Theoretical studies on the methylsulfenyl chloride addition to propene

Vektarienė, Aušra; Vektaris, Gytis

doi:10.1002/hc.20571

Cited by 5 publications

(9 citation statements)

References 38 publications

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“…This distinguishes HF and DFT from other methods and qualifies them for wider use and makes the results obtained are more accurate and consistent. This is in line with previous studies 21 in this field on the thiophene and furan derivatives because they gave significant differences between C-3 and oxygen which have high electronegativity. Table 1.…”

Section: From the Observation Of The Values Of The Charges Insupporting

confidence: 93%

Quantum-Chemical Calculation Methods to Determine the Ionization Constants of N-Substituted Amino Acid Derivatives

Al-Abady¹,

Saeed²

2017

ECB

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A theoretical study was conducted to determine the ionization constants of N-substituted amino acid derivatives using HF, DFT, and MP2 calculation methods. The extent of compatibility of these methods was determined by discussing the theoretical variables calculated in the three methods mentioned above, the relationship between the calculated physical variables have been found to be theoretical and to determine their nature. These variables were then correlated with the known chemical values of amino acids as pKa ionization parameters. The results obtained by this relationship were found to be good. This is indicated by the results of the statistical analysis across the correlation coefficient values. The theory that gave the best agreement between the values of the theoretical and the experimental ionization parameters were the MP2 method with good correlation coefficient (0.997) and standard error (0.162). As well as the large overlap between pKa values calculated theoretically with practical values where the difference (0.008) gives the opportunity to apply these variables in other studies. * Corresponding Authors

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Section: From the Observation Of The Values Of The Charges Insupporting

confidence: 93%

Quantum-Chemical Calculation Methods to Determine the Ionization Constants of N-Substituted Amino Acid Derivatives

Al-Abady¹,

Saeed²

2017

ECB

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“…Global reactivity parameters, such as absolute electron negativity (χ), chemical potential (µ), absolute hardness (η), global softness (S) and electrophilicity index (ω), listed in Table 2, also indicate the better stability of CIP_ZW. Hardness is a measure of resistance to change in the electron distribution in a molecule, 57 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 Color change has been noted to occur when proton transfer is induced by external stimuli. 42 This may explain why CIP changes color upon milling and when heated close to its melting point.…”

Section: Investigation Of Proton Transfer In Cipmentioning

confidence: 99%

Two Faces of Ciprofloxacin: Investigation of Proton Transfer in Solid State Transformations

Mesallati

Mugheirbi

Tajber

2016

Crystal Growth & Design

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Ciprofloxacin (CIP) can exist in two different forms: the zwitterion and the unionized form. While the crystal structure of each has been described independently, the ability of CIP to transform from one to the other in the solid state has not been described. The crystal structures of unionized and zwitterionic CIP were therefore compared using computational methods, including their packing arrangement, hydrogen bonding, packing energy, intermolecular potentials and HOMO/LUMO energy gap. The pure amorphous form of CIP has also never been prepared or studied. Ball milling, cryomilling and spray drying were used in this study to prepare partially and fully amorphous CIP for the first time. The physical characteristics were examined by PXRD, FTIR and DSC. CIP proved to be very difficult to amorphize, and only spray drying in pure water resulted in a fully amorphous product. It was discovered that while most processing methods resulted in the more stable zwitterionic form of the drug, spray drying in an ethanol/water mixture produced the unionized form. The zwitterion was found to convert to the unionized form upon heating to its melting point, whereas the reverse transformation occurred when unionized CIP was exposed to high humidity. This study thus provides insight into the proton transfer which can occur in a zwitterionic drug in the solid state, and the resultant changes to its crystal structure. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 3 Abstract Ciprofloxacin (CIP) can exist in two different forms: the zwitterion and the unionized form.While the crystal structure of each has been described independently, the ability of CIP to transform from one to the other in the solid state has not been described. The crystal structures of unionized and zwitterionic CIP were therefore compared using computational methods, including their packing arrangement, hydrogen bonding, packing energy, intermolecular potentials and HOMO/LUMO energy gap. The pure amorphous form of this drug has also never been prepared or studied. Ball milling, cryomilling and spray drying were used in this study to prepare partially and fully amorphous CIP for the first time. The physical characteristics, and in particular ionization state, of these samples were examined by PXRD, FTIR and DSC. Analysis of the crystal packing of unionized and zwitterionic CIP revealed that the presence of ionic interactions between the charged groups of the latter results in a denser and more stable crystal lattice. A greater HOMO/LUMO energy gap was also calculated for this sample, confirming its lower reactivity. CIP proved to be very difficult to amo...

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“…In contrast to the addition of sulfenylhalides to alkyl substitutes olefins, the addition of sulfenyl chlorides to conjugated olefins (CH 2 =CH-C 6 H 5 , CH 2 =CH 2 -CH 2 =CH 2 ) gives an exclusive product of the M orientation [8][9][10][11][12][13][14][15][16][17][18][19][20][21]. Therefore, the presence of an unsymmetrical episulfonium ion intermediate II ( Fig.…”

Section: Introductionmentioning

confidence: 99%

“…Intensive kinetics investigations of the sulfenyl chlorides addition to a diversity of alkyl substituted olefins, however, have not been sufficient to completely confirm the general postulate of an episulfonium ion intermediate I [8,14]. More recently, the theoretical investigations of the reaction potential energy profile of the sulfenylchloride addition to propene confirmed the episulfonium ion intermediate formation on the reaction path [15][16]. Two transition states corresponding to two possible directions of the addition of halide forming a kinetically controlled aM adduct and a thermodynamically stable Markovnikov (M) product as well as an isomerization transition state from the aM kinetically controlled to the thermodynamically stable M product have been detected by computations as presented in Fig.…”

Section: Introductionmentioning

confidence: 99%

“…Two transition states corresponding to two possible directions of the addition of halide forming a kinetically controlled aM adduct and a thermodynamically stable Markovnikov (M) product as well as an isomerization transition state from the aM kinetically controlled to the thermodynamically stable M product have been detected by computations as presented in Fig. 2 taken from [15][16].…”

Section: Introductionmentioning

confidence: 99%

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A theoretical study of styrene and sulfenyl chloride reaction mechanism

Vektarienė¹,

Vektaris²

2018

chemija

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The classical description of sulfenyl halides additions to olefins proposes the formation of an episulfonium ion intermediate during the reaction path. However, a careful analysis of experiments performed in the past suggests that there should not be a single mechanistic picture of sulfenyl halide additions to substituted olefins. Our work is the first theoretical study of detailed insights into the mechanism of methylsulfenchloride addition to styrene. The reaction potential energy profile has been calculated by means of the B3LYP functional with the 6-31++G(d, p) basis set. Mixing of the molecular orbital shapes of reaction stationary points has been described. The addition proceeds as a single step reaction from the methylsulfenchloride and styrene reactants via the concerted transition state (TS) to the final product along the reaction path estimated by the calculation of the intrinsic reaction coordinate. The reaction intermediate was not detected by calculations. The polar solvent has a significant effect on the decrease of reaction activation energy barriers. The large charge separation of the S–Cl bond in TS implies that the addition reaction should proceed through the ionic TS.

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Theoretical studies on the methylsulfenyl chloride addition to propene

Abstract: Thiiranium heterocycles play an important role in biocatalytic processes of cells. Usually formation of thiiranium ions is known to pro-

Cited by 5 publications

References 38 publications

Quantum-Chemical Calculation Methods to Determine the Ionization Constants of N-Substituted Amino Acid Derivatives

Quantum-Chemical Calculation Methods to Determine the Ionization Constants of N-Substituted Amino Acid Derivatives

Two Faces of Ciprofloxacin: Investigation of Proton Transfer in Solid State Transformations

A theoretical study of styrene and sulfenyl chloride reaction mechanism

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