- Base mediated spirocyclization of quinazoline: One-step synthesis of spiro-isoindolinone dihydroquinazolinones
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A novel approach for the spiro-isoindolinone dihydroquinazolinones has been demonstrated from 2-aminobenzamide and 2-cyanomethyl benzoate in the presence of KHMDS as a base to get moderate yields. The reaction has been screened in various bases followed by solvents and a gram scale reaction has also been executed under the given conditions. Based on the controlled experiments a plausible reaction mechanism has been proposed. Further the substrate scope of this reaction has also been studied.
- Jinkala, Rajesh,Madhu Babu, M. V.,Murthy, V. Narayana,Nikumbh, Satish P.,Raghunadh, Akula,Rama Mohan, Hindupur,Siddaiah, Vidavalur,Tadiparthi, Krishnaji,Venkateshwarlu, Rapolu
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Read Online
- Stepwise benzylic oxygenation via uranyl-photocatalysis
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Stepwise oxygenation at the benzylic position (1°, 2°, 3°) of aromatic molecules was comprehensively established under ambient conditions via uranyl photocatalysis to produce carboxylic acids, ketones, and alcohols, respectively. The accuracy of the stepwise oxygenation was ensured by the tunability of catalytic activity in uranyl photocatalysis, which was adjusted by solvents and additives demonstrated through Stern–Volmer analysis. Hydrogen atom transfer between the benzylic position and the uranyl catalyst facilitated oxygenation, further confirmed by kinetic studies. Considerably improved efficiency of flow operation demonstrated the potential for industrial synthetic application.
- Hu, Deqing,Jiang, Xuefeng
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supporting information
p. 124 - 129
(2022/01/19)
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- o-Cyanobenzoate: A Recyclable and Reusable Stereo-directing Group for β-O-Glycosylation via Pd(0)-catalyzed Ferrier Rearrangement
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Inner sphere Tsuji-Trost reaction has found recent application for β-selective Ferrier rearrangement of glycal substrates with alcohol nucleophiles. Herein, we report an efficient and stereoselective synthesis of 2,3-dideoxy-β-O-glycosides from C3-(o-cyan
- Das, Pradip,Kumar, Amit,Rahaman Molla, Mosidur,Thakur, Rima
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supporting information
(2022/01/06)
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- Photoinduced FeCl3-Catalyzed Alkyl Aromatics Oxidation toward Degradation of Polystyrene at Room Temperature?
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While polystyrene is widely used in daily life as a synthetic plastic, the subsequently selective degradation is still very challenging and highly required. Herein, we disclose a highly practical and selective reaction for the catalytically efficient oxidation of alkyl aromatics (including 1°, 2°, and 3° alkyl aromatics) to carboxylic acids. While dioxygen was used as the sole terminal oxidant, this protocol was catalyzed by the inexpensive and readily available ferric compound (FeCl3) with irradiation of visible light (blue LEDs) under only 1 atmosphere of O2 at room temperature. This system could further facilitate the selective degradation of polystyrene to benzoic acid, providing an important and practical tool to generate high-value chemical from abundant polystyrene wastes.
- Zhang, Guoxiang,Zhang, Zongnan,Zeng, Rong
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supporting information
p. 3225 - 3230
(2021/09/28)
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- Cleavage of Carboxylic Esters by Aluminum and Iodine
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A one-pot procedure for deprotecting carboxylic esters under nonhydrolytic conditions is described. Typical alkyl carboxylates are readily deblocked to the carboxylic acids by the action of aluminum powder and iodine in anhydrous acetonitrile. Cleavage of lactones affords the corresponding ω-iodoalkylcarboxylic acids. Aryl acetylates undergo deacetylation with the participation of the neighboring group. This method enables the selective cleavage of alkyl carboxylic esters in the presence of aryl esters.
- Sang, Dayong,Yue, Huaxin,Fu, Yang,Tian, Juan
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p. 4254 - 4261
(2021/03/09)
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- Methyl esters of 2-(N-hydroxycarbamimidoyl)benzoyl-substituted α-amino acids as promising building blocks in peptidomimetic synthesis: a comparative study
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Abstract: An efficient and simple synthetic protocol for the synthesis of a number methyl esters of 2-(N-hydroxycarbamimidoyl)benzoyl-substituted (S)-α-amino acids via subsequent coupling and hydroxyamination of 2-cyanobenzamide derivatives has been developed. Comparative analysis of three pseudopeptide series based on 2-cyano- and 2-amidoxime-substituted benzoic acid and its pyridine and pyrazine counterparts has been provided and it has revealed a practical advantage of the benzoic acid derivatives due to their greater availability. The impact of the nitrogen atom in the aromatic ring on the trans/cis-amide equilibrium in the proline derivatives is discussed. Graphical abstract: [Figure not available: see fulltext.]
- Tkachuk, Volodymyr A.,Hordiyenko, Olga V.,Omelchenko, Irina V.,Medviediev, Volodomir V.,Arrault, Axelle
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p. 2293 - 2309
(2018/11/02)
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- Pd-Catalyzed debenzylation and deallylation of ethers and esters with sodium hydride
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Herein we demonstrate simply that the addition of Pd(OAc)2 as a promotor switches the reactivity of a commonly used base NaH to a nucleophilic reductant. The reactivity is engineered into a palladium-catalyzed reductive debenzylation and deallylation of aryl ethers and esters. This operationally simple, mild protocol displays a broad substrate scope and a broad spectrum of functional group tolerance (>50 examples) and high chemoselectivity toward aryl ethers over aliphatic structures. Moreover, the dual reactivity of NaH as a base and a reductant is demonstrated in efficient synthetic elaboration.
- Mao, Yujian,Liu, Ye,Hu, Yanwei,Wang, Liang,Zhang, Shilei,Wang, Wei
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p. 3016 - 3020
(2018/04/14)
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- Application of metallide/palladium compound catalytic reduction system in debenzylation reaction and deuterization reaction
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The invention discloses an application of a metallide/palladium compound catalytic reduction system in debenzylation reaction and deuterization reaction of benzyl-containing compounds. The reaction comprises the following steps: under the protection of nitrogen, suspending a palladium compound and a metallide in a solvent, stirring for 5 minutes, adding the benzyl-containing compounds, carrying out a reaction for 0.5 to 48 h at the temperature of -30 DEG C to 150 DEG C, adding ice water to stop the reaction, adjusting the pH value to 3.5 with diluted hydrochloric acid, extracting the reactionsolution by a solvent, drying by distillation, purifying by column chromatography, and thus completing the reaction.
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Paragraph 0051
(2018/09/08)
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- Catalyst-free, efficient and one pot protocol for synthesis of nitriles from aldehydes using glycerol as green solvent
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We described herein the novel, efficient and one-pot catalyst free protocol for the synthesis of nitriles from aldehydes by using hydroxyl amine hydrochlorides in glycerol as a green solvent. This protocol was efficiently used for transformation of aromatic aldehydes bearing electron-withdrawing and electron-donating groups into a aryl nitriles in good to excellent yields. The methodology offers a very simple, efficient and environmentally benign procedure.
- Ingale, Ajit P.,Patil, Shripad M.,Shinde, Sandeep V.
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p. 4845 - 4848
(2017/11/30)
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- NH4I/tert-butyl hydroperoxide-promoted oxidative C–N cleavage of tertiary amines leading to nitroaromatic compounds
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A NH4I/tert-butyl hydroperoxide-promoted oxidation of tertiary N-aryl-N,N-dialkylamines in DMSO has been developed to access nitroaromatic compounds. This methodology involves sequential N-dealkylation reactions in one-pot and a radical pathway is proposed.
- Shao, Ying,Zheng, Hao,Wu, Zhuhong,Huang, Lei,Tong, Jingjing,Wu, Ming,Sun, Xiaoqiang
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p. 504 - 508
(2017/10/03)
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- Synthesis of benzoic acids containing a 1,2,4-oxadiazole ring
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A new approach to the synthesis of 4and 3-(5-R-1,2,4-oxadiazol-3-yl)benzoic acids via a selective oxidation of 5-R-3-tolyl-1,2,4-oxadiazoles with air oxygen in the presence of a catalytic system based on cobalt acetate was suggested. This synthesis allowed us to obtain the products in higher yields and with shorter sequence of steps as compared to the known procedures.
- Krasouskaya,Danilova,Baikov,Kolobov,Kofanov
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p. 142 - 145
(2015/10/05)
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- Transnitrilation from Dimethylmalononitrile to Aryl Grignard and Lithium Reagents: A Practical Method for Aryl Nitrile Synthesis
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An electrophilic cyanation of aryl Grignard or lithium reagents, generated in situ from the corresponding aryl bromides or iodides, by a transnitrilation with dimethylmalononitrile (DMMN) was developed. DMMN is a commercially available, bench-stable solid. The transnitrilation with DMMN avoids the use of toxic reagents and transition metals and occurs under mild reaction conditions, even for extremely sterically hindered substrates. The transnitrilation of aryllithium species generated by directed ortho-lithiation enabled a net C-H cyanation. The intermediacy of a Thorpe-type imine adduct in the reaction was supported by isolation of the corresponding ketone from the quenched reaction. Computational studies supported the energetic favorability of retro-Thorpe fragmentation of the imine adduct. (Chemical Equation Presented).
- Reeves, Jonathan T.,Malapit, Christian A.,Buono, Frederic G.,Sidhu, Kanwar P.,Marsini, Maurice A.,Sader, C. Avery,Fandrick, Keith R.,Busacca, Carl A.,Senanayake, Chris H.
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supporting information
p. 9481 - 9488
(2015/08/11)
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- Copper-catalyzed formal c-h carboxylation of aromatic compounds with carbon dioxide through arylaluminum intermediates
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The C-H bond carboxylation of various aromatic compounds with CO2 was achieved by the deprotonative alumination with a mixed alkyl amido lithium aluminate compound iBu3Al(TMP)Li followed by the NHC-copper-catalyzed carboxylation of the resulting arylaluminum species, which afforded the corresponding carboxylation products in high yield and high selectivity. In addition to benzene derivatives, heteroarenes such as benzofuran, benzothiophene, and indole derivatives are also suitable substrates. Functional groups such as Cl, Br, I, vinyl, amide, and CN could survive the reaction conditions. Some key reaction intermediates such as the copper aryl and isobutyl complexes and their carboxylation products were isolated and structurally characterized by X-ray crystallographic analyses, thus offering important information on the reaction mechanism.
- Ueno, Atsushi,Takimoto, Masanori,Wylie,Nishiura, Masayoshi,Ikariya, Takao,Hou, Zhaomin
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supporting information
p. 1010 - 1016
(2015/03/31)
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- Extremely fast gas/liquid reactions in flow microreactors: Carboxylation of short-lived organolithiums
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Carboxylation of short-lived organolithiums bearing electrophilic functional groups such as nitro, cyano, and alkoxycarbonyl groups with CO 2 to give carboxylic acids and active esters was accomplished in a flow microreactor system. The successful reactions indicate that gas/liquid mass transfer and the subsequent chemical reaction with CO2 are extremely fast. Carboxylation of short-lived organolithiums bearing electrophilic functional groups such as nitro, cyano, and alkoxycarbonyl groups with CO 2 to give carboxylic acids and active esters was accomplished in a flow microreactor system. The successful reactions indicate that gas/liquid mass transfer and the subsequent chemical reaction with CO2 are extremely fast (see scheme).
- Nagaki, Aiichiro,Takahashi, Yusuke,Yoshida, Jun-Ichi
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p. 7931 - 7934
(2014/07/07)
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- Electrophilicity and nucleophilicity of commonly used aldehydes
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The present approach for determining the electrophilicity (E) and nucleophilicity (N) of aldehydes includes a kinetic study of KMNO4 oxidation and NaBH4 reduction of aldehydes. A transition state analysis of the KMNO4 promoted aldehyde oxidation reaction has been performed, which shows a very good correlation with experimental results. The validity of the experimental method has been tested using the experimental activation parameters of the two reactions. The utility of the present approach is further demonstrated by the theoretical versus experimental relationship, which provides easy access to E and N values for various aldehydes and offers an at-a-glance assessment of the chemical reactivity of aldehydes in various reactions. the Partner Organisations 2014.
- Pratihar, Sanjay
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p. 5781 - 5788
(2014/07/22)
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- Per-6-amino-β-cyclodextrin/CuI catalysed cyanation of aryl halides with K4[Fe(CN)6]
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Efficient cyanation of aryl halides is achieved using less toxic K 4[Fe(CN)6] as the reagent and amino-β-cyclodextrins as supramolecular ligands for CuI. Four different amino cyclodextrins viz. per-6-amino-β-CD, per-6-methylamino-β-CD, per-6-butyl-amino-β-CD and mono-6-amino-β-CD are prepared and studied. Aryl and heteroaryl nitriles are obtained in good to excellent yield for even bromo derivatives of flavone and 2-aminopyrans. This system uses catalytic amounts (10 mol%) of both copper iodide and per-6-amino-β-cyclodextrin. Easy separation, the absence of nitrogen atmosphere and excellent yield are the other significant outcomes of this protocol. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.
- Azath, Ismail Abulkalam,Suresh, Palaniswamy,Pitchumani, Kasi
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supporting information
p. 2334 - 2339
(2013/01/15)
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- Method for estimating SN1 rate constants: Solvolytic reactivity of benzoates
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Nucleofugalities of pentafluorobenzoate (PFB) and 2,4,6-trifluorobenzoate (TFB) leaving groups have been derived from the solvolysis rate constants of X,Y-substituted benzhydryl PFBs and TFBs measured in a series of aqueous solvents, by applying the LFER equation: log k = sf(Ef + Nf). The heterolysis rate constants of dianisylmethyl PFB and TFB, and those determined for 10 more dianisylmethyl benzoates in aqueous ethanol, constitute a set of reference benzoates whose experimental ΔG ? have been correlated with the ΔH? (calculated by PCM quantum-chemical method) of the model epoxy ring formation. Because of the excellent correlation (r = 0.997), the method for calculating the nucleofugalities of substituted benzoate LGs have been established, ultimately providing a method for determination of the SN1 reactivity for any benzoate in a given solvent. Using the ΔG? vs ΔH? correlation, and taking sf based on similarity, the nucleofugality parameters for about 70 benzoates have been determined in 90%, 80%, and 70% aqueous ethanol. The calculated intrinsic barriers for substituted benzoate leaving groups show that substrates producing more stabilized LGs proceed over lower intrinsic barriers. Substituents on the phenyl ring affect the solvolysis rate of benzhydryl benzoates by both field and inductive effects.
- Matic, Mirela,Denegri, Bernard,Kronja, Olga
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supporting information
p. 8986 - 8998,13
(2012/12/12)
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- Kinetics and mechanism of the oxidation of substituted benzaldehydes with bis(pyridine)silver permanganate
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The oxidation of thirty-six ortho-, meta- and para-substituted benzaldehydes by bis(pyridine)silver permanganate (BPSP) resulted in the formation of the corresponding benzoic acids. The reaction is first order with respect to both BPSP and aldehydes. The reaction is catalyzed by hydrogen ions. The rate of reaction increases with an increase in the amount of acetic acid in the solvent. The correlation analyses of the rate of oxidation of thirty-six aldehydes were performed in terms of Charton's LDR and LDRS equations. The rate of oxidation of meta- and para-substituted benzaldehydes showed excellent correlation with Charton's LDR equation. The rates of ortho-compounds showed excellent correlation with LDRS equation. The oxidation para-compounds is more susceptible to the delocalization effect. The oxidation of ortho- and meta-compounds exhibited a greater dependence on the field effect. The polar reaction constants are negative indicating an electron-deficient centre in the rate-determining step. A mechanism involving a nucleophilic attack on the carbonyl group by a permanganate-oxygen and a subsequent hydride transfer has been proposed.
- Purohit, Trupti,Banerji, Jayshree,Kotai, Laszlo,Sajo,Banerji,Sharma, Pradeep K.
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p. 1045 - 1052
(2013/01/14)
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- Structure-Reactivity correlation in the oxidation of substituted benzaldehydes by tetraethylammonium chlorochromate
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Oxidation of 36 monosubstituted benzaldehydes by tetraethylammonium chlorochromate in dimethyl sulphoxide, leads to the formation of corresponding benzoic acids. The reaction is of first order with respect to chlorochromate and aldehydes. The reaction is promoted by H+; the H+ dependence has the form kobs = a + b[H+]. The oxidation of duteriated benzaldehyde exhibits substantial primary kinetic isotope effect. The reaction was studied in 19 different organic solvents and the effect of solvent was analyzed using Taft's and Swain's multiparametric equations. The rates of the oxidation of para- and meta-substituted benzaldehydes showed excellent correlation in terms of Charton's triparametric LDR equation, whereas the oxidation of ortho-substituted benzaldehydes were correlated well with tetraperametric LDRS equation. The oxidation of para-substituted benzaldehydes is more susceptible to the delocalized effect than is the oxidation of ortho- and meta- substituted compounds, which display a greater dependence on the field effect. The positive value of h suggests the presence of an electron-deficient reaction centre in the rate-determining step. The reaction is subjected to steric acceleration by the orthosubstituents. A suitable mechanism has been proposed.
- Gehlot,Prasadrao,Sharma
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experimental part
p. 1173 - 1178
(2012/01/05)
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- Electronic and steric effects: How do they work in ionic liquids? the case of benzoic acid dissociation
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(Figure Presented) The need to have a measure of the strength of some substituted benzoic acids in ionic liquid solution led us to use the protonation equilibrium of sodium p-nitrophenolate as a probe reaction, which was studied by means of spectrophotometric titration at 298 K. In order to evaluate the importance of electronic effect of the substituents present on the aromatic ring, both electron-withdrawing and -donor substituents were taken into account. Furthermore, to have a measure of the importance of the steric effect of the substituents both para- and ortho-substituted benzoic acids were analyzed. The probe reaction was studied in two ionic liquids differing for the ability of the cation to give hydrogen bond and π-π interactions, namely [bm 2im][NTf2] and [bmpyrr][NTf2]. Data collected show that benzoic acids are less dissociated in ionic liquid than in water solution. Furthermore, the equilibrium constant values seem to be significantly affected by both the nature of ionic liquid cation and the structure of the acid. In particular, the ortho-steric effect seems to operate differently in water and in the aromatic ionic liquid, determining in this solvent medium a particular behavior for ortho-substituted benzoic acids.
- D'Anna, Francesca,Marullo, Salvatore,Vitale, Paola,Noto, Renato
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experimental part
p. 4828 - 4834
(2010/10/04)
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- Influence of solvent on the ortho substituent effect in the alkaline hydrolysis of phenyl esters of substituted benzoic acids
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The second-order rate constants k (dm3mol-1 s -1) for the alkaline hydrolysis of phenyl esters of meta-, para-and ortho-substituted benzoic acids in aqueous 5.3 M NaClO4 and 1.0 M Bu4NBr were measured by UV/Vis spectrophotometry at 25 °C. The variations in the ortho inductive, ortho resonance, as well as meta and para polar effects with solvent parameters were studied using data for the alkaline hydrolysis of phenyl esters of substituted benzoic acids in various media. The dependence of the ortho substituent effect on solvent can be precisely described with the following equation: δlog kortho = log k ortho - log kH = 0.059 + 2.19σ1 +0.304σ°R + 2.79EBs -0.016 δEσ1-0.085δEσ°R, where δE is the solvent electrophilicity, δE = ES-E H2O, characterizing the hydrogen-bond donating power of the solvent. The increase in the meta and para polar substituent effects with decrease in the solvent hydrogen-bond donor capacity (electrophilicity) was approximately to the same extent (-0.068δEσ°m, p) as the resonance term for the ortho substituents. The steric term of ortho substituents was independent of the solvent parameters. The variations in the ortho inductive, ortho resonance, as well as meta and para polar substituent effects with the solvent electrophilicity were to the same extent as in phenyl benzoates containing the substituents in the phenyl part. The substituent effects in the alkaline hydrolysis of ethyl benzoates appeared to vary with the solvent electrophilicity nearly to the same extent as in the alkaline hydrolysis of substituted phenyl esters of benzoic acids. Copyright 2009 John Wiley Sons, Ltd.
- Nummert, Vilve,Piirsalu, Mare,Koppel, Ilmar A.
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experimental part
p. 497 - 504
(2011/08/08)
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- Kinetic study of hydrolysis of benzoates. part xxvii. ortho substituent effect in alkaline hydrolysis of phenyl esters of substituted benzoic acids in aqueous BU4NBr
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The second-order rate constants k (in dm3 mol-1 s-1) for alkaline hydrolysis of phenyl esters of meta-, para- and ortto-substituted benzoic acids, X-C6H4CO 2C6H5, have been measured spectrophotometrically in aqueous 0.5 and 2.25 m Bu4NBr at 25 °C. The substituent effects for para and meta derivatives were described using the Hammett relationship. For the ortho derivatives the Charton equation was used. For ort/io-substituted esters two steric scales were involved: the E SB and the Charton steric (v) constants. When going from pure water to aqueous 0.5 and 2.25 m Bu4NBr, the meta and para polar effects, the ortho inductive and resonance effects in alkaline hydrolysis of phenyl esters of substituted benzoic acids, became stronger nearly to the same extent as found for alkaline hydrolysis of C6H5CO 2C6H4-X. The steric term of ortfto-substituted esters was almost independent of the media considered. The rate constants of alkaline hydrolysis of ortho-, meta- and para-substituted phenyl benzoates (X-C6H4CO2C6H5, C 6H5CO2C6H4-X) and alkyl benzoates, C6H5CO2R, in water, 0.5 and 2.25 m Bu4NBr were correlated with the corresponding IR stretching frequencies of carbonyl group, (δvco)x.
- Nummert, Vilve,Piirsalu, Mare,Vahur, Signe,Travnikova, Oksana,Koppel, Ilmar A.
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experimental part
p. 29 - 42
(2009/06/18)
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- Correlation analysis of reactivity in the oxidation of substituted benzaldehydes by morpholinium chlorochromate
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Oxidation of thirty six monosubstituted benzaldehydes by morpholinium chlorochromate (MCC) in dimethylsulphoxide (DMSO), leads to the formation of corresponding benzoic acids. The reaction is of first order with respect to MCC. A Michaelis-Menten type kinetics is observed with respect to benzaldehydes. The reaction is promoted by hydrogen ions; the hydrogen-ion dependence has the form kobs = a + b [H+]. The oxidation of [2H] benzaidehyde (PhCDO) exhibited a substantial primary kinetic isotope effect. The reaction was studied in nineteen organic solvents and the effect of solvent was analysed using Taft's and Swain's multi-parametric equations. The rates of the oxidation of para- and meta-substituted benzaldehydes showed excellent correlation in terms of Charton's triparametric LDR equation, whereas the oxidation of ortho-substituted benzaldehydes were correlated well with tetraparametric LDRS equation. The oxidation of para-substituted benzaldehydes is more susceptible to the delocalized effect than is the oxidation of ortho- and meta-substituted compounds, which display a greater dependence on the field effect. The positive value of η suggests the presence of an electron-deficient reaction centre in the rate-determining step. The reaction is subjected to steric acceleration by the ortho-substituents. A suitable mechanism has been proposed.
- Choudhary, Anurag,Malani,Agarwal,Sharma,Sharma, Vinita
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experimental part
p. 927 - 935
(2010/07/16)
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- Selective generation of lithiated benzonitriles: The importance of reaction conditions
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(Chemical Equation Presented) Lithiated benzonitriles can be generated in high yields from reactions of bromobenzonitriles with n-BuLi in THF under standard cryogenic conditions (ca. -70°C) provided the reverse addition mode is employed. The resultant ary
- Lulinski, Sergiusz,Zajac, Katarzyna
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p. 7785 - 7788
(2008/12/22)
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- Structure-reactivity correlation in the oxidation of substituted benzaldehydes by 2,2-bipyridinium chlorochromate
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Oxidation of thirty six monosubstituted benzaldchydes by 2,2′-bipyridiniuin chlorochromate (BPCC) in diniethylsulphoxide (DMSO), leads to the formation of corresponding benzoic acids. The reaction is of first order with respect to both BPCC and aldehydes. The reaction is promoted by hydrogen ions; the hydrogen ion dependence has the form kobs= a + b[H+]. The oxidation of [2H]benzaldehyde (PhCDO) exhibited a substantial primary kinetic isotope effect. The reaction was studied in nineteen different organic solvents and the effect of solvent was analysed using Taft's and Swain's multi-parametric equations. The rates of the oxidation of para- and mete-substituted benzaldehydes showed excellent correlation in terms of Charton's triparametric LDR equation, whereas the oxidation of orfAo-substituted benzaldehydes were correlated well with tetraparametric LDRS equation. The oxidation of para-substituted benzaldehydes is more susceptible to the delocalized effect than is the oxidation of ortho- and mem-substituted compounds, which display a greater dependence on the field effect. The positive value of η suggests the presence of an electron-deficient reaction centre in the rate-determining step. The reaction is subjected to steric acceleration by the ortho-substituents. A suitable mechanism has been proposed.
- Sharma, Pradeep K.
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experimental part
p. 1281 - 1288
(2009/12/31)
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- Benzimidazol-2-yl or benzimidazol-2-ylthiomethyl benzoylguanidines as novel Na+/H+ exchanger inhibitors, synthesis and protection against ischemic-reperfusion injury
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A novel series of benzimidazol-2-yl or benzimidazol-2-ylthiomethyl benzoylguanidines were designed and synthesized as Na+/H+exchanger inhibitors. Most of them were found to inhibit NHE1-mediated platelet swelling in a concentration-dependent manner, and to have significant cardioprotective effect against myocardial ischemic-reperfusion injury, among which compounds 10a and 34 were more potent than cariporide in both in vivo and in vitro tests.
- Zhang, Rui,Lei, Lin,Xu, Yun-Gen,Hua, Wei-Yi,Gong, Guo-Qing
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p. 2430 - 2433
(2008/04/18)
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- Kinetics and mechanism of the oxidation of substituted benzaldehydes by tetrabutylammonium tribromide
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The oxidation of thirty-six monosubstituted benzaldehydes by tetrabutylammonium tribromide (TBATB), in aqueous acetic acid solution, leads to the formation of the corresponding benzoic acids. The reaction is first order with respect to both TBATB and aldehydes. The reaction failed to induce the polymerization of acrylonitrile. There is no effect of tetrabutylammonium chloride ions on the reaction rate. The oxidation of [2H]benzaldehyde (PhCDO) indicated the presence of a substantial kinetic isotope effect. The effect of solvent composition indicated that the reaction rate increases with an increase in the polarity of the medium. The rates of oxidation of meta- and para-substituted benzaldehydes showed excellent correlations in terms of Charton's triparametric LDR equation whereas the oxidation of ortho-substituted benzaldehydes correlated well with tetraparametric LDS equation. The oxidation of para-substituted benzaldehydes is more susceptible to the delocalization effect but the oxidation of ortho- and meta-substituted compounds displayed a greater dependence on the field effect. The positive value of η suggests the presence of an electron-deficient reaction center in the rate-determining step. The reaction is subjected to steric acceleration when ortho-substituents are present.
- Chouhan,Sharma, Monica,Sharma, Vinita
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p. 582 - 587
(2008/09/21)
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- Synthesis of valsartan via decarboxylative biaryl coupling
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(Chemical Equation Presented) An efficient synthesis of the angiotensin II inhibitor valsartan (Diovan) is presented. Two routes were evaluated, both making use of an advanced version of our decarboxylative coupling for the construction of the biaryl moiety. Thus, in the presence of a catalyst system consisting of copper(II) oxide, 1,10-phenanthroline, and palladium(II) bromide, 2-cyanocarboxylic acid was coupled with 1-bromo(4-dimethoxymethyl)benzene in 80% yield and with 4-bromotoluene in 71% yield. The valsartan synthesis using 1-bromo(4-dimethoxymethyl)benzene was completed in four steps overall with a total yield of 39%, via a novel route that presents substantial economical and ecological advantages over the literature process, as it is more concise and stoichiometric amounts of expensive organometallic reagents are avoided.
- Goossen, Lukas J.,Melzer, Bettina
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p. 7473 - 7476
(2008/02/12)
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- Preparation of highly potent and selective non-peptide antagonists of the arginine vasopressin V1A receptor by introduction of a 2-ethyl-1H-1-imidazolyl group
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To find a new series of arginine vasopressin (AVP) V1A receptor antagonists, the influence of the 2-phenyl group of 2-phenyl-4′-[(2,3,4,5- tetrahydro-1H-1-benzazepin-1-yl)carbonyl]benzanilide (7) was investigated. Replacement of the 2-phenyl group by a 2-ethyl-1H-imidazol-1-yl group was effective in yielding a V1A-selective compound. Moreover, this imidazolyl group was introduced in the same position in YM-35471 (6), and further studies of these compounds were performed. Consequently, we found that the (Z)-4′-({4,4-difluoro-5-[(N-cyclo-propylcarbamoyl) methylene]-2,3,4,5-tetrahydro-1H-1-benzazepin-1-yl}carbonyl)-2-(2-ethyl-1H-1- imidazol-1-yl)benzanilide (9f) exhibited highly potent affinity and selectivity, and was the most potent antagonist for the V1A receptor among our compounds. The synthesis and pharmacological evaluation of these compounds are described in this paper
- Shimada, Yoshiaki,Akane, Hiroaki,Taniguchi, Nobuaki,Matsuhisa, Akira,Kawano, Noriyuki,Kikuchi, Kazumi,Yatsu, Takeyuki,Tahara, Atsuo,Tomura, Yuichi,Kusayama, Toshiyuki,Wada, Koh-Ichi,Tsukada, Junko,Tsunoda, Takashi,Tanaka, Akihiro
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p. 764 - 769
(2007/10/03)
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- Carboxylation and esterification of functionalized arylcopper reagents
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Functionalized arylcopper reagents have been produced in good yields at 25 °C from activated copper and the corresponding functionalized aryl iodides without the need of traditional organolithium or Grignard precursors. These organocopper compounds will undergo carboxylation with CO2 to form the corresponding copper benzoates. In turn, these salts can be acidified to produce the functionalized aryl acids or treated with appropriate alkyl halides in the presence of a dipolar aprotic solvent to generate the corresponding aryl esters. This methodology permits the formation of functionalized organic acids and esters that could not be generated by the carboxylation of organomagnesium compounds.
- Ebert, Greg W.,Juda, Wayne L.,Kosakowski, Robert H.,Ma, Bing,Dong, Liming,Cummings, Keith E.,Phelps, Mwita V. B.,Mostafa, Adel E.,Luo, Jianyuan
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p. 4314 - 4317
(2007/10/03)
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- Oxidation of toluenes to benzoic acids by oxygen in non-acidic solvents
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Oxidation of substituted toluenes by molecular oxygen at one atmosphere to the corresponding substituted benzoic acids in non-acidic solvents was investigated. Satisfactory oxidation of halo-, methoxy-, and cyano-toluenes were achieved using Co(C18H35O2) 2/NH4Br or Co(OAc)2/NaBr/AcOH as catalysts in the presence of a radical initiator.
- Yang, Fan,Sun, Jing,Zheng, Rui,Qiu, Wenwei,Tang, Jie,He, Mingyuan
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p. 1225 - 1228
(2007/10/03)
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- Correlation analysis of reactivity in the oxidation of substituted benzaldehydes by benzyltrimethylammonium tribromide
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The oxidation of benzaldehyde and thirty-five monosubstituted benzaldehydes by benzyltrimethylammonium tribromide (BTMAB) in aqueous acetic acid leads to the formation of the corresponding benzoic acids, The reaction is first order with respect to each the benzaldehyde and BTMAB. The reaction failed to induce the polymerization of acrylonitrile. There is no effect of benzyltrimethylammonium chloride on the reaction rate. The oxidation of [2H]benzaldehyde (PhCDO) indicated the presence of a substantial kinetic isotope effect. The effect of solvent composition indicated that the reaction rate increases with an increase in the polarity of the solvent. The rates of oxidation of meta- and para-substituted benzaldehydes are correlated in terms of Charton's triparametric LDR equation whereas the oxidation of ortho-substituted benzaldehydes are correlated with tetraparametric LDRS equation. The oxidation of para- substituted benzaldehydes is more susceptible to the delocalization effect than is the oxidation of ortho-and meta-substituted compounds, which display a greater dependence on the field effect. The positive value of η suggests the presence of an electron-deficient reaction centre in the rate-determining step. The reaction is subjected to steric hindrance by the ortho-substituents.
- Mehla, Satish K.,Kothari, Seema,Banerji, Kalyan K.
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p. 832 - 838
(2007/10/03)
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- An efficient and mild procedure for the preparation of benzoic acids via oxidation of aromatic carbonyl compounds by employing N-bromoimides and mercuric acetate system
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Aromatic carbonyl compounds are efficiently converted into the corresponding benzoic acids under mild reaction conditions by employing N-bromoimide and mercuric acetate in good to excellent yields. This procedure works efficiently at room temperature for aromatic aldehydes as well as aromatic ketones to give the corresponding benzoic acids.
- Anjum, Amena,Srinivas
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p. 900 - 901
(2007/10/03)
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- Correlation analysis of reactivity in the oxidation of substituted benzaldehydes by pyridinium hydrobromide perbromide
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The oxidation of benzaldehyde and 35 monosubstituted benzaldehydes by pyridinium hydrobromide perbromide (PHPB) in aqueous acetic acid leads to the formation of the corresponding benzoic acids. The reaction is first order with respect to each of the benzaldehydes and PHPB. Addition of pyridinium bromide has no effect on the rate of oxidation. The oxidation of [2H]benzaldehyde (PhCDO) indicated the presence of a substantial kinetic isotope effect. The effect of solvent composition indicated that the reaction rate increases with increase in the polarity of the solvent. The rates of oxidation of meta- and para-substituted benzaldehydes were correlated in terms of Charton's triparametric LDR equation whereas those of ortho-substituted benzaldehydes were correlated with a tetraparametric LDRS equation. The oxidations of para- and ortho-substituted benzaldehydes are more susceptible to the delocalization effect while the oxidation of meta-substituted compounds displays a greater dependence on the fi eld effect. The positive value of η suggests the presence of an electron-deficient reaction centre in the rate-determining step. The reaction is subjected to steric hindrance by the ortho substituents.
- Aneja, Meenakshi,Kothari, Seema,Banerji, Kalyan K.
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p. 650 - 656
(2007/10/03)
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- Kinetics and mechanism of the oxidation of substituted benzaldehydes by hexamethylenetetramine-bromine
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The oxidation of thirty-six monosubstituted benzaldehydes by hexa-methylenetetramine-bromine (HABR), in aqueous acetic acid solution, leads to the formation of the corresponding benzoic acids. The reaction is first order with respect to HABR. Michaelis-Menten-type kinetics were observed with respect to aldehyde. The reaction failed to induce the polymerization of acrylonitrile. There is no effect of hexamethylenetetramine on the reaction rate. The oxidation of [2H]benzaldehyde (PhCDO) indicated the presence of a substantial kinetic isotope effect. The effect of solvent composition indicated that the reaction rate increases with an increase in the polarity of the solvent. The rates of oxidation of meta- and para-substituted benzaldehydes showed excellent correlations in terms of Charton's triparametric LDR equation, whereas the oxidation of ortho-substituted benzaldehydes correlated well with tetraparametric LDRS equation. The oxidation of para-substituted benzaldehydes is more susceptible to the delocalization effect but the oxidation of ortho- and meta-substituted compounds displayed a greater dependence on the field effect. The positive value of γ suggests the presence of an electron-deficient reaction center in the rate-determining step. The reaction is subjected to steric acceleration when ortho-substituents are present.
- Gangwani,Sharma,Banerji
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p. 615 - 622
(2007/10/03)
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- Kinetics and mechanism of the oxidation of substituted benzaldehydes by benzyltrimethylammonium chlorobromate
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The oxidation of 35 monosubstituted benzaldehydes by benzyltrimethylammonium chlorobromate (BTMACB) in aqueous acetic acid leads to the formation of the corresponding benzoic acids. The reaction is first order with respect to both benzaldehyde and BTMACB. The reaction failed to induce the polymerization of acrylonitrile. There is no effect of benzyltrimethylammonium chloride or potassium bromide on the reaction rate. The oxidation of [2H]benzaldehyde (PhCDO) indicated the presence of a substantial kinetic isotope effect. The effect of solvent composition indicated that the reaction rate increases with an increase in the polarity of the solvent. The rates of oxidation of meta- and para-substituted benzaldehydes were correlated in terms of Charton's triparametric LDR equation, whereas the oxidation of ortho-substituted benzaldehydes was correlated with the tetraparametric LDRS equation. The oxidation of para- substituted benzaldehydes is more susceptible to the delocalization effect, whereas the oxidation of ortho-and meta-substituted compounds displayed a greater dependence on the field effect. The positive value of η suggests the presence of an electron-deficient reaction center in the rate-determining step. The reaction is subjected to steric hindrance by the ortho substituents.
- Raju, V. Sitarama,Sharma, Pradeep K.,Banerji, Kalyan K.
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p. 3322 - 3325
(2007/10/03)
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- Regioselective biotransformations of dinitriles using Rhodococcus sp. AJ270
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A variety of dinitriles have been hydrolysed selectively under very mild conditions using Rhodococcus sp. AJ270. Aliphatic dinitriles NC[CH2]nCN 1 undergo regioselective hydrolysis to give the mono acids 2 with up to 4 methylenes between the nitrile functions while those with n > 4 give the diacids 3 in good yield. Dinitriles NC[CH2]nX[CH2]nCN 4 bearing an ether or sulfide linkage are efficiently transformed into the mono acids 5 when an oxygen is placed β, γ or δ to the cyano group or a β- or γ-sulfur is present. Hydrolysis of N,N-bis(2-cyanoethyl)anilines 4h-j takes place slowly affording exclusively the monoacids 5h-j while the monocyano amides 5o-p are obtained as the sole isolable product from rapid hydrolysis of the corresponding N,N-bis(2-cyanomethyl)butylamine 4o and N,N-bis(3-cyanopropyl)butylamine 4p. Higher homologues of arylimino- and butylimino-dinitriles are inert to enzymatic hydrolysis. A variety of other aliphatic dinitriles have been converted readily into mono acids in good to excellent yields except for o-phenylenediacetonitrile which gives o-phenylenediacetamide as the major product. The title organism also effects the hydrolysis of aromatic dinitriles with regiocontrol such as m- and p-dicyanobenzenes, but nct the ortho-substituted analogue. The scope and limitations of this enzymatic process have been systematically studied and the mechanism of regioselective hydrolysis has been discussed in terms of a chelation-deactivation effect.
- Meth-Cohn, Otto,Wang, Mei-Xiang
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p. 3197 - 3204
(2007/10/03)
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- Kinetics and mechanism of the oxidation of substituted benzaldehydes by bis(2,2′-bipyridylyl)copper(II) permanganate
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The oxidation of 35 monosubstituted benzaldehydes by bis(2,2′-bipyridylyl)copper(II) permanganate (BBCP) in aqueous acetic acid leads to the formation of the corresponding benzoic acids. The reaction is first order with respect to BBCP. Michaelis - Menten-type kinetics were observed with respect to the aldehyde concentrations. The oxidation of [2H]benzaldehyde (PhCDO) indicated the presence of a substantial kinetic isotope effect. The rates of oxidation of meta- and para-substituted benzaldehydes were correlated in terms of Charton's triparametric LDR equation, whereas the oxidation of ortho-substituted benzaldehydes was correlated with the four parametric LDRS equation. The oxidation of para-substituted benzaldehydes is more susceptible to the delocalization effect than is the oxidation of ortho- and meta-substituted compounds which displays a greater dependence on the field effect. The positive value of η suggests the presence of an electron-deficient reaction center in the rate-determining activated complex. The reaction is subjected to steric acceleration when ortho-substituents are present.
- Mohnot, Kavita,Sharma, Pradeep K.,Banerji, Kalyan K.
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p. 1310 - 1314
(2007/10/03)
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- Intramolecular Trapping of a Ketenimine Carbene Formed on Flash Vacuum Pyrolysis of 3-Phenylimino-3H-indazole and 3-Phenyliminoisobenzofuran-1-one
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Flash vacuum pyrolysis of 3-phenylimino-3H-indazole yielded biphenylene, benzonitrile and, by loss of dinitrogen followed by intramolecular trapping of a ketenimine carbene intermediate, the isomers fluorenimine, phenanthridine and 2-phenylbenzonitrile.Pyrolysis of 3-phenyliminoisobenzofuran-1-one gave the same five products together with N-phenylphthalimide.It is proposed that the same ketenimine carbene intermediate is involved in the two reactions.Pyrolysis of 3-o-tolylimino- and 3-benzylimino-isobenzofuran-1-one led to fragmentation without intramolecular trapping.Pyrolysis of 3-t-butyliminoisobenzofuran-1-one gave o-cyanobenzoic acid.
- Brown, Roger F. C.,Coulston, Karen J.,Eastwood, Frank W.
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- Separation of polar and steric effects in the oxidation of ortho-substituted benzaldehydes by ethyl chlorocarbamate
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Kinetics of oxidation of twelve ortho-substituted benzaldehydes by ethyl chlorocarbamate (ECC) to the corresponding benzoic acids have been studied.The reaction is first order each in , and +>.Addition of ethyl carbamate has no effect on the reaction rate. (EtOC(OH)NHCl)+ has been postulated as the reactive oxidizing species.The correlation of rates with single substituent parameter equations is poor.The correlation with Charton's eqution of inductive, resonance and steric parameters is satisfactory.However, excellent correlations are obtained, when Charton's steric parameter is used along with Taft's ?r and ?R+ substituent constants.The polar reaction constants have negative values.The reaction is subject to steric hindrance by the ortho-substituents.Mechanistic aspects are discussed.
- Varshney, Seema,Kothari, Seema,Banerji, Kalyan K.
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p. 205 - 209
(2007/10/02)
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- Electrosynthesis of aryl-carboxylic acids from chlorobenzene derivatives and carbon dioxide
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The electrocarboxylation of a large variety of chlorobenzenic compounds is achieved in N,N-dimethylformamide by constant current electrolysis between a stainless steel cathode and a sacrificial magnesium anode in a diaphragmless cell. Substituted benzoic acids are obtained in high yield in simle conditions thus avoiding the usual preparation of organometallic intermediates.
- Heintz, Monique,Sock, Oumar,Saboureau, Christophe,Perichon, Jacques,Troupel, Michel
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p. 1631 - 1636
(2007/10/02)
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- Correlation Analysis of the Reactivity in the Oxidation of Aromatic Aldehydes by N-Bromoacetamide
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The oxidation of thirty two para-, meta- and ortho-substituted benzaldehydes by N-bromoacetamide (NBA), to the corresponding benzoic acid, is first order with respect to the aldehyde, NBA and hydrogen ion.The oxidation of benzaldehyde exhibited a substantial primary kinetic isotope effect (kH/kD = 4.75).Addition of acetamide reduced the rate of oxidation.The postulated oxidising species is (H2OBr)+.The rates of the oxidation of the meta- and para-substituted aldehydes were separately correlated in Taft's and Swain's dual substituent parameter equations.For para-substituted aldehydes, the best correlation was obtained with ?I and ?R+ values, while the meta-substituted compounds correlated best with ?I and ?R0 values.The ortho-substituted aldehydes showed excellent correlation in a triparametric equation of Taft's ?I, ?R+ and Charton's steric parameters.The polar reaction constants have negative values.The reaction is subject to steric hindrance by the ortho-substituents.A mechanism involving transfer of a hydride from the aldehyde to the oxidant, in the rate-determining step, has been proposed.
- Gupta, Anita,Mathur, Sandhya,Banerji, Kalyan K.
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p. 201 - 223
(2007/10/02)
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- Mechanism and models for homogeneous copper mediated ligand exchange reactions of the type: CuNu + ArX (*) ArNu + CuX
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The title reactions are an important class of copper mediated nucleophilic aromatic substitution processes, which constitute a useful tool in the molecular design and synthesis of small molecules.We report the results of extensive investigation of these processes, primarily focussing on cyanodeiodination (ArI + CuCN CuI + ArCN).Among the interesting features of these processes are: (a) an unusual rate equation involving autocatalysis by CuI product; (b) retardation by both excess nucleophile (as KCN) and excess leaving group (as KI), which complete with ArX to complex with CuNu; (c) only cuprous nucleophiles are active (ligand exchanged products from cupric salts arise from prior redox equilibria which form CuNu); (d) the halogen effect is large (kI ca 40 - 100 kBr ca 300 - 5000 kCl) but the Hammett q value is zero; (e) ortho-alkyl groups do not hinder the reaction ( and actually cause mild acceleration by relief of steric strain).Finally, the introduction of an ortho-COO- group accelerates the reaction by a factor of 104 - 105 , but the general features of the accelerated reactions are also the same, again indicating a common mechanism, with entropic acceleration by ortho-carboxylate.Both kinetic and thermodynamic factors were considered in detail, the latter apparently for the first time.Applications to practical syntheses are considered, and novel mechanistic models for these interesting processes are discussed.
- Couture, Christiane,Paine, Anthony James
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p. 111 - 120
(2007/10/02)
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- The Synthesis of Isoindolin-3-ones, Phthalazin-4(3H)-ones and Related Systems
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The reaction between methyl 2-cyanobenzoate and its pyridine analogues gave isoindolin-3-ones, phthalazin-4(3H)-ones and their corresponding aza analogues.Some reactions of 1-benzylaminoiminoisoindolin-3-one 5b were investigated.
- Dunn, A.D.
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p. 961 - 964
(2007/10/02)
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- The Separation of Polar Steric Effects. Part 14. Kinetics of the Reactions of Benzoic Acid and of ortho-Substituted Benzoic Acids with Diazodiphenylmethane in Various Alcohols
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The main results now discussed are rate coefficients for the reactions of benzoic acid and 32 ortho-substituted benzoic acids with diazodiphenylmethane (DDM) at 30.0 deg C in 11 alcohols including 2-methoxyethanol.The reaction involves a rate-determining proton transfer.The results have been subjected to correlation analysis in two ways. (a) For the reactions of a given acid in the various alcohols, the log k values are correlated through multiple regression on appropriate solvent parameters. (b) For reactions in a given alcohol, the log k values for the various acids are correlated by using the appropriate form of the extended Hammett equation involving inductive, resonance, and steric parameters.Analyses of type (a), as in earlier work, involve the ?* value of the group R in the alcohol ROH, the Kirkwood function of dielectric constant, f(ε)=(ε-1)/(2ε+1) and nγH, the number of hydrogen atoms in the γ-position in the alcohol.These correlations yield information on the influence of ortho-substituents on the relative importance of specific and non-specific solvent effects.In analyses of type (b) the correlation equations are established with a limited set of substituents (up to 18), whose characteristic parameters ?I, ?R, and υ (determined by Charton) are well established, and are unlikely to show effects due to hydrogenbonding or substituent conformation.The results for other substituents are then interpreted by comparing log k(calc.) from a correlation expression with log k(obs.).
- Aslam, Hanif M.,Burden, Alan G.,Chapman, Norman B.,Shorter, John,Charton, Marvin
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p. 500 - 508
(2007/10/02)
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