- Alkoxyphosphonium Salts. 3. Kinetics and Thermodynamics in Alkylation by Alkoxyphosphonium Salts
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Several methoxyphosphonium trifluoromethanesulfonates (triflates) are characterized by the rates of methyl transfer to the 2,4-dinitrophenoxide ion.In acetone at 25 deg C, the measured second-order rate constants range from about 0.2 to about 40 M-1s-1, putting substances of this class among the most powerful methylating agents.The methylating power is confirmed by the measurement of the equilibrium extent of methylation of the counterion, the triflate ion.The Arbuzov rearrangement of trimethyl phosphite is slow with the catalyst methyl iodide but is fast enough with the cata lyst methyltrimethoxyphosphonium triflate to allow calorimetric measurement for the conversion of trimethyl phosphite to dimethyl methylphosphonate; ΔH = -24 +/- 2 kcal/mol.An earlier error in the measurement of the rate of this reaction is corrected, so that the mechanism of the methyl iodide catalyzed Arbuzov reaction of trimethyl phosphite is no longer in question; the first step is rate-determining.
- Lewis, Edward S.,Colle, Karla S.
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Read Online
- Reactions in Strongly Basic Media. Part 9. Correlation of the Rates of Methoxide-catalysed Methanolysis of 1-Substituted 2,4-Dinitrobenzenes and 2-Substituted 5-Nitropyridines in Methanolic Dimethyl Sulphoxide with an Acidity Function. Details of the Mechanistic Pathway
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The rate coefficients for the methoxide-catalised methanolysis of a series of 1-substituted 2,4-dinitrobenzenes and 2-substituted 5-nitropyridines have been measured in methanolic DMSO at 20.0 or 21.0 deg C.For the 2-substituted 5-nitropyridines and for the 1-substituted 2,4-dinitrobenzenes below ca. 55 mol percent DMSO, the rates have been correlated with an acidity function of the medium.The slopes of these linear relations are discussed.The 1-substituted 2,4-dinitrobenzenes above ca. 55 mol percent DMSO give rise to Meisenheimer complexes as intermediates and/or as the product of the reaction.The product of the reaction then becomes the 1,1-Meiseheimer complex of methoxide and 2,4-dinitroanisole.For the 1-fluoro substrate the formation of the latter becomes rate determining.For other 1-substituted substrates the decomposition of a 1,3-Meisenheimer complex becomes rate determining.
- Bowden, Keith,Nadvi, Nighat S.
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Read Online
- Nitration of aromatics with dinitrogen pentoxide in a liquefied 1,1,1,2-tetrafluoroethane medium
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Regardless of the sustainable development path, today, there are highly demanded chemical productions still operating that bear environmental and technological risks inherited from the previous century. The fabrication of nitro compounds, and nitroarenes in particular, is traditionally associated with acidic wastes formed in nitration reactions exploiting mixed acids. However, nitroarenes are indispensable for industrial and military applications. We faced the challenge and developed a greener, safer, and yet effective method for the production of nitroaromatics. The proposed approach comprises the application of an eco-friendly nitrating agent, namely dinitrogen pentoxide (DNP), in the medium of liquefied 1,1,1,2-tetrafluoroethane (TFE) - one of the most non-hazardous Freons. Importantly, the used TFE is not emitted into the atmosphere but is effortlessly recondensed and returned into the process. DNP is obtainedviathe oxidation of dinitrogen tetroxide with ozone. The elaborated method is characterized by high yields of the targeted nitro arenes, mild reaction conditions, and minimal amount of easy-to-utilize wastes.
- Fauziev, Ruslan V.,Kharchenko, Alexandr K.,Kuchurov, Ilya V.,Zharkov, Mikhail N.,Zlotin, Sergei G.
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p. 25841 - 25847
(2021/08/09)
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- Ipso Nitration of Aryl Boronic Acids Using Fuming Nitric Acid
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The ipso nitration of aryl boronic acid derivatives has been developed using fuming nitric acid as the nitrating agent. This facile procedure provides efficient and chemoselective access to a variety of aromatic nitro compounds. While several activating agents and nitro sources have been reported in the literature for this synthetically useful transformation, this report demonstrates that these processes likely generate a common active reagent, anhydrous HNO3. Kinetic and mechanistic studies have revealed that the reaction order in HNO3 is >2 and indicate that the ?NO2 radical is the active species.
- Baucom, Kyle D.,Brown, Derek B.,Caille, Seb,Murray, James I.,Quasdorf, Kyle,Silva Elipe, Maria V.
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supporting information
(2021/06/30)
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- Process for synthesizing 2-amino-4-acetylaminoanisole
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The invention discloses a process for synthesizing 2-amino-4-acetylaminoanisole. The process comprises the steps of preparing 2,4-dinitroanisole from 2,4-dinitrochlorobenzene, which serves as a raw material, in methanol, in the presence of sodium hydroxide or potassium hydroxide, carrying out reduction in the presence of action of Pd/C catalyst by taking hydrazine monoformate as a hydrogen sourceso as to prepare a 2,4-diaminoanisole-methanol solution, and then, subjecting 2,4-diaminoanisole and acetic anhydride to a partial acylation reaction in the presence of an acid binding agent, therebypreparing the 2-amino-4-acetylaminoanisole. According to the process disclosed by the invention, the energy consumption is low, the cost is low, the volume of solid waste and waste liquid is small, the process is environmentally friendly, the operation is simple, the reaction conditions are mild, the industrial safety coefficient is big, the total yield of a target compound is 85% or more (by initial reactants), the HPLC purity is 99.0% or more, and the target compound is high in yield and good in quality, so that the process is more applicable to industrial production.
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Paragraph 0054-0056; 0062; 0068; 0074
(2019/05/08)
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- 2 - Amino - 4 - acetamido anisole novel synthesis process (by machine translation)
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The present invention provides a novel 2 - amino - 4 - acetamido anisole synthesis process, the usage of palladium bi-metal catalysts and the palladium/carbon catalyst to replace Rany - Ni catalyst, to the anisole on the nitro-selective catalytic hydrogenation, which not only reduces use Rany - Ni catalyst of post-industrial risks, while at the same time, the resulting 2 - amino - 4 - acetyl anisole purity higher, greater yield. (by machine translation)
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Paragraph 0057-0058
(2018/03/01)
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- Synthesis process of 2-amidogen-4-acetamido anisole
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The invention discloses a synthesis process of 2-amidogen-4-acetamido anisole. The synthesis process of the 2-amidogen-4-acetamido anisole comprises the steps of adopting p-methoxyaniline as a raw material, carrying out partial acylation reaction on the p-methoxyaniline and acetic anhydride, and preparing to obtain p-acetamido anisole; then carrying out nitration reaction, carrying out one-pot method'reaction to obtain 2-nitro-4-acetamido anisole, and under the action of a Pd/C catalyst, reducing the 2-nitro-4-acetamido anisole by adopting hydrazine monoformate as a hydrogen source to preparethe 2-amidogen-4-acetamido anisole. The synthesis process provided by the invention is low in energy consumption, low in cost, less in solid wastes and waste liquids, green and environmentally friendly, simple to operate, mild in reaction conditions, and high in industrial safety coefficient, the total yield of the target compound is 85 percent or above (on the basis of an initial reaction raw material), the HPLC (High Performance Liquid Chromatography) purity is 99.0 percent or above, the target compound is high in yield and good in quality, and the synthesis process is more suitable for industrial production.
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Paragraph 0055-0057; 0061-0062
(2020/03/28)
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- Synthesis process of 4-acetamino-2-aminoanisol
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The invention belongs to the field of fine chemical engineering, and discloses a synthesis process of 4-acetamino-2-aminoanisol. The synthesis method comprises the following steps: step one, adding 0.25 mol of 2,4-dinitrochlorobenzene and 100 ml of methyl alcohol, carrying out heating to 35-45 DEG C, adding a sodium hydroxide solution with a mass fraction of 20% with a decreasing speed, carrying out heating to 55-65 DEG C, carrying out filtering, diluting the filter cake with water, and carrying out drying under reduced pressure to obtain 2,4-nitroanisole; step two, preparing 200 ml of a sodium disulfide solution with a concentration of 20%, adding 0.25 mol of the 2,4-dinitroanisole, carrying out heating to a reflux temperature, then carrying out cooling to 80 DEG C, carrying out standing,washing a filter cake by using cold water, and carrying out drying under reduced pressure to obtain 2,4-diaminophenyl ether; and step three, adding 0.25 mol of 2,4-diaminoanisole, 50 ml of acetic acid and 0.1 mol of a catalyst, carrying out ice bath, adding 0.25 mol of acetic anhydride, adding 125 ml of ice water, carrying out filtering, washing a filter cake with a solution of sodium dithionite,and carrying out drying under reduced pressure to obtain the 4-acetamino-2-aminoanisol. The invention aims at providing the synthesis process of 4-acetamino-2-aminoanisol, and the synthesis method has the advantages of high recovery rate, simple process and low cost.
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Paragraph 0035; 0040-0042
(2018/09/11)
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- Convenient, metal-free ipso-nitration of arylboronic acids using nitric acid and trifluoroacetic acid
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A feasible protocol for the direct ipso-nitration of arylboronic acids using trifluoroacetic acid and nitric acid as nitration reagent has been developed. Various aromatic nitro compounds are produced in moderate to good yields under the metal-free conditions. The method is operationally simple and regioselective, and might have potential application in industry.
- Shen, Guodong,Zhao, Lingyu,Liu, Wanxing,Huang, Xianqiang,Song, Huina,Zhang, Tongxin
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supporting information
p. 10 - 14
(2016/12/30)
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- A 2, 4 - dinitrobenzene synthesizing method (by machine translation)
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The invention discloses a 2, 4 - dinitrobenzene synthesizing method. The method of the invention to 2, 4 - dinitro chlorobenzene as raw materials, the use of methanol as a solvent, under mild conditions, and sodium methoxide reaction synthesis of 2, 4 - dinitro anisole. And the reported 2, 4 - dinitrobenzene ether synthesis method comparison, this invention has low cost of material, mild reaction conditions, the operation is simple, high reaction efficiency, without side reaction product purity and the like. (by machine translation)
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Paragraph 0022; 0023; 0024; 0025; 0026; 0027; 0028-0060
(2017/08/29)
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- NITRATION OF AROMATIC COMPOUNDS
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The present invention provides a process for nitrating aromatic compounds without the need for a solid catalyst and/or any organic solvents and/or any other additives. A typical process includes combining or admixing a nitric acid and an anhydride compound under conditions sufficient to produce a reactive intermediate. The aromatic compound to be nitrated is then added to this reactive intermediate to produce a nitroaromatic compound. The nitroaromatic compound can be substituted with one or more, typically, one to three, and often one or two nitrate (-NO2) groups.
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Paragraph 0039; 0040
(2016/08/17)
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- 2-amino-4-acetamino anisole synthesis process
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The invention discloses a 2-amino-4-acetamino anisole synthesis process. The process comprises the following steps that in methyl alcohol, 2,4-diaminobenzene methyl ether (III) and acetic anhydride are subjected to an acylation reaction as follows under the effect of an acid-binding agent to obtain 2-amino-4-acetamino anisole (IV), wherein the mole ratio of the acid-binding agent to the 2,4-diaminobenzene methyl ether is 0.3:1-0.6:1. The synthesis process is low in energy consumption, low in cost, small in amount of solid waste and liquid waste, free of pollution, environmentally friendly, easy to operate, mild in reaction condition and high in industrial safety coefficient, the target compound yield is 86% or above (based on initial reaction raw materials), the HPLC purity is 99.0% or above, and the target compound is high in yield, good in quality, and more applicable to industrial production.
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Paragraph 0050; 0051
(2016/10/08)
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- Selective O-methylation of phenols and benzyl alcohols in simple pyridinium based ionic liquids
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Synthesis of pyridinium based ionic liquids were reported and applied as catalyst for the selective O-methylation of phenols and benzyl alcohols. The reactions were carried out by using dimethylcarbonate (DMC) as the methylating agent. High selectivity, high yield and recyclability of the ionic liquids are important features of the reactions.
- Das, Pranab Jyoti,Das, Jupitara
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- THERAPEUTIC DNP DERIVATIVES AND METHODS USING SAME
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The present invention includes DNP derivatives that are useful for preventing or treating a metabolic disease or disorder in a subject in need thereof. In certain embodiments, the subject is further administered at least one additional therapeutic agent.
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Page/Page column 56; 57
(2015/03/16)
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- Synthesis of 13C and 15N labeled 2,4-dinitroanisole
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Syntheses of [13C6]-2,4-dinitroanisole (ring- 13C6) from [13C6]-anisole (ring-13C6) and [15N2]-2,4- dinitroanisole from anisole using in situ generated acetyl nitrate and [ 15N]-acetyl nitrate, respectively, are described. Treatment of [ 13C6]-anisole (ring-13C6) with acetyl nitrate generated in 100% HNO3 gave [13C 6]-2,4-dinitroanisole (ring-13C6) in 83% yield. Treatment of anisole with [15N]-acetyl nitrate generated in 10 N [15N]-HNO3 gave [15N2]-2,4- dinitroanisole in 44% yield after two cycles of nitration. Byproducts in the latter reaction included [15N]-2-nitroanisole and [ 15N]-4-nitroanisole.
- Jagadish, Bhumasamudram,Field, Jim A.,Chorover, Jon,Sierra-Alvarez, Reyes,Abrell, Leif,Mash, Eugene A.
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p. 434 - 436
(2014/07/07)
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- Regioselective dinitration of simple aromatics over zeolite Hβ/nitric acid/acid anhydride systems
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Various nitration systems comprising nitric acid, acid anhydride and zeolite H£] in the absence of solvent are described. Direct double nitration of toluene with a nitric acid, propanoic anhydride and zeolite Hβ system has been developed to give 2,4-dinitrotoluene in 98% yield, with a 2,4-:2,6-dinitrotoluene ratio of 123:1. This system also nitrates activated mono-substituted benzenes (anisole and phenetole) and moderately activated mono-substituted benzenes (ethylbenzene and propylbenzene) to give mainly 2,4-dinitro derivatives. The zeolite can be recovered, regenerated and reused to give almost the same yield as that given when fresh zeolite is used. ARKAT-USA, Inc.
- Smith, Keith,Alotaibi, Mohammad Hayal,El-Hiti, Gamal A.
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p. 107 - 123
(2014/04/17)
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- Highly regioselective dinitration of toluene over reusable zeolite Hβ
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A nitration system comprising nitric acid, propanoic anhydride, and zeolite Hβ has been developed for dinitration of toluene to give 2,4-dinitrotoluene in 98% yield, with a 2,4-:2,6-dinitrotoluene ratio of over 120. This represents the most selective quantitative method for 2,4-dinitration of toluene; the catalyst is reusable, solvent is not needed, and an aqueous work-up is not required.
- Smith, Keith,Alotaibi, Mohammad Hayal,El-Hiti, Gamal A.
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p. 244 - 247
(2013/02/22)
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- Aromatic nitration with bismuth nitrate in ionic liquids and in molecular solvents: A comparative study of Bi(NO3)3·5H 2O/[bmim][PF6] and Bi(NO3)3· 5H2O/1,2-DCE systems
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A suspension of bismuth nitrate pentahydrate (BN) in [bmim][PF6] or [bmim][BF4] imidazolium ionic liquid (IL) is an effective reagent for ring nitration of activated aromatics under mild conditions without the need for external promoters. Nitration can also be effected in 1,2-DCE, MeCN, or MeNO2 without additives. Nitration of activated arenes (anisole, toluene, ethylbenzene, cumene, p-xylene, mesitylene, durene, and 1,3-dimethoxybenzene) is considerably faster (time to completion) in BN/[bmim][PF6] relative to BN/1,2-DCE and there are also differences in isomer distributions (for anisole, toluene, and ethylbenzene). With introduction of strongly deactivating substituents (-CHO; -MeCO; -NO 2) the BN/IL system is no longer active but reactions still proceed with BN/1,2-DCE in reasonable yields. The ready availability and low cost of BN, simple operation, and absence of promoters, coupled to recycling and reuse of the IL, provide an attractive alternative to classical nitration methods for activated arenes. Switching from Bi(NO3)3·5H 2O/[bmim][PF6] to Bi(NO3)3· 5H2O/1,2-DCE increases the scope of the substrates that can be nitrated.
- Jacoway, Jonathan,Kumar, G. G. K. S. Narayana,Laali, Kenneth K.
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p. 6782 - 6785,4
(2012/12/12)
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- METHODS FOR THE NITRATION OF AROMATIC COMPOUNDS
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According to the invention there is provided a method for the nitration of an aromatic compound including the step of reacting the aromatic compound with nitric acid in the presence of an acid anhydride and an aluminosilicate catalyst, in which the acid anhydride is at least one of: ((CnH2n+1)CO)20, where n is 1 to 4 and the moiety CnH2n+1 can be straight or branched chain; ((CHpClq)CO)20, where p is 0 to 2, q is 1 to 3, and p+q = 3; and oxoiane -2, 5-dione, with the proviso that when the acid anhydride is (CH3CO)20, the aromatic compound is toluene, 2-nitrotoluene or 4-nitrotoluene, and the nitration is performed to produce 2,4-dinitrotoluene.
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Page/Page column 14
(2012/05/04)
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- Ethylammonium nitrate (EAN)/Tf2O and EAN/TFAA: Ionic liquid based systems for aromatic nitration
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Acting as in situ sources of triflyl nitrate (TfONO2) and trifluoroacetyl nitrate (CF3COONO2), the EAN/Tf 2O and EAN/TFAA systems, generated via metathesis in the readily available ethylammonium nitrate (EAN) ionic liquid as solvent, are powerful electrophilic nitrating reagents for a wide variety of aromatic and heteroaromatic compounds. Comparative nitration experiments indicate that EAN/Tf2O is superior to EAN/TFAA for nitration of strongly deactivated systems. Both systems exhibit low substrate selectivity (K T/KB = 5-10) in (Figure presented) between values reported for covalent nitrates and preformed nitronium salts.
- Aridoss, Gopalakrishnan,Laali, Kenneth K.
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experimental part
p. 8088 - 8094
(2011/11/13)
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- PROCESS FOR PRODUCING 3-NITRO-4-ALKOXYBENZOIC ACID
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The present invention provides a process for preparing 3-nitro-4-alkoxybenzoic acid, which comprises the step of subjecting a mixture comprising 4-alkoxybenzoic acid and 40-80% nitric acid, wherein the amount of the 40-80% nitric acid is equal to or more than 8 times that of 4-alkoxybenzoic acid by weight, to a reaction at a temperature of 30-100°C.
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Page/Page column 4-5
(2008/06/13)
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- Transformations of para-substituted benzylcyclopropanes, allylbenzenes, and diphenylmethanes under nitration with nitric acid in acetic anhydride
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Electrophilic nitration of benzylcyclopropanes, allylbenzenes, and diphenylmethanes containing ortho, para-orienting substituents in the para position of the benzene ring results mainly in replacement of the cyclopropylmethyl, allyl, or benzyl group, respectively (ipso substitution). The nitration of 4-cyclopropylallylbenzene is not accompanied by nitrodealkylation, and the products are only 2- and 3-nitro-4-cyclopropylallylbenzenes.
- Mochalov,Gazzaeva,Fedotov,Archegov,Trofimova,Shabarov,Zefirov
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p. 406 - 416
(2007/10/03)
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- The Design of Boronic Acid Spectroscopic Reporter Compounds by Taking Advantage of the pKa-Lowering Effect of Diol Binding: Nitrophenol-Based Color Reporters for Diols
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The complex that forms between a boronic acid and a diol is often much more acidic than the starting boronic acid. In conditions where the solution pH is between the two pKa values, the boron atom will convert from a neutral trigonal form to an anionic tetrahedral form upon complexation. Such a change is likely to dramatically alter the electron density of neighboring groups. Utilizing this effect, we have designed and synthesized two nitrophenol-based boronic acid reporter compounds that change ionization states and therefore spectroscopic properties upon diol binding. Both compounds show significant UV changes upon addition of saccharides. For example, a blue shift of the absorption max from 373 to 332 nm was observed with the addition of D-fructose to 2-hydroxy-5-nitrophenylboronic acid at neutral pH. Such a reporter compound can be used as a recognition and signaling unit for the construction of polyboronic acid sensors for the selective and specific recognitions of saccharides of biological significance.
- Ni, Weijuan,Fang, Hao,Springsteen, Greg,Wang, Binghe
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p. 1999 - 2007
(2007/10/03)
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- Continuous process for preparing alkoxynitroarenes
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A continuous process for preparing alkoxynitroarenes, such as 2,4-dinitroanisole (DNAN) and 1-isopropoxy-2,4-dinitrobenzene, is provided. The continuous process of the present invention provides for the effective handling and manufacture of alkoxynitroarenes and permits the utilization of the continuous processing equipment already in place in a number of trinitrotoluene (TNT) manufacturing facilities. Thus, the present invention provides a continuous process for the large scale manufacture of TNT alternatives which does not require re-facilitization.
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- Relative reactivity of methyl iodide to ethyl iodide in nucleophilic substitution reactions in acetonitrile and partial desolvation accompanying activation
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Through the examination of empirical correlations involving activation parameters for nucleophilic substitution of methyl iodide and of ethyl iodide, nucleophiles have been classified into three series: (1) nucleophiles with two equivalent reaction sites, (2) nucleophiles with a chlorine atom in the para-position, and (3) nucleophiles with a single reaction site. Three types of partial desolvation processes accompanying activation have been deduced on the basis of these classifications. A major factor determining the relative reactivity of methyl iodide to ethyl iodide in the substitution reaction of an anionic nucleophile having a single reaction site in acetonitrile (kMeI/kEtI) is suggested to be partial desolvation around the nucleophilic center on going from reactant to transition-state.
- Kondo, Yasuhiko,Urade, Miyuki,Yamanishi, Yukari,Chen, Xinyu
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p. 1449 - 1454
(2007/10/03)
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- Nucleophilic aromatic substitution for heteroatoms: An oxidative electrochemical approach
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The nucleophilic aromatic substitution for heteroatom through electrochemical oxidation of the intermediate σ-complexes (Meisenheimer complexes) in simple nitroaromatic compounds is reported for the first time (NASX process). The studies have been carried out with hydride, cyanide, fluoride, methoxy, and ethanethiolate anions and n-butylamine as a nucleophile, at the cyclic voltammetry (CV) and preparative electrolysis level. The cyclic voltammetry experiments allow for detection and characterization of the σ-complexes and they have led us to a proposal for the mechanism of the oxidation step. Furthermore, the power of the CV technique in the analysis of the reaction mixture throughout the whole chemical and electrochemical process is described.
- Gallardo, Iluminada,Guirado, Gonzalo,Marquet, Jordi
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p. 2548 - 2555
(2007/10/03)
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- The secondary amine/nitric oxide complex ion R2N[N(O)NO]- as nucleophile and leaving group in SNAr reactions
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Ions of structure R2N[N(O)NO]- and their alkylation products have seen increasing use as nitric oxide (NO)-generating agents for biomedical research applications. Here we show that such diazeniumdiolate anions can readily displace halide from a variety of electrophilic aza- or nitroaromatic substrates to form O2-arylated derivatives of structure R2N-N(O)=N-OAr. The site of arylation and the cis arrangement of the oxygens were confirmed by X-ray crystallography. Displacement by various nucleophiles showed R2N[N(O)NO]- to be a reasonably good leaving group, with rate constants for displacement by hydroxide, methoxide, and isopropylamine that were between those of chloride and fluoride in the SNAr reactions we surveyed. The Meisenheimer intermediate could be spectrally observed. These O2-aryl diazeniumdiolates proved capable of reacting with the nucleophilic sulfur of the HIV-1 p7 nucleocapsid protein's zinc finger assembly to eject the zinc, disrupting a structural motif critical to viral replication and suggesting possible utility in the drug discovery realm.
- Saavedra,Srinivasan,Bonifant,Chu,Shanklin,Flippen-Anderson,Rice,Turpin,Davies,Keefer
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p. 3090 - 3098
(2007/10/03)
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- An exceptionally stable Ti superoxide radical ion: A novel heterogeneous catalyst for the direct conversion of aromatic primary amines to nitro compounds
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A matrix-bound superoxide radical anion, generated by treating Ti(OR)4 (R =iPr, nBu) with H2O2, is a selective heterogeneous catalyst for the oxidation of anilines to the corresponding nitroarenes with 50 % aqueous H2O2 [Eq. (1)]. Yields of 82-98 % are obtained, even with anilines bearing electron-withdrawing substituents (R = NO2, COOH).
- Dewkar, Gajanan K.,Nikalje, Milind D.,Ali, Iliyas Sayyed,Paraskar, Abhimanyu S.,Jagtap,Sudalai
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p. 405 - 408
(2007/10/03)
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- Direct methoxylation of nitroarenes and nitroazaarenes with alkaline methoxides via nucleophilic displacement of an aromatic hydrogen atom
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Treatment of 1,3-dinitrobenzene and 5-substituted derivatives with excess potassium or sodium methoxide in 1,3-dimethylimidazolidin-2-one (DMI) at room temperature results in the displacement of an aromatic hydrogen at the 4-position by methoxide, affording 2,4-dinitroanisole and its 6-substituted derivatives, respectively, in low to moderate yield. In contrast, an equimolar reaction under similar conditions leads to the replacement of the nitro group in preference to the ring hydrogen. The reaction does not take place with lithium methoxide as a base. Mono- and dinitronaphthalenes and nitroquinolines undergo similar displacement of a hydrogen atom at the position ortho or para to the nitro group, giving the corresponding methoxy derivatives in moderate yield. A slow addition of the nitro compound to a large excess of potassium methoxide under an oxygen atmosphere has been found to enhance the conversion and improve the product yield. On the basis of the product distribution as well as the kinetic isotope effect kH/kD = 2.1, direct displacement of a ring hydrogen atom by methoxide ion has been interpreted in terms of the rate-determining release of an ipso-hydrogen atom as a proton from the initially formed Meisenheimer adduct.
- Kawakami, Takehiko,Suzuki, Hitomi
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p. 1259 - 1264
(2007/10/03)
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- Regioselective nitration of arylboronic acids
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A convenient and simple regioselective ipso-nitration of arylboronic acids to nitroarenes has been developed. Under certain conditions even dinitro products were isolated.
- Salzbrunn,Simon,Prakash,Petasis,Olah
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p. 1485 - 1487
(2007/10/03)
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- Chemoselective O-methylation of phenols under non-aqueous condition
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Chemoselective O-methylation of substituted phenols takes place in dry. tetrahydrofuran (THF) in the presence of LiOH.H2O and dimethylsulfate (DMS). Quantitative methyl transfer from DMS preserves the atom economy.
- Basak, Anindita,Nayak, Mrinal K.,Chakraborti, Asit K.
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p. 4883 - 4886
(2007/10/03)
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- Zirconium-catalysed Oxidation of Primary Aromatic Amines to Nitro Compounds Using tert-Butylhydroperoxide
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A broad range of primary aromatic amines (1a-x) with electron donating and accepting substituents are oxidized in good to excellent yields to the nitro compounds 3a-x using tert-butylhydroperoxide as the oxidant and Zr(OtBu)4 as the catalyst. The corresponding nitroso compounds 2m,-2n, 2s and 2u can be isolated in the conversion of electron-rich anilines 1m, 1n, 1s and 1u. The aminopyridines 5a-d are also converted to the corresponding nitropyridines 6a-d, but in lower yields (41-47%).
- Krohn, Karsten,Kuepke, Jochen,Rieger, Hagen
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p. 335 - 339
(2007/10/03)
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- Mild and Selective Nitration by "Claycop"
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A one-pot nitration of aromatic compounds by "claycop", a reagent consisting of an acidic montmorillonite clay impregnated with anhydrous cupric nitrate, is reported.Simply by varying the conditions, it is possible to drive the reaction at will toward either mono- or polynitration.Both the yields and selectivities are superior to those obtained under homogeneous reaction conditions.
- Gigante, Barbara,Prazeres, Angela O.,Marcelo-Curto, Maria J.,Cornelis, Andre,Laszlo, Pierre
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p. 3445 - 3447
(2007/10/02)
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- Reactivity of 1-(2-nitrophenyl)-5-aminopyrazoles under basic conditions and synthesis of new 3-, 7-, and 8-substituted pyrazolo [5,1-c][1,2,4]benzotriazine 5-oxides, as benzodiazepine receptor ligands
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The reaction of 1-(2-nitrophenyl)-5-aminopyrazoles under basic conditions has been reinvestigated and the structures of the obtained pyrazolo[5,1-c][1,2,4]benzotriazine 5-oxides confirmed by spectroscopic means. In particular the different aromatic nucleophilic attack on 8-chloro derivatives 4a and 6a and 7-nitro derivatives 11a and 12a was determined. From these latter compounds unexpected (phenyl-ONN-azoxy)pyrazoles were isolated.
- Costanzo,Guerrini,Bruni,Selleri
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p. 1369 - 1376
(2007/10/02)
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- Correlation of Reaction Rates with a Substituent Constant Scale Derived from Calculated Electron Densities for a Computer Control Algorithm
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A new ? substituent scale based on electron density calculations by the AM1 quantum mechanical model has been established and used to correlate rates of O-methylation of substituted phenols, as part of a chemical artificial intelligence to control a fully automated apparatus for methyl iodide labeling.
- Cork, David G.,Hayashi, Nobuyoshi
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p. 1583 - 1585
(2007/10/02)
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- Reaction of (E)-O-Arylbenzaldoximes with Sodium Methoxide in Methanol. Effect of Leaving Group upon Nitrile-Forming Transition State
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Reactions of (E)-O-arylbenzaldoximes 1-3 with MeONa-MeOH have been studied kinetically.The reactions proceed via competing E2 and SNAr reactions, in which the first step is rate-determining.Although the reactions were strongly influenced by the electronic effect of the β- and O-aryl substituents, they were insensitive to the steric effect of the O-aryl group, except that the SNAr reaction was retarded by the CF3 group of 2.For eliminations from 1-3 promoted by MeONa-MeOH, the kH/kD value increased and the Hammett ρ value decreased with better leaving groups.From these results, the effect of leaving group variation upon the nitrile-forming transition state is assessed.
- Cho, Bong Rae,Jung, Jinhee,Ahn, Eun Kyung
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p. 3425 - 3429
(2007/10/02)
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- Two-Phase Nitration of Phenols, Part 3: The Nitration of Anisole
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The two-phase nitration procedure previously described for phenols can be modified to lead to successful nitration of anisole but through a different mechanism.The addition of N(III) species is unnecessary and the reaction is not suppressed by nitrous aci
- Thompson, Malcolm J.,Zeegers, Petrus J.
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p. 8787 - 8790
(2007/10/02)
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- Micellar Catalysis of Organic Reactions. XXI. A Study of the Effects of Micelles of Cetyltrimethylammonium Bromide on Some SNAr Reactions in Aqueous Binary Mixtures
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The effect of micelles of cetyltrimethylammonium bromide (ctab) on the SNAr reactions of 1-fluoro-2,4-dinitrobenzene (1), 2-fluoro-5-nitrobenzoate (2) and 4-fluoro-3-nitrobenzoate (3) with sodium hydroxide in aqueous binary mixtures with several alcohols has been studied.Two products were detected in all of these reactions: the phenol from reaction with hydroxide ions, and an aryl alkyl ether from reaction with the alkoxide ions.Micelles of ctab increased the percentage yield of the ether product at the expense of the phenol for compounds (1) and (2) in most of the binary mixtures used.For compound (3), however, micelles of ctab had little effect on the product distribution.These differences were attributed to differences in the orientation of substrates (2) and (3) when solubilized by micelles of ctab.Very high yields of the ether were obtained for the reaction of compound (1) with hydroxide ions in trifluoroethanol/water mixtures, and this was attributed to the considerable ionization of trifluoroethanol which was the most acidic alcohol used in this work.The lowest yield of the ether product was obtained in reactions of compound (1) with hydroxide ions in propan-2-ol/water mixtures since propan-2-ol was the least acidic alcohol used.These results are compared with those previously reported for the reaction of compound (1) in the presence of hydroxy-funcionalized micelles and β-cyclodextrin.In the presence of micelles of ctab the aryl alkyl ethers derived from compounds (1) and (2) underwent a subsequent SNAr reaction with hydroxide ions during which the alkoxide ion was displaced.For compound (3) no subsequent reaction of the ether was detected in the presence of micelles of ctab.This was also attributed to the orientation of this product within the micelle.The reaction centre was buried in the micellar interior, and hence was shielded from a subsequent reaction.The rates of this subsequent reaction for compound (1), and of the decomposition of micellar aryl ethers and of cyclodextrin aryl ethers derived from compound (1), are also compared.The increase in the yield of the ether product in the presence of micelles was attributed to the increased ionization of alcohols in the presence of cationic micelles.
- Broxton, Trevor J.
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p. 667 - 676
(2007/10/02)
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- Reactions of the super-electrophile, 2-(2',4'-dinitrophenyl)-4,6-dinitrobenzotriazole 1-oxide, with methoxide and tert-butoxide: basicity and steric hindrance as factors in ?-complex formation versus nucleophilic displacement
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The course of the reactions of methoxide and tert-butoxide with 2-(2',4'-dinitrophenyl)-4,6-dinitrobenzotriazole 1-oxide (4) clearly shows that the C-7 electrophilic site is significantly more reactive than the C-1' site of the substrate.The reaction pathways of these alkoxides, which differ in basicity (as a measure of nucleophilicity) and steric bulk, were followed by 400 MHz 1H nuclaear magnetic resonance spectroscopy.While both alkoxides lead to immediate formation of the respective C-7 anionic ?-adducts, a greater percentage of C-7 adduct formation occurs with methoxide as attacking nucleophile.Reactions with excess alkoxide results in attack at C-1' being observed, as well.This leads to formation of metastabile C-1' ?-adducts, whose rapid decomposition results in formation of 2,4-dinitrophenyl ethers and the dinitrobenzotriazole 1-oxyanion in an overall nucleophilic displacement reaction.Under these excess conditions, methoxide also causes a faster rate of displacement than does tert-butoxide as nucleophile.These results are discussed on the basis of the basicity of the nucleophiles, the relative electrophilicity of the positions in the substrate (C-7 versus C-1'), the steric hindrance involved in attack and in the resultant C-7 and C-1' complexes, and in terms of an activation energy/reaction coordinate profile comparing the pathways for attack at the two electrophilic sites. Key words: anionic ?-complexes, super-electrophiles, aromatic nucleophilic substitution (SNAr)
- Dust, Julian M.,Buncel, Erwin
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p. 978 - 986
(2007/10/02)
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- Process for the preparation of 2,4-dinitrophenyl ethers
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A process for the preparation of 2,4-dinitrophenyl ethers of the general formula (1) STR1 in which R denotes an alkyl(C1 -C6) or alkoxy(C1 -C4)alky(C1 -C4) group by reacting 1 mole of 2,4-dinitrochlorobenzene in the anhydrous alcohol which is required for the ether formation and is of the general formula (2) in which R has the abovementioned meaning, in the presence of 1.0 to 3.0 mole of an anhydrous alkali metal carbonate, at temperatures of 20° C. to 150° C., where appropriate under pressure.
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- Process for the preparation of aromatic ether and thioether compounds
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The invention relates to a novel process for the preparation of ether and thioether compounds of formula STR1 by reacting compounds of formula STR2 with compounds of formula wherein R, R1, X, Y and n are as defined in claim 1, in the presence of an acid acceptor and in an aliphatic ketone, which process is carried out under pressure in the temperature range from 115° to 200° C.
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- SYNTHESIS OF 4-NITRO-1,2,3-TRIAZOLES
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Preparative methods were studied for the synthesis of 4-nitro-1,2,3-triazole and its N-oxide by the nitration of 2-phenyl-substituted triazoles followed by elimination of the nitrophenyl fragment, which can be successfully removed when it contains two nitro groups.
- Vereshchagin, L. I.,Nikitin, V. M.,Meshcheryakov, V. I.,Gareev, G. A.,Kirillova, L. P.,Shul'gina, V. M.
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p. 1574 - 1577
(2007/10/02)
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- Kinetics and mechanism of reaction of 1-chloro-2,4-dinitrobenzene with potassium phenoxide, 1-naphthoxide and 2-naphthoxide in methanol
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In the title reaction at different temperatures (30-45 deg C) the rates have been measured as a function of free .A linear relationship is found between the observed second order rate coefficient and the ratio /.This has been attributed to concurrent and consecutive methanolysis by methoxide ions arising from the possible proton exchange between methanol and phenoxide ion.The thermodynamic parameters of activation of the reaction of 1-chloro-2,4-dinitrobenzene with aryl oxides and methoxide anions have been calculated.From the kinetic results it is possible to calculate the equilibrium constant of the reaction: CH3OH + ArO(-) CH3O(-) + ArOH
- El-Kholy, Ali E.,Kasem, Taher S.,El-Kashlan, Howaida M.
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p. 388 - 391
(2007/10/02)
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- TERT-BUTYL AND 2,2,2-TRIFLUORO-1,1-DIPHENYLETHANE-SULFONATES - HINDRANCE OF S-O-SCISSION IN SN2-SUBSTITUTION REACTIONS
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By application of the tert-butyl sulfonates (4a) and the 2,2,2-trifluoro-1,1-diphenylethane (TDE-) sulfonates (4b) S-O-scission in SN2-substitution reactions can be drastically reduced.
- Netscher, Thomas,Schwesinger, Reinhard
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p. 2115 - 2118
(2007/10/02)
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- Polyfunctionalised Cyclohexanes from Dianhydrodeoxyinositols. cis-Deoxy-1,3(1,4)-inosadiamines from Benzene
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A ca. 9 : 1 mixture (yield 87 - 90percent) of the stereoisomeric (1α,2α,6α)-/(1α,2β,6α)-2-bromo-7-oxa-bicyclohept-3-enes (7a/8a) is obtained via controlled NBS bromination of 4,5-epoxycyclohexene (5). 7a/8a are quantitatively equilibrated in the presence of tetraalkylammonium bromides (the equilibrium being controlled by the polarity of the solvent (3 : 7 in acetonitrile) and are isolated pure by chromatography.Through selective halogen substitution (7b/8b, 9b - d/10b - d) and ammonolysis the allylic epoxy alcohols 9a/10a are obtained in high yields.Stereospecific epoxidation of 7a/8a yields the (1α,2α,3α,5α,7α)-/(1α,2β,3α,5α,7α)-diepoxy bromides 12a/14a.The latter are equilibrated quantitatively to mixtures favoring either one in the ratio of ca. 9 : 1 (CCl4) and 1 : 9 (CH3CN), respectively.Upon SN2 substitution with ammonium acylates (-> 13b, c/15b, c) and ammonolysis the naturally not occurring dianhydrodeoxyinositols 13a/15a are isolated in practically quantitative yields.The usefulness of 13a/15a and of various derivatives for the stereoselective synthesis of cis-1,4- and cis-1,3-disubstituted cyclohexanetriols is exemplified by reactions with monovalent (H2O, HI, NaN3) and divalent nucleophiles (NH2NH2, CH3NHNH2).I.a. the cis-deoxy-1,3-inosadiamines 1 (2-deoxystreptamine)/2 and the cis-deoxy-1,4-inosadiamines 3/4 become available in high yields.
- Kuehlmeyer, Rainer,Keller, Reinhold,Schwesinger, Reinhard,Netscher, Thomas,Fritz, Hans,Prinzbach, Horst
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p. 1765 - 1800
(2007/10/02)
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- Cyano and Nitro Group Effect on the Rate of Methoxy Denitration Reaction in the Pyrrole and Benzene Ring
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In both the pyrrole and benzene ring the methoxy denitration reaction is accelerated by a nitro or a cyano group flanking the reaction center.However, because of the different geometry of the rings, in the pyrrole ring a nitro group is more effective than a cyano group, at variance whit what is observed in the benzene ring.
- Bazzano, Francesca,Mencarelli, Paolo,Stegel, Franco
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p. 2375 - 2377
(2007/10/02)
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- CORRELATION OF THE RATE CONSTANTS OF SN2Ar REACTIONS WITH RITCHIE'S NUCLEOPHILICITY PARAMETERS
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The results from a spectrophotometric investigation into the kinetics of the methoxylation of a series of nitrohalogenobenzenes with sodium methoxide in mixtures of methanol with aprotic solvents at 25 deg C are given.By analysis of the results and also from published data with allowance for Ritchie's nucleophilic constants N+ an equation was derived, which describes the effect of the nucleophilic reagent-binary solvent systems on the kinetics of SN2Ar reactions.
- Kuznetsova, V. P.,Sinev, V. V.,Ginzburg, O. F.
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p. 623 - 627
(2007/10/02)
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- Selective weed control with m-dinitrobenzene
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Weeds can be controlled by the application as a herbicide of m-dinitrobenzene. This compound is particularly effective for selectively controlling weeds in agronomic crops.
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