Thermodynamic parameters for ionisation and dissociation of alkyl halides in water and nonaqueous solvents. Comments on the ion-pair mechanism of nucleophilic substitution

1973 ◽  
pp. 1893 ◽  
Author(s):  
Michael H. Abraham
Keyword(s):  
Nucleophilic Substitution ◽  
Thermodynamic Parameters ◽  
Ion Pair ◽  
Alkyl Halides ◽  
Nonaqueous Solvents

The synthesis, thermochromism, and cycloadditive properties of an O-methylenethioquinone system

1977 ◽  
Vol 55 (21) ◽  
pp. 3763-3773 ◽  
Author(s):  
P. de Mayo ◽  
H. Y. Ng
Keyword(s):  
Thermodynamic Parameters ◽  
Acid Derivative ◽  
Acid Catalysis ◽  
Ion Pair ◽  
Pair Formation ◽  
Membered Ring ◽  
Diels Alder ◽  
Ion Pair Formation ◽  
Thiosalicylic Acid

The irradiation of 4,5-benzo-1,2-dithiole-3-thione (1) in the presence of cyclopentene and of tetramethylethylene gives 1:1 adducts. In solution these adducts are in equilibrium with eight-membered-ring dimers. The thermodynamic parameters for this equilibrium have been determined. The available evidence suggests a head-to-head configuration. These same monomeric adducts give Diels–Alder addition products with normal dienophiles, but also react similarly with simple thiones (adamantanethione, norbornanethione, cyclohexanethione) to give thioorthoesters. The structures of the latter substances have been demonstrated both spectroscopically and, chemically, by hydrolysis to a thiosalicylic acid derivative. The thioorthoesters have been shown to undergo stereoisomerization on acid catalysis. Of the two mechanisms considered for this process (reversal to thiones and ion-pair formation) the former has been excluded.

scholarly journals Conductometric studies of 1, 3, 5 –triazinothiocarbamide at different concentration and temperature

2021 ◽  
Vol 16 (2) ◽  
pp. 151-157
Author(s):  
DD Sonone ◽  
ME Shelke ◽  
DT Tayade
Keyword(s):  
Thermodynamic Parameters ◽  
Association Constant ◽  
Ion Association ◽  
Vital Role ◽  
Ion Pair ◽  
Pair Formation ◽  
Drug Diffusion ◽  
Ion Pair Formation

Conductivity plays vital role in drug diffusion. Thermodynamic parameters affected by substituents of drug. Thermodynamic parameters of 1, 3, 5 –triazinothiocarbamide (1a) have been investigated by using conductometrically carried out at different molar concentrations. This work highlights investigation of G, K and µ values. The thermodynamic parameters viz. ΔH, ΔS and ∆G for ion pair formation determine from the value of ion association constant. This technique is suitable and accurate to study of pharmokinetics and pharmodynamics parameters.

scholarly journals Comparison of Free-Energy Methods to Calculate the Barriers for the Nucleophilic Substitution of Alkyl Halides by Hydroxide

2020 ◽  
Vol 124 (31) ◽  
pp. 6835-6842
Author(s):  
Hafiz Saqib Ali ◽  
Jonathan Higham ◽  
Sam P. de Visser ◽  
Richard H. Henchman
Keyword(s):  
Free Energy ◽  
Nucleophilic Substitution ◽  
Alkyl Halides ◽  
Energy Methods
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