Polymerization of styrene and methyl methacrylate in the presence of 2,2-diethyl-4,5,5-trimethyl-2,5-dihydroimidazol-1-oxyl

Pavlovskaya, M. V.; Kirilyuk, Igor A.; Щепалов, А. А.; Grigoriev, I. A.; Гришин, Д. Ф.

doi:10.1134/s1560090408110134

Cited by 4 publications

(5 citation statements)

References 11 publications

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“…Ether was evaporated under reduced pressure and the residue was recrystallized from ethylacetate/hexane mixture 1: 2 to give 2 as yellow crystals, mp 147À148 °C. Found: C, 59 25 (300 mg, 1.15 mmol), 2-bromo-2-methylpropionic acid ethyl ester (300 mg, 1.54 mmol), Cu powder (350 mg, 5.52 mmol), 4,4 0 -di-tert-butyl-2,2 0 -bipyridine (12 mg, 0.045 mmol), Cu(OTf) 2 (12 mg, 0.033 mmol), and benzene (5 mL) was placed in a Schlenk flask and degassed by three freezeÀpumpÀthaw cycles. The solution was stirred for 5 h at 60 °C.…”

Section: ' Experimental Sectionmentioning

confidence: 99%

“…Analysis of the titration curve reveals two pK a values of 5.08 and 2.86, assigned to the protonation of amidine and pyridine groups, respectively (Scheme 3). 25 pK a values of nitroxide 2 were obtained using the experimentally measured dependence of EPR spectra on pH shown in Figure 1. Analysis of the titration curve was performed in the same way as in ref 23 using two pK a values of 0.…”

Section: Scheme 1 Simplified Reaction Scheme Of Nmp Chart 1 Structumentioning

confidence: 99%

“…The nitroxide 1 was prepared according to the previously published procedures. 25 To confirm the NMR peak assignments of alkoxyamines 3À7, 9 we used 1 H NMR, 13 C NMR J-mod spectrum and COSY 45, 200 MHz for 1 H. 1 H and 13 C NMR spectra of compounds 3À5, 9. 1 H NMR spectra of alkoxyamine 3, 4, 6, 7, 9 were recorded in CDCl 3 ; 1 H NMR spectrum of alkoxyamine 5 was recorded in CDCl 3 /CD 3 OD; 13 C NMR J-mod spectra of alkoxyamines 3, 4, 6, 7, 9 were recorded in CDCl 3 ; 13 C NMR J-mod spectrum of alkoxyamine 5 was recorded in CDCl 3 / CD 3 OD; COSY 45 NMR spectra of alkoxyamines 4, 5 were recorded in D 2 O; COSY 45 NMR spectrum of alkoxyamine 6 was recorded in DMSO-d 6 .…”

Section: ' Experimental Sectionmentioning

confidence: 99%

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pH-Sensitive C–ON Bond Homolysis of Alkoxyamines of Imidazoline Series with Multiple Ionizable Groups As an Approach for Control of Nitroxide Mediated Polymerization

et al. 2011

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Recently, a new concept of pH-switchable agents for reversible addition-fragmentation chain transfer (RAFT) polymerization has been introduced by Benaglia et al. (J. Am. Chem. Soc.2009, 131, 6914-6915). In this paper we extended the concept of pH-switchable mediators to nitroxide mediated polymerization (NMP) by employing nitroxides with basic or acidic groups as controlling agents. Four alkoxyamines, the derivatives of 2-(4-(dimethylamino)-2-ethyl-5,5-dimethyl-2-(pyridin-4-yl)-2,5-dihydro-1H-imidazol-1-oxyl and 2-(2-carboxyethyl)-5,5-diethyl-2,4-dimethyl-2,5-dihydro-1H-imidazol-1-oxyl, have been prepared. The influence of pH on alkoxyamine homolysis rate constants (k(d)) and on the nitroxide-alkyl radical recombination rate constants (k(c)) was studied. All alkoxyamines under study as well as the parent nitroxides have several basic groups, which under pH variation can undergo consecutive protonation. It was shown that the k(d) value under basic conditions are significantly (up to 15-fold) higher than in acidic solution at the same temperature, whereas the k(c) value in basic solutions decrease by a factor of 2 only. The efficiency of NMP is known to be dependent on k(d) and k(c), both constants being dependent on the monomer structure; therefore the performance of NMP of different monomers in the controlled mode requires different conditions. It is shown that the pH value crucially affects the polymerization regime, changing it from the controlled to the uncontrolled mode. The controlled regime of NMP of different hydrophilic monomers (sodium 4-styrenesulphonate and acrylamide) in aqueous solution under mild conditions (90 °C) can be achieved using the same alkoxyamine by the variation of the pH value. The chain length of polymers depends on pH value during the polymerization.

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Section: ' Experimental Sectionmentioning

confidence: 99%

Section: Scheme 1 Simplified Reaction Scheme Of Nmp Chart 1 Structumentioning

confidence: 99%

Section: ' Experimental Sectionmentioning

confidence: 99%

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pH-Sensitive C–ON Bond Homolysis of Alkoxyamines of Imidazoline Series with Multiple Ionizable Groups As an Approach for Control of Nitroxide Mediated Polymerization

et al. 2011

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“…In all cases, the increase in molecular weight and the absence of macroinitiator traces were observed by gel permeation chromatography indicating the living character of the polymerization. The importance of this work is also exemplified by the expansion of applications of imidazoline-based nitroxides to aqueous monomers because this type of nitroxides is effective at polymerization of acrylates, styrene, [ 15 , 36 , 37 , 38 , 39 , 40 ] and even methacrylate. [ 41 , 42 ]…”

Section: Chemical Activation Of C–on Bond Homolysismentioning

confidence: 99%

Smart Control of Nitroxide-Mediated Polymerization Initiators’ Reactivity by pH, Complexation with Metals, and Chemical Transformations

et al. 2019

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Because alkoxyamines are employed in a number of important applications, such as nitroxide-mediated polymerization, radical chemistry, redox chemistry, and catalysis, research into their reactivity is especially important. Typically, the rate of alkoxyamine homolysis is strongly dependent on temperature. Nonetheless, thermal regulation of such reactions is not always optimal. This review describes various ways to reversibly change the rate of C–ON bond homolysis of alkoxyamines at constant temperature. The major methods influencing C–ON bond homolysis without alteration of temperature are protonation of functional groups in an alkoxyamine, formation of metal–alkoxyamine complexes, and chemical transformation of alkoxyamines. Depending on the structure of an alkoxyamine, these approaches can have a significant effect on the homolysis rate constant, by a factor of up to 30, and can shorten the half-lifetime from days to seconds. These methods open new prospects for the application of alkoxyamines in biology and increase the safety of (and control over) the nitroxide-mediated polymerization method.

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“…Imidazoline nitroxides are known to be efficient mediators of styrene polymerization . Recently, we reported synthesis of a series of sterically hindered imidazoline nitroxides and corresponding alkoxyamines.…”

Section: Introductionmentioning

confidence: 99%

Controlled/living polymerization of methyl methacrylate using new sterically hindered imidazoline nitroxides prepared via intramolecular 1,3-dipolar cycloaddition reaction

Edeleva

Parkhomenko

Morozov

et al. 2013

J. Polym. Sci. Part A: Polym. Chem.

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A series of imidazoline nitroxides with bulky spirocyclic moieties at the positions 2 or 5 of imidazole ring were synthesized using intramolecular 1,3-dipolar cycloaddition in 2Himidazole 1-oxides or 4H-imidazole 3-oxides with pent-4-enyl groups followed by isoxazolidine ring opening and oxidation. Capability of the nitroxides to control radical polymerization of methyl methacrylate (MMA) and styrene was investigated. For that purpose, alkoxyamines were synthesized from the aforementioned nitroxides and tert-butyl a-bromoisobutyrate. Homolysis rate constants of the alkoxyamines were measured and possible contributions of side reactions were quantified.Nitroxide-mediated polymerization of styrene and MMA was studied using the alkoxyamines as initiators. MMA polymerization was found to proceed in controlled regime up to 55% of monomer conversion and the polymer obtained was able to reinitiate the polymerization of styrene. Quota of "living" chains estimated to reach 90%. V C 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 929-943 Additional Supporting Information may be found in the online version of this article.

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Polymerization of styrene and methyl methacrylate in the presence of 2,2-diethyl-4,5,5-trimethyl-2,5-dihydroimidazol-1-oxyl

Cited by 4 publications

References 11 publications

pH-Sensitive C–ON Bond Homolysis of Alkoxyamines of Imidazoline Series with Multiple Ionizable Groups As an Approach for Control of Nitroxide Mediated Polymerization

pH-Sensitive C–ON Bond Homolysis of Alkoxyamines of Imidazoline Series with Multiple Ionizable Groups As an Approach for Control of Nitroxide Mediated Polymerization

Smart Control of Nitroxide-Mediated Polymerization Initiators’ Reactivity by pH, Complexation with Metals, and Chemical Transformations

Controlled/living polymerization of methyl methacrylate using new sterically hindered imidazoline nitroxides prepared via intramolecular 1,3-dipolar cycloaddition reaction

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