One Century of Physical Organic Chemistry: The Menshutkin Reaction

Abboud, José‐Luis M.; Notario, Rafael; Bertrán, Juan; Solà, Miquel

doi:10.1002/9780470171981.ch1

Cited by 86 publications

(59 citation statements)

References 340 publications

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“…Table 2 shows that an increase in polarity of the solvent entails a marked gain in the molecular mass of the polymer. This finding is in agreement with the well known fact that the alkylation of tertiary nitrogen atoms accelerates with an increase in the permittivity of a solution [19]. Higher molecular masses of the polymers that were attained when acetonitrile was replaced with nitromethane should probably be attrib uted to a marked acidity of the methyl group of nitromethane; as a consequence, the electrophilic catalysis of the alkylation of oxazoline occurs.…”

Section: Resultssupporting

confidence: 87%

Thermoresponsive star-shaped poly(2-isopropyl-2-oxazolines) based on octa-tert-butylcalix[8]arene

2012

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The cationic polymerization of 2 oxazolines is a simple and suitable approach to the incorporation of polyethyleneimine into copolymers of various struc tures. After the biocompatibility of poly(2 alkyl 2 oxazolines) was discovered [1], the interest in poly mers of this type increased appreciably. In addition, aqueous solutions of a number of poly(2 alkyl 2 oxazolines) possess lower critical solution tempera tures, a circumstance that makes it possible to create new types of thermoresponsive materials on their basis [2].Poly(2 isopropyl 2 oxazoline) is one of the best studied thermosensitive polymers. In aqueous solu tions below the LCST (~40°С), the amide groups of this polymer are heavily hydrated; as a result, macro molecules turn out to be hydrophilized. Above the LCST, the degree of hydration decreases and intramo lecular hydrogen bonds form between amide frag ments. Owing to transition to the globular conforma tion, macromolecules become hydrophobic and the polymer loses the ability to dissolve in water [3].The incorporation of fragments able to efficiently bind inorganic ions and organic compounds into poly mers is a new strategy to designing supramolecular colloid structures and thus allows modeling of pro cesses occurring in living nature [4]. It was shown that the transition from linear to star shaped macromole cules significantly improves the capability of polymers for molecular recognition [5]. As is known [6], calix arenes are substances that can form complexes with low molecular mass compounds and metal ions that are capable of molecular recognition and formation of supramolecular structures. In our opinion, star shaped polymers with the central calixarene core and thermoresponsive poly(2 isopropyl 2 oxazoline) arms may be used as molecular containers for low molecu lar mass compounds and metal ions; moreover, they serve as elements of thermoresponsive colloid systems.There are two main approaches to the synthesis of star shaped macromolecules. In the first case, arms are synthesized separately and then are bound by poly functional crosslinking agents. In the second case, arms grow on a multicentered initiator. This variant was found to be efficient for the synthesis of star shaped polymers based on calixarenes, especially when living ionic or controlled radical polymerization is used. For example, initiators based on calix[8]arene and tetraethylresorcinarene were employed to imple ment the living cationic polymerization of isobutylene [7,8] and 2 methyloxazoline [9], respectively. Con trolled radical polymerization, primarily atom trans fer radical polymerization (ATRP), is also in wide use for the synthesis of star shaped polymers with calix(resorcinarene)arene cores and arms that are polystyrene [10,11], polyacrylate [11,12], or poly methacrylate [13] moieties. Therefore, the approach based on the use of the macrocyclic polyfunctional initiator for the cationic polymerization of 2 isopro pyl 2 oxazoline was selected for the synthesis of star shaped polymers with octa tert butylcalix[8]arene cores...

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Section: Resultssupporting

confidence: 87%

Thermoresponsive star-shaped poly(2-isopropyl-2-oxazolines) based on octa-tert-butylcalix[8]arene

2012

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“…1). Earlier studies [28][29][30] likewise demonstrated that the complex formation during S N 2 reactions is exothermic in vacuo but less exothermic in dipolar Table 1. Substituent and solvent effects on activation and thermodynamic parameters in the nucleophilic substitution reactions and in the ion-dipole complex formations between benzyl bromides and nucleophiles.…”

Section: Results and Discussion Exchange Reactions Of Benzyl Bromidementioning

confidence: 81%

Computational Study of Reactivity and Transition Structures in Nucleophilic Substitutions on Benzyl Bromides

2006

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Keywords: Nucleophilic substitutions / Benzyl bromides / Substituent effect / Solvent effect / Density functional calculations / Activation parameters DFT computations on the mechanisms of nucleophilic substitutions on benzyl bromides were performed and the calculated activation parameters were compared with experimentally acquired data. In vacuo, the presence of electron-withdrawing (e-w) groups on the benzyl bromides accelerated the reactions and the calculated ∆G ‡ /∆H ‡ /∆S ‡ vs. σ plots were linear, while in solvents there were breaks in the calculated and measured ∆G ‡ /∆H ‡ vs. σ + plots of the reactions between the benzyl bromides and Br -, both with electron-donating (e-d) and with e-w substituents accelerating the reactions. The calculated ∆S ‡ values appeared to be independent of the substituents. In solvents, the calculated ∆G ‡ /∆H ‡ /∆S ‡ vs. σ + plots for the reactions between benzyl bromides and pyridine were linear, whereas breaks were observed in the plots of the measured data. These reactions were promoted by e-d substituents, but the measured reactivities of sub-

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“…The low yields obtained for S N Ar fluorination of relatively unactivated trimethylanilinium triflates stems, in part, from formation of methyl fluoride from a competing S N 2 (reverse Menschutkin [38]) reaction. Formation of [ 18 F] methyl fluoride has been observed in some cases where it is suspected to be the main deleterious side reaction [11,28].…”

Section: Introductionmentioning

confidence: 91%

Competitive demethylation and substitution in N,N,N-trimethylanilinium fluorides

Sun

DiMagno

2007

Journal of Fluorine Chemistry

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One Century of Physical Organic Chemistry: The Menshutkin Reaction

Cited by 86 publications

References 340 publications

Thermoresponsive star-shaped poly(2-isopropyl-2-oxazolines) based on octa-tert-butylcalix[8]arene

Thermoresponsive star-shaped poly(2-isopropyl-2-oxazolines) based on octa-tert-butylcalix[8]arene

Computational Study of Reactivity and Transition Structures in Nucleophilic Substitutions on Benzyl Bromides

Competitive demethylation and substitution in N,N,N-trimethylanilinium fluorides

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