The Experts below are selected from a list of 192 Experts worldwide ranked by ideXlab platform
Yuho Tsuno - One of the best experts on this subject based on the ideXlab platform.
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The Yukawa–Tsuno Relationship for the β-Silicon Effect in the Solvolysis Rates of 2-(Aryldimethylsilyl)ethyl Chlorides
Bulletin of the Chemical Society of Japan, 2005Co-Authors: Mizue Fujio, Hans-ullrich Siehl, Mai Uchida, Ayumi Okada, Ashadul Alam, Ryoji Fujiyama, Yuho TsunoAbstract:Solvolysis rates of 2-(aryldimethylsilyl)ethyl chlorides were determined conductimetrically in 60% (v/v) aqueous ethanol. The effects of aryl substituents at the silyl atom on the Solvolysis rates ...
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OXYGEN-18 SCRAMBLING STUDIES IN THE Solvolysis OF BENZYL TOSYLATES
Tetrahedron Letters, 1995Co-Authors: Yutaka Tsuji, Mizue Fujio, Ken-ichi Yatsugi, Yoshihiro Saeki, Sung Hong Kim, Yuho TsunoAbstract:The ion-pair return process during the Solvolysis of benzyl tosylates was studied in typical solvents by means of the sulfonate18O-scrambling experiments using carbon-13 NMR spectroscopy. The substituent and solvent dependency of amount of ion-pair return in this borderline Solvolysis was discussed.
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Solvent Effects on the Solvolysis of Benzyl p-Toluenesulfonates.
Bulletin of the Chemical Society of Japan, 1994Co-Authors: Mizue Fujio, Yutaka Tsuji, Toshihiro Susuki, Masahiro Goto, Ken-ichi Yatsugi, Yoshihiro Saeki, Sung Hong Kim, Yuho TsunoAbstract:Solvolysis rates of benzyl p-toluenesulfonate were determined in a wide variety of solvents. The solvent effects were analyzed based on the Winstein–Grunwald equation. The solvent effect on benzyl Solvolysis failed to give a single linear correlation with the 2-adamantyl YOTs parameter. The lower response to the solvent polarity and the pattern of dispersion for each binary solvent series can be qualitatively interpreted in terms of nucleophilic solvent assistance. The Winstein–Grunwald analysis gave m = 0.67 and l = 0.36, but with less satisfactory precision. The use of the polarity scale Yneo derived from 2-methyl-2-phenylpropyl Solvolysis in place of YOTs gave an improved correlation. A solvent polarity scale Yneo is better applicable to benzyl Solvolysis than 2-adamantyl-based YOTs, since the former is compatible with the entire π-delocalization of cationic charge between aryl ring and the reaction center in the transition state.
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Solvent effects on the Solvolysis of 1-(p-methoxyphenyl)-2-methylpropen-1-yl tosylate
Tetrahedron Letters, 1992Co-Authors: Mizue Fujio, Yuho Tsuno, Naoko Tomita, Shinjiro Kobayashi, Hiroshi Taniguchi, Joseph Kaspi, Zvi RappoportAbstract:Abstract The solvent effect on the Solvolysis rates of 1-(p-methoxyphenyl)-2-methylpropen-1-yl tosylate is better correlated with the kinetic polarity scale (Y Δ value) of neophyl k Δ Solvolysis than with adamantyl Y OTs . Dispersion behavior of solvent effects was explored for these aryl substituted substrates. The solvent effect in the reaction above is correlated linearly with the Y Δ based on neophyl Solvolysis rather than with the adamantyl Y OTs .
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Solvent effects on the Solvolysis of α-t-butylbenzyl tosylate
Tetrahedron Letters, 1992Co-Authors: Yutaka Tsuji, Mizue Fujio, Yuho TsunoAbstract:Abstract The Solvolysis rates of α-t-butylbenzyl tosylate resulted in a single straight-line correlation with unit slope against 2-adamantyl Y OTs value. The result is compatible with k c Solvolysis mechanism without nucleophilic solvent and/or β-methyl participation.
J. R. Leis - One of the best experts on this subject based on the ideXlab platform.
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Cyclodextrin effect on Solvolysis of ortho benzoyl chlorides
Journal of Inclusion Phenomena and Macrocyclic Chemistry, 2007Co-Authors: J. Báscuas, Luis García-río, J. R. Leis, María Méndez-pérezAbstract:A kinetic study was carried out on the Solvolysis of ortho benzoyl chlorides in the presence of α-, β- and γ-Cyclodextrin (CD). The Solvolysis mechanism of benzoyl chlorides is sensitive to the substituents, and to the solvent in which the reaction takes place. In water, the behaviour exhibited by benzoyl chlorides which have electron-attracting groups, is consistent with an associative mechanism whilst electron-donating substituents induce a dissociative mechanism. The results obtained in the presence of CD show a decrease in the observed rate constant, k obs, as the CD concentration increases. This behaviour can be explained if these substrates undergo Solvolysis through a dissociative path in the presence of α-, β- and γ-CD.
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Cyclodextrin effect on Solvolysis of substituted benzoyl chlorides.
Organic & biomolecular chemistry, 2004Co-Authors: J. Báscuas, Luis García-río, J. R. LeisAbstract:A kinetic study was carried out on the Solvolysis of substituted benzoyl chlorides in the presence of α-, β- and γ-CD. Combination of the substituent dependent mechanism for Solvolysis of benzoyl chlorides and the complexation ability of the cyclodextrin yields the following experimental behavior: (i) catalysis by β- and γ-CD for Solvolysis of electron-attracting substituted benzoyl chlorides due to the reaction with its hydroxyl group C(6); (ii) absence of α-CD influence on Solvolysis of benzoyl chlorides with electron withdrawing substituents; (iii) inhibition of Solvolysis of benzoyl chlorides with electron-donating groups. This behavior is observed for Solvolysis of meta/para substituted substrates in the presence of β-CD, Solvolysis of meta-substituted benzoyl chlorides in the presence of α-CD and Solvolysis of para-substituted benzoyl chlorides in the presence of γ-CD. This decrease in the rate constant is a consequence of the complexation of the substrate in the cyclodextrin cavity and its low solvation ability, causing the rate of Solvolysis in its interior to be negligible. (iv) The Solvolysis of meta-substituted benzoyl chlorides in the presence of γ-CD yields a new behavior where the reaction of the complexed substrate is not negligible in the interior of the cyclodextrin cavity, which has been interpreted as a consequence of incomplete expulsion of hydration water from its cavity when the complexation takes place. (v) The experimental results obtained in the presence of α-CD show that meta-substituted benzoyl chlorides give rise to host : guest complexes with 1 : 1 stoichiometries, whereas those which are para-substituted cause a 2 : 1 stoichiometry to be formed. This difference in behavior has been interpreted taking into account the size of the different benzoyl chlorides and their accommodation in the α-CD cavity.
Mizue Fujio - One of the best experts on this subject based on the ideXlab platform.
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The Yukawa–Tsuno Relationship for the β-Silicon Effect in the Solvolysis Rates of 2-(Aryldimethylsilyl)ethyl Chlorides
Bulletin of the Chemical Society of Japan, 2005Co-Authors: Mizue Fujio, Hans-ullrich Siehl, Mai Uchida, Ayumi Okada, Ashadul Alam, Ryoji Fujiyama, Yuho TsunoAbstract:Solvolysis rates of 2-(aryldimethylsilyl)ethyl chlorides were determined conductimetrically in 60% (v/v) aqueous ethanol. The effects of aryl substituents at the silyl atom on the Solvolysis rates ...
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OXYGEN-18 SCRAMBLING STUDIES IN THE Solvolysis OF BENZYL TOSYLATES
Tetrahedron Letters, 1995Co-Authors: Yutaka Tsuji, Mizue Fujio, Ken-ichi Yatsugi, Yoshihiro Saeki, Sung Hong Kim, Yuho TsunoAbstract:The ion-pair return process during the Solvolysis of benzyl tosylates was studied in typical solvents by means of the sulfonate18O-scrambling experiments using carbon-13 NMR spectroscopy. The substituent and solvent dependency of amount of ion-pair return in this borderline Solvolysis was discussed.
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Solvent Effects on the Solvolysis of Benzyl p-Toluenesulfonates.
Bulletin of the Chemical Society of Japan, 1994Co-Authors: Mizue Fujio, Yutaka Tsuji, Toshihiro Susuki, Masahiro Goto, Ken-ichi Yatsugi, Yoshihiro Saeki, Sung Hong Kim, Yuho TsunoAbstract:Solvolysis rates of benzyl p-toluenesulfonate were determined in a wide variety of solvents. The solvent effects were analyzed based on the Winstein–Grunwald equation. The solvent effect on benzyl Solvolysis failed to give a single linear correlation with the 2-adamantyl YOTs parameter. The lower response to the solvent polarity and the pattern of dispersion for each binary solvent series can be qualitatively interpreted in terms of nucleophilic solvent assistance. The Winstein–Grunwald analysis gave m = 0.67 and l = 0.36, but with less satisfactory precision. The use of the polarity scale Yneo derived from 2-methyl-2-phenylpropyl Solvolysis in place of YOTs gave an improved correlation. A solvent polarity scale Yneo is better applicable to benzyl Solvolysis than 2-adamantyl-based YOTs, since the former is compatible with the entire π-delocalization of cationic charge between aryl ring and the reaction center in the transition state.
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Solvent effects on the Solvolysis of 1-(p-methoxyphenyl)-2-methylpropen-1-yl tosylate
Tetrahedron Letters, 1992Co-Authors: Mizue Fujio, Yuho Tsuno, Naoko Tomita, Shinjiro Kobayashi, Hiroshi Taniguchi, Joseph Kaspi, Zvi RappoportAbstract:Abstract The solvent effect on the Solvolysis rates of 1-(p-methoxyphenyl)-2-methylpropen-1-yl tosylate is better correlated with the kinetic polarity scale (Y Δ value) of neophyl k Δ Solvolysis than with adamantyl Y OTs . Dispersion behavior of solvent effects was explored for these aryl substituted substrates. The solvent effect in the reaction above is correlated linearly with the Y Δ based on neophyl Solvolysis rather than with the adamantyl Y OTs .
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Solvent effects on the Solvolysis of α-t-butylbenzyl tosylate
Tetrahedron Letters, 1992Co-Authors: Yutaka Tsuji, Mizue Fujio, Yuho TsunoAbstract:Abstract The Solvolysis rates of α-t-butylbenzyl tosylate resulted in a single straight-line correlation with unit slope against 2-adamantyl Y OTs value. The result is compatible with k c Solvolysis mechanism without nucleophilic solvent and/or β-methyl participation.
Zeferino Gamiño-arroyo - One of the best experts on this subject based on the ideXlab platform.
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Solvolysis of acrylate-urethane coatings cured by electron-beam and UV radiation
Progress in Organic Coatings, 2019Co-Authors: Lorena Sánchez-cadena, Gilles Tersac, Xavier Coqueret, Zeferino Gamiño-arroyoAbstract:Solvolysis was investigated for two different types of thermosetting polyacrylate-urethane resin coatings. One type of resin was cross-linked by ultra violet (UV) radiation and the other by electron beam (EB). The cured coatings were deposited on aluminum sheets. Solvolysis was carried out with diethylene glycol (DEG) catalyzed by KOH. The resins were characterized by FT-IR ATR spectroscopy prior to Solvolysis. The kinetics of the Solvolysis process were investigated, and the depolymerization products were studied by FT-IR ATR spectroscopy and size exclusion chromatography. The results show that total Solvolysis is possible for both cured resins, albeit it is faster for resins cured by UV radiation.
Dennis N. Kevill - One of the best experts on this subject based on the ideXlab platform.
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the effect of the ortho nitro group in the Solvolysis of benzyl and benzoyl halides
International Journal of Molecular Sciences, 2019Co-Authors: Kyoungho Park, Jin Burm Kyong, Chan Joo Rhu, Dennis N. KevillAbstract:A kinetic study was carried out on the Solvolysis of o-nitrobenzyl bromide (o-isomer, 1) and p-nitrobenzyl bromide (p-isomer, 3), and o-nitrobenzoyl chloride (o-isomer, 2) in a wide range of solvents under various temperatures. In all of the solvents without aqueous fluoroalcohol, the reactions of 1 were solvolyzed at a similar rate to those observed for 3, and the reaction rates of 2 were about ten times slower than those of the previously studied p-nitrobenzoyl chloride (p-isomer, 4). For Solvolysis in aqueous fluoroalcohol, the reactivity of 2 was kinetically more reactive than 4. The l/m values of the extended Grunwald–Winstein (G–W) equation for Solvolysis of 1 and 2 in solvents without fluoroalcohol content are all significantly larger than unity while those in all the fluoroalcohol solvents are less than unity. The role of the ortho-nitro group as an intramolecular nucleophilic assistant (internal nucleophile) in the solvolytic reaction of 1 and 2 was discussed. The results are also compared with those reported earlier for o-carbomethoxybenzyl bromide (5) and o-nitrobenzyl p-toluenesulfonate (7). From the product studies and the activation parameters for solvolyses of 1 and 2 in several organic hydroxylic solvents, mechanistic conclusions are drawn.
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Communication Additional Solvent Ionizing Power Values for Binary Water- 1,1,1,3,3,3-Hexafluoro-2-propanol Solvents
2015Co-Authors: Dennis N. Kevill, Zoon Ha RyuAbstract:Abstract: Determinations of the specific rates of Solvolysis of 1-adamantyl bromide and 1-adamantyl iodide in 1,1,1,3,3,3-hexafluoro-2-propanol-water mixtures, in conjunction with earlier reported values in 80 % ethanol, have led to additional YBr and YI solvent ionizing power values. These new values will be especially important in avoiding multicollinearity when the extended Grunwald-Winstein equation (extended by addition of a term involving solvent nucleophilicity) is used to correlate solvent-induced changes in the specific rates of solvolyses involving a bromide or iodide ion leaving group
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use of the simple and extended grunwald winstein equations in the correlation of the rates of Solvolysis of highly hindered tertiary alkyl derivatives
ChemInform, 2011Co-Authors: Dennis N. Kevill, Malcolm J DsouzaAbstract:Abstract The original Grunwald-Winstein equation (1948) involved the development of a scale of solvent ionizing power (Y). Subsequent work has refined this scale and involved the development of scales of solvent nucleophilicity (N) and a term to correct for deviations when aromatic rings are present, governed by the aromatic ring parameter (I). These three scales, and the sensitivities towards each, can be related to specific rates of Solvolysis through linear free energy relationships (LFERs).One important area of application of LFERs has been to the solvolyses of tert-alkyl halides. It has been proposed that the Solvolysis of tert-butyl chloride involves a nucleophilic component, although other workers have suggested that the effects observed are related to electrophilic not nucleophilic influences. Takeuchi (1997) studied a compound with two of the methyl groups of tert-butyl chloride replaced by neopentyl groups. For this highly-hindered substrate there was no evidence for nucleophilic participation. Liu (1998) and Takeuchi (2001) have reported concerning the solvolyses of additional significantly-hindered tertiary alkyl chlorides. Liu (2009) has presented a parallel study of bromides. Martins (2008) has considered hindered tertiary alkyl halides, mainly with carbon-carbon multiple bonds as substituents. It was proposed that the hI term was of importance, with the sensitivities (h) sometimes positive and sometimes negative. To explain negative values, it was suggested that the I scale might contain a nucleophilicity component. In this review, we bring together, with analysis and commentary, the work of Takeuchi, Liu, Martins and others concerning the solvolyses of tertiary alkyl halides, with emphasis on the relevance of the three scales that have been developed for use in Grunwald-Winstein correlations.
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Correlation of the Rates of Solvolysis of Phenyl Fluorothionoformate
Bulletin of the Korean Chemical Society, 2011Co-Authors: Song Hee Choi, Mi Hye Seong, Yong-woo Lee, Jin Burm Kyong, Dennis N. KevillAbstract:The specific rates of Solvolysis of phenyl fluorothionoformate (PhOCSF, 1) have been determined in 22 pure and binary solvents at . The extended Grunwald-Winstein equation has been applied to the specific rates of Solvolysis of 1 over the full range of solvents. The sensitivities (l = and m = ) toward the changes in solvent nucleophilicity and solvent ionizing power, and the values are similar to those previously observed for solvolyses of acyl haloformate esters, consistent with the addition step of an additionelimination pathway being rate-determining. The large negative values for the entropies of activation are consistent with the bimolecular nature of the proposed rate-determining step. The results are compared with those reported earlier for phenyl chloroformate and chlorothionoformate esters and mechanistic conclusions are drawn.
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application of the extended grunwald winstein equation to solvolyses of n propyl fluoroformate and a consideration of leaving group effects
Bulletin of The Korean Chemical Society, 2008Co-Authors: Mi Hye Seong, Jin Burm Kyong, Dong Kook Kim, Dennis N. KevillAbstract:Reactions of n-propyl fluoroformate in a variety of pure and binary solvents have been studied at 40.0 {^{\circ}C}. The extended (two-term) Grunwald-Winstein equation has been applied to the specific rates of Solvolysis of npropyl fluoroformate. The sensitivities (l = 1.80 0.17 and m = 0.96 0.10) to changes in solvent nucleophilicity and solvent ionizing power and the values are similar to those for solvolyses of n-octyl fluoroformate over the full range of solvents, suggesting that the addition step of an addition-elimination mechanism is ratedetermining. These observations are also compared with those previously reported for the corresponding chloroformate and fluoroformate esters.
