13C NMR Chemical Shifts Calculation for Model Compounds of Ethylene–Propylene Copolymer with a Low Ethylene Content

Hayashi, Tetsuo; Inoue, Yoshio; Chûjô, Riichirǒ; Asakura, Tetsuo

doi:10.1295/polymj.20.107

Cited by 8 publications

(4 citation statements)

References 22 publications

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“…-"0(5) ri_S7a|sa (10) mi-S7Q^ (13) ri-Sr"6i (20) m0-T«s(24) 34.2-34.8 -'1 ß(5) mi-ST"fli (10) -'µ« (17) mi-S7aSS (20) r0-Tai(24) -< ( 16)…”

Section: Resultsmentioning

confidence: 99%

“…This method is especially useful for the 13C NMR tacticity assignments of polyolefins and has been successfully applied to the tacticity assignment of the 13C NMR spectra of a series of linear polyolefins,1-8"16 poly-(3-methyl-l-butene),17 E-P copolymer,2-18"20 and B-P copolymer. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] The additive rules for predicting the 13C NMR chemical shifts of methyl-substituted alkanes proposed empirically by Cheng and Bennett22-23 are also available for the assignments.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Carbon-13 NMR spectral assignments of regioirregular polypropylene determined from two-dimensional INADEQUATE spectra and chemical shift calculations

Asakura¹,

Nakayama²,

Demura³

et al. 1992

Macromolecules

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The 13C NMR spectrum of regioirregular polypropylene containing up to 40 mol % of inverted propylene units was assigned using the 2D INADEQUATE technique, the INEPT technique, and 13C chemical shift calculations based on the 13C NMR 7-effect and the application of the rotational isomeric state model and also on the additive rules for 13C chemical shifts of methyl-substituted alkanes. The presence of four kinds of sequences containing head-to-head and/or tail-to-tail units in the sample was confirmed. The 13C-13C connectivities of the 2D INADEQUATE spectrum were extremely useful in the assignment of overlapping peaks as well as the identification of several such sequences. The peaks were assigned to each carbon in these sequences by taking tacticity into account. There is exclusively a meso head-to-head unit in the sequence where a single inverted unit is contained in several head-to-tail units.

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“…-"0(5) ri_S7a|sa (10) mi-S7Q^ (13) ri-Sr"6i (20) m0-T«s(24) 34.2-34.8 -'1 ß(5) mi-ST"fli (10) -'µ« (17) mi-S7aSS (20) r0-Tai(24) -< ( 16)…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Carbon-13 NMR spectral assignments of regioirregular polypropylene determined from two-dimensional INADEQUATE spectra and chemical shift calculations

Asakura¹,

Nakayama²,

Demura³

et al. 1992

Macromolecules

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“…In the preceding paper, 19 we demonstrated that the chemical shifts due to the gamma-effect is sensitive to the displacement between the ethylene and propylene units. It has been confirmed that the chemical shift calculation via the gamma-effect is applicable to the pentad and hexad comonomer sequence assignments of methyl and methylene resonances in the 13 C NMR spectrum of stereoregular E-P copolymer.…”

Section: Resultsmentioning

confidence: 89%

Pentad Assignments of Methine Carbon Resonances in Stereoregular Ethylene–Propylene Copolymer Based on Two-Dimensional INADEQUATE NMR Spectrum

Hayashi

Inoue

Chûjô

et al. 1988

Polym J

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ABSTRACT:It is demonstrated that the 13 C double quantum two dimensional (2D-INADEQUATE) NMR spectrum is very useful for 13 C NMR chemical shift assignments of split peaks arising from differences in long range sequences. The 2D-INADEQUATE spectrum of streoregular ethylene-propylene copolymer revealed the detailed connectivities between methyl and methine carbons. By tracing these connectivities, the pentad comonomer sequence assignments of methine carbons could be determined for the first time. The 13 C chemical shifts of methyl carbons in the different pentad sequences, predicted by the chemical shift calculation via the gamma-effect, were used as references for the assignments of methine carbon resonances.KEY WORDS 13 C NMR / 2D-INADEQUATE NMR / Stereoregular Ethylene-Propylene Copolymer / Pentad Assignments / 13 C NMR is the most powerful method to investigate microstructures of ethylenepropylene (E-P) copolymers. 1 -8 By improvements in the sensitivity and resolution of 13 C NMR spectra, the split peaks arising from the different hexad sequences have been observed in the spectrum of stereoregular E-P copolymer. 5 Ray et al. 1 proposed the 13 C NMR chemical shift assignments of stereoregular E-P copolymer which have been widely used for the sequential analyses. 6 -8 Their assignments are reasonable for the spectra of E-P copolymers with low and high ethylene contents. As for the methine carbon resonances, the provided assignments of T /i/i (PPP sequence), Tp~ (PPE or EPP sequence), and TM (EPE sequence) carbons are only up to the triad level (where the nomenclature proposed by Carman et al.2 is used for designation of carbon types). The 13 C chemical shifts for methyl and methine carbons in the heptad and pentad stereoisomers of polypropylenes have been proposed from the chemical shift calculation based on the gamma-effect. 9 · 10 Only the empirical rule proposed by Cheng 11 tentatively provides the chemical shifts of methine carbons in different pentad comonomer-sequences of stereoregular E-P copolymer.13 C double quantum two-dimensional (2D-INADEQU A TE) NMR has been developed as a reliable method to determine the connectivity of carbon atoms. 12 -t 4 By using this method, Hikichi et al. 15 confirmed the validity of the 13 C chemical shift assignments of various types of carbons in stereoirregular E-P copolymer proposed by Randall. 7 In this study, we establish the pentad assignments of methine carbon resonances arising from the 895

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“…The same procedure can be performed on the (mrr) fraction, giving (rrrm) + 2(mrrm) = (rmrr) + (mmrr) (4) Note that this also follows from Eq. 1) and (2), however, are added for explanation and allow generalization to hexads, heptads, etc.…”

Section: The Conservation Lawsmentioning

confidence: 92%

Application of conservation law to NMR measurements of poly(propylene) stereoregularity

Burg

Chadwick

Sudmeijer

et al. 1993

Macro Theory & Simulations

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A new method is presented for data reconciliation in the 13C NMR determination of the pentad distribution in regioregular poly(propy1ene). Deviations of experimentally measured data from mathematically derived conservation laws are corrected by a maximum-likelihood method. In this method some assumptions are made about the structure of the errors to obtain better estimates of the correct data. The validity of this procedure was demonstrated with Monte Car10 simulation, after which the method has been applied to real 13C NMR data to show what corrections may be obtained. Conservation laws for hexads and heptads are derived as well, for possible future use. 0 1993, Hiithig & Wepf Verlag, Basel

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13C NMR Chemical Shifts Calculation for Model Compounds of Ethylene–Propylene Copolymer with a Low Ethylene Content

Cited by 8 publications

References 22 publications

Carbon-13 NMR spectral assignments of regioirregular polypropylene determined from two-dimensional INADEQUATE spectra and chemical shift calculations

Carbon-13 NMR spectral assignments of regioirregular polypropylene determined from two-dimensional INADEQUATE spectra and chemical shift calculations

Pentad Assignments of Methine Carbon Resonances in Stereoregular Ethylene–Propylene Copolymer Based on Two-Dimensional INADEQUATE NMR Spectrum

Application of conservation law to NMR measurements of poly(propylene) stereoregularity

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