The consequences of steric effects in the cleavage step of the sulfohaloform reaction

1979 ◽  
Vol 57 (16) ◽  
pp. 2185-2190 ◽  
Author(s):  
Denis George Kay ◽  
Richard Francis Langler ◽  
June Ellen Trenholm
Keyword(s):  
Carbon Atom ◽  
Chloride Ions ◽  
Nucleophilic Attack ◽  
Steric Effects ◽  
Water Molecules ◽  
Sulfonyl Group ◽  
Cleavage Step

The pathway for the aqueous chlorinolysis of a series of β-sulfonyl-sulfides is elucidated and the SN2 cleavage step examined. Steric effects in the cleavage of the α-polychloro-oxochloro-sulfonium chloride intermediates are held to be responsible for the suppression of the established nucleophilic competition between water molecules and chloride ions with the result that all cleavage products arise from nucleophilic attack by chloride ions. This report details the second known example of successful SN2 displacement on a carbon atom α to a sulfonyl group.

scholarly journals Understanding the reaction mechanism of the regioselective piperidinolysis of aryl 1-(2,4-dinitronaphthyl) ethers in DMSO: Kinetic and DFT studies

2021 ◽  
Vol 46 ◽  
pp. 146867832110274
Author(s):  
Yasmen M Moghazy ◽  
Nagwa MM Hamada ◽  
Magda F Fathalla ◽  
Yasser R Elmarassi ◽  
Ezzat A Hamed ◽  
...  
Keyword(s):  
Carbon Atom ◽  
Density Functional ◽  
Function Analysis ◽  
Density Functional Theory Method ◽  
Activation Parameters ◽  
Kinetic Studies ◽  
Nucleophilic Attack ◽  
Common Mechanism ◽  
Slow Step ◽  
Rate Determining Step

Reactions of aryl 1-(2,4-dinitronaphthyl) ethers with piperidine in dimethyl sulfoxide at 25oC resulted in substitution of the aryloxy group at the ipso carbon atom. The reaction was measured spectrophotochemically and the kinetic studies suggested that the titled reaction is accurately third order. The mechanism is began by fast nucleophilic attack of piperidine on C1 to form zwitterion intermediate (I) followed by deprotonation of zwitterion intermediate (I) to the Meisenheimer ion (II) in a slow step, that is, SB catalysis. The regular variation of activation parameters suggested that the reaction proceeded through a common mechanism. The Hammett equation using reaction constant σo values and Brønsted coefficient value showed that the reaction is poorly dependent on aryloxy substituent and the reaction was significantly associative and Meisenheimer intermediate-like. The mechanism of piperidinolysis has been theoretically investigated using density functional theory method using B3LYP/6-311G(d,p) computational level. The combination between experimental and computational studies predicts what mechanism is followed either through uncatalyzed or catalyzed reaction pathways, that is, SB and SB-GA. The global parameters of the reactants, the proposed activated complexes, and the local Fukui function analysis explained that C1 carbon atom is the most electrophilic center of ether. Also, kinetics and theoretical calculation of activation energies indicated that the mechanism of the piperidinolysis passed through a two-step mechanism and the proton transfer process was the rate determining step.

Hydroboration of acyclic allenes with disiamylborane

1969 ◽  
Vol 47 (6) ◽  
pp. 1083-1086 ◽  
Author(s):  
D. S. Sethi ◽  
G. C. Joshi ◽  
D. Devaprabhakara
Keyword(s):  
Carbon Atom ◽  
Transition State ◽  
Steric Effects ◽  
Electrophilic Attack ◽  
Terminal Carbon Atom ◽  
Central Carbon Atom ◽  
Central Carbon

The present investigation demonstrates the hydroboration of 1,2-nonadiene, phenylpropadiene, 3-phenyl-1,2-butadiene, 4,5-nonadiene, and tetramethylallene with disiamylborane. All the allenes except tetramethylallene underwent 100% conversion. Examination of the products indicated preferential electrophilic attack of boron on the least substituted terminal carbon atom in the case of 1,2-nonadiene, phenylpropadiene, 3-phenyl-1,2-butadiene, and on the central carbon atom in 4,5-nonadiene. In tetramethylallene boron, attack was exclusively on the central carbon atom. These results have been explained in terms of steric effects on a four-centered transition state.

Hydrogen-bonding patterns in bis[2,4,6-triazaniumylcyclohexane-1,3,5-tris(olate)-κ3O,O′,O′′]germanium(IV) tetrachloride hexahydrate

2016 ◽  
Vol 72 (1) ◽  
pp. 28-34
Author(s):  
Christian Neis ◽  
Bernd Morgenstern ◽  
Kaspar Hegetschweiler
Keyword(s):  
Hydrogen Bonding ◽  
Hydration Shell ◽  
Chloride Ions ◽  
Three Dimensions ◽  
Water Molecules ◽  
Amino Groups ◽  
Compound C ◽  
Hydrated Salt ◽  
Phd Thesis ◽  
Hydroxy Groups

A first preliminary report on the crystal structure of a hydrated salt formulated as [Ge(taci)2]Cl4·13H2O (taci is 1,3,5-triamino-1,3,5-trideoxy-cis-inositol) appeared more than 20 years ago [Ghisletta (1994). PhD thesis, ETH Zürich. Switzerland]. At that time it was not possible to discriminate unambiguously between the positions of some of the chloride ions and water O atoms, and disorder was thus postulated. In a new determination, a conclusive scheme of hydrogen bonding proves to be a particularly appealing aspect of the structure. Single crystals of the title compound, C12H30GeN6O64+·4Cl−·6H2O or [Ge(taci)2]2Cl8·12H2O, were grown from an aqueous solution by slow evaporation of the solvent. The two [Ge(taci)2]4+cations exhibit a double-adamantane-type structure with exclusive O-atom coordination and approximateD3dsymmetry. The taci ligands adopt a zwitterionic form with deprotonated hydroxy groups and protonated amino groups. Both cations are hydrogen bonded to six water molecules. The structure of the hydration shell of the two cations is, however, slightly different. The {[Ge(taci)2]·6H2O}4+aggregates are interlinked in all three dimensions by further hydrogen bonds of the types N—H...Cl...H—N, N—H...O(H)2...H—N, (Ge)O...H—O(H)...H—N, N—H...O(H)—H...Cl...H—N, (Ge)O...H—O—H...Cl...H—N, N—H...O(H)—H...Cl...H—(H)O...H—N, (Ge)O...H—O—H...Cl...H—(H)O...H—N and Ge(O)...H—O—H...Cl...H—O—H...O(Ge).

scholarly journals QUANTUM-CHEMICAL STUDY OF THE REACTION MECHANISM 1,2-ETHANEDIIOL WITH 1,3-DICHLOROPROPENE

2020 ◽  
Vol 2018 (1) ◽  
pp. 56-57
Author(s):  
Elena Chirkina ◽  
Leonid Krivdin ◽  
Nikolay Korchevin
Keyword(s):  
Carbon Atom ◽  
Sulfur Atom ◽  
Density Functional ◽  
Quantum Chemical Study ◽  
Thiol Group ◽  
Chemical Study ◽  
Nucleophilic Attack ◽  
Substitution Product ◽  
Reaction Proceeds ◽  
Theoretical Mechanism

The theoretical mechanism of the interaction of 1,3-dichloropropene with 1,2- ethanedithiol in the system "hydrazine hydrate-KOH" has been proposed by the method of B3LYP / 6- 311 ++ G (d, p) in the framework of the theory of the electron-density functional according to which the reaction proceeds successively in several stages, including the nucleophilic substitution of the chlorine atom present in the sp3-hybridized carbon atom with a sulfur atom to form a mono-substitution product that undergoes a prototropic allylic rearrangement that migrates the double bond to the sulfur atom, followed by closure in the dithiolane cycle due to the nucleophilic attack of the sulfide anion of the second thiol group of the reagent per carbon atom located in the γ-position with respect to the second chlorine atom.

scholarly journals THEORETICAL STUDY OF THE REACTION MECHANISM 1,2-ETHANEDIIOL WITH 1,3-DICHLOROPROPENE

2020 ◽  
Vol 2018 (1) ◽  
pp. 68-77
Author(s):  
Elena Chirkina ◽  
Leonid Krivdin ◽  
Nikolay Korchevin
Keyword(s):  
Carbon Atom ◽  
Chlorine Atom ◽  
Sulfur Atom ◽  
Density Functional ◽  
Theoretical Study ◽  
Thiol Group ◽  
Nucleophilic Attack ◽  
Substitution Product ◽  
Reaction Proceeds ◽  
Theoretical Mechanism

The theoretical mechanism of the interaction of 1,3-dichloropropene with 1,2-ethanedithiol in the system "hydrazine hydrate-KOH" has been proposed by the method of B3LYP / 6-311 ++ G (d, p) in the framework of the theory of the electron-density functional according to which the reaction proceeds successively in several stages, including the nucleophilic substitution of the chlorine atom present in the sp3-hybridized carbon atom with a sulfur atom to form a mono-substitution product that undergoes a prototropic allylic rearrangement that migrates the double bond to the sulfur atom, followed by closure in the dithiolane cycle due to the nucleophilic attack of the sulfide anion of the second thiol group of the reagent per carbon atom located in the γ-position with respect to the second chlorine atom.

scholarly journals Icephobicity of Functionalized Graphene Surfaces

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Xiang-Xiong Zhang ◽  
Min Chen
Keyword(s):  
Molecular Dynamics ◽  
Freezing Temperature ◽  
Ice Nucleation ◽  
Chloride Ions ◽  
Water Molecules ◽  
Sodium Ions ◽  
Functionalized Graphene ◽  
Functionalized Surfaces ◽  
The Difference ◽  
Dynamics Simulations

Manipulating the ice nucleation ability of liquid water by solid surface is of fundamental importance, especially in the design of icephobic surfaces. In this paper, the icephobicity of graphene surfaces functionalized by sodium ions, chloride ions, or methane molecules is investigated using molecular dynamics simulations. The icephobicity of the surface is evaluated by the freezing temperature. The freezing temperature on surface functionalized by methane molecules decreases at first and then increases as a function of the number groups, while the freezing temperature increases monotonically as a function of the number groups upon surfaces functionalized by sodium ions or chloride ions. The difference can be partially explained by the potential morphologies near the surfaces. Additionally, the validity of indicating the ice nucleation ability of water molecules using the number of six rings in the system is examined. Current study shows that the ice nucleation upon functionalized surfaces is inhibited when compared with smooth graphene substrate, which proves the feasibility of changing the icephobicity of the surfaces by functionalizing with certain ions or molecules.

scholarly journals Study of Kinetics, Equilibrium and the Influence of Steric Effects on Proton-Transfer in the Reactions of 2, 2, 4- and 2, 6- Substituted Anilines with 2-Phenoxy-3,5-dinitropyridine in DMSO

2010 ◽  
Vol 7 (1) ◽  
pp. 253-259 ◽  
Author(s):  
Basim H. Asghar
Keyword(s):  
Proton Transfer ◽  
Steric Effect ◽  
Nucleophilic Attack ◽  
Steric Effects ◽  
Substituted Anilines ◽  
Phenoxy Group ◽  
Kinetics Studies ◽  
Zwitterionic Intermediate ◽  
Rate Limiting ◽  
Step Mechanism

Kinetic and equilibrium results for the reactions of 2-phenoxy-3,5-dinitropyridine (1), with a series of 2, 2, 4- and 2, 6- substituted anilines (2a-f), in the presence of DABCO in DMSO are reported. The reactions yield the 2-anilino derivatives (5), without the accumulation of intermediates. Kinetics studies are compatible with a two-step mechanism involving initial nucleophilic attack by amine at the ring carbon substituted by phenoxy group followed by either base-catalyzed or uncatalyzed conversion to the product. The base-catalyzed pathway is likely to involve rate-limiting proton-transfer from the zwitterionic intermediate to base. This work indicates a steric effect to proton transfer in reactions involving 2, 6-disubstituted anilines. The results were compared with those for reactions of 1, 3, 5-trinitrobenzene with anilines.

A Molecular Dynamics Study of Aqueous Solutions II. Cesium Chloride in H2O

1975 ◽  
Vol 30 (6-7) ◽  
pp. 789-796 ◽  
Author(s):  
P. C. Vogel ◽  
K. Heinzinger
Keyword(s):  
Molecular Dynamics ◽  
Elevated Temperatures ◽  
Pure Water ◽  
Pair Correlation ◽  
Cesium Chloride ◽  
Pair Interaction ◽  
Chloride Ions ◽  
Water Molecules ◽  
Static Properties ◽  
Average Potential Energy

Abstract Results of a molecular dynamics study of an aqueous CsCl solution are reported. The system consisted of 216 particles, 200 water molecules, 8 cesium ions and 8 chloride ions and was run over 8000 time steps equivalent of 9 · 10-13 sec. On the basis of radial pair correlation functions, average potential energy of the water molecules and pair interaction energy distribution the static properties of the first hydration shells of the ions are discussed in detail. The self diffusion coefficient for the water molecules is calculated and compared with NMR measurement as well as with molecular dynamics calculations for pure water at elevated temperatures and pressures.

Crystal Structure of Adeninium Trichloromercurate(II),

1975 ◽  
Vol 53 (15) ◽  
pp. 2345-2350 ◽  
Author(s):  
Monique Authier-Martin ◽  
André L. Beauchamp
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Least Squares ◽  
Title Compound ◽  
Heavy Atom ◽  
Chloride Ions ◽  
Water Molecules ◽  
Hydrogen Atoms ◽  
Space Group ◽  
Heavy Atom Method

The title compound belongs to space group P21/c with a = 23.99(1), b = 4.245(2), c = 25.98(1) Å, β = 117.58(7)°, and Z = 8. The structure was solved by the heavy-atom method and refined by block-diagonal least squares on 2589 independent observed reflections. All non-hydrogen atoms were refined anisotropically and some of the hydrogen atoms were located but their parameters were not refined. The final values of R and Rw were 0.042 and 0.047, respectively.The two nonequivalent mercury atoms have very similar environments. Two short Hg—Cl bonds (2.34–2.38 Å) at ∼ 165° define a quasi-molecular HgCl2 unit. Overall octahedral coordination is completed with two chloride ions at 2.76–2.84 Å and two chlorine atoms at 3.19–3.26 Å on neighboring HgCl2 quasi-molecules. HgCl6 octahedra share edges to form twofold ribbons in the b direction. This pattern of octahedra is identical with the onereported for β-NH4HgCl3. The cations are pairs of N(1)-protonated adenine molecules linked by two N(10)—H(10)… N(7) hydrogen bonds and stacked in the b direction. Water molecules act as acceptors in moderately strong hydrogen bonds with acidic protons H(1) and H(9) of adeninium ions. Other generally weaker hydrogen bonds exist between the various parts of the structure.

A single crystal X-ray study of a sulphate-bearing buttgenbachite, Cu36Cl7.8(NO3)1.3(SO4)0.35(OH)62.2.5.2H2O, and a re-examination of the crystal chemistry of the buttgenbachite-connellite series

2003 ◽  
Vol 67 (1) ◽  
pp. 47-60 ◽  
Author(s):  
D. E. Hibbs ◽  
P. Leverett ◽  
P. A. Williams
Keyword(s):  
Single Crystal ◽  
Democratic Republic ◽  
Democratic Republic Of Congo ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Water Molecules ◽  
Data Set ◽  
X Ray ◽  
Positional Disorder ◽  
Anion Substitution

AbstractThe single-crystal X-ray structure of a sulphate-bearing buttgenbachite, Cu36Cl7.8(NO3)1.3(SO4)0.35(OH)62.2.5.2H2O, from Likasi, Democratic Republic of Congo, has been determined at 100 and 288 K. The basic framework of the structure is the same as has been previously reported for buttgenbachite, except for the identification of a hydrogen-bonded chloride ion (occupancy 0.6) at the origin instead of a Cu ion with partial occupancy. The nature of nitrate positional disorder along channels in the c direction and how this relates to the presence of other species such as chloride ions and water molecules and, most importantly, sulphate ions has been elucidated. One nitrate ion, with an occupancy of 0.18, lies at 2/3,l/3,l/4 and shares the site with a chloride ion (occupancy 0.30) and also a sulphate ion (occupancy 0.09); a second nitrate, with an occupancy of 0.24, lies at 2/3,1/3,0.084 and shares the site with a water molecule (occupancy 0.06). As a result, a formula of Cu36Cl7.8(NO3)1.3(SO4)0.35(OH)62.2.5.2H2O is obtained. Re-refinement of deposited data for a supposed connellite crystal from the Toughnut mine,Tombstone, Arizona gives a related, but different, pattern of anion substitution. No sulphate could be detected in the structure and it is evident that this structure refers to buttgenbachite. A nitrate nitrogen atom and a chloride ion are disordered at 2/3,l/3,l/4, the overall site being fully occupied. A chloride ion with ∼0.5 occupancy is sited at the origin and the formula Cu36Cl7.9(NO3)1.1(OH)63.4H2O is indicated. Re-refinement of a deposited data set for another buttgenbachite crystal from the Likasi mine reveals a partially occupied nitrate centred at 2/3,l/3, z and a partially occupied chloride at 2/3,l/3,l/4. Either 0.5Cl–, OH–, H2O or H3O+ is located at the origin. If the latter is the case, the stoichiometry for this buttgenbachite is Cu36Cl6.5(NO3)1.5(OH)64.5.5H2O. The present study has highlighted the fact that a range of compositions for buttgenbachite exists, depending on the pH and relative activities of chloride, nitrate and sulphate ions in solutions from which the mineral crystallizes.

Sign in / Sign up

Export Citation Format

Share Document