2D-INADEQUATE NMR Evidence for the Termination Mechanism of Styrene Free Radical Polymerization

Hensley, Darlene R.; Goodrich, Stephen D.; Harwood, H. James; Rinaldi, Peter L.

doi:10.1021/ma00086a063

Cited by 24 publications

(19 citation statements)

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“…The best fit of the m / z data is for: I‐(b) x (s) y , where I is the fragment of initiator, namely NC(CH 3 ) 2 C. If in propagation termination occurs on the …‐s • (styryl radical), then, as it is known, termination takes place by combination. A few peaks (being, however, in minority), and having fragments of initiator at both ends, could be detected and are indicated in Figure .…”

Section: Resultsmentioning

confidence: 99%

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Copolymerizations of tetraethyl vinylidene phosphonate. Bisphosphonate units in the main polymer chain. II

Pretula

Kałużyński

Penczek

2014

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

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This is the second part of the article with a subtitle ". . . The First Synthesis" published by us previously. For this, second part, we have chosen copolymers with low proportion of (-b-) units, as well as random copolymers with substantial proportions of (-b-) units. This is in contrast to the part I, in which we mostly described alternating copolymerization. In this article, radical copolymerization of tetraethyl vinylidene phosphonate (B) with several vinyl/ethylenic monomers (M 2 ), namely acrylamide, methacrylamide, methyl methacrylate, n-butyl acrylate, n-butyl methacrylate, and styrene has been described and reactivity ratios of monomers as well as the average length of the comonomer blocks (n) have been determined (r 1 5 0). It has been found, that (as it should be) there is a proportionality between r 2 (5k m2M2 /k m2B ) and n. Moreover, there is a proportionality between r 2 (or n) and the comonomer (M 2 ) "reactivity," defined as the rate constant of M 2 addition to the styrene radical.

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Section: Resultsmentioning

confidence: 99%

“…. .-s • (styryl radical), then, as it is known, 6 termination takes place by combination. A few peaks (being, however, in minority), and having fragments of initiator at both ends, could be detected and are indicated in Figure 6.…”

Section: Copolymerization Of B With Styrene (S) (This Description Completes the General Procedures Given Above)mentioning

confidence: 99%

Copolymerizations of tetraethyl vinylidene phosphonate. Bisphosphonate units in the main polymer chain. II

Pretula

Kałużyński

Penczek

2014

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

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“…At low field regions, the signals at 137.5 and 133.2 ppm can be assigned to the carbon of the double bond of the vinylene end-group (-CH== CHPh) derived from β-H elimination from the ultimately secondarily inserted styrene unit [24][25][26] . No resonances corresponding to irregular styrene head-to-head or tail-to-tail growth in the middle of the polymer chain were observed [36,37] . It is supported by the structure of dimer of styrene obtained in the case of low Al/Ni ratio [34] .…”

Section: Run Complexmentioning

confidence: 99%

Styrene polymerization catalyzed by nickel complexes bearing hydroxyindanone-iminate ligands

Tang

Jin

2008

Sci. Bull.

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“…95 Radical polymerization of styrene also gives a polymer with head-to-head connectivity, supporting the assumption that the principal mode of chain termination is dimerization of polystyrene radicals. 96 Grafting of some polyolefins with maleic anhydride (99% 13 C of the olefinic carbons) was studied with magnitude calculated 1D-INADEQUATE. Different doublets originating from the enriched carbons were displayed, the υ values of which gave an insight into the kind of grafting.…”

Section: H T H T H T H T H T (A) H T H T T H H T H T (B) Inverted Unitmentioning

confidence: 99%

Connectivities in molecules by INADEQUATE: recent developments

Buddrus

Lambert

2001

Magnetic Reson in Chemistry

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The INADEQUATE (Incredible Natural Abundance DoublE QUAntum Transfer Experiment) consists of a pulse sequence which eliminates the NMR signals from isolated spins (spin system A) displaying signals from coupled spins (spin system AX or higher spin systems). It is of great importance when applied to molecules with skeleton elements such as carbon, silicon or tungsten, all of which contain a small percentage of spin-1 2 isotopes embedded in magnetically inactive isotopes. Analysis of the AX type spectra gives one-bond and long-range coupling constants (see compound 6) and, most important, the connectivity pattern of the skeleton atoms in molecules of unknown structure such as the carbon compounds 1 or 2, the silicon compound 3 or the lithium compound 4b. Unfortunately, INADEQUATE is rather insensitive, in the case of carbon only one out of 10 4 molecules gives the desired response. Efforts to reduce this drawback are described; recently, a remarkable step forward has been made by concentrating the four lines of an AX spin system to just two signals (see Fig. 2).

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2D-INADEQUATE NMR Evidence for the Termination Mechanism of Styrene Free Radical Polymerization

Cited by 24 publications

References 0 publications

Copolymerizations of tetraethyl vinylidene phosphonate. Bisphosphonate units in the main polymer chain. II

Copolymerizations of tetraethyl vinylidene phosphonate. Bisphosphonate units in the main polymer chain. II

Styrene polymerization catalyzed by nickel complexes bearing hydroxyindanone-iminate ligands

Connectivities in molecules by INADEQUATE: recent developments

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