- Discovery of novel triazolophthalazine derivatives as DNA intercalators and topoisomerase II inhibitors
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A new series of triazolophthalazine derivatives was designed and synthesized as topoisomerase II (Topo II) inhibitors and DNA intercalators. The synthesized derivatives were evaluated in vitro for their cytotoxic activities against three human cancer cell lines: HepG2, MCF-7, and HCT-116 cells. Compound IXb was the most potent counterpart with IC50 values of 5.39 ± 0.4, 3.81 ± 0.2, and 4.38 ± 0.3 μM, as it was about 1.47, 1.77, and 1.19 times more active than doxorubicin (IC50 = 7.94 ± 0.6, 6.75 ± 0.4, and 5.23 ± 0.3 μM) against HepG2, MCF-7, and HCT-116 cells, respectively. Additionally, the binding affinity of the synthesized compounds toward the DNA molecule was assessed using the DNA/methyl green assay. Compound?IXb showed an excellent DNA binding affinity with an IC50 value of 27.16 ± 1.2 μM, which was better than that of the reference drug doxorubicin (IC50 = 31.02 ± 1.80 μM). Moreover, compound IXb was the most potent member among the tested compounds when investigated for their Topo II inhibitory activity. Furthermore, compound IXb induced apoptosis in HepG2 cells and arrested the cell cycle at the G2/M phase. Additionally, compound IXb showed Topo II poisoning effects at 2.5 μM and Topo II catalytic inhibitory effects at 5 and 10 μM. Finally, molecular docking studies were carried out against the DNA–Topo II complex and DNA, to investigate the binding patterns of the designed compounds.
- Sakr, Helmy,Ayyad, Rezk R.,El-Helby, Ali A.,Khalifa, Mohamed M.,Mahdy, Hazem A.
-
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- New Diesters Derived from Piperine: In silico Study and Evaluation of Their Antimicrobial Potential
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Piperine, previously extracted from black pepper (Piper nigrum L.), was used as a precursor for the synthesis of twelve new diester derivatives. The final products were obtained through the bimolecular nucleophilic substitution reaction (SN2) of the alkyl 2-chloroacetates and the salt of piperic acid, obtained from the basic hydrolysis of piperine. The compounds were synthesized with yields of 55-84% and characterized by infrared spectroscopy and 1H and 13C nuclear magnetic resonance. The evaluation of the compounds’ potential as new drug candidates was done through an in silico study of ADME properties (absorption, distribution, metabolization and excretion) and evaluation of antimicrobial activity against bacterial strains (Staphylococcus aureus and Pseudomonas aeruginosa), yeasts (Candida albicans and Candida tropicalis) and filamentous fungi (Aspergillus fumigatus, Aspergillus flavus and Aspergillus niger). The in silico study showed that the compounds were good drug candidates and antimicrobial evaluation demonstrated that 9 of the 12 compounds exhibited a minimum inhibitory concentration (MIC) ranging 1024-256 μg mL?1
- Barbosa-Filho, José M.,Brand?o, Maria Cláudia R.,Lima, Edeltrudes O.,Lira, Bruno F.,Neto, Hermes D.,Souza, Helivaldo D. S.,Trindade, Emmely O.,de Athayde-Filho, Petr?nio F.
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p. 1668 - 1678
(2020/10/09)
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- Synthesis, in silico Study and Antimicrobial Evaluation of New Diesters Derived from Phthaloylglycine
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New diesters derived from phthaloylglycine (7a-7i) were synthesized and their structures characterized by infrared, 1H and 13C nuclear magnetic resonance (NMR) spectroscopy. The compounds were evaluated in an in silico study, which demonstrated positive features indicating a possible drug candidate. The diesters showed antifungal activity ranging from moderate to strong against strains of Candida. Compounds 7a, 7b, 7c, 7e and 7i had a moderate minimum inhibitory concentration (MIC) of 1024 μg mL?1 against all fungal strains, while 7h showed a very good MIC of 256 μg mL?1 against Candida albicans, Candida parapsilosis and Candida krusei and 64 μg mL?1 against Candida tropicalis. However, only 7h and 7i were able to inhibit bacterial growth of strains of Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa and Escherichia coli with an MIC of 1024 μg mL?1
- Alves, Francinara S.,Barbosa-Filho, José M.,Cordeiro, Laísa V.,Huang, Min-Fu N.,Lima, Edeltrudes O.,Neto, Hermes Diniz,Souza, Helivaldo D. S.,Trindade, Emmely O.,de Athayde-Filho, Petr?nio F.,de Lima, Priscila S. V.,de Oliveira, Rafael F.,de Sousa, Abra?o P.
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p. 953 - 962
(2020/10/14)
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- Preparation method of 2-methyl-4-chloro-phenoxyacetic acid
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The invention belongs to the technical field of pesticide synthesis, and particularly relates to a 2-methyl-4-chloro-phenoxyacetic acid preparation method, which uses o-methylphenol sodium as a reactant, and uses an organic phase methyl chloroacetate solution as a reaction solvent in a condensation reaction. The method has the advantages that the method is simple; in the condensation reaction, anorganic phase methyl chloroacetate solution is used as a reaction solvent to replace a water phase in the traditional technology; and the organic phase can be continued to the subsequent chlorinationreaction, so that the problems of decomposition of sodium chloroacetate and low reaction yield can be solved, no wastewater can be generated in the production of MCPA sodium salt, the yield can be greatly improved, and the method is a green and environment-friendly synthesis method.
- -
-
Paragraph 0028; 0032; 0033
(2020/09/21)
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- Green synthesis method of methyl cyanoacetate
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The invention discloses a green synthesis method of methyl cyanoacetate. The preparation process comprises the following steps: heating methyl chloroacetate and acetone cyanohydrin to 40-100 DEG C inthe absence of a catalyst and a solvent, and reacting to obtain methyl cyanoacetate. Acetone cyanohydrin serves as a cyaniding reagent and directly reacts with methyl chloroacetate to generate methylcyanoacetate, no other solvent or catalyst is needed, the yield is high, and the production cost is greatly reduced.
- -
-
Paragraph 0029-0041
(2020/10/30)
-
- Preparation method for 2,4-dichlorophenoxyacetic acid
-
The invention provides a preparation method for 2,4-dichlorophenoxyacetic acid, belonging to the technical field of organic synthesis. The preparation method comprises the following steps: a) reactinghalogenated acetate with 2,4-dichlorophenolate in the presence of a phase-transfer catalyst so as to obtain 2,4-dichlorophenoxyacetate; and b) hydrolyzing 2,4-dichlorophenoxyacetate so as to obtain 2,4-dichlorophenoxyacetic acid. According to the invention, oil-phase halogenated acetate reacts with 2,4-dichlorophenolate under the action of the phase-transfer catalyst to prepare 2,4-dichlorophenoxyacetate, and then 2,4-dichlorophenoxyacetate is hydrolyzed to obtain 2,4-dichlorophenoxyacetic acid and corresponding alcohols. Under the action of the phase-transfer catalyst, few hydrolysis by-products are produced during a reaction, fast reaction speed and high conversion rate and yield are obtained, and the amount of produced waste water is low; so industrial application of the preparation method can be easily implemented.
- -
-
Paragraph 0051; 0052
(2018/09/08)
-
- Preparation method for 2,4-dichlorophenoxyacetic acid
-
The invention provides a preparation method for 2,4-dichlorophenoxyacetic acid, belonging to the technical field of organic synthesis. The preparation method comprises the following steps: a) reactinghalogenated acetate with an anhydrous 2,4-dichlorophenolate solid so as to obtain 2,4-dichlorophenoxyacetate; and b) hydrolyzing 2,4-dichlorophenoxyacetate so as to obtain 2,4-dichlorophenoxyacetic acid. According to the invention, the anhydrous 2,4-dichlorophenolate solid reacts with halogenated acetate to prepare 2,4-dichlorophenoxyacetate, and then 2,4-dichlorophenoxyacetate is hydrolyzed to obtain 2,4-dichlorophenoxyacetic acid and corresponding alcohols. The mass transfer effect of a solid-liquid reaction in the invention is good; few hydrolysis by-products are produced during the reaction; fast reaction speed and high conversion rate and yield are obtained; the amount of produced waste water is low; so industrial application of the preparation method can be easily implemented.
- -
-
Paragraph 0050; 0051
(2018/09/08)
-
- Preparation method for 2,4-dichlorophenoxyacetic acid
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The invention provides a preparation method for 2,4-dichlorophenoxyacetic acid. The preparation method comprises the following steps: a) reacting haloacetic acid with 2,4-dichlorophenolate in a strong-polarity solvent so as to obtain 2,4-dichlorophenoxy acetate; and B) hydrolyzing 2,4-dichlorophenoxyacetate so as to obtain 2,4-dichlorophenoxyacetic acid. According to the invention, the strong-polarity solvent is utilized, so the mass transfer effect of the reaction is improved, reaction time is reduced, the reaction is more complete, and the conversion rate and yield of the reaction are greatly improved.
- -
-
Paragraph 0034; 0035
(2018/09/29)
-
- Preparation method of alkyl esters
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The invention provides a preparation method of alkyl esters, wherein the preparation method comprises the steps: S1) feeding alcohols from the tower bottom of a tower reactor, feeding first acid compounds from the tower top of the tower reactor, and feeding second acid compounds from the tower top of the tower reactor after being vaporized through a reboiler; S2) carrying out reaction of the alcohols with the first acid compounds and the second acid compounds in the tower reactor, and discharging out from the tower top to obtain a mixture; and S3) cooling the mixture, and then stratifying to obtain the alkyl esters. Compared with the prior art, the acid compounds in the tower reactor are controlled to still keep excessive, the alkyl esters and water are directly obtained from the tower topby controlling the temperature of the tower top, the alkyl esters and water are cooled and then stratified directly, the conversion rate of the alcohols is high and can reach 99.9%, the alcohols doesnot need to be concentrated and separated, and thus the tower efficiency is improved; at the same time, the overall process of the method is simple, and the temperature of the reaction stage is increased, the reaction rate is improved, the productivity is improved and energy consumption is low.
- -
-
Paragraph 0041; 0042; 0043; 0044; 0045-0048
(2019/01/08)
-
- Preparation method of phenoxyacetic ester
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The invention provides a preparation method of phenoxyacetic ester, wherein the preparation method includes the following steps: A) carrying out esterification reaction of acetic acid and alcohol to obtain acetic ester; B) introducing chlorine gas into acetic ester, and carrying out reaction to obtain chloroacetic ester; C) dehydrating a phenol compound and alkaline hydroxide into a salt in an organic solvent to obtain a salt of the phenol compound; D) after salt formation, mixing with chloracetic ester prepared in the step B), and carrying out condensation reaction to obtain phenoxyacetic ester, wherein the organic solvent is a mixture of any two kinds of toluene, xylene, chlorobenzene, phenol, butanol and isobutanol. The phenol is dehydrated into the salt in the mixed organic solvent, the system still maintains a uniform state in the dehydration process, continuous production is achieved, the dehydration efficiency is high and the efficiency of the whole production process is high. Moreover, the raw materials are easy to obtain, the production period is short, water is not needed in the reaction process, the energy consumption is low, the production cost is low, the yield of acetic acid is 99% or more, and the total yield of phenol can reach 99% or more.
- -
-
Paragraph 0052; 0053; 0056; 0058; 0060; 0062
(2019/01/08)
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- Self-assembled orthoester cryptands: Orthoester scope, post-functionalization, kinetic locking and tunable degradation kinetics
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Dynamic adaptability and biodegradability are key features of functional, 21st century host-guest systems. We have recently discovered a class of tripodal supramolecular hosts, in which two orthoesters act as constitutionally dynamic bridgeheads. Having previously demonstrated the adaptive nature of these hosts, we now report the synthesis and characterization-including eight solid state structures-of a diverse set of orthoester cages, which provides evidence for the broad scope of this new host class. With the same set of compounds, we demonstrated that the rates of orthoester exchange and hydrolysis can be tuned over a remarkably wide range, from rapid hydrolysis at pH 8 to nearly inert at pH 1, and that the Taft parameter of the orthoester substituent allows an adequate prediction of the reaction kinetics. Moreover, the synthesis of an alkyne-capped cryptand enabled the post-functionalization of orthoester cryptands by Sonogashira and CuAAC "click" reactions. The methylation of the resulting triazole furnished a cryptate that was kinetically inert towards orthoester exchange and hydrolysis at pH > 1, which is equivalent to the "turnoff" of constitutionally dynamic imines by means of reduction. These findings indicate that orthoester cages may be more broadly useful than anticipated, e.g. as drug delivery agents with precisely tunable biodegradability or, thanks to the kinetic locking strategy, as ion sensors.
- L?w, Henrik,Mena-Osteritz, Elena,Von Delius, Max
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p. 4785 - 4793
(2018/06/07)
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- Chloracetate water phase synthesis technology and novel method for preparing 2,4-D ester
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The invention discloses a chloracetate water phase synthesis technology and a novel method for preparing 2,4-D ester, and belongs to the technical field of organic synthesis. According to the chloracetate water phase synthesis technology, alcohol and chloroacetic acid are used as raw materials for preparing chloracetate in the water phase. The method for preparing 2,4-D ester comprises the following steps that (1) chloracetate is prepared; (2) 2,4-dichloroindophenol sodium is prepared; (2) the chloracetate directly takes a reaction with 2,4-dichloroindophenol sodium under the alkaline condition to obtain the corresponding 2,4-D ester. The operation of the preparation method of the chloracetate provided by the invention is performed in the water phase, so that the purity of the obtained coarse ester is higher, and can reach 99.3 percent or higher only through simple distillation; the corresponding 2,4-D ester is prepared from the chloracetate; the preparation process of the 2,4-D ester is greatly simplified; the cost is effectively reduced; the reaction time is greatly shortened; in addition, the product yield is improved; the waste water quantity is effectively reduced; the green chemical industrial requirements are met.
- -
-
Paragraph 0040; 0041
(2017/08/25)
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- Calix[4]resorcinarene-Chitosan Hybrid via Amide Bond Formation
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Hybrid of calix[4]resorcinarene and chitosan has been prepared via amide bond formation as the key step between ester groups attached on calix[4]resorcinarene and amine group of chitosan. The synthesis was commenced by functionalizing hydroxyl group of vanillin with methyl-2-chloroacetate via Williamson synthesis. The acid catalyzed-tandem condensation-cyclization of vanillin derivative and resorcinol gave C-4-methoxycarbonylmethoxy-3-methoxyphenylcalix[4]resorcinarene. The calix[4]resorcinarene installed with the ester group was then coupled with amine group of chitosan to form hybrid of calix[4]resorcinarene and chitosan. The IR, XRD and SEM analyses of the hybrid revealed that physical properties of the hybrid were similar to chitosan.
- Jumina,Siswanta, Dwi,Anggraeni, Mayliana,Mardjan, Muhamad Idham Darusalam,Mulyono, Panut,Ohto, Keisuke
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p. 2273 - 2276
(2015/12/01)
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- Organic-inorganic hybrid supermicroporous iron(III) phosphonate nanoparticles as an efficient catalyst for the synthesis of biofuels
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Here we report a novel family of crystalline, supermicroporous iron(III) phosphonate nanomaterials (HFeP-1-3, HFeP-1-2, and HFeP-1-4) with different FeIII-to-organophosphonate ligand mole ratios. The materials were synthesized by using a hydrothermal reaction between benzene-1,3,5-triphosphonic acid and iron(III) chloride under acidic conditions (pH≈4.0). Powder X-ray diffraction, N2 sorption, transmission and scanning electron microscopy (TEM and SEM) image analysis, thermogravimetric and differential thermal analysis (TGA-DTA), and FTIR spectroscopic tools were used to characterize the materials. The triclinic crystal phase [P1(2) space group] of the hybrid iron phosphonate was established by a Rietveld refinement of the PXRD analysis of HFeP-1-3 by using the MAUD program. The unit cell parameters are a=8.749(1), b=8.578(1), c=17.725(3) ?; α=104.47(3), β=97.64(1), γ=113.56(3)°; and V=1013.41 ?3. With these crystal parameters, we proposed an 24-membered-ring open framework structure for HFeP-1. Compound HFeP-1-3, with an starting Fe/ligand molar ratio of 3.0, shows the highest Brunauer-Emmett-Telller (BET) surface area of 556 m2g -1 and uniform supermicropores of approximately 1.1 nm. The acidic surface of the porous iron(III) phosphonate nanoparticles was used in a highly efficient and recyclable catalytic transesterification reaction for the synthesis of biofuels under mild reaction conditions. Iron brews biofuels: Highly crystalline, supermicroporous iron(III) phosphonate nanoparticles have been synthesized through a hydrothermal reaction between benzene-1,3,5- triphosphonic acid and FeCl3. The resulting material was used as an efficient and recyclable catalyst for the synthesis of biofuels under mild reaction conditions (see scheme). Copyright
- Pramanik, Malay,Bhaumik, Asim
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p. 8507 - 8514
(2013/07/26)
-
- Total synthesis of (+)-pentamethylsalvianolic acid C
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The total synthesis of a methylated analogue of (+)-Salvianolic acid C has been achieved. Key aspects of the synthetic route include an economical Cu(i) acetylide coupling, unique carboxyl activation conditions via microwave irradiation and a novel lipase catalysed kinetic resolution of a racemic mixture of secondary alcohol Danshensu. The preparation of this methylated analogue will not only improve the bioavailability, but also enable access to new and wider bioactivity applications for (+)-Salvianolic acid C.
- Alford, Benjamin L.,Huegel, Helmut M.
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supporting information
p. 2724 - 2727
(2013/06/04)
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- A simple criterion for gas chromatography/mass spectrometric analysis of thermally unstable compounds, and reassessment of the by-products of alkyl diazoacetate synthesis
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Rationale: A principal limitation of gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS) is the thermal instability of analytes. We propose that the injector and column temperatures should not exceed the atmospheric pressure boiling point, without decomposition, of the highest homologue of the series being analyzed, instead of the time-consuming procedure of obtaining chromatograms using different temperatures. Methods: A series of thermally unstable diazocarbonyl compounds, alkyl diazoacetates (predicted limit of stability approx. 140 °C, the boiling point of ethyl diazoacetate), was selected for GC/MS analysis using standard equipment. Different GC separation conditions were selected so that the retention temperatures of target compounds were both below and above 140°C. Results: Analyzing alkyl diazoacetates within their thermal stability range permitted reanalysis of their typical synthesis by-products. No dialkyl fumarate or maleate impurities, principal decomposition products which have often been reported previously, were found. Instead, alkyl esters of glycolic acid nitrate, O2NOCH 2CO2R, and 'pseudo-dimeric' products, ROCO[C 2H3NO]CO2R, were discovered for the first time. Conclusions: Avoiding the decomposition of thermally unstable organic compounds during GC and/or GC/MS analysis requires estimating their degradation temperature limits. This limit can be estimated as being equal to the atmospheric pressure boiling point of the highest homologue in the homologous series under consideration that does not decompose on boiling. Copyright
- Kornilova, Tatiana A.,Ukolov, Anton I.,Kostikov, Rafael R.,Zenkevich, Igor G.
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p. 461 - 466
(2013/03/14)
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- Organic-inorganic hybrid porous sulfonated zinc phosphonate material: Efficient catalyst for biodiesel synthesis at room temperature
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A new porous zinc phosphonate material (HZnP-1) has been synthesized via the reaction between p-xylenediphosphonic acid and anhydrous ZnCl2 under hydrothermal and mildly acidic conditions (pH ～ 5) in the absence of any structure directing agent. The phenyl group of this material has been sulfonated with concentrated sulfuric acid to obtain sulfonic acid functionalized material HZnPS-1. Powder X-ray diffraction (XRD), field emission scanning electron microscopy (FE SEM), N2 sorption, solid state 13C CP MAS and 31P MAS NMR, and FT IR spectroscopic tools are employed to characterize these materials. The crystal structures of both the materials are indexed corresponding to the new orthorhombic phases with unit cell parameters a = 11.00, b = 8.74, c = 14.62 A, α = β = γ = 90° for HZnP-1, and a = 10.65, b = 13.52, c = 15.30 A and α = β = γ = 90° for HZnPS-1. HZnPS-1 showed outstanding catalytic activity and high recycling efficiency for the synthesis of different biodiesel compounds via esterification of long chain fatty acids by using methanol as both reactant and solvent at room temperature. The green and eco-friendly catalytic system described herein can overcome the problem faced by the existing catalytic systems known in biodiesel synthesis, such as drastic conditions (high reaction temperature) and requirement of hazardous organic solvents.
- Pramanik, Malay,Nandi, Mahasweta,Uyama, Hiroshi,Bhaumik, Asim
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experimental part
p. 2273 - 2281
(2012/09/08)
-
- Mechanism of halogen exchange in ATRP
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Detailed mechanistic studies reveal that halogen exchange (HE) in ATRP can occur not only by a radical pathway (atom transfer) but also by an ionic pathway (SN2 reaction) because Cu(I)(L)X and Cu (II)(L)X2 complexes contain weakly associated halide anion that can participate in the SN2 reaction with alkyl halide (ATRP initiator). Both pathways were kinetically studied, and their contributions to the HE process were quantitatively evaluated for seven alkyl halides and three Cu(I)(L)Cl complexes. Radical pathway dominates the HE process for 3° and 2° alkyl bromides with more active complexes such as Cu (I)(TPMA)Cl. Interestingly, ionic pathway dominates for 1° alkyl bromides and less active ATRP catalysts. These studies also revealed that degree of association of alkyl halide anion depends on the structure of copper complexes. In addition, radical pathway is accompanied by the reverse reactions such as deactivation of radicals to alkyl bromides and also activation of alkyl chlorides, reducing the efficiency of halogen exchange.
- Peng, Chi-How,Kong, Jing,Seeliger, Florian,Matyjaszewski, Krzysztof
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scheme or table
p. 7546 - 7557
(2012/07/28)
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- Reactions of diazo esters with electron-deficient alkenes in the presence of Lewis acids
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1,3-Dipolar cycloaddition reaction of diazo esters to electron-deficient dipolarophiles to yield the corresponding 1- or 2-pyrazolines was found to be significantly accelerated with Lewis acids (Yb(OTf)3, Sc(OTf) 3, GaCl3, EtAlCl2). The use of GaCl3 as the catalyst leads to the acceleration not only of the 1,3-dipolar cycloaddition reaction, but also subsequent insertion of the CHCO2Me electrophilic fragment of methyl diazoacetate into the N-H bond of 2-pyrazolines formed. Such Lewis acids as SnCl4, BF3, TiCl4, and In(OTf)3 are not efficient in the described processes, since they rapidly decompose starting diazo compounds.
- Novikov,Platonov,Dokichev,Tomilov,Nefedov
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experimental part
p. 984 - 990
(2011/02/27)
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- ZrOCl2·8H2O: An efficient, cheap and reusable catalyst for the esterification of acrylic acid and other carboxylic acids with equimolar amounts of alcohols
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Esterifications of carboxylic acids with equimolar amount of alcohols could be efficiently catalyzed by ZrOCl2·8H2O. Acrylate esters were obtained in good yields under solvent-free conditions at ambient temperature. The esterification of other carboxylic acids with alcohols also proceeded at ambient temperature or at 50°C to afford esters in high yields. If the esterification was performed in toluene under azeotropic reflux conditions to remove water, both the catalytic activity of ZrOCl 2·8H2O and the rate of esterification could be increased greatly. Furthermore, in the present catalytic system, the esters could be easily separated from the reaction mixtures and the catalyst could be easily recovered and reused.
- Sun, Hong-Bin,Hua, Ruimao,Yin, Yingwu
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p. 263 - 271
(2007/10/03)
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- Mechanisms of solvolyses of acid chlorides and chloroformates. Chloroacetyl and phenylacetyl chloride as similarity models
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Rate constants and product selectivities (S = ([ester product]/[acid product]) × ([water]/[alcohol solvent]) are reported for solvolyses of chloroacetyl chloride (3) at -10 °C and phenylacetyl chloride (4) at O °C in ethanol/and methanol/water mixtures. Additional kinetic data are reported for solvolyses in acetone/water, 2,2,2-trifluoroethanol(TFE)/water, and TFE/ethanol mixtures. Selectivities and solvent effects for 3, including the kinetic solvent isotope effect (KSIE) of 2.18 for methanol, are similar to those for solvolyses of p-nitrobenzoyl chloride (1, Z = NO2); rate constants in acetone/water are consistent with a third-order mechanism, and rates and products in ethanol/and methanol/water mixtures can be explained quantitatively by competing third-order mechanisms in which one molecule of solvent (alcohol or water) acts as a nucleophile and another acts as a general base (an addition/elimination reaction channel). Selectivities increase for 3 as water is added to alcohol. Solvent effects on rate constants for solvolyses of 3 are very similar to those of methyl chloroformate, but acetyl chloride shows a lower KSIE, and a higher sensitivity to solvent-ionizing power, explained by a change to an SN2/SN1 (ionization) reaction channel. Solvolyses of 4 undergo a change from the addition/elimination channel in ethanol to the ionization channel in aqueous ethanol (80% v/v alcohol). The reasons for change in reaction channels are discussed in terms of the gas-phase stabilities of acylium ions, calculated using Gaussian 03 (HF/6-31G(d), B3LYP/6-31G(d), and B3LYP/6-311G(d,p) MO theory).
- Bentley, T. William,Harris, H. Carl,Ryu, Zoon Ha,Lim, Gui Taek,Sung, Dae Dong,Szajda, Stanley R.
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p. 8963 - 8970
(2007/10/03)
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- Fe2(SO4)3·4H 2O/concentrated H2SO4: An efficient catalyst for esterification
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The mixed catalyst system, Fe2(SO4) 3·4H2O/concentrated H2SO4 has been applied to catalyse effectively the esterification of α,β-unsaturated acids, aliphatic acids and heterocyclic aromatic acids with ethanol and methanol.
- Liang, Yong-Min,Xu, Qi-Hai,Wu, Xiao-Li,Ma, Yong-Xiang
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p. 226 - 227
(2007/10/03)
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- In situ derivatization/solid-phase microextraction for the determination of haloacetic acids in water
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An in situ derivatization solid-phase microextraction method has been developed for the determination of haloacetic acids (HAAs) in water. The analytical procedure involves derivatization of HAAs to their methyl esters with dimethyl sulfate, headspace sampling using solid-phase microextraction (SPME), and gas chromatography-ion trap mass spectrometry (GC/ITMS) determination. Parameters affecting both derivatization efficiency and headspace SPME procedure, such as the selection of the SPME coating, derivatization-extraction time and temperature, and ionic strength, were optimized. The commercially available Carboxen-poly(dimethylsiloxane) (CAR-PDMS) fiber appears to be the most suitable for the determination of HAAs. Moreover, the formation of HAA methyl esters was dramatically improved (up to 90-fold) by the addition of tetrabutylammonium hydrogen sulfate (4.7 μmol) to the sample as ion-pairing agent in the derivatization step. The precision of the in situ derivatization/HS-SPME/GC/ITMS method evaluated using an internal standard gave relative standard deviations (RSDs) between 6.3 and 11.4%. The method was linear over 2 orders of magnitude, and detection limits were compound-dependent, but ranged from 10 to 450 ng/L. The method was compared with the EPA method 552.2 for the analysis of HAAs in various water samples, and good agreement was obtained. Consequently, in situ derivatization/HS-SPME/GC/ITMS is proposed for the analysis of HAAs in water.
- Sarrion,Santos,Galceran
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p. 4865 - 4873
(2007/10/03)
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- Chloropyridylcarbonyl derivatives
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Novel chloropyridylcarbonyl derivatives of the formula STR1 in which Het is STR2 n is 1 or 2, R1 is hydrogen, optionally substituted C1-6 alkyl, optionally substituted C2-6 alkenyl, optionally substituted C3-6 alkynyl, optionally substituted phenyl or optionally substituted pyrimidinyl, and R2 and R3, independently of each other, are hydrogen or C1-4 alkyl, and acid addition salts and metal salt complexes thereof, are outstandingly active as microbicides.
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- Intramolecular Geminal and Vicinal Element Effects in Substitution of Simple Bromo(chloro)alkenes by Methoxide and Thiolate Ions. An Example of a Single Step Substitution?
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Intramolecular element effects kBr/kCl for substitution of geminal bromochloroalkenes BrC(Cl)=C-(Br)Cl (1), BrC(Cl)=CCl2 (2), Me2C=C(Br)Cl (3), and XCH=C(Br)Cl (X = Cl, 4; X = Br, 5), with MeO- and RS- nucleophiles were investigated. 3 did not give substitution, and 4 and 5 gave substitution with MeO- via an initial elimination (to acetylene)-addition route, followed by further reactions. In reactions of 4 with thiolates, geminal element effects of 2-10 were obtained. Formation of RSC(Cl)=C(Cl)Y, Y = SR, Br, is ascribed to an initial halophilic reaction, followed by addition of RSCl to the formed acetylene. Reaction of 2 with MeO- gave a high vicinal element effect, and RS- gave a high geminal element effect. Reaction of 1 with both MeO- and RS- ions gave high (2 orders of magnitude) geminal element effects, which were interpreted as indicating a rate-determining C-X bond cleavage. This is supported by the high kBr/kCl intermolecular element effects (k(1)/k(Cl2C=CCl2) with MeO- and PhCH2S- ions. Mechanistic alternatives based on these observations are discussed.
- Beit-Yannai, Michal,Rappoport, Zvi,Shainyan, Bagrat A.,Danilevich, Yuri S.
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p. 8049 - 8057
(2007/10/03)
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- Nucleophilic Substitution Reactions at Chloro-Substituted Ozonides and at a Chlorinated Dimeric Peroxide
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Reactions of substituted 3-chloro- (2a-4a) and 3,5-dichloro-1,2,4-trioxolanes (9a, 10a) with AgBF4 in the presence of LiF gave the corresponding fluoro-substituted ozonides (2b - 4b and 9b and 10b).Substitutions of some of these chlorinated ozonides by the methoxy and by the acetoxy groups, and of 3,6-dichloro-3,6-dimethyl-1,2,4,5-tetroxane (22a) with the acetoxy group have been achieved too.
- Griesbaum, Karl,Schlindwein, Konrad
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p. 8062 - 8066
(2007/10/03)
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- Ozonides of Acyclic Olefins Having Mono- and Dichloro-Substituted Double Bonds
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Ozonolyses of acyclic olefins containing 1,2-dichloro-substituted (4a,b) and monochloro-substituted double bonds (7a, b, 12) as well as two (4a, b, 7a, b) or one halomethyl group (12) attached to the double bond afford the corresponding ozonides as the first representatives of monocyclic chlorinated ozonides.Their stability decreases in order 5a, 5b > 8a, 8b > 13. - Key Words: Ozonides/ 1,2,4-Trioxolanes, 3-chloro-, 3,5-dichloro- / Polyethylene
- Griesbaum, Karl,Schlindwein, Konrad,Hilss, Michael
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p. 1843 - 1848
(2007/10/02)
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- Analyse structurale des derives fonctionnels des acides carboxyliques. Partie II. Halogeno et cyanoacetates de methyle
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Methylene bending mode analysis and dipole moment determinations were carried out in solution (CCl4) for some methyl esters ΣCH2CO2Me with Σ =F(I), Cl(II), Br(III), I(IV), CN(V), in order to identify the conformers induced by ΣCH2 group rotating motion and determine their relation amounts.The results are consistent with the existence of two conformations; syn and anti for (I), syn and gauche for (II) and (III).Compounds (IV) and (V) occur almost exclusively in gauche and syn forms respectively.A theoretical study of compounds (I), (II) and (V) by P.C.I.L.O. methods and the Onsager formalism was performed.The collected data show that the conformers have the O-Me bond syn to the carbonyl.The calculated value of ΔE for the equilibrium between the syn and anti rotamers (Ea-Es =600 cal mol-1) is in good agreement with ΔH0298 estimated from the temperature-dependence studies (ΔE =158 cal mol-1).
- Maury, Catherine,Petrissans, Jean
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p. 267 - 278
(2007/10/02)
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- Specific esterase activity of subtilisin toward esters of α-haloacids
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Esters of α-haloacids are specific substrates for subtilisin which catalyses their hydrolysis in aqueous media. The same esters undergo transesterifications in organic solvents in the presence of subtilisin immobilized on an alumina-phosphate complex.
- Pugniere,Juan, C. San,Previero
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p. 4883 - 4886
(2007/10/02)
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- General Base Catalysis in the Methanolysis of 4-Nitrophenyl Acetates
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The rates of methanolysis of 4-nitrophenyl acetate, chloroacetate, and dichloroacetate have been measured in the presence of pyridines and imidazoles.Methyl substitution at the 2- and 6-positions in pyridine causes only a slight reduction in reactivity.A
- Neuvonen, Helmi
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p. 669 - 673
(2007/10/02)
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- Lipase-catalyzed Stereoselective Acylation of -2,2'-diol and Deacylation of Its Esters in an Organic Solvent
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A kinetic resolution of -2,2'-diol (binaphthol) and its esters was first accomplished by lipase-catalyzed transesterification in an organic solvent.Acylation of binaphthol with enol esters in diisopropyl ether-acetone (9:1, v/v) gave solely (R)-2-acyloxy-2'-hydroxy-1,1'-binaphthyl (binaphthyl monoesters) having 90-95percent optical purities.The unreacted binaphthol, which was also recovered in high chemical yields, was the S enantiomer with 69-89percent e.e.On the other hand, the lipase-catalyzed deacylation or alcoholysis of racemic binaphthyl monoesters gave (S)-monoesters and (R)-binaphthol in high chemical and optical yields (>90percent e.e.).In deacylation, the reaction period was much shortened by introducing the more electronegative chlorine atom into the acetyl group of the substrate.
- Inagaki, Minoru,Hiratake, Jun,Nishioka, Takaaki,Oda, Jun'ichi
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p. 1879 - 1884
(2007/10/02)
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- STRUCTURAL EFFECT ON THE MECHANISTIC PATHWAY OF THE DECOMPOSITION OF 3-ALKYL-1-ARYLTRIAZENES: A KINETIC STUDY
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A kinetic study of the reaction between 3-alkyl-1-aryltriazenes and substituted acetic acids has been made in solvent acetone over the temperature range 21-37 deg C.Ea is 17.3 +/- 0.3 kcal mol-1 and log A is 10.3 +/- 0.1.Influence of the substituents on the reaction rate has been analyzed.The Hammett correlation with ? gave a ρ value of -0.96 for para-aryl substituted triazenes and +0.35 for meta- and para-substituted phenylacetic acid.The rate of decomposition of triazenes is also affected by changing the alkyl group.From these results a duality in mechanism is proposed; first, a simultaneous protonation and alkyl group expulsion to be the rate-determining step when R is tertiary, benzylic and possibly secondary.Secondly, a concerted mechanism for the protonation of nitrogen and cleavage of the N-R bond for primary alkyl groups.
- Laila, Abdulhameed A. R.
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p. 453 - 456
(2007/10/02)
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- AMBERLYST 15: A PRACTICAL, MILD AND SELECTIVE CATALYST FOR METHYL ESTERIFICATON OF CARBOXYLIC ACIDS
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Mild and selective methyl esterification of carboxylic acids are realized using Amberlyst 15 as acid catalyst in methanol.No racemization, epimerization or ketalization products have been observed with this method.Excellent results are obtained in the esterifications of bile acids.
- Petrini, Marino,Ballini, Roberto,Marcantoni, Enrico
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p. 847 - 854
(2007/10/02)
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- Alkylcobalt carbonyls. 8. (Chloromethyl)- and (chloroacetyl)cobalt carbonyls
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(Chloroacetyl)cobalt tetracarbonyl, ClCH2C(O)Co(CO)4 (1), was prepared by the reaction of ClCH2C(O)Cl with Na[Co(CO)4]. 1 readily decarbonylates to (chloromethyl)cobalt tetracarbonyl (2). 1 is formed from 2 at ～5 bar of CO pressure and room temperature or at 1 bar of CO by cooling to ～-10°C in a reversible reaction. 2 gives with PPh3 the CO-substituted acyl derivative ClCH2C(O)Co(CO)3PPh3 (3) that can be decarbonylated at 50°C to the corresponding alkyl complex ClCH2Co(CO)3PPh3 (4). 4 takes up CO even under 1 bar of pressure at room temperature. The 3 ? 4 equilibrium is reversible. 1 was characterized by IR spectra, 2-4 could be isolated, and the structures of 3 and 4 were determined by X-ray diffraction. 2 reacts with the methoxide ion to yield CH2(COOMe)2. These results represent the first examples of (a) the carbonylation/decarbonylation reaction couple of an XCH2M vs. XCH2C(O)M (X = Cl, Br, I; M = transition metal) pair, (b) a ligand substitution reaction of a chloromethyl complex with a tertiary phosphine, and (c) the structure determination of a chloromethyl complex as well as (d) the structural study of an alkyl-/acylcobalt carbonyl pair with the same organic group. 3 crystallizes with monoclinic symmetry in the space group P21/c with Z = 4 and cell dimensions of a = 1212.3 (2) pm, b = 928.9 (3) pm, c = 2029.9 (4) pm, and β = 104.15 (2)°. Structure solution by Patterson methods and refinement with 3305 unique observed reflections led to a final R value of 0.057. The crystals of 4 are tetragonal of space group P43, with Z = 4 in a unit cell of dimensions a = b = 1086.3 (1) pm and c = 1815.5 (4) pm. The structure was determined by direct methods and refined with 4358 unique observed reflections to a final R value of 0.033.
- Galamb, Vilmos,Pályi, Gyula,Boese, Roland,Schmid, Günter
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p. 861 - 867
(2008/10/08)
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- About the Ozone Cleavage of Chloroprene and of 2-Chloro-3-methyl-1,3-butadiene in Methanol
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Monoozonolyses of chloroprene (1a) and of 2-chloro-3-methyl-1,3-butadiene (1b) in methanol occur with more than 90percent at the non-chlorinated double bonds to afford the corresponding α,β-unsaturated oxo compounds 2 with selectivities of 96 and 80percent respectively.The latter subsequently react with methanol, and 2a also with the complementary fragment methoxymethyl hydroperoxide (5).The α,β-unsaturated methoxy hydroperoxides 3 which have also been obtained, are less stable than similarly structured, non-α-chlorinated methoxy hydroperoxides.Diozonolyses of 1a and 1b in methanol afforded in 50-60percent the corresponding α-oxocarboxylates (21) and/or the corresponding ketals.In addition, anomalous products were obtained viz. ca. 15percent of methyl hydroxyacetate (12d) from 1a and 1b, as well as ca. 30percent of dimethyl oxalate (27b) from 1a and ca. 35percent of methyl acetate (13) from 1b.The modes of formation of these products have been postulated according to model reactions.
- Griesbaum, Karl,Meister, Martin
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p. 1573 - 1580
(2007/10/02)
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- Esterification, Etherification, and Aldol Condensation Using Cathodically-Generated Organic Olate Anions
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Cathodic methods for the esterification of carboxylic acids and the etherification of phenol and benzenethiol under mild conditions were developed.The esterification was successfully carried out at room temperature by the reaction of alkylating reagents with cathodically-generated quaternary ammonium carboxylates.The etherification was similarly achieved using electrogenerated quaternary ammonium phenolate and halonitrobenzenes.A hindered phenolate anion cathodically-generated from 2,6-di-t-butyl-p-cresol remarkably promoted aldol condensation of aromatic ketones and aldehydes, and allowed subsequent Michael reaction to provide efficiently symmetrical 1,5-diketones.
- Fuchigami, Toshio,Awata, Takeshi,Nonaka, Tsutomu,Baizer, Manuel M.
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p. 2873 - 2880
(2007/10/02)
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- PERFLUORINATED RESINSULFONIC ACID - A CATALYST FOR CERTAIN ORGANIC REACTIONS.
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The purpose of this work was to examine the possibility of using, as a catalyst in certain organic reactions, the perfluorinated resinsulfonic acid F-4SK in the H form, which is an analog of the perfluorinated resinsulfonic acid Nafion-H. To compare catalyst activity of the perfluorinated resinsulfonic acid in decomposition of cumene hydroperoxide, CHP was also decomposed in presence of KU-2 resin. It was found that during repeated use over a period of 150 h the activity of KU-2 catalyst under analogous conditions fell by 4-6%. During the same time the activity of the perfluorinated resinsulfonic acid remained unchanged. It is also known that the presence of a strong acid in the reaction mixture causes formation of by-products, namely the products of condensation of phenol with acetone and dimethylphenylcarbinol, and of dehydration of dimethylphenylcarbinol, with formation of alpha -methylstyrene and products of greater complexity.
- Etlis,Beshenova,Semenova,Shomina,Dreiman,Balaev
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p. 551 - 555
(2007/10/02)
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- CATHODIC ESTERIFICATION OF CARBOXYLIC ACIDS
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A cathodic method for the esterification of carboxylic acids under mild conditions was found.The esterification proceeded smoothly at room temperature by the reaction of alkylating with quaternary ammonium carboxylates formed in a cathode chamber.
- Awata, Takeshi,Baizer, Manuel M.,Nonaka, Tsutomu,Fuchigami, Toshio
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p. 371 - 374
(2007/10/02)
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- Disproval of Claimed Unusually Stable Primary Ozonides of 1,4-Dichloro-2-butenes
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Ozonolysen von cis- und trans-1,4-Dichlor-2-buten (1) in Methanol ergaben ca. aequimolare Anteile an 2-Chlor-1-methoxyethanol (6a) und 2-Chlor-1-methoxyethylhydroperoxid (7a) als Hauptprodukte sowie eine geringe Menge 2,2'-Dichlor-1-hydroxy-1'-methoxydiethylperoxid (8a).Ozonolyse von 1 in Methanol ergab die entsprechenden deuterierten Produkte 6c - 8c.Die postulierte Existenz von ungewoehnlich stabilen Primaerozoniden wird widerlegt.
- Griesbaum, Karl,Meister, Martin
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p. 845 - 850
(2007/10/02)
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- Reactions of Tributyltin Methoxide with Cloromethyl Esters
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Reactions of tributyltin methoxide with esters RCO2R' (R'=CH2Cl, CHCl2 or CCl3) have been performed to study the influence of the halogens in the alkyl component of an ester on the course of the reaction.In all reactions tributyltin chloride and methyl ester were formed whereas the subsequent reaction depended on the number of halogens in the methyl group.
- Vihanto, Jouko
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p. 699 - 702
(2007/10/02)
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- FACILE ESTERIFICATION OF CARBOXYLIC ACIDS WITH ORGANOPHOSPHORUS REAGENTS. NOVEL APPLICATION OF ALKYLPHOSPHORIC ESTERS (APE)
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A mixture of alkyl phosphate esters (APE) obtained from P4O10 and alkanols taken in 1:6 mole ratio is an excellent esterification reagent for several classes of carboxylic acids.This new reagent offers several advantages compared to conventional reagents.
- Balasubramaniyan, V.,Bhatia, V. G.,Wagh, S. B.
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p. 1475 - 1485
(2007/10/02)
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- Dialkyl sulphites: Convenient Reagents for Esterification of Carboxylic Acids
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Several mono and dicarbocylic acids undergo esterification with dimethyl/ diethyl sulphite in the presence of traces of sulphuric acid in a one-pot reaction.
- Bhatia, V. G.,Shaik, A. S.,Tongare, D. B.,Balasubramaniyan, V.
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p. 259 - 260
(2007/10/02)
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- A FACILE METHOD OF TRANSESTERIFICATION USING PHOSPHORUS YLID
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The transesterification of carboxylic esters catalysed with phosphorus ylid under neutral and mild conditions has been investigated.The reactions of esters having an electron withdrawing group with methanol proceeded rapidly and with high yield, whereas the reverse reactions proceeded slowly or not at all.
- Hashimoto, Shizunobu,Furukawa, Isao,Kuroda, Tomoyuki
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p. 2857 - 2860
(2007/10/02)
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- The mechanism of oxidation of acetals by ozone. I. Stoichiometry, order of reaction, solvent effects, and substituent effects
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A systematic investigation of the reaction between ozone and acetals to form acetal hydrotrioxides A has been undertaken.The stoichiometry of the reaction has been shown to be 1:1 in each reactant and the order of the reaction was also one in each reactant.Substituent effects measured in a variety of systems and under several conditions of temperature and solvent were found to be small (ρ=-1.10 to -1.58).Solvent polarity was also found to have little effect on the rate of the reaction.Mechanistically, these facts are interpreted in terms of a 1,3-dipolar insertion of ozone into the C-H bond of the acetal function.
- Taillefer, Roland J.,Thomas, Shirley E.,Nadeau, Yves,Fliszar, S.,Henry, Herve
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p. 1138 - 1143
(2007/10/02)
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- Ozonolysis of olefins containing monochloro substituted double bonds
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Ozone cleavage of 12 substituted vinyl chlorides (1) in methanol occurred such that the chlorinated moiety of the double bond afforded the carbonyl fragment (i. e. acyl chloride) and the nonchlorinated moiety afforded the carbonyl oxide fragment.All of these fragments underwent secondary reactions: formyl chloride gave carbon monoxide and hydrogen chloride; all other acyl chlorides yielded the corresponding methyl esters.The carbonyl oxides were converted into the corresponding methoxy hydroperoxides.Under the influence of hydrochloric acid unsubstituted and monosubstituted methoxy hydroperoxides were dehydrated to form the corresponding methyl esters, whereas the disubsituted methoxy hydroperoxide of acetone produced the cyclic trimeric peroxide of acetone.
- Keul, Helmut,Griesbaum, Karl
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p. 2049 - 2054
(2007/10/02)
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- Process for preparation of 5-cyanopyrid-6-ones
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5-Cyanopyrid-6-ones are manufactured by reacting haloacetic acid esters with nitrogen compounds, then reacting the mixture with alkali metal cyanides, and finally reacting it with dicarbonyl compounds. The products are starting materials for the manufacture of dyes, assistants, pharmaceuticals, vitamin B 6, crop protection agents and aminoacids.
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- Novel pyrazolyloxyacetic acid derivatives and process for the preparation thereof
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Compounds of the formula SPC1 Wherein X and Y each are a bond or methylene, R is H or lower-alkyl and Z is a carboxyl, amide, nitrile or alkoxycarbonyl of 1-6 carbon atoms in the alkoxy group and the corresponding compounds bearing 1-2 halogen, lower-alkyl or lower-alkoxy groups on one or both benzene rings and, when Z is carboxyl, salts thereof with physiologically acceptable bases, possess anti-inflammatory and antipyretic activities.
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