- A systematic study of the degradation of dimethyl phthalate using a high-frequency ultrasonic process
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A comprehensive study of the sonochemical degradation of dimethyl phthalate (DMP) was carried out using high-frequency ultrasonic processes. The effects of various operating parameters were investigated, including ultrasonic frequency, power density, initial DMP concentration, solution pH and the presence of hydrogen peroxide. In general, a frequency of 400 kHz was the optimum for achieving the highest DMP degradation rate. The degradation rate was directly proportional to the power density and inversely related to the initial DMP concentration. It was interesting to find that faster removal rate was observed under weakly acidic condition, while hydrolysis effect dominated in extreme-basic condition. The addition of hydrogen peroxide can increase the radical generation to some extent. Furthermore, both hydroxylation of the aromatic ring and oxidation of the aliphatic chain appear to be the major mechanism of DMP degradation by sonolysis based on LC/ESI-MS analysis. Among the principle reaction intermediates identified, tri- and tetra-hydroxylated derivatives of DMP, as well as hydroxylated monomethyl phthalates and hydroxylated phthalic acid were reported for the first time in this study. Reaction pathways for DMP sonolysis are proposed based on the detected intermediates.
- Xu,Chu,Graham, Nigel
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Read Online
- Synthesis of New Dialkyl 2,2′-[Carbonyl bis (azanediyl)]dibenzoates via Curtius Rearrangement
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The 2-(alkylcarbonyl)benzoic acids obtained by esterification of phthalic anhydride are converted into azide derivatives: alkyl 2-[(azidocarbonyl)amino]benzoates and to ureas: dialkyl 2,2′-[carbonyl bis (azanediyl)]dibenzoates. These transformations were carried out using classical Curtius rearrangement conditions in the presence of diphenylphosphoryl azide (DPPA) in a basic medium, followed by hydrolysis. Subsequently, a final condensation reaction of these urea derivatives enabled us to obtain, for the first time, the new alkyl derivatives, alkyl 2-[2,4-dioxo-1,2-dihydroquinazolin-3(4 H)-yl]benzoates. All the new compounds obtained in satisfactory yields were characterized by 1H and 13C NMR, and by X-ray crystallographic analysis.
- Yassine, Hasna,Bouali, Jamila,Oumessaoud, Asmaa,Ourhzif, El Mahdi,Hamri, Salha,Hafid, Abderrafia,Khouili, Mostafa,Pujol, Maria Dolors
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p. 1971 - 1979
(2021/01/21)
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- A Br?nsted acidic, ionic liquid containing, heteropolyacid functionalized polysiloxane network as a highly selective catalyst for the esterification of dicarboxylic acids
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A Br?nsted acidic, ionic liquid containing, heteropolyanion functionalized polysiloxane network was formed by self-condensation of dodecatungstophosphoric acid and a zwitterionic organosilane precursor containing both imidazolinium and sulfonate groups. The resulting hybrid material POS-HPA-IL was investigated as a catalyst for the selective esterification of dicarboxylic acids.
- Rajabi, Fatemeh,Wilhelm, Christian,Thiel, Werner R.
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supporting information
p. 4438 - 4444
(2020/08/10)
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- Carbonylative Suzuki-Miyaura couplings of sterically hindered aryl halides: Synthesis of 2-aroylbenzoate derivatives
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We have developed a carbonylative approach to the synthesis of diversely substituted 2-aroylbenzoate esters featuring a new protocol for the carbonylative coupling of aryl bromides with boronic acids and a new strategy to favour carbonylative over non-carbonylative reactions. Two different synthetic pathways-(i) the alkoxycarbonylation of 2-bromo benzophenones and (ii) the carbonylative Suzuki-Miyaura coupling of 2-bromobenzoate esters-were evaluated. The latter approach provided a broader substrate tolerance, and thus was the preferred pathway. We observed that 2-substituted aryl bromides were challenging substrates for carbonylative chemistry favouring the non-carbonylative pathway. However, we found that carbonylative Suzuki-Miyaura couplings can be improved by slow addition of the boronic acid, suppressing the unwanted direct Suzuki coupling and, thus increasing the yield of the carbonylative reaction.
- Bayer, Annette,Ismael, Aya,Skrydstrup, Troels
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supporting information
p. 1754 - 1759
(2020/03/17)
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- Automated on-line monitoring of the TiO2-based photocatalytic degradation of dimethyl phthalate and diethyl phthalate
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A fully automated on-line system for monitoring the TiO2-based photocatalytic degradation of dimethyl phthalate (DMP) and diethyl phthalate (DEP) using sequential injection analysis (SIA) coupled to liquid chromatography (LC) with UV detection was proposed. The effects of the type of catalyst (sol-gel, Degussa P25 and Hombikat), the amount of catalyst (0.5, 1.0 and 1.5 g L-1), and the solution pH (4, 7 and 10) were evaluated through a three-level fractional factorial design (FFD) to verify the influence of the factors on the response variable (degradation efficiency, %). As a result of FFD evaluation, the main factor that influences the process is the type of catalyst. Degradation percentages close to 100% under UV-vis radiation were reached using the two commercial TiO2 materials, which present mixed phases (anatase/rutile), Degussa P25 (82%/18%) and Hombikat (76%/24%). 60% degradation was obtained using the laboratory-made pure anatase crystalline TiO2 phase. The pH and amount of catalyst showed minimum significant effect on the degradation efficiencies of DMP and DEP. Greater degradation efficiency was achieved using Degussa P25 at pH 10 with 1.5 g L-1 catalyst dosage. Under these conditions, complete degradation and 92% mineralization were achieved after 300 min of reaction. Additionally, a drastic decrease in the concentration of BOD5 and COD was observed, which results in significant enhancement of their biodegradability obtaining a BOD5/COD index of 0.66 after the photocatalytic treatment. The main intermediate products found were dimethyl 4-hydroxyphthalate, 4-hydroxy-diethyl phthalate, phthalic acid and phthalic anhydride indicating that the photocatalytic degradation pathway involved the hydrolysis reaction of the aliphatic chain and hydroxylation of the aromatic ring, obtaining products with lower toxicity than the initial molecules.
- Salazar-Beltrán, Daniel,Hinojosa-Reyes, Laura,Maya-Alejandro, Fernando,Turnes-Palomino, Gemma,Palomino-Cabello, Carlos,Hernández-Ramírez, Aracely,Guzmán-Mar, Jorge Luis
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p. 863 - 870
(2019/04/17)
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- Selective Synthesis in Microdroplets of 2-Phenyl-2,3-dihydrophthalazine-1,4-dione from Phenyl Hydrazine with Phthalic Anhydride or Phthalic Acid
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Pyridazine derivatives are privileged structures because of their potential biological and optical properties. Traditional synthetic methods usually require acid or base as a catalyst under reflux conditions with reaction times ranging from hours to a few days or require microwave assistance to induce the reaction. Herein, this work presents the accelerated synthesis of a pyridazine derivative, 2-phenyl-2,3-dihydrophthalazine-1,4-dione (PDHP), in electrosprayed microdroplets containing an equimolar mixture of phenyl hydrazine and phthalic anhydride or phthalic acid. This reaction occurred on the submillisecond timescale with good yield (over 90 % with the choice of solvent) without using an external catalyst at room temperature. In sharp contrast to the bulk reaction of obtaining a mixture of two products, the reaction in confined microdroplets yields only the important six-membered heterocyclic product PDHP. Results indicated that surface reactions in microdroplets with low pH values cause selectivity, acceleration, and high yields.
- Gao, Dan,Jin, Feng,Yan, Xin,Zare, Richard N.
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supporting information
p. 1466 - 1471
(2019/01/04)
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- Preparation method of butylphthalide and pharmaceutical intermediate thereof
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The present invention provides a new pharmaceutical intermediate and a method for preparing butylphthalide by using the new pharmaceutical intermediate. According to the method, o-phthalic acid monoester as a raw material and valerate are subjected to ester condensation, o-pentanoylbenzoic acid is prepared through hydrolysis and decarboxylation, and reducing with sodium borohydride and ring closure are performed to obtain the product. According to the present invention, the method has characteristics of inexpensive and easily-available raw material, mild reaction condition, no high-temperaturereaction, no Grignard reaction, production energy consumption reducing, production cost reducing and operation safety improving.
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Paragraph 0022
(2018/11/03)
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- Practical selective monohydrolysis of bulky symmetric diesters
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The highly efficient selective monohydrolysis reaction we previously reported has been applied to monohydrolysis of several bulkyl symmetric diesters, including diethyl esters, dipropyl esters, and dibutyl esters. A greater proportion of a polar aprotic co-solvent, DMSO, and aqueous KOH appear to help improve the reactivity of bulky diesters compared to the corresponding dimethyl esters. The procedure is mild and practical, yielding the corresponding half-esters in high yields under simple conditions.
- Shi, Jianjun,Niwayama, Satomi
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p. 799 - 802
(2018/02/10)
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- Practical selective monohydrolysis of bulky symmetric diesters: Comparing with sonochemistry
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The conditions of the practical selective monohydrolysis of symmetric diesters we previously reported have been modified and applied to selective monohydrolysis of bulky symmetric diesters. While ultrasound is generally considered effective for two-phase reactions, its effect actually turned out to be rather marginal. Instead, use of a larger proportion of a polar aprotic co-solvent, DMSO, and aqueous KOH helped enhance the reaction rates and improve the yields of the half-esters. The reactions are simple, mild and practical without special devices.
- Shi, Jianjun,Zhao, Tian,Niwayama, Satomi
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p. 6815 - 6820
(2018/10/20)
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- Oxalic acid as the: In situ carbon monoxide generator in palladium-catalyzed hydroxycarbonylation of arylhalides
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An efficient palladium-catalyzed hydroxycarbonylation reaction of arylhalides using oxalic acid as a CO source has been developed. The reaction features high safety, low catalyst loading, and a broad substrate scope, and provides a safe and tractable approach to access a variety of aromatic carboxylic acid compounds. Mechanistic studies revealed the decomposition pattern of oxalic acid.
- Shao, Changdong,Lu, Ailan,Wang, Xiaoling,Zhou, Bo,Guan, Xiaohong,Zhang, Yanghui
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supporting information
p. 5033 - 5040
(2017/07/10)
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- Methylation of mono- and dicarboxylic acids with dimethyl carbonate catalyzed with binder-free zeolite NaY
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Synthesis of methyl mono- and dicarboxylates was developed consisting in treating the corresponding acids with dimethyl carbonate in the presence of a heterogenic catalyst, crystalline aluminosilicate whose mechanically strong granules to 90–95% were built of crystal aggregates of zeolite Y with modulus of about 5.0 in the Na-form. Optimum catalyst and reagents ratio and the reaction conditions were found for the preparation in high yields of methyl esters of mono- and dicarboxylic acids.
- Khusnutdinov,Shchadneva,Mayakova, Yu. Yu.,Konovalova, Yu. S.,Khazipova,Kutepov
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p. 163 - 168
(2017/04/24)
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- Direct Carboxylation of Aryl Tosylates by CO2 Catalyzed by in situ-Generated Ni0
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A novel Ni0-catalyzed carboxylation of aryl tosylates with carbon dioxide has been achieved under moderate temperatures and atmospheric pressure. In this procedure, the active Ni0 species is generated in situ by simply mixing the Ni0 precatalyst [NiBr2(bipy)] with an excess of manganese metal. This approach requires neither a glove-box nor the tedious preparation of sophisticated intermediate organometallic derivatives. This mild, convenient, and user-friendly process is successfully applied to the valorization of carbon dioxide and the synthesis of versatile reactants with broad tolerance of substituents.
- Rebih, Fatima,Andreini, Manuel,Moncomble, Aurlien,Harrison-Marchand, Anne,Maddaluno, Jacques,Durandetti, Muriel
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supporting information
p. 3758 - 3763
(2016/03/08)
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- An expeditious synthesis of imides from phthalic, maleic and succinic anhydrides and chemoselective C=C reduction of maleic amide esters
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Phthalic, maleic and succinic anhydrides have been reacted with aromatic amines to obtain the corresponding monoacid monoamides. The latter have been each transformed into the corresponding cyclic imide derivatives by treating with SOCl2. Alternatively, anhydrides have been reacted with methanolic KOH to obtain monomethyl ester derivatives which on reaction with aromatic amines in the presence of EDC. HCl and HOBt give cyclic imide derivatives. Reaction of monoacid monoamides independently, with SOCl 2 at 0-5°C give the monoamide monoester derivatives. Treatment of monoamide monoester of malic anhydride with NaBH4 leads to the unusual reduction of C=C grouping as well as the carbonyl group of the ester group to from monoamide monoalcohol of succinic anhydride. Preparation of monoamide monoalcohol of succinic anhydride can also be achieved by chemoselective reduction of monoamide monoester of malic anhydride with Mg turnings yielding monoamide monoester of succinic anhydride followed by reduction of the latter with NaBH4.
- Kumar, Padam Praveen,Reddy, Y. Dathu,Kumari, Y. Bharathi,Devi, B. Rama,Dubey
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p. 392 - 398
(2014/05/06)
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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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- Proton-exchanged montmorillonite-mediated reactions of methoxybenzyl esters and ethers
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Proton-exchanged montmorillonite (H-mont) was found to be an eco-friendly and cost-effective catalyst for the generation of O-methylated quinone methides (QM) from the corresponding p or o-methoxybenzyl esters and ethers. Nucleophilic trapping of the O-methylated QM with arenes, alcohols, 1,3-dicarbonyl compounds, silyl enol ethers, and allylsilanes has been carried out, respectively, leading to eco-friendly benzylation reactions. Using this protocol, H-mont-mediated deprotection of PMB-protected esters and ethers have been realized for the first time. This work would pave the way for further exploration in O-alkylated QM that are of chemical and biological significance.
- Chen, Dongyin,Xu, Chang,Deng, Jie,Jiang, Chunhuan,Wen, Xiaoan,Kong, Lingyi,Zhang, Ji,Sun, Hongbin
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p. 1975 - 1983
(2014/03/21)
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- Total synthesis of a novel isoquinolinone alkaloid marinamide and its methyl ester
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A naturally occurring isoquinolinone alkaloid marinamide and its methyl ester were synthesised from phthalic anhydride over eight steps in 46% and 52% overall yield. The key intermediate methyl 2-(1-benzyl-1H-pyrrole-2-carbonyl) benzoate was synthesised from the acid chloride of mono methyl phthalate and 1-benzyl-1H-pyrrole catalysed by Zinc oxide under solvent-free conditions at room temperature.
- Zhang, Shuguang,Feng, Chengliang,Cai, Jin,Chen, Junqing,Ji, Min
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p. 291 - 293
(2013/07/27)
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- First total synthesis of isoquinolinone alkaloid marinamide and its methyl ester
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The first total synthesis of isoquinolinone alkaloid marinamide 1 and its methyl ester 2 was described. The key steps involved a regioselective Friedel-Crafts reaction of 1-benzyl-1H-pyrrole to form the intermediate 8.
- Feng, Cheng-Liang,Zhang, Shu-Guang,Chen, Jun-Qing,Cai, Jin,Ji, Min
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p. 767 - 769
(2013/07/26)
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- Diorganotin complexes of carboxylates: Synthesis and characterization
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Diorganotin complexes of monoisopropyl and monomethyl nadiate, succinate, and phthalate were synthesized and characterized by elemental analysis, FT-IR, 1H NMR, 13C NMR, and 119Sn NMR spectroscopic techniques. The spectroscopic investigation demonstrated that carboxylate is bidentate in the diorganotin complexes. On the basis of 1J(119Sn-13C) and 2J(119Sn-1H) values, C-Sn-C bond angles were also calculated. The newly synthesized complexes were also screened for their antibacterial activities against Gram-positive and Gram-negative pathogenic strains of bacteria.
- Chilwal, Asha,Deep, Gagan,Malhotra, Priti,Narula
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p. 1046 - 1057
(2013/07/28)
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- Synthesis, spectroscopic and bactericidal investigation of some transition metal complexes of monomethyl phthalate
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Seven novel transition metal complexes have been synthesized by using monomethyl phthalate as ligand and characterized through physical techniques such as melting point, elemental analyses, IR and 1H NMR spectroscopy. The complexes of Co(II), Ni(II), Fe(II), Zn(II), Mn(II) and hydrous and anhydrous Cu(II) exhibit trigonal bipyramidal and square planner geometry in solution state. It has been observed that monomethyl phthalate bound to the central metal atom through oxygen atom of the carboxylate group. The complexes formed were then treated with five different types of bacterial strains in order to check whether the synthesized compound is bioactive or not and the results were compared with the standard drug imipenem. Copper(II) complex showed highest inhibition zone against these microbes. The bactericidal activities indicated that metal complexes showed enhanced activity as compared to the free ligand.
- Rehman, Wajid,Hassan, Zonera,Shakir, Yasmeen
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experimental part
p. 2329 - 2332
(2012/09/07)
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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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- CHROMENE COMPOUNDS, A PROCESS FOR THEIR PREPARATION AND PHARMACEUTICAL COMPOSITIONS CONTAINING THEM
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The invention relates to compounds of formula (I): wherein R1 and R2 together form the following carbon-containing chain: wherein: R3 represents a hydrogen atom or an alkyl group, R4 represents a hydrogen atom or an alkyl, aryl, heteroaryl, 3,4-dioxocyclobutenyl, alkylcarbonyl, cycloalkylcarbonyl, heterocycloalkylcarbonyl, benzoyl, arylsulphonyl or heteroarylsulphonyl group, each of those groups optionally being substituted, or R3 and R4 together with the nitrogen atom carrying them form a 5- to 8-membered ring, the ring thereby formed optionally being substituted. Medicinal products containing the same which are useful in treating conditions requiring a D3 receptor antagonist
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Page/Page column 4-5
(2011/02/18)
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- Synthesis and characterization of the luminescent lanthanide complexes with two similar benzoic acids
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2-((4-Methoxyphenoxy) carbonyl) benzoic acid, 2-(1-methoxyvinyl) benzoic acid and their rare earth complexes LnL2(OH)·3H2O (Ln = La, Eu, Tb) were synthesized and characterized by means of elemental analysis, FTIR, 1H NMR, UV and luminescence spectroscopy. The FTIR and 1H NMR results show that the carboxylic groups in the complexes coordinated to the rare earth ions in the form of one dentate, and the ester carboxylic groups have taken part in the coordination. Among these complexes, Eu(III) complexes and Tb(III) complexes exhibit characteristic fluorescence with comparatively high brightness and good monochromaticity, which indicated that the ligands of HLI and HLII are good organic chromophore to absorb and transfer energy to metal ions.
- Liu, Tonghuan,Duan, Guojian,Zhang, Yaping,Fang, Jian,Zeng, Zhengzhi
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experimental part
p. 843 - 848
(2010/03/30)
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- Ring-opening of cyclic anhydrides using ionic liquids
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Four novel Bronsted acidic ionic liquids with two different acid sites on the imidazolium cations were synthesised and employed as catalysts and solvents for the ring-opening of cyclic anhydrides to synthesise half-esters. The results showed that these novel Bronsted acidic ionic liquids were efficient and recyclable. Good yields, short reaction times and mild reaction conditions were achieved.
- Jiang, Dong,Wang, Yuan Yuan,Xu, Yan Nan,Dai, Li Yi
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experimental part
p. 167 - 169
(2009/10/15)
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- Rapid chemoselective deprotection of benzyl esters by nickel boride
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Benzyl esters of a variety of acids can be chemoselectively cleaved on treatment with nickel boride in methanol at ambient temperature to give the parent carboxylic acids in high yields. Other protecting functionalities such as methyl, ethyl, tert-butyl, and trityl esters as well as benzyl ethers, tert-butyl ethers, and Nbenzylamides are unaffected under these conditions. Georg Thieme Verlag Stuttgart.
- Khurana, Jitender M.,Arora, Reema
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experimental part
p. 1127 - 1130
(2009/12/03)
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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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- 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.
-
experimental part
p. 1281 - 1288
(2009/12/31)
-
- 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 characterization and biological study of diorganotin(IV) complexes of monomethyl phthalate
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The synthesis and characterization of new coordination compounds of some organotin(IV) chlorides with monomethyl phthalate is reported; the ligand molecules appear to be bound to the tin atom through carbonyl oxygen atoms. Their structures have been characterized by elemental analyses, molar conductance, and bonding in these complexes is discussed in terms of their IR, 1H, 13C, 119Sn NMR and 119mSn Moessbauer spectral studies. The spectroscopic results obtained are in full agreement with the proposed 2:1 stoichiometry. The complexes soluble in DMSO have been screened against a wide spectrum of bacteria and the results obtained are quite promising. The LD50 values have also been determined in the albino rats. Some of the complexes also exhibit high anti-inflammatory activity.
- Rehman, Wajid,Baloch, Musa Kaleem,Badshah, Amin,Ali, Saqib
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p. 689 - 694
(2007/10/03)
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- A convenient method for the preparation of 4-hydroxy-2-methyl-1-oxo-1,2- dihydroisoquinoline-3-carboxylic acid derivatives
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An improved method for the synthesis of 4-hydroxy-2-methyl-1-oxo-1,2- dihydroisoquinoline-3-carboxylic acid derivatives is described. The synthetic route involves initial phthalic anhydride aminolysis with alkylaminoacetic acid derivatives, further esterification with diazomethane and final heterocyclization of the phthalamic ester intermediates by alkoxide-induced Dieckmann condensation. The best yields are reached for esters and N,N-disubstituted carboxamides. Georg Thieme Verlag Stuttgart.
- Blanco, Maria Mercedes,Shmidt, Maria Sol,Schapira, Celia Beatriz,Perillo, Isabel Amalia
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p. 1971 - 1974
(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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- Facile and selective deprotection of allyl esters catalyzed by H-β zeolite
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Carboxylic acids are regenerated from their corresponding allyl or cinnamyl esters by H-β zeolite under environmentally safe, heterogeneous reaction conditions in excellent yields.
- Pandey, Rajesh K.,Kadam, Vijay S.,Upadhyay, Rajesh K.,Dongare, Mohan K.,Kumar, Pradeep
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p. 3017 - 3024
(2007/10/03)
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- Cation-exchange resin-catalysed acylations and esterifications in fine chemical and perfumery industries
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Acylation and esterification reactions are typically carried out by using homogeneous acids as catalysts which can be profitably replaced with heterogeneous solid acid catalysts to develop green chemistry. Solid acids that give the desired level of activity but which can be easily removed from the reaction mixture with no residual inorganic contamination of the organic products offer obvious advantages over existing methods. This contribution is concerned with eco-friendly synthesis of some commercially valuable products such as p-methoxyacetophenone, dimethyl phthalate, diethyl phthalate, methyl anthranilate, methyl salicylate, and methyl p-hydroxybenzoate (methyl paraben). The specifications require the esters to be free of halide impurities on ppm level for perfumery use, and thus use of chlorine-containing agents or catalysts must be avoided. The following catalysts were evaluated: Amberlyst-36, Bayer K2441, Amberlyst-15, Dowex 50Wx8, Indion-130, Deloxane ASP, Filtrol-24 clay, K-10 Montmorrilonite clay, and sulphated zirconia. Anisole was acylated with acetic anhydride to get 100% selectivity of p-methoxyacetophenone, and Amberlyst-36 was found to be the most active and reusable catalyst. A kinetic model is also presented. Amberlyst-36 was also the most active catalyst for the esterification reactions.
- Yadav,Mujeebur Rahuman
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p. 706 - 713
(2013/09/06)
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- Highly selective deprotection of tert-butyl esters using ytterbium triflate as a catalyst under mild conditions
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Ytterbium triflate catalyses the deprotection of tert-butyl esters selectively in the presence of other esters under mild conditions in almost quantitative yields. The reactions are carried out in nitromethane (45°-50°C) using 5 mole percent of the catalyst.
- Sridhar, P. Ramu,Sinha, Surajit,Chandrasekaran
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p. 157 - 160
(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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- Monitoring of phthalic acid monoesters in river water by solid-phase extraction and GC-MS determination
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An analytical method for monitoring 10 phthalic acid monoesters in river water was investigated by solid-phase extraction, methylation with diazomethane, and GC-MS. Two cartridge-type solid phases packed with octadesyl-coated silica (C18) and styrenedivinyl polymer (PS-2) and one disk-type solid phase made from octadesyl-coated styrene-divinylbenzene polymer (SDB-XD) were investigated in solid-phase extraction. PS-2 gave the highest recoveries of the three solid phases, and recoveries of more than 80% of the monoesters in filtered water samples were obtained at pH 2 to 3 with PS-2 at the spiked level of 0.1 μg L-1, except for monomethyl-phthalate (MMP), in which more than 72% of the monoesters were recovered. For the monoesters in the suspended solids (SS), an acidic methanol extract of SS was added to purified water acidified to pH 2, and the monoesters were extracted with PS-2. The recoveries of the monoesters in SS were more than 80%, but the recoveries of MMP were more than 57%. The method detection limit (MDL) of each phthalic acid monoester in 500 mL of water sample and in 2 mg of dry weight of SS ranged from 0.010 to 0.030 μg L-1 and from 1 to 11 μg g-1 respectively. Monitoring of phthalic acid monoesters in the Tama River in Tokyo was conducted every month from March 1999 to February 2000 using the present method. MMP, mono-n-butyl-phthalate (MBP), and mono-(2-ethylhexyl)-phthalate (MEHP) were detected at concentrations of 0.030-0.0340, 0.010-0.480, and 0.010-1.30 μg L-1. respectively, in the filtered water samples but were not detected in SS. Dimethyl-phthalate (DMP), di-n-butyl-phthalate (DBP), and di-(2-ethylhexyl)-phthalate (DEHP) were detected in the river water at concentrations of 0.010-0.092, 0.008-0.540, and 0.013-3.60 μg L-1, respectively. Diethyl-, di-iso-butyl-, and benzylbutyl-phthalates were also detected at concentrations of nanograms per liter, whereas the corresponding monoesters did not appear. The concentrations of MBP and MEHP in the river water were slightly lower than those of the corresponding diesters at the majority of sampling sites and sampling times.
- Suzuki,Yaguchi,Suzuki,Suga
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p. 3757 - 3763
(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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- Ring opening of cyclic anhydrides: Synthesis of achiral half-esters using Lewis acids
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A rapid and high yield preparation of half-esters from cyclic anhydrides using alcohols and Lewis acids is described.
- Sabitha, Gowravaram,Srividya,Yadav
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p. 4015 - 4018
(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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- Pig liver esterase catalyzed hydrolyses of diesters. A new route to the syntheses of achiral half-esters
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Pig liver esterase catalyzed hydrolyses of diesters of alkanes, aromatic and heterocyclic compounds gave high yields of the corresponding half-esters under mild reaction conditions.
- Ager,Prakash
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p. 739 - 742
(2007/10/02)
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- Pressure Effect on the Esterification of Phthalic Anhydride in Supercritical CO2
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Measurements of the bimolecular rate constants for the uncatalysed esterification of phthalic anhydride with methanol in supercritical CO2 indicate that the reaction rate is enhanced when operating in the compressible region due to increased local concentrations of the methanol around the phthalic anhydride.
- Ellington, J. Bryan,Brennecke, Joan F.
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p. 1094 - 1095
(2007/10/02)
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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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- Phenylmethyl-4,4-dimethyl-3-isoxazolidinone plant regulators
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Novel 2-[(4-substituted phenyl)methyl]-4,4-dimethyl-3-isoxazolidinone plant regulators of the following structural formula STR1 or an agriculturally acceptable salt thereof, agricultural compositions thereof and a method for regulation growth and development of plant growth therewith are disclosed and exemplified.
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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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- Methylation of Alcohols, Phenols, and Carboxylic Acids, and Selective Monomethylation of Diols and Dicarboxylic Acids with Dimethyl Sulfate by Use of Alumina
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Alcohols in cyclohexane give their methyl ethers in high yields by the use of a combination of dimethyl sulfate and alumina.Some diols and dicarboxylic acids adsorbed on alumina react with dimethyl sulfate and produce the corresponding monomethyl ethers and esters in high selectivities.
- Ogawa, Haruo,Ichimura, Youko,Chihara, Teiji,Teratani, Shousuke,Taya, Kazuo
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p. 2481 - 2484
(2007/10/02)
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- Kinetics and Mechanism of Hydrolytic Cleavage of Dimethyl Phthalate in Highly Alkaline Medium
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Kinetics of hydrolysis of dimethyl phthalate in the range 0.05-2.0 mol dm-3 at 25 deg C and at constant (2.073E-3 mol dm-3) follows an irreversible first order consecutive reaction path of the type: Dimethyl phthalate --> monomethyl phthalate --> phthalic acid.Both the pseudo-first order rate constants, k1obs and k2obs vary linearly with with zero intercept.The ratios k1obs/k2obs have been observed to be ca. 35-42.The data on the effect of different organic cosolvents on k1obs and K2obs obey the Grunwald-Winstein empirical equation.The rate constants, k2obs, decrease with increase in 1,4-dioxan content from 5percent to ca. 40percent; beyond 40percent k2obs values increase.The dependence of activation parameters upon organic cosolvents has been also explored.
- Khan, Mohammad Niyaz
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p. 831 - 835
(2007/10/02)
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