenzene (CCB)-based organic photocatalysts with a broad range of photoredox capabilities were designed and synthesized, allowing precise control of the photocatalytic reactivity for the controllable reduction of aryl halides via a metal-free process. The screened-out CCB (5CzBN), a metal-free, low-cost, scalable and sustainable photocatalyst with both strong oxidative and reductive ability, exhibits superior performance for both dehalogenation and C[sbnd]C bond-forming arylation reactions.
- Ou, Wei,Zou, Ru,Han, Mengting,Yu, Lei,Su, Chenliang
-
supporting information
p. 1899 - 1902
(2019/12/27)
-
- Base-catalyzed aryl halide isomerization enables the 4-selective substitution of 3-bromopyridines
-
The base-catalyzed isomerization of simple aryl halides is presented and utilized to achieve the 4-selective etherification, hydroxylation and amination of 3-bromopyridines. Mechanistic studies support isomerization of 3-bromopyridines to 4-bromopyridines proceedsviapyridyne intermediates and that 4-substitution selectivity is driven by a facile aromatic substitution reaction. Useful features of a tandem aryl halide isomerization/selective interception approach to aromatic functionalization are demonstrated. Example benefits include the use of readily available and stable 3-bromopyridines in place of less available and stable 4-halogenated congeners and the ability to converge mixtures of 3- and 5-bromopyridines to a single 4-substituted product.
- Bandar, Jeffrey S.,Puleo, Thomas R.
-
p. 10517 - 10522
(2020/10/18)
-
- Oxidative bromination of non-activated aromatic compounds with AlBr3/KNO3 mixture
-
Bromination of non-activated aromatic compounds with reaction mixture containing KNO3 and AlBr3 was studied in liquid substrates and in solvent. Aluminium bromide has three different roles in this reaction mixture. First, it is a source of bromide ions, which are essential in oxidative bromination application. Second, it acts as a catalyst, and lastly, it forms acidic environment via its hydrolysis, which is necessary for enhancement of the oxidising properties of nitrate ions. It was shown that when changing the reaction conditions, different side reactions (like nitration or Friedel–Crafts type arylation) can occur. However, it is possible to guide the reaction path and receive the desired outcome by choosing the suitable reaction conditions. In addition, it was shown that there has to be water content in this reaction mixture as the bromine formation rate depends on it, while there exists an optimal volume of water, where bromine formation is the fastest.
- Rahu, Ida,J?rv, Jaak
-
p. 1219 - 1227
(2019/11/13)
-
- Preparation method of M-dibromobenzene
-
The invention provides a preparation method of m-dibromobenzene. The preparation method comprises the following steps: (1) adding a strong acid into 2,4-dibromoaniline or 2,6-dibromoaniline, then adding a sodium nitrite aqueous solution to performing diazotization reaction on the 2,4-dibromoaniline or 2,6-dibromoaniline at low temperature and acid conditions, and preparing diazo dibromoaniline salt aqueous solution after the reaction is completed; (2) adding a reducing agent into the diazo dibromoaniline salt aqueous solution prepared in the step (1), and enabling the system to react fully toprepare an m-dibromobenzene-containing mixed liquid; (3) standing to layer the mixed liquid prepared in the step (2), then separating an inorganic phase from an organic phase, and distilling the organic phase to obtain the m-dibromobenzene. The method is simple in process steps; the obtained product is low in production cost.
- -
-
Paragraph 0010-0015
(2019/09/17)
-
- Compounds and methods for the reduction of halogenated hydrocarbons
-
The present application relates to methods for the reduction of halogenated hydrocarbons using compounds of Formula (I): wherein the reduction of the halogenated compounds is carried out, for example, under ambient conditions without the need for a transition metal containing co-factor. The present application also relates to methods of recovering precious metals using compounds of Formula (I) that are absorbed onto a support material.
- -
-
Page/Page column 16
(2017/12/27)
-
- PROCESS FOR THE PREPARATION OF ORGANIC BROMIDES
-
The present invention provides a process for the preparation of organic bromides, by a radical bromodecarboxylation of carboxylic acids with a bromoisocyanurate.
- -
-
Paragraph 00164
(2017/07/28)
-
- Substd. photoisomerization arom. compd. method
-
Isomerizing substituted aromatic compounds (I), comprises carrying out isomerization in the presence of a salt melt, which contains a metal compound (II) and at least one metal compound (III). Isomerizing substituted aromatic compounds of formula (Ar1-R n) (I) or their mixtures, comprises carrying out isomerization in the presence of a salt melt, which contains a metal compound of formula ([M1][X1] m 1) (II) and at least one metal compound of formula ([M2][X2] m 2) (III). Ar1 : n-valent aryl radical; R : halo, alkyl, fluoroalkyl, aryl, alkyl-aryl or amino; M1 : Al, Ga, In, Cu, Fe, Co or Ni; X1, X2 : halo, preferably Cl or Br; M2, m2 : alkaline earth metal or alkali metal, where M2 is preferably Li, Na, or K; m1 : Al, Ga, In, Fe(III), Co, Ni or Cu(II); and n : >= 2, preferably 2.
- -
-
Paragraph 0068
(2017/01/02)
-
- Reversible multicomponent self-assembly mediated by bismuth ions
-
Bi(iii) ions are capable of reversible, multicomponent self assembly with suitable tris-coordinate ligands. The nature of the self-assembled structures observed are dependent on the ligand coordination geometry, ligand protonation state and Bi concentration. These assemblies can exploit the maximum number of coordination sites at the Bi vertices (nine), and the self-assembly process has been studied by 1D NMR, Diffusion NMR, ESI-MS and X-ray crystallographic analysis. V-shaped coordinating ligands reversibly form discrete M 2L4, M2L3, and M2L 2 complexes dependent on ligand/bismuth concentration, whereas a linear coordinating ligand forms a single discrete M3L3 assembly.
- Johnson, Amber M.,Young, Michael C.,Hooley, Richard J.
-
p. 8394 - 8401
(2013/07/28)
-
- Palladium-catalyzed conversion of aryl and vinyl triflates to bromides and chlorides
-
The palladium-catalyzed conversion of aryl and vinyl triflates to aryl and vinyl halides (bromides and chlorides) has been developed using dialkylbiaryl phosphine ligands. A variety of aryl, heteroaryl, and vinyl halides can be prepared via this method in
- Shen, Xiaoqiang,Hyde, Alan M.,Buchwald, Stephen L.
-
supporting information; experimental part
p. 14076 - 14078
(2011/01/10)
-
- Route to prepare 4-bromo-1-oxypentafluorosulfanylbenzene
-
A process for preparing bromo-1-oxypentafluorosulfanylbenzene is provided, the process including the step of brominating pentafluorosulfanyloxybenzene with a bromination agent to provide the bromo-1-oxypentafluorosulfanylbenzene. The process is more effective than prior art processes for preparing such compounds.
- -
-
Page/Page column 4
(2008/06/13)
-
- Method for separating substances
-
An objective of the present invention is to provide electrophoretic separation methods and devices that enable the various features of a substrate surface that comes in contact with an electrophoresis medium to be controlled. The present invention provides methods for electrophoresing substances, which comprises the steps of: (a) adding a substance to be analyzed to an electrophoresis medium retained in a substrate, whose surface that has come in contact with the electrophoresis medium has been coated with a polymer membrane; and (b) adding electrophoretic pressure to the electrophoresis medium. For example, the use of a plasma-polymerized membrane allows the formation of a membrane with homogeneous quality and thickness on the surface of an arbitrary shape. In addition, desired characteristics can be conferred on the surface through selection of monomeric substances. Protein adsorption onto micro-chips can be effectively prevented as well.
- -
-
-
- Hydrodediazoniation of dry arenediazonium o-benzenedisulfonimides with hydrogen peroxide
-
This report describes the hydrodediazoniation of dry arenediazonium o-benzenedisulfonimides 1 with hydrogen peroxide (2) in THF at reflux. The new procedure is general, giving positive results in the presence of both electron-donating and electron-withdrawing substituents. Furthermore, it does not suffer from steric effects and always gives the pure reduction products 3 in excellent yields (15 examples, average yield = 93%). All the reactions show over 90% recovery of o-benzenedisulfonimide (4) that can be reused to prepare the salts 1. The collateral proofs we performed led us to hypothesize, for this reaction, a free-radical chain mechanism in which 2 is the exclusive hydrogen source in the arenes Ar-H 3.
- Barbero, Margherita,Degani, Iacopo,Dughera, Stefano,Fochi, Rita
-
p. 2386 - 2390
(2007/10/03)
-
- 1-Aryl-3,3-dialkyltriazenes: A convenient synthesis from dry arenediazonium o-benzenedisulfonimides - A high yield break down to the starting dry salts and efficient conversions to aryl iodides, bromides and chlorides
-
This research comprises three parts. The first part regards the synthesis of 1-aryl-3,3-dialkyltriazenes 3 by reaction of dry arenediazonium o-benzenedisulfonimides 1, also coming from weakly basic aromatic amines with dimethylamine or diethylamine in aqueous solution at 0-5 °C. Yields were usually greater than 90% and there was the possibility of recovering the o-benzenedisulfonimide (5), which could be reused to prepare the salts 1. In the second part it was demonstrated that there is the possibility of reconverting the triazenes 3 into the starting stable dry salts 1 by using 5 as acid. The reactions were carried out in glacial acetic acid at 50-55 °C and normally afforded salts 1 in yields of around 90-99%. The third part concerns the setting up of two procedures for the conversion of 3 to aryl iodides 9, bromides 10 and chlorides 11. Procedure A used the corresponding aqueous hydrogen halides in acetonitrile at r.t. or 60 °C, sometimes in the presence of aqueous HBF4, sometimes Cu powder (25 examples, yields 65%-88%). Procedure B usually used anhydrous methanesulfonic acid and tetraalkylammonium halides in anhydrous acetonitrile at temperatures varying from r.t. to 80 °C, sometimes in the presence of Cu (16 examples, yields 65-88%).
- Barbero,Degani,Diulgheroff,Dughera,Fochi
-
p. 2180 - 2190
(2007/10/03)
-
- Alkyl- and Arylthiodediazoniations of Dry Arenediazonium o-Benzenedisulfonimides. Efficient and Safe Modifications of the Stadler and Ziegler Reactions to Prepare Alkyl Aryl and Diaryl Sulfides
-
The reaction between dry arenediazonium o-benzenedisulfonimides 1 and sodium thiolates in anhydrous methanol represents an efficient and safe procedure, of general validity, for the preparation of unfunctionalized or variously functionalized alkyl aryl and diaryl sulfides. As a rule, the reaction temperature was maintained at 0-5°C for the alkylthiodediazoniations and at room temperature (20-25°C) for the arylthiodediazoniations. The sulfide yields are generally high; of the 63 considered examples, 43 gave yields greater than 80% and 13 were between 70% and 80%. Lower yields were obtained only when sterically hindered diazonium salts or thiols were used. A good amount of the o-benzenedisulfonimide (8) was always recovered from the reactions and could be reused to prepare salts 1. The copious experimental data collected in homogeneous conditions have offered several starting points for the study of the mechanism of these reactions.
- Barbero, Margherita,Degani, Iacopo,Diulgheroff, Nicola,Dughera, Stefano,Fochi, Rita,Migliaccio, Mara
-
p. 5600 - 5608
(2007/10/03)
-
- Halodediazoniations of dry arenediazonium o-benzenedisulfonimides in the presence or absence of an electron transfer catalyst. Easy general procedures to prepare aryl chlorides, bromides, and iodides
-
The paper reports the results of a wide study aimed at preparing aryl chlorides 3 (19 examples), bromides 4 (19 examples), and iodides 5 (9 examples) by halodediazoniation of dry arenediazonium o-benzenedisulfonimides 1 with tetraalkylammonium halides 2. The reactions were carried out in anhydrous acetonitrile at room temperature (~20 °C) in the presence of copper powder and at 60 °C or room temperature without the catalyst. In optimal conditions the yields were from good to excellent (60 reactions, 61- 94% yield), with only a few exceptions (8 reactions, 51-55% yield). A good amount of the o-benzenedisulfonimide (7) was always recovered from the reactions and could then be reused to prepare salts 1. An interesting aspect of this research is the surprising role of the anion of o- benzenedisulfonimide (9) as an electron transfer agent.
- Barbero,Degani,Dughera,Fochi
-
p. 3448 - 3453
(2007/10/03)
-
- Mild preparation of haloarenes by ipso-substitution of arylboronic acids with N-halosuccinimides
-
Aryl and heteroaryl boronic acids react with N-iodosuccinimide and N-bromosuccinimide to give the corresponding iodo-and bromo- arenes in good to excellent yields. The reaction is usually highly regioselective and yields only the ipso-substituted product. Esters of arylboronic acids react similarly, but less readily.
- Thiebes, Christoph,Prakash, G. K. Surya,Petasis, Nicos A.,Olah, George A.
-
p. 141 - 142
(2007/10/03)
-
- Synthesis and characterization of stilbene derivatives for possible incorporation as smart additives in polymers used as packaging films
-
Several series of stilbene derivatives for possible use as smart additives in polymers used as packaging films have been prepared and characterized. Differential scanning calorimetry was performed on some of the stilbenes in order to determine any liquid crystal properties. Those compounds which had multiple phase transitions were also shown to have two liquid crystalline phases according to optical microscopy.
- Day, Gary M.,Howell, Owen T.,Metzler, Michael R.,Woodgate, Paul D.
-
p. 425 - 434
(2007/10/03)
-
- Hydrodehalogenation of Polyhalogenated Aromatics under Multiphase Conditions with H2 and Metal Catalyst: Kinetics and Selectivity
-
Aryl halides have been catalytically hydrodehalogenated by bubbling H2 at atmospheric pressure into a biphasic system constituted by an organic solvent and an aqueous solution (aq., KOH 50percent), in the presence of a metal catalyst (Pd/C or Ranay-Ni) and a quaternary onium salt as a phase-transfer (PT) catalyst.Under such new conditions, the hydrodehalogenation of aromatic halides, even of sterically hindered ones, proceeds quickly at low temperatures (20-50 deg C) and affords the corresponding non-halogenated hydrocarbons in substantially quantitative yields.The addition of a quaternary onium salt to the multiphase system may induce remarkable effects both in the enhancement of the reduction rate and in the regio- and chemo-selectivity of the reaction.For instance, when Aliquat 336 (tricaprylmethylammonium chloride) is used, the isomeric chloroethylbenzenes react 50 times faster, para-dichlorobenzene is reduced slower than the ortho isomer, and halogenated aromatic ketones can be effectively dehalogenated, without any reduction of the carbonyl group.Under the same reaction conditions, the addition of an onium salt is required for the Raney-Ni catalyst to become effective as a hydrodehalogenation catalyst.
- Marques, Carlos Alberto,Selva, Maurizio,Tundo, Pietro
-
p. 317 - 328
(2007/10/03)
-
- Exchange of halogens between aromatic compounds in the presence of Cu-HZSM-5 zeolite
-
The reactions between various haloaromatics in binary mixtures which were approximately equimolar, were studied in gas-phase (673 K, atmospheric: pressure) in the presence of a 2 wt % Cu-HZSM-5 zeolite. The exchange of halogens (ipso substitution) between the two compounds was assumed to occur either through a radical mechanism involving an electron transfer between an atom of copper (I) and one aromatic molecule or through a nucleophilic substitution involving arylcopper complexes as intermediates.
- Imhaoulne,Imhaoulene,Vivier,Guisnet,Petot,Perot,Gubelmann
-
p. 12913 - 12922
(2007/10/02)
-
- Process for preparing aromatic bromine compounds
-
Aromatic bromine compounds are prepared by reacting aromatic nitro compounds with elemental bromine in the gas phase at temperatures between about 310° to 550° C. In this reaction, the nitro groups are selectively replaced by bromine; further bromination of the aromatic system beyond that does not take place.
- -
-
-
- Carbene Reactions, XVIII. Thermal Behaviour of 7-Alkylidenebicycloheptadiene Derivatives
-
Thermolysis of 7-alkylidenenorbornadienes 2 results in a retro-Diels-Alder cleavage to fulvenes and acetylene.A different mode of cleavage - into benzene and a carbene - is observed with such derivatives of 2 which carry ?- or ?-donor functions at C-8.The dependence of the reaction pathways on the nature of the substituent at C-8 is discussed on the basis of MO-calculations.
- Hoffmann, Reinhard W.,Riemann, Achim,Mayer, Bernhard
-
p. 2493 - 2513
(2007/10/02)
-
- Photochemical Bromination of Simple Arenes
-
Photochemical bromination of benzene, fluorobenzene, chlorobenzene, t-butylbenzene, α,α,α-trifluorotoluene, and (in tetrachloromethane) biphenyl and naphthalene gives substitution products and adducts such as 1,2,3,4,5,6-hexabromocyclohexane (1).The decomposition of (1) and of the analogous chlorobenzene adduct (3) under photochemical conditions gives the parent arene, the monobrominated halogenobenzene, and bromine which may be scavenged by toluene to give benzyl bromide or by benzene to give bromobenzene and dibromobenzenes.Addition is a kinetically controlled process, so that the mechanism of formation of these aryl bromides must be largely through the reversible formation of these adducts.This is consistent with the unusual orientation of apparent attack by bromine upon the arene substrates, since the relative amounts of the isomeric aryl bromides is a consequence of the relative stabilities and ease of elimination of HBr and Br2 from a family of adducts. The range of isomer distribution found within the reaction of each arene with bromine is consistent with two competing processes involved in the formation of the aryl bromides; one of these might by the direct homolytic substitution by bromine atoms upon the arene.
- Bolton, Roger,Bhangar, Muhammad Iqbal,Williams, Gareth H.
-
p. 893 - 896
(2007/10/02)
-
- REGIOSPECIFIC SYNTHESIS OF AROMATIC COMPOUNDS VIA ORGANOMETALLIC INTERMEDIATES. II. 1,3,5-(TRIMETHYLMETAL(IV))BENZENE COMPOUNDS
-
Sequential metal-halogen exchange reactions between n-C4H9Li and 1,3,5-tribromobenzene and reaction at each step with (CH3)3MIVCl(MIV = Si, Ge, Sn) has provided a 1,3,5-(trimethylmetal(IV))benzene compound.This class of compounds can be synthesized either trough a step-wise procedure, where the various intermediates are isolated, or in a continuous metal-halogen exchange process without isolation of various intermediates.
- Chen, Grace J.,Tamborski, Christ
-
p. 149 - 158
(2007/10/02)
-
- Bromination of Azobenzenes by Acidified Hypobromus Acid; Orientation, Reactivity and Mechanism
-
The rate of bromination of azobenzene by acidified hypobromousacid has been measured and compared with those of benzene, toluene, and bromobenzene under the same conditions.Determination of o/m/p ratios for attack on azobenzene show that the rate of attack at the meta position is much lower than expected on the basis of the Hammett ?m value for the phenylazo substituent.Abnormally low amounts of meta isomer were also observed for the case of bromobenzene, but not toulene.The rates of bromination of two monosubstituted azobenzenes (m-Br, and p-F) were alsodetermined and comparedwith that of azobenzene.
- Christoforou, Demetrius,Happer, Duncan A. R.,Munro, Murray H. G.
-
p. 741 - 749
(2007/10/02)
-
