A Kinetic Study of the Solvolyses of Methyl and Ethyl Chloroglyoxalates

Kevill, Dennis N.; Park, Byoung-Chun; Kyong, Jin Burm

doi:10.1021/jo050998m

Cited by 6 publications

(5 citation statements)

References 34 publications

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“…The chloromethyl ethyl ether (3, Sigma-Aldrich, 95%), chloromethyl octyl ether (4, Sigma-Aldrich, 95%) and chloromethyl methyl sulfide (5, Sigma-Aldrich, 95%) were used as received. Solvents were purified 20 and kinetic runs performed 41 conductimetrically as previously reported. A substrate concentration of about 0.0046 M was used for the solvolyses of 3 and 5 and of about 0.0025 M for the solvolyses of the considerably less soluble 4.…”

Section: Cautionmentioning

confidence: 99%

Extent of Nucleophilic Participation in the Solvolyses of Alkyl Chloromethyl Ethers and Sulfides

Park

Kevill

2012

Journal of Chemical Research

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The specific rates of solvolysis have been determined for chloromethyl ethyl ether (3) and chloromethyl octyl ether (4) at -10.0 °C and for chloromethyl methyl sulfide (5) at 25.0 °C in a variety of pure and binary solvents. These values were used for a correlation analysis treatment using the extended Grunwald-Winstein equation incorporating literature values for solvent nucleophilicity (N T ) and solvent ionising power (Y Cl ). Appreciable values were found for the sensitivities towards changes in both N T and Y Cl values. Using a literature specific rate of hydrolysis at 25.0 °C for fluoromethyl methyl ether (2), the required value for chloromethyl methyl ether (1) was obtained from use of N T and Y Cl values and the sensitivities for 3 to changes in their values, to adjust an experimental specific rate value for 1 in 100% ethanol to the corresponding value in 100% water. In this way, an estimated k Cl /k F of 1.2 x 10 5 was obtained, essentially identical to values for the solvolyses of tert-butyl halides. A unimolecular mechanism for the solvolyses, with appreciable nucleophilic solvation of the developing carbocation, is proposed. Electronic supplementary information provides, for several solvents, specific rates of solvolysis for 3, 4, and 5 at additional temperatures and the calculated activation parameters.

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Section: Cautionmentioning

confidence: 99%

Extent of Nucleophilic Participation in the Solvolyses of Alkyl Chloromethyl Ethers and Sulfides

Park

Kevill

2012

Journal of Chemical Research

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“…Much faster (~10 6 times) specific rates of solvolysis of chloroglyoxalate esters (ROCOCOCl), with the insertion of a carbonyl (C=O) group, were observed relative to those of corresponding ROCOCl solvolyses. The acceleration, caused by enhanced reactivity (addition-elimination channel with addition step being rate determining) was due to the inductive effect of the alkoxy carbonyl (RCO 2 -) group (super electron withdrawing group), as was demonstrated by Kevill et al 6 In certain solvent systems, these reactions were more recently shown to give a quite different reaction pathway (with an O-atom replacing a S-atom: addition-elimination channel → ionization channel with carbocation stabilization in part through nucleophilic solvation) by Kevill et al…”

Section: 3mentioning

confidence: 87%

Evaluation of Methylthio and Phenylthio Group Effects in the Solvolyses of 2-Chloro-2-(methylthio)acetone and 2-Chloro-2-(phenylthio)acetophenone Using Extended Grunwald-Winstein Equations

Ryu

Bentley²

2008

Bulletin of the Korean Chemical Society

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The specific solvolysis rates of 2-chloro-2-(methylthio)acetone (3) at 25.0 o C, and 2-chloro-2-(4-methoxyphenylthio)-acetophenone (4) at 50.0 o C have been measured in more than 34 aqueous solvent mixtures including aqueous 2,2,2-trifluoroethanol (TFE), for 4, and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP), and in TFE-ethanol. The kinetic solvent isotope effect in methanol and solvolysis rate ratios, at identical ionizing power in 40 (v/v)% ethanol/water compared with 97 (w/w)% TFE/water have been determined. Additional data were also obtained for solvolyses of other substrates related to this work. The investigation of structural effects, caused by the existence of neighboring sulfur-containing and carbonyl (C=O) groups, on the solvolytic reactivity and/or mechanism and the possibility for the stabilization of the solvolytic TS by the developing mesomeric cation, due to the role of the PhS-group, have been attempted using various Grunwald-Winstein (GW) parameter treatments. Regardless of -COPh or -COCH 3 neighboring groups as neighboring group, the solvolytic reactions for both 3 and 4 were evaluated as reactions primarily influenced by the sulfur atom of the -SR group as the activator to make the positive polar TS. In particular, the solvolytic reactions of 4, having an electron donating p-OCH3 substituent, were indicative of the possibility of an ionization pathway with development of a mesomeric cation, stabilised by the sulfur atom and its attached group.

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“…General Remarks: All chemicals and solvents were obtained from Enamine, and were used without further purification. Ethyl (2,2,2‐trifluoroethyl) oxalate, methyl (2,2,2‐trifluoroethyl) oxalate, and bis(2,2,2‐trifluoroethyl) oxalate were synthesized according to previously reported procedures 42,43 . 1 H and 13 C NMR spectra were acquired with Bruker Avance DRX 400 and Bruker Avance DRX 500 spectrometers, using [D 6 ]DMSO as a solvent, and tetramethylsilane (TMS) as an internal standard.…”

Section: Methodsmentioning

confidence: 99%

Synthesis and Cytotoxicity of a Diazirine‐Based Photopsammaplin

et al. 2014

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The first photoreactive derivative of the cytotoxic marine natural product psammaplin A (1) has been synthesized by appending 1‐azi‐2,2,2‐trifluoroethyl moieties at both benzene rings. Photopsammaplin 8 exhibited anticancer activity in vitro with a geomean IC50 value of 1.4 μM in a panel of 42 human cancer cell lines. Particularly sensitive cell lines were found among bladder, lung, mammary, and prostate cancer as well as melanoma (MEXF 276), with IC50 values ≤ 0.6 μM. In a COMPARE analysis, diazirine‐functionalized photopsammaplin exhibited a very similar cytotoxicity profile to that of the natural product 1. Furthermore, photopsammaplin 8 was found to be a potent HDAC inhibitor (IC50 35 nM) and can be considered as a suitable candidate for photoaffinity labeling, which may assist in the identification of new targets of psammaplin A. Irradiation experiments with a model diazirine‐functionalized α‐hydroxy iminoester in dichloromethane in the presence or absence of acetic acid and methanol revealed the stability of the oxime unit and confirmed that reactions took place solely at the carbene center. The isolation of triplet and singlet photoproducts is consistent with DFT calculations [B3LYP 6‐311G (2d,2p)] showing that, in polar solvents, the triplet‐singlet gap is very small.

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A Kinetic Study of the Solvolyses of Methyl and Ethyl Chloroglyoxalates

Cited by 6 publications

References 34 publications

Extent of Nucleophilic Participation in the Solvolyses of Alkyl Chloromethyl Ethers and Sulfides

Extent of Nucleophilic Participation in the Solvolyses of Alkyl Chloromethyl Ethers and Sulfides

Evaluation of Methylthio and Phenylthio Group Effects in the Solvolyses of 2-Chloro-2-(methylthio)acetone and 2-Chloro-2-(phenylthio)acetophenone Using Extended Grunwald-Winstein Equations

Synthesis and Cytotoxicity of a Diazirine‐Based Photopsammaplin

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