- Palladium-catalyzed ortho-C-H hydroxylation of benzoic acids
-
A simple Pd(OAc)2 catalyzed ortho-hydroxylation of benzoic acids using TBHP as the sole oxidant has been explored. This protocol features relatively broad substrate scope and operational simplicity. The compatibility of ortho-substituted substrates is an effective complement to the previous ortho-hydroxylation reaction.
- Luo, Feihua,He, Shuhua,Gou, Quan,Chen, Jinyang,Zhang, mingzhong
-
-
- A convenient and efficient H2SO4-promoted regioselective monobromination of phenol derivatives using N-bromosuccinimide
-
A convenient, rapid H2SO4-promoted regioselective monobromination reaction with N-bromosuccinimide was developed. The desired para-monobrominated or ortho-monobrominated products of phenol derivatives were obtained in good to excellent yields with high selectivity. Regioselective chlorination and iodination were also achieved in the presence of H2SO4 using N-chlorosuccinimide and N-iodosuccinimide, respectively.
- Wu, Yong-Qi,Lu, Hai-Jia,Zhao, Wen-Ting,Zhao, Hong-Yi,Lin, Zi-Yun,Zhang, Dong-Feng,Huang, Hai-Hong
-
supporting information
p. 813 - 822
(2020/02/15)
-
- In situ Generation of Hypervalent Iodine Reagents for the Electrophilic Chlorination of Arenes
-
Efficient metal-free methods for the electrophilic chlorination of arenes using PIFA and simple chlorine sources are reported. The in situ formation of PhI(Cl)OCOCF3 from PIFA and KCl is proposed, which resulted in a chlorinating species for moderately activated arenes. Moreover, the in situ formation of PhICl2 from PIFA and TMSCl resulted in an excellent approach for the chlorination of a great variety of arenes (20 examples) in high yields, even when working on a multigram scale.
- Granados, Albert,Jia, Zhiyu,del Olmo, Marc,Vallribera, Adelina
-
p. 2812 - 2818
(2019/04/08)
-
- A O-substituted benzoic acid meta chlorination method (by machine translation)
-
The present invention provides O-substituted benzoic acid meta chloride method, the O substituted benzoic acid, chlorinated reagent in the catalyst under catalysis of the chlorination reaction, to obtain the meta chlorinated product; the chlorination reaction of reaction solvent comprises organic solvent; wherein said organic solvent is acetonitrile, DMF, dichloromethane and dichloroethane in at least one of; the chlorination reagent is hydrogen peroxide - hydrochloric acid system, or hypochlorous acid and salts thereof; and the catalyst is an alkali metal carbonate, nitrate or percarbonate. The present inventors study found that, in the stated under a reaction system, can be unexpectedly high selectivity to get the 5 - position single-substituted product, and the yield of the product is high; in addition, the method of the invention does not need such as the existing technology commonly adopted through chlorine substitution method, easy to control reaction condition, and will not be a burden to personnel and the environment. The method of the invention high conversion rate of raw materials, 5 - position single-substituted good selectivity, few by-products, the production environment friendly, low cost, and is suitable for industrial mass production. (by machine translation)
- -
-
Paragraph 0073; 0074; 0076; 0078
(2018/09/08)
-
- Rate enhancements due to ultrasound in isoquinolinium dichromate and isoquinolinium chlorochromate catalyzed chlorination of aromatic compounds in presence of KHSO4/KCl
-
Chlorination of aromatic compounds underwent magnificent rate accelerations in isoquinolinium dichromate and isoquinolinium chlorochromate catalyzed chlorination of aromatic hydrocarbons in the presence of KCl and KHSO4. Reaction times reduced highly significantly from 4-5 h in conventional protocol to 30-40 min under sonication, followed by high yields of monochloro derivatives as products with high regioselectivity.
- Rajanna,Rao, A. Sambashiva,Chakravarthi,Reddy, K. Rajendar
-
p. 167 - 170
(2017/12/26)
-
- Synthetic method of 5-chlorosalicylic acid
-
The invention discloses a synthetic method of 5-chlorosalicylic acid. The synthetic method comprises the following steps of: (1) in a mixed solvent of a water-insoluble solvent and water, adding parachlorophenol and strong base with the molar ratio of 1:1, adopting an oil-water separation method to remove water to obtain suspension liquid of parachlorophenol sodium salt; (2) adding a catalyst which can dissolve the parachlorophenol sodium salt and also can absorb carbon dioxide into the suspension liquid of the parachlorophenol sodium salt, then placing in a carbon-dioxide atmosphere, rising the temperature to 100-150 DEG C, reacting till carbon dioxide is not absorbed, cooling, removing carbon dioxide to obtain mixed liquid; (3) refining the mixed liquid to obtain 5-chlorosalicylic acid.The synthetic method disclosed by the invention has the advantages of simpleness, convenience in operation and low synthetic cost.
- -
-
Paragraph 0047-0049; 0056; 0057; 0058; 0059
(2018/07/30)
-
- Improved synthesis method of 5-chlorosalicylic acid
-
The invention relates to an improved synthesis method of 5-chlorosalicylic acid. The improved synthesis method comprises the following steps of (a) sequentially adding an organic solvent and salicylic acid into a reaction container, heating to 80 to 130 DEG C, warming, and reducing the content of water in the reaction container to be less than 0.03%; (b) filling chlorine into the reaction container to react, wherein the filling amount of chlorine is at least equal to 90% of theoretical amount; then, cooling to 30 to 50 DEG C, and sucking and filtering; (c) refining a filter cake by the organic solvent, so as to obtain the 5-chlorosalicylic acid. The improved synthesis method has the advantages that the product only contains a small amount of unreacted chlorosalicylic acid and required 5-chlorosalicylic acid, so that the purity of the 5-chlorosalicylic acid is high; the solution after refining can be applied into chlorinating reaction, and the recycling purpose is realized; the wastewater is not produced in the whole production process, and the byproduct is not produced in the reaction process.
- -
-
Paragraph 0010-0012
(2017/08/29)
-
- Carboxylation of o-, m-, and p-chlorophenols with sodium ethyl carbonate
-
The possibility for the synthesis of 5-chloro-2-hydroxybenzoic, 4-chloro-2-hydroxybenzoic, and 3-chloro-2-hydroxybenzoic acids via regioselective carboxylation of p-, m-, and o-chlorophenols, respectively, with sodium ethyl carbonate has been demonstrated
- Suerbaev, Kh. A.,Chepaikin,Kudaibergenov, N. Zh.
-
p. 436 - 440
(2017/07/05)
-
- Synthesis process of glibenclamide intermediate 5-chlorosalicylic acid
-
The invention provides a synthesis process of a glibenclamide intermediate 5-chlorosalicylic acid. The synthesis process is characterized by comprising the following steps of adding salicylic acid and chlorobenzene into a reaction tank according to the weight ratio of 1:(5-10), and meanwhile adding acetic acid, wherein the adding weight ratio of salicylic acid to acetic acid is 1:(0.02-0.03); heating to 20 DEG C, and dissolving by stirring; heating to 70-85 DEG C, reacting for 3 hours by preserving the heat, and meanwhile introducing chlorine gas once every half an hour, wherein the weight ratio of salicylic acid to the chlorine gas is 1:(0.4-0.6); after ending reaction, cooling, and filtering by swinging to obtain wet 5-chlorosalicylic acid; and carrying out vacuum drying to obtain 5-chlorosalicylic acid with the yield of 80-90%. The synthesis process of the glibenclamide intermediate 5-chlorosalicylic acid has the advantages of simplicity in operation, high repeatability and high production yield.
- -
-
Paragraph 0014; 0015
(2016/11/02)
-
- Carboxylation of Phenols with CO2 at Atmospheric Pressure
-
A convenient and efficient method for the ortho-carboxylation of phenols under atmospheric CO2 pressure has been developed. This method provides an alternative to the previously reported Kolbe-Schmitt method, which requires very high pressures of CO2. The addition of a trisubstituted phenol has proved essential for the successful carboxylation of phenols with CO2 at standard atmospheric pressure, allowing the efficient preparation of a broad variety of salicylic acids.
- Luo, Junfei,Preciado, Sara,Xie, Pan,Larrosa, Igor
-
supporting information
p. 6798 - 6802
(2016/05/11)
-
- A versatile approach for the synthesis of para -substituted arenes via palladium-catalyzed C-H functionalization and protodecarboxylation of benzoic acids
-
While a great number of ortho C-H functionalization reactions have been developed and several breakthroughs have been achieved in meta C-H activation, para C-H functionalization is still in its infancy stage. In this article, a versatile strategy for the synthesis of para-substituted arenes has been developed via a tandem process consisting of palladium-catalyzed C-H functionalization and subsequent copper-catalyzed protodecarboxylation of benzoic acids. Both electron-withdrawing and electron-donating functionalities can be introduced into the para positions of arenes bearing a variety of substituents.
- Pan, Shulei,Zhou, Bo,Zhang, Yanghui,Shao, Changdong,Shi, Guangfa
-
supporting information
p. 277 - 281
(2016/01/20)
-
- General method for the synthesis of salicylic acids from phenols through palladium-catalyzed silanol-directed C-H carboxylation
-
A silanol-directed, palladium-catalyzed C-H carboxylation reaction of phenols to give salicylic acids has been developed. This method features high efficiency and selectivity, and excellent functional-group tolerance. The generality of this method was demonstrated by the carboxylation of estrone and by the synthesis of an unsymmetrically o,o′-disubstituted phenolic compound through two sequential C-H functionalization processes.
- Wang, Yang,Gevorgyan, Vladimir
-
p. 2255 - 2259
(2015/02/19)
-
- Regioselective ortho-carboxylation of phenols catalyzed by benzoic acid decarboxylases: A biocatalytic equivalent to the Kolbe-Schmitt reaction
-
The enzyme catalyzed carboxylation of electron-rich phenol derivatives employing recombinant benzoic acid decarboxylases at the expense of bicarbonate as CO2 source is reported. In contrast to the classic Kolbe-Schmitt reaction, the biocatalytic equivalent proceeded in a highly regioselective fashion exclusively at the ortho-position of the phenolic directing group in up to 80% conversion. Several enzymes were identified, which displayed a remarkably broad substrate scope encompassing alkyl, alkoxy, halo and amino- functionalities. Based on the crystal structure and molecular docking simulations, a mechanistic proposal for 2,6-dihydroxybenzoic acid decarboxylase is presented.
- Wuensch, Christiane,Gross, Johannes,Steinkellner, Georg,Lyskowski, Andrzej,Gruber, Karl,Glueck, Silvia M.,Faber, Kurt
-
p. 9673 - 9679
(2014/03/21)
-
- Sodium lauryl sulfate-catalyzed oxidative chlorination of aromatic compounds
-
Chlorination of commercially important aromatic compounds using sodium chloride as chlorine source and sodium periodate as oxidant in acidic medium catalyzed by sodium lauryl sulfate (SLS) led to the chloro-substituted aromatics in good yields and purity. Addition of sodium lauryl sulfate led to increased chlorination rate, better yield, excellent purity, and better quality of end product. The advantages of the present method are greater yield, excellent purity, and shorter reaction time at room temperature. Also dichlorinated product can be obtained by increasing the amount of sodium chloride and sodium periodate at slightly higher temperature (40C).
- Mahajan, Tanu,Kumar, Lalit,Dwivedi, K.,Agarwal, D. D.
-
p. 3655 - 3663,9
(2020/08/31)
-
- The reaction of hydroxylamine with aspirin
-
Hydroxylamine reacts with aspirin in aqueous solution at 25 °C predominantly through oxygen, to give O-acetylhydroxylamine as the initial product (Scheme 3). The reaction is much faster than the intramolecular general base catalysed hydrolysis of the carboxylate anion, as it is also for the CO2H form of aspirin. Both reactions are faster than expected, consistent with moderate activation and/or proton transfer catalysis of hydroxylaminolysis by both CO2- and CO2H groups. Calculations support oxygen attack as the preferred reaction, but do not permit a clear choice between mechanisms involving NH2OH and +NH3-O- as the effective nucleophile. ARKAT-USA, Inc.
- Medeiros, Michelle,Souza, Bruno S.,Orth, Elisa S.,Brandao, Tiago A. S.,Rocha, Willian,Kirby, Anthony J.,Nome, Faruk
-
scheme or table
p. 461 - 476
(2011/10/05)
-
- PD(II)-CATALYZED HYDROXYLATION OF ARENES WITH O2 OR AIR
-
Pd (II) -catalyzed ortho-hydroxylat ion of variously substituted aromatic carboxylic acids under O2 or air is achieved under non-acidic conditions. Extensive labeling studies support a direct oxygenation of aryl C-H bonds with molecular oxygen.
- -
-
Page/Page column 14; 19-20
(2011/04/24)
-
- A simple and practical copper-catalyzed approach to substituted phenols from aryl halides by using water as the solvent
-
Water surprise! A simple and practical copper-catalyzed approach to substituted phenols by hydroxylation of aryl halides has been developed by using environmentally benign water as the solvent (see scheme). The method proceeds under mild conditions and is tolerant towards various functional groups in the substrates.
- Yang, Daoshan,Fu, Hua
-
supporting information; experimental part
p. 2366 - 2370
(2010/06/15)
-
- Pd(II)-catalyzed hydroxylation of arenes with 1 atm of O2 or air
-
(Chemical Equation Presented) Pd(II)-catalyzed ortho-hydroxylation of variously substituted benzoic acids under 1 atm of O2 or air is achieved under nonacidic conditions. Extensive labeling studies support a direct oxygenation of aryl C-H bonds with molecular oxygen.
- Zhang, Yang-Hui,Yu, Jin-Quan
-
supporting information; experimental part
p. 14654 - 14655
(2010/01/06)
-
- Iron-promoted ortho-And/or ipso-hydroxylation of benzoic acids with H 2O2
-
Regioselective hydroxylation of aromatic acids with hydrogen peroxide proceeds readily in the presence of iron(II) complexes with tetradentate aminopyridine ligands [FeII(BPMEN)-(CH3CN) 2](ClO4)2 (1) and [FeII(TPA)- (CH3CN)2](OTf)2 (2), where BPMEN=N, N'-dimethyl-N, N'-bis(2-pyridylmethyl)-1,2-ethylenediamine, TPA=tris-(2- pyridylmethyl)amine. Two cis-sites, which are occupied by labile acetonitrile molecules in 1 and 2, are available for coordination of H2O 2 and substituted benzoic acids. The hydroxylation of the aromatic ring occurs exclusively in the vicinity of the anchoring carboxylate functional group: ortho-hydroxylation affords salicylates, whereas ipso-hydroxylation with concomitant decarboxylation yields phenolates. The outcome of the substituent directed hydroxylation depends on the electronic properties and the position of substituents in the molecules of substrates:3-substituted benzoic acids are preferentially ortho-hydroxylated, whereas 2-and, to a lesser extent, 4-substituted substrates tend to undergo ipso-hydroxylation/decarboxylation. These two pathways are not mutually exclusive and likely proceed via a common intermediate. Electron-withdrawing substituents on the aromatic ring of the carboxylic acids disfavor hydroxylation, indicating an electrophilic nature for the active oxidant. Complexes 1 and 2 exhibit similar reactivity patterns, but 1 generates a more powerful oxidant than 2. Spectroscopic and labeling studies exclude acylperoxoiron(III) and FeIV=O species as potential reaction intermediates, but strongly indicate the involvement of an FeIII-OOH intermediate that undergoes intramolecular acid-promoted heterolytic O-O bond cleavage, producing a transient iron(V) oxidant.
- Makhlynets, Olga V.,Das, Parthapratim,Taktak, Sonia,Flook, Margaret,Mas-Balleste, Ruben,Rybak-Akimova, Elena V.,Que Jr., Lawrence
-
experimental part
p. 13171 - 13180
(2010/07/03)
-
- The site-selective functionalization of halogen-bearing phenols: An exercise in diversity-oriented organometallic synthesis
-
The organometallic approach to diversity-oriented organic synthesis was subjected to a further test, this time in the phenol series. The model compounds selected were 2,3,6-trifluorophenol, the three isomers of (trifluoromethoxy) phenol and the three isomers of chlorophenol. A combination of optionally site selective metalations and protective group-controlled metalations enabled the selective generation of several isomeric intermediates in each case and their subsequent conversion into functionalized derivatives, in particular hydroxybenzoic acids.
- Marzi, Elena,Schlosser, Manfred
-
p. 3393 - 3401
(2007/10/03)
-
- ortho-Hydroxylation of benzoic acids with hydrogen peroxide at a non-heme iron center
-
The iron-assisted hydroxylation of benzoic acid to salicylic acid by 1/H2O2 has been achieved in good yield under mild conditions (where 1 is [Fe(II)(BPMEN)(CH3CN)2](CIO 4)2 and BPMEN = N,N-dimethyl-N,N-bis(2- pyridylmethyl)ethane-1,2-diamine); the product of this reaction is a novel mononuclear iron(m) complex with a chelating salicylate. The Royal Society of Chemistry 2005.
- Taktak, Sonia,Flook, Margaret,Foxman, Bruce M.,Que Jr., Lawrence,Rybak-Akimova, Elena V.
-
p. 5301 - 5303
(2007/10/03)
-
- Synthesis of salicylic acid derivatives in presence of ultrasonic irradiation using water as solvent
-
An improved synthesis of salicylic acid using ultrasonic irradiation and water as solvent can be achieved with copper and pyridine as catalysts. A number of salicylic acids were prepared in good yield and in a short reaction time.
- Docampo Palacios, Maite L.,Pellon Comdom, Rolando F.
-
p. 1783 - 1787
(2007/10/03)
-
- 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)
-
- Synthesis of salicylic acid derivatives from the corresponding 2-chlorobenzoic acid using water as solvent
-
An improved synthesis of salicylic acid using water as solvent can be achieved using the Ullmann-Goldberg reaction conditions in presence of pyridine as cocatalyst. A number of salicylic acids were prepared in good yield.
- Pellon Comdom, Rolando F.,Docampo Palacios, Maite L.
-
p. 2055 - 2059
(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)
-
- A kinetic study into the hydrolysis of the ochratoxins and analogues by carboxypeptidase A
-
The hydrolyses of the ochratoxins and analogues by carboxypeptidase A were assessed. This was done by measuring the amount of phenylalanine formed with liquid chromatography coupled to tandem electrospray mass spectrometry. The kinetic data of ochratoxin A, ochratoxin B, and the synthetic bromo-ochratoxin B were compared to the values of a number of synthesized structure analogues, namely, ochratoxin A methyl ester, ochratoxin B methyl ester, N-(2-hydroxybenzoyl)phenylalanine, N-(5-chloro-2-hydroxybenzoyl)phenylalanine, N-(5-bromo-2-hydroxybenzoyl)phenylalanine, and N-(5-fluoro-2-hydroxybenzoyl)phenylalanine. The halogen-containing analogues had lower turnovers than their des-halo analogues. There are no substantial differences in the kinetic data between the different halogen-containing analogues.
- Stander,Steyn,Van der Westhuizen,Payne
-
p. 302 - 304
(2007/10/03)
-
- Mild chlorination of aromatic compounds with tin(IV) chloride and lead tetraacetate
-
SnCl4/Pb(OAc)4 acts as a safe source of Cl2 for the chlorination of aromatic compounds. A variety of aromatic compounds are effectively chlorinated with SnCl4/Pb(OAc)4 under mild conditions. The mixture is a selective chlorinating agent, particularly with polyalkylbenzenes, polycyclic aromatic compounds and anisoles.
- Muathen, Hussni A.
-
p. 8863 - 8866
(2007/10/03)
-
- SOME REACTIONS OF 6-CHLORO-2-METHYL-4H-1-BENZOPYRAN-4-ONE. I
-
4H-1-Benzopyran-4-ones (Chromones) are proved to be of special importance in medicine as stimulants of the central nervous system, spasmolytics, coronary dilators, inhibitors for the growth of human cancer cells, reductants for blood pressure, diuretics, antiallergic, antibiotics and cardiovascular agents. In the course of the present work several new derivatives containing the chromone moiety were prepared. Some of their reactions were investigated in the hope of obtaining new compounds having biological activities. The reactivities of chromone nucleus towards cycloaddition reactions under Diels-Alder conditions, nucleophilic and electrophilic reagents, photocyclodehydrogenation and thiation have been investigated.
- Salem, Mounir A. I.,Hamed, Ashraf A.,El-Shekeil, Ali G.,Babaqui, A. S.,Madkour, Hassan M. F.
-
p. 495 - 508
(2007/10/03)
-
- SOME REACTIONS OF 6-CHLORO-2-METHYL-4H-1-BENZOPYRAN-4-ONE. PART II
-
6-Chloro-2-methyl-4H-1-benzopyran-4-one (I) gave the isoxazole derivative IIa on reaction with hydroxylamine hydrochloride. The action of hydrazine and phenylhydrazine on I resulted in pyrazole dervatives IIIa and IIIb, respectively. The reactivity of I with ethyloxalate and aromatic nitroso compounds have been investigated. Phthalide VIIIa derived from the chromone I was synthesised and rearranged easily into phthalone IX upon refluxing with alcoholic sodium methoxide. Cleavage of VIIIa with amines and hydrazine hydrate was studied. Thiation of phthalide VIIIa with either Lawesson's reagent or phosphorous pentasulphide yielded the corresponding thione VIIIe.
- Salem, Mounir A. I.,Hamed, Ashraf A.,El-Shekeil, Ali G.,Qui, A. S. Baba,Madkour, Hassan M. F.
-
p. 605 - 618
(2007/10/03)
-
- Highly Selective Aromatic Chlorinations. Part 2. The Chlorination of Substituted Phenols, Anisoles, Anilines, and Related Compounds with N-Chloroamines in Acidic Solution
-
Phenols, anisoles, anilines, and related compounds are chlorinated in trifluoroacetic acid at room temperature by N-chlorodialkylamines and N-chlorotrialkylammonium salts.With monsubstituted compounds and their 2- and 3-substituted derivatives the reaction occurs efficiently and selectively at the 4-position.The reactivity of these substrates and the selectivity of their chlorinations are determined by electronic rather than steric effects of the substituent.Blocking the reaction with a substituent at the 4-position generally leads to only poor or moderate yields of the 2-chlorinated product.Evidence for radical and cation radical intermediates has been obtained in the reactions of some of the 4-substituted reactants and the mechanism of chlorination is discussed in the light of these findings.The reactions of selected substrates have been scaled up to give laboratory syntheses.
- Smith, John R. Lindsay,McKeer, Linda C.,Taylor, Jonathan M.
-
p. 385 - 392
(2007/10/02)
-
- Kinetics of Nuclear Chlorination of Some Phenol, Anisole and Aniline Derivatives by Trichloroisocyanuric Acid in Aqueous Acetic Acid - Perchloric Acid Media
-
Kinetics of nuclear chlorination of some substrates(S) like phenol, anisole and aniline derivatives by trichloroisocyanuric acid (TCICA) at 35 deg C in aqueous acetic acid - HClO4 media follow a pseudo-first order pattern in TCICA disappearance.The pseudo-first order rate constants show the following trends: (a) increase with increase in 0 and , (b) increase with decrease in dielectric constant of the medium: and (c) increase with increase in added Cl(-), tending to saturate at higher relative ad.Based on the results observed, a probable mechanism has been proposed, which envisages equilibrium formation of charge transfer (CT) complexes between the unprotonated forms of the substrates and the effective chlorinating species produced by the hydrolysis of TCICA (i.e., H2OCl(+) in the absence of added Cl(-) and H2OCl(+) + Cl2 in the presence of added Cl(-)), followed by the rate-determining decomposition of the CT complexes.The reactivity order of the chlorinating species is Cl2 > H2OCl(+), and that of the substrates follows the relative directing ability of the substituents in the benzene nucleus.The N-chloro intermediates in the chlorination of aniline derivatives are not discernible under the conditions of the study.
- Radhakrishnamurti, P. S.,Rath, N. K.,Panda, R. K.
-
p. 407 - 411
(2007/10/02)
-
- Some Observations on Chlorination of Salicylic Acid and Its 5-Sulphonic Acid Derivative
-
Chlorination of salicylic acid with t-butyl hypochlorite in CCl4 affords only 5-chlorosalicylic acid and not 3-chloro isomer as reported earlier.Direct chlorination of 5-sulphosalicylic acid in acetic acid yields 3,5-dichlorosalicylic acid besides the sulphonated product, showing that SO3H group undergoes electrophilic displacement by Cl+.
- Jain, A. C.,Gupta, S. K.,Bambah, P. K.
-
p. 575 - 576
(2007/10/02)
-
- Synthesis and Evaluation of Diaryl Oxalate Esters for Low-Intensity Chemiluminescent Illumination
-
Various diaryl oxalate esters have been prepared from oxalyl chloride and substituted salicylates.A number of intermediates and byproducts were obtained from chlorinations of salicylic acid and their mechanistic significance has been discussed.The chemiluminescent emission from the oxalates in the presence of hydrogen peroxide has been examined in the search for low-intensity illumination of at least 10 h duration.Bis(2-alkoxycarbonyl-4,6-dinitrophenyl) oxalates were too unstable while the chemiluminescence of the bis(6-alkoxycarbonyl-2,4,5-trichlorophenyl) oxalates c ould not be adjusted suitably.Some bis(6-alkoxycarbonyl-2,4-dichlorophenyl) oxalates were prepared and, by treatment with various combinations of potassium salicylate and oxalic acid, satisfactory low-intensity light emission could be achieved.
- Dowd, Christopher D.,Paul, D. Brenton
-
-
- PHOTOREACTION OF BENZOIC ACID WITH SODIUM HYPOCHLORITE IN AQUEOUS ALKALI
-
The photoreaction of benzoic acid with sodium hypochlorite in aqueous alkali (pH > 12) has been studied.At a low initial ratio of , e.g, 0.1, hydroxylation and chlorination at the aromatic ring occur simultaneously with ipso-substitution of the carboxylate group to give hydroxy- and chlorobenzoic acids together with phenol.The product distribution depends on the wavelength of the light, which implies the dependence on the concentration of avtive species generated from ClO(1-) and on the light stability of products.At comparable concentrations of ClO(1-) and PhCOO(1-), the products initially formed from the photoreaction react further with ClO(1-) in the dark to give polychlorinated derivatives.The initial steps for the photoreaction are discussed on the basis of the reactivity of the active species, O(3P), O(1D), O(1-)(.), and Cl(.), generated by photolysis of ClO(1-).
- Ogata, Yoshiro,Tomizawa, Kohtaro
-
p. 985 - 988
(2007/10/02)
-
- Binary and Ternary Chelates of Scandium(III), Yttrium(III) and Lanthanum(III) with Ethyleneglycol-Bis(β-Aminoethylether)-Tetraacetic Acid as Primary and Substituted Salicylic Acids as Secondary Ligands
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Formation constants of binary and ternary complexes of the systems of the type: M-L and M-egta-L have been determined pH-metrically at 25 deg and μ=0.1 M (KNO3) in 50 percent (v/v) aqueous-ethanol medium.The order of stabilities of ternary complexes have compared with those of corresponding binary complexes, and results discussed on the basis of coulombic interactions.
- Pandey, Ashok Kumar,Chandra, M.,Agarwala, B. V.,Dey, A. K.
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- Dual Fluorescence and Ground State Equilibria in Methyl Salicylate, Methyl 3-Chlorosalicylate, and Methyl 3-tert-Butylsalicylate
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Fluorescence spectra of methyl 3-chlorosalicylate, methyl 3-tert-butylsalicylate, and o-hydroxyacetophenone in cyclohexane and ethanol at room temperature have been measured, together with the corrected dual fluorescence excitation spectra of gas-phase methyl salicylate.Based on these observations a ground state equilibrium between two tautomers is proposed, both having an intramolecular hydrogen bond.This model is consistent with a number of methyl salicylate H-bond energy estimates.It also allowed an interpretation of the multiple fluorescence emitted from these and related compounds either in solution or in gas phase.
- Acuna, A. U.,Amat-Guerri, F.,Catalan, J.,Gonzalez-Tablas, F.
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p. 629 - 631
(2007/10/02)
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- Benzamide derivatives
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Benzamide derivatives of the formula:- STR1 wherein R1 represents a fluorine, chlorine or bromine atom, or an alkyl, alkoxy, alkylthio, alkylsulphonyl, alkanoylamino, alkylamino or alkylsulphamoyl group, each such group containing from 1 to 6 carbon atoms, a dialkylsulphamoyl, dialkylamino or dialkylcarbamoyl group (wherein the two alkyl groups may be the same or different and each contains from 1 to 4 carbon atoms), an alkanoyl, alkoxycarbonyl, alkoxycarbonylamino or alkylcarbamoyl group containing from 2 to 6 carbon atoms, or a hydroxy, formyl, nitro, trifluoromethyl, aryl, benzyloxycarbonylamino, amino, sulphamoyl, cyano, tetrazol-5-yl, carboxy, carbamoyl or aroyl group, and n represents an integer 1, 2 or 3, are new compounds possessing pharmacological properties, in particular properties of value in the treatment of respiratory disorders manifested by the interaction of tissue-fixed antibodies with specific antigens.
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