- Electron-withdrawing substituents decrease the electrophilicity of the carbonyl carbon. An investigation with the aid of 13C NMR chemical shifts, v(C=O) frequency values, charge densities, and isodesmic reactions to interprete substituent effects on reactivity
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13C NMR chemical shifts and v(C=O) frequencies have been measured for several series of phenyl-or acyl-substituted phenyl acetates and for acyl-substituted methyl acetates to investigate the substituent-induced changes in the electrophilic character of the carbonyl carbon. Charge density, bond order, and energy calculations have also been performed. The spectroscopic and charge density results indicate that opposite to the conventional thinking, electron-withdrawing substituents do not increase the electrophilicity of the carbonyl carbon but instead decrease it. On the other hand, reaction energies of the isodesmic reactions designed show that electron-withdrawing substituents destabilize the carbonyl derivatives investigated. So, a significant ground-state destabilization of carboxylic acid esters, and carbonyl compounds in general, due to the decreased resonance stabilization, is proposed as a novel concept to explain both the increase in their reactivity and the changes in the chemical shifts and carbonyl frequencies induced by electron-withdrawing substituents.
- Neuvonen, Helmi,Neuvonen, Kari,Koch, Andreas,Kleinpeter, Erich,Pasanen, Paavo
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- CuCl/bpy-promoted unusual Z-stereoselective synthesis of trichloroacetic acid phenyl ester for Hirshfeld surface analysis and DFT study
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A trichloromethyl ester devoid of suitably substituted C[dbnd]C bond, any leaving group or a H-atom at the β-position to the radical, which are otherwise known for ATRA/ATRC, 1,2-rearrangement/fragmentation or simple 1,2-H shift respectively, in a reaction of trichloro-acetic acid phenyl ester with 2 mol equiv CuCl/bpy in reflux DCE or benzene under inert N2 condition resulted to stereoselective synthesis of Z-2,3-dichloro-but-2-enedioic acid diphenyl ester and/or formation of reductive de-chlorination side product. The Z-stereochemistry of the product was confirmed by X-ray diffraction spectroscopy of Z-2,3-dichloro-but-2-enedioic acid dinaphthalen-1-yl ester which crystalizes in monoclinic system of P21/c symmetry elements. Hirshfeld surface analysis of experimentally established structure of Z-2,3-dichloro-but-2-enedioic acid diphenyl ester unrevealed the intermolecular interactions showing both H-bonding and short contacts. The stereochemistry was also interpreted computationally using Density Functional Theory at B3LYP/6-311G(d,p) level of theory. The calculated energies, energy gap and balance between the electrostatic potential on the molecular surface were computed which revealed unusual formation of less stable Z-isomer.
- Tittal, Ram Kumar,Ram, Ram Nath,Nirwan, Ayushi,Ghule, Vikas D.,Kumar, Satish
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p. 300 - 309
(2019/03/12)
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- METHOD FOR PRODUCING CARBONATE COMPOUND AND METHOD FOR PRODUCING AROMATIC POLYCARBONATE
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The present invention relates to a method for producing a carbonate compound containing: a first step of reacting a compound represented by the following Formula (1) with a compound represented by the following Formula (21) or a compound represented by the following Formula (22) to obtain a reaction mixture containing a carbonate compound, and a second step of bringing the reaction mixture containing a carbonate compound into contact with a strongly basic compound, in which R1 represents a monovalent organic group, and R2 represents a divalent organic group.
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Paragraph 0190-0192
(2015/06/10)
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- Platinum on carbon-catalyzed precise reduction control of trichloromethyl to Geminal-dichloromethyl groups
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Geminal-dichloromethyl derivatives could be efficiently synthesized by the highly chemoselective platinum on carbon-catalyzed mono-dechlorination of trichloromethyl substrates in dimethylacetamide (DMA) as a specific solvent at 25 °C under a hydrogen atmosphere. Copyright
- Imanishi, Takahiro,Fujiwara, Yuta,Sawama, Yoshinari,Monguchi, Yasunari,Sajiki, Hironao
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supporting information; experimental part
p. 771 - 776
(2012/06/30)
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- Polysulfonylamines, XIII. N-Acylonium Salts of Dimesylamine: Synthesis and Mass Spectra
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N-Acyl dimesylamines, like acyl chlorides, react with 4-dimethylaminopyridine and other tertiary nitrogen bases to give either solid N-acylonium dimesylaminides (1-3), or onium dimesylaminides (e. g. 4) originating from ketene elimination (eq. (5)).The expected acyl transfer properties of N-acylonium dimesylaminides are confirmed by reactions of 1a with phenol, 4-nitrophenol, p-thiocresol, and N-methylaniline, and of 1b with phenol, resulting in O-, S-, or N-acylation, respectively.With exception of compounds 1b and 3, all dimesylaminides could be characterized by their cation and anion mass spectra using field desorption, secondary ion mass spectrometry or fast atom bombardment. - Keywords: Reaction of N-Acyl Dimesylamines with Nitrogen Bases, Preparation of N-Acylonium Dimesylaminides, Acylation, Ketene Formation, Mass Spectra
- Blaschette, Armand,Linoh, Karin,Safari, Firouz,Schiebel, Hans-Martin
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p. 1639 - 1646
(2007/10/02)
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- Oxiranes from Methylenation of the Ester Carbonyl Group by Diazomethane
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Esters suitably substituted by electronegative groups were found to react with diazomethane with the anchimeric assistance of a ?-system or a trifluoromethyl group close to the ester oxygen to yield 2-alkoxy-2-substituted-oxiranes in good to excellent yields without catalysts.
- Strazzolini, Paolo,Verardo, Giancarlo,Giumanini, Angelo G.
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p. 3321 - 3325
(2007/10/02)
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