Rates of Bimolecular Substitution Reactions in Protic and Dipolar Aprotic Solvents

1967 ◽  
pp. 173-235 ◽  
Author(s):  
A.J. Parker
Keyword(s):  
Aprotic Solvents ◽  
Substitution Reactions ◽  
Dipolar Aprotic Solvents

scholarly journals PREPARATION OF NEW POLYETHERPHTHALIMIDES BASED ON CHLORAL DERIVATIVES USING NUCLEOPHILIC POLYNITRO SUBSTITUTION REACTIONS

2018 ◽  
Vol 62 (1) ◽  
pp. 78-84
Author(s):  
Abdullakh B. Ittiev ◽  
Ruslan M. Kumykov
Keyword(s):  
Reaction Rate ◽  
Thermal Characteristics ◽  
Aprotic Solvents ◽  
Substitution Reactions ◽  
High Oxygen Content ◽  
Rate Of Dissolution ◽  
Significant Difference ◽  
Bridging Groups ◽  
Derivatives Of ◽  
Dipolar Aprotic Solvents

Non-previously described new bis (3-nitropthalimide) arylenes activated with two carbonyls and containing flexible “bridging” groups, in particular dichloroethylene and ketones between the phthalimide fragments of the dinitrocompounds were obtained. The reactivity of the dinitrophthalimides used is determined, first of all, by the position of (3 or 4) nitro groups, and not by the nature of the Ar residue; monomers containing nitro groups in position 3 are more reactive than systems containing nitro groups in position 4. The interaction of synthesized bis (nitropthalimide) arylenes containing central dichloroethylene and ketone groups between phthalimide fragments and bis-phenolate derivatives of chloral was carried out. Synthesis of polyetherphthalimides using the process of polynitro substitution was carried out under modified conditions with complete absence of moisture. In general, the reactions of polynitro substitution proceed rapidly under relatively mild conditions; when dipolar aprotic solvents or a mixture of them with toluene are used, relatively high molecular weight polymers are formed. It has been established that the rate of dissolution of monomers is an important factor affecting the reaction rate; this determines the possibility of the formation of relatively high-molecular polymers, even with some deviation from the equimolarity of the monomers. As the general conditions for the synthesis of polyetherphthalimides based on synthesized bis (3-nitropthalimide) arylenes and bis-phenols, the optimal conditions were: reaction temperature -60 °C, reaction time -1 h with equimolar monomer ratio and concentration of each of them 0.25 mol/l. The influence of moisture on the synthesis of polyetherimides using the reaction of nucleophilic polynitro substitution was studied. It is shown that the process in the maximally dry system in the DMSO medium or (DMSO / toluene) leads to the formation of polymers with hr at least 0.63 dl/g. All the polymers obtained are readily soluble in dipolar and aprotic solvents. The structure of all the obtained intermediates and monomers was confirmed by elemental analysis and IR spectroscopy. An analysis of the primary thermal characteristics of the polymers obtained showed that they are characterized by relatively high and near destruction temperatures was found that the largest oxygen index (CI) in polymers, where more macromolecules contain more dichloroethylene fragments, and the lowest CI in polymers with a high oxygen content. It is shown that the polymers obtained have satisfactory deformation-strength characteristics. A feature of synthesized polyetherphthalimides is a significant difference between the temperatures of intensive destruction and softening temperatures, which determines the possibility of their processing into products by injection molding.  

Nucleophilic Substitution Reactions of Thienyl Neopentyl Substrates

1987 ◽  
Vol 40 (1) ◽  
pp. 49 ◽  
Author(s):  
FI Mclure ◽  
RK Norris ◽  
K Wilson
Keyword(s):  
Dimethyl Sulfoxide ◽  
Nucleophilic Substitution ◽  
Aprotic Solvents ◽  
Substitution Reactions ◽  
Nucleophilic Substitution Reactions ◽  
Benzene Series ◽  
Dipolar Aprotic Solvents

The reaction of the chlorides (4)-(6), which are both neopentylic and thenylic , were studied. The chloride (4), unlike its analogue (13) in the benzene series, undergoes ready solvolysis with alcohols to give the corresponding ethers, e.g. (7)-(9). The chlorides (5) and (6) react more slowly than (4) but undergo methanolysis to give the methyl ethers (11) and (12) respectively. In the dipolar aprotic solvents, dimethyl sulfoxide and dimethylformamide, the reactions of the chlorides (4), (5) and (6) with the thiolate salt (16) appear to proceed by an SN1-like, an SN(AEAE) and an SRNl process respectively.

Solvation of ions by dipolar aprotic solvents and water. A CNDO/2 study

1985 ◽  
Vol 50 (11) ◽  
pp. 2493-2508 ◽  
Author(s):  
Petr Kyselka ◽  
Zdeněk Havlas ◽  
Ivo Sláma
Keyword(s):  
Binary Mixtures ◽  
Quantum Chemical ◽  
Chemical Method ◽  
Molecular Structures ◽  
Dimethyl Sulphoxide ◽  
Ternary Mixtures ◽  
Aprotic Solvents ◽  
Quantum Chemical Method ◽  
Solvation Of Ions ◽  
Dipolar Aprotic Solvents

Solvation of Li+, Be2+, Na+, Mg2+, and Al3+ ions has been studied in binary mixtures with dimethyl sulphoxide, dimethylformamide, acetonitrile and water, and in ternary mixtures of the organic solvents with water. The CNDO/2 quantum chemical method was used to calculate the energies of solvation, molecular structures and charge distributions for the complexes acetonitrile...ion (1:1, 2:1, 4:1), dimethyl sulphoxide...ion (1:1), dimethylformamide...ion (1:1), and acetonitrile (dimethyl sulphoxide, dimethylformamide)...ion...water (1:1:1).

Sign in / Sign up

Export Citation Format

Share Document