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  • 1975-1979  (13)
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  • 1
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The initiation of various vinyl monomers with tert-butoxyl radicals derived from the decomposition of di-tert-butyl peroxalate (DBPOX) was investigated by using the spin trapping technique with 2-methyl-2-nitrosopropane (BNO), to detect and identify the intermediate radical species, and to evaluate the monomer reactivities toward the tert-butoxyl radical. When the reaction of DBPOX with vinyl monomers, which have no α-methyl group (CH2=CH(X)), was carried out in the presence of BNO at room temperature, the propagating radical 1 ((H3C)3CO—CH2—CHX) was trapped as its nitroxyl radical. However, in the cases of using α-methylvinyl monomers (CH2=CH(X)CH3), such as methyl methacrylate and methacrylonitrile, two kinds of radicals, 6 ((H3C)3CO—CH2—C(X)(CH3), similar to 1) and 8 (CH2=CH(X)CH2), were trapped as corresponding nitroxyl radicals. The coupling constants of the nitroxyls obtained from 1 and 6 were determined and discussed on the basis of their structure. When these reactions were performed in a reference solvent, p-xylene, the above radicals, 1 (or 6) and/or 8, together with the p-tolylmethyl radical (2), were trapped as their nitroxyls. From the ESR peak areas the relative reactivities of vinyl monomers toward the tert-butoxyl radical were evaluated and found to depend not only on the polar nature, but also on the resonance effect of the substituents. In α-methylvinyl monomers such as methyl methacrylate, the hydrogen-abstraction from the α-methyl group by the tert-butoxyl radical was important.
    Additional Material: 7 Ill.
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  • 2
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The mechanism of photo-decomposition of dibenzoyl disulfide (DBDS) in benzene or in monomers, and the evaluation of relative reactivities of various vinyl monomers toward the benzoylthiyl radical (4) were investigated by means of the spin trapping technique using 2-methyl-2-nitrosopropane (BNO). When DBDS photo-decomposed in benzene at 22±2°C in the presence of BNO, both 4 and benzoyl radicals were trapped as their nitroxyl radicals, indicating that both S—S and C—S bonds in DBDS were decomposed during its photolysis. However, when the photo-decompositions were performed in the monomers, propagating radicals (7) were trapped, but no allyl-type radicals (11). The coupling constants of the nitroxyl radicals of various propagating radicals were determined. From the ESR spectra of the systems DBDS/vinyl monomers/methyl methacrylate (as reference)/BNO the relative concentrations of the nitroxyls, [8]/[10, X = COOCH3], were determined by computer simulation, and the relative reactivities of the vinyl monomers toward 4 were estimated. It was found that the relative reactivities of these monomers are correlated with their e values to give a linear relationship with a negative slope, similar to those toward the tert-butoxyl radical found in the previous paper.
    Additional Material: 8 Ill.
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  • 3
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The initiation mechanism for spontaneous alternating copolymerization of styrene (St) with maleic anhydride (MAn) was investigated by means of spin trapping technique. using 2-methyl-2-nitrosopropane (7) as spin trapping agent. By means of ESR spectroscopy of the system St/MAn in ethylbenzene, a cyclic radical (13), produced via the Diels-Alder intermediate 25, was detected as its aminyl oxide. A similar radical was also trapped from the system p-methyl-St/MAn and p-dimethylamino-St/MAn. It is formed faster in these systems than in the system St/MAn. In chloroform, however, two types of initiating radicals. 13 and the α-styryl radical (15), were trapped. This indicates that these radicals are produced via 25 and the charge transfer complex 27, respectively. From these results an initiation mechanism is proposed. To clarify further the propagation mechanism, the spin trapping technique was applied to the system, which is initiated by tert-butoxyl radical formed from di-tert-butyl peroxalate (8). The effect of the concentration of 7 on the ESR spectrum of the system St/MAn/8 shows that 27 also participates in the propagation of this alternating copolymerization. Finally, the high reactivity of 27, as compared with free monomers in alternating copolymerization systems, was attempted to be explained on the basis of the Evans-Polanyi theory.
    Additional Material: 6 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 561-571 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die bei der Vinylpolymerisation mit binären Systemen von Diacylperoxiden und tertiären Aminen intermediär entstehenden Radikale wurden durch ESR-Spektroskopie unter Verwendung einer “spin trapping”-Technik mit 2-Methyl-2-nitrosopropan (8) charakterisiert. Bei den Reaktionen von N,N-Dimethylanilin (2a) und N,N-Diäthylanilin (2b) mit Benzoylperoxid (1a) wurden N-Methylanilinomethyl- (7) bzw. N-Äthylanilino-1-äthyl-Radikale (16) abgefangen, während Benzoyloxyl- (4a) und Phenylradikale nicht gefunden wurden. Dies wurde Durch die Annahme erklärt, daß die Benzoyloxylradikale (4a) schneller mit 2a bzw. 2b zu den Radikalen 7 bzw. 16 reagieren, als daß sie von 8 abgefangen werden. Daraus wurde geschlossen, daß die Radikale 4a und 7 bzw. 16 in diesen Systemen initiierend wirken. Bei der Reaktion von Lauroylperoxid (1b) mit 2a und 2b hingegen wurden Undecylradikale zusammen mit den Radikalen 7 bzw. 16 abgefangen. Im Fall von N-Äthyl-N-methylanilin (2c) wurden sowohl N-Äthylanilinomethyl- (18) als auch N-Methylanilino-1-äthylradikale (20) abgefangen. Des weiteren wurden bei der Reaktion von 1a mit Poly(p-dimethylaminostyrol) sowohl Poly{1-[4-(N-methyl-N-methylylamino)-phenyl]ethylene} (22) als auch Phenylradikale (im Gegensatz zur Reaktion von 1a mit 2a) abgefangen.
    Notes: To characterize the intermediate radicals produced in the initiation of vinyl polymerization with binary systems of diacyl peroxides and tertiary amines, spin trapping technique was applied by using 2-methyl-2-nitrosopropane (8) as a spin trapping reagent. In the reactions of N,N-dimethylaniline (2a) and N-N-diethylaniline (2b) with benzoyl peroxide (1a), N-methylanilinomethyl (7) and N-ethylanilino-1-ethyl radicals (16), respectively, were trapped, contrary to benzoyloxyl (4a) and phenyl radicals which were not trapped. This was explained by assuming that benzoyloxyl radicals (4a) react faster with 2a or 2b to give the radicals 7 and 16, than being trapped with 8. From this, 4a and 7 or 16 were concluded to be the initiating radicals in these systems. In the reaction of lauroyl peroxide (1b) with 2a or 2b, however, undecyl radicals were trapped together with the radicals 7 or 16. In the case of N-ethyl-N-methylaniline (2c) both, N-ethylanilinomethyl (18) and N-methylanilino-1-ethyl radicals (20), were trapped. Further, it was found that in the reaction of 1a with poly(p-dimethylaminostyrene), both poly{1-[4-(N-methyl-N-methylylamino)phenyl]ethylene} (22) and phenyl radicals were trapped, contrary to the reaction of 1a with 2a.
    Additional Material: 7 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 177 (1976), S. 2009-2019 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die radikalische Polymerisation von Vinyl Monomeren, speziell von Methylmethacrylat (MMA) und Äthylacrylat wird durch das System N,N-Dimethylanilin-N-oxid (1)/2,2′-(2,5-Cyclohexadien-1,4-diyliden)-dimalonodinitril (2) ausgelöst. Kinetische Untersuchungen der Polymerisation von MMA sowie dessen Copolymerisation mit Styrol zeigen, daß dieses System eine radikalische Polymerisation mit einer Gesamtaktivierungsenergie von 40,6 kJ/mol (9,7 kcal/mol) initiiert. Die spektroskopischen Untersuchungen zeigen die Bildung eines 2:1 „Chargetransfer-Komplexes“ 3 aus 1 und 2. Aus ESR-Messungen wurde mit Hilfe der Abfangtechnik gezeigt, daß die beiden Radikale N,N-Dimethylanilin-N-oxyl (7) und das Anion-Radikal 8 in diesem System entstehen. Diese intermediären Radikale scheinen durch eine Elektronenübertragungsreaktion von 1 im Komplex 3 zu entstehen und an der Initiierungsreaktion teilzunehmen. Anhand dieser Ergebnisse wird ein wahrscheinlicher Initiierungsmechanismus diskutiert.
    Notes: A combined system of N,N-dimethylaniline N-oxide (1) and 2,2′-(2,5-cyclohexadiene-1,4-diylidene)dimalonodinitrile (tetracyanoquinodimethane) (2) was found to induce radical polymerization of vinyl monomers, especially methyl methacrylate (MMA) and ethyl acrylate. From the kinetic investigation of the polymerization of MMA and its copolymerization with styrene, it was found that this initiator system induced a radical polymerization which proceeded with an overall activation energy of 40,6 kJ/mol (9,7 kcal/mol). The spectroscopic measurements of this system showed the formation of the 2:1 charge-transfer complex 3 of 1 with 2. From the ESR determination it was also found by means of the spin trapping technique that both the radical N,N-dimethylanilin N-oxyl (7) and the anion radical 8 were produced in this system. These intermediate radicals seemed to be formed by an electron-transfer reaction from 1 in the complex 3, and to participate in the initiation reaction. Based on these results, the probable initiation mechanism is discussed.
    Additional Material: 11 Ill.
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  • 6
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: To clarify the initiation and propagation mechanisms of the polymerization of N-vinylcarbazole (1) initiated by benzoyl peroxide (2), the spin trapping technique using 2-methyl-2-nitrosopropane (5) was applied. From the ESR spectrum observed from this system, the 1-(N-carbazolyl)-2-benzoyloxyethyl radical (6a) was found to be trapped as its nitroxyl radical 6b, which was confirmed by a comparison with similar nitroxyl radicals (7b and 8b) derived from the systems, di-tert-butyl peroxalate/1/5 and 2/N-ethylcarbazole/5, respectively. Therefore, it was concluded that the 1/2 system produces easily a primary propagating radical of 1 viz. 6a. Further, the monomer 1 was found to show a remarkable accelerating effect on the radical decomposition of 2. From the copolymerization of 1 with styrene initiated by 2, it was concluded that 6a propagates by ordinary successive ß-attack to the monomer 1.
    Additional Material: 4 Ill.
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  • 7
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The polymerization of methyl methacrylate (MMA) with 1,2,3,10a-tetrahydrophenanthrene-1,2-dicarboxylic anhydride (TH) (10), which is a stable Diels-Alder adduct of α-vinylnaphthalene and maleic anhydride, was investigated by kinetic and spin trapping methods. TH could induce radical polymerizations of MMA and methyl acrylate with a considerably high rate, and the rate of polymerization (Rp) of MMA was found to follow the equation: Rp = k[TH]0,3 [MMA]1,6. The overall activation energy and the chain transfer constant to TH for this polymerization were determined to be 47,7 kJ/mol and 0,52, respectively. From these results, an initiation mechanism involving a hydrogen-transfer from TH to MMA was proposed, which is similar to Mayo's initiation mechanism for the thermal polymerization of styrene. To confirm this mechanism, the spin trapping technique was applied. The results obtained regarding the trapping of the initiating radicals supported this hydrogen-transfer initiation mechanism.
    Additional Material: 7 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 180 (1979), S. 267-269 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 3 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 180 (1979), S. 299-305 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Oxidation of tertiary amines with N-chloronylon 66 (NCN) was investigated in several organic solvents. NCN was found to oxidize N,N-dimethylaniline (DMA) at room temperature to give N-methylaniline with 15-50% yield, depending on the solvents used. Oxidation of N,N-dimethylbenzylamine (DMBA) gave benzaldehyde with 15-30% yield and a small amount of N-methylbenzylamine. A mechanism was discussed. For comparison, N-chlorosuccinimide, a low molecular N-chloro-compound, was also used for oxidation of DMA and DMBA.
    Additional Material: 3 Tab.
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  • 10
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: N-hydroxysuccinimide (NHS) and N-hydroxyphthalimide were found to initiate effectively vinyl polymerizations of acrylate monomers. The polymerization of methyl methacrylate (MMA) with NHS was investigated in detail. The polymerization rate (Rp) was found to depend highly on the solvents. The over-all activation energy of the polymerization in ethyl acetate was calculated to be 76,2 kJ/mol (18,2 kcal/mol). In the low monomer concentration, Rp can be expressed as Rp = k [NHS]1/2 [MMA]3/2. The copolymerization of MMA with styrene, initiated by NHS, could be shown to proceed via radical mechanism. In order to elucidate the initiation mechanism, spin trapping technique was applied to this polymerization system. In the reaction of MMA with NHS in acetone, the 2-carbomethoxypropyl radical was trapped by 2-methyl-2-nitrosopropane, a spin trapping reagent, to give the corresponding aminyl oxide radical 2. From the results, the initiation mechanism of this polymerization is proposed and discussed.
    Additional Material: 7 Ill.
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