scholarly journals Copolymer chain formation of 2-oxazolines by in situ1H-NMR spectroscopy: dependence of sequential composition on substituent structure and monomer ratios

RSC Advances ◽  
2021 ◽  
Vol 11 (18) ◽  
pp. 10468-10478
Author(s):  
Sabina Abbrent ◽  
Andrii Mahun ◽  
Miroslava Dušková Smrčková ◽  
Libor Kobera ◽  
Rafał Konefał ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Polymer Chains ◽  
Chain Formation ◽  
Molar Ratios ◽  
H Nmr ◽  
Copolymer Chain ◽  
Nmr Characterization ◽  
Insight Into

In situ1H NMR characterization of copolymerization reactions of various 2-oxazoline monomers at different molar ratios offers detailed insight into the build-up and composition of the polymer chains.

Nine-Vertex Polyhedral Monoazaborane Chemistry: Synthesis and NMR Characterization of exo-6-Ligand-arachno-4-azanonaboranes(11), 6-L-4-NB8H11

1994 ◽  
Vol 59 (10) ◽  
pp. 2244-2252 ◽  
Author(s):  
Tomáš Jelínek ◽  
Bohumil Štíbr ◽  
John D. Kennedy
Keyword(s):  
Mass Spectrometry ◽  
Nmr Spectroscopy ◽  
Lewis Bases ◽  
H Nmr ◽  
Nmr Characterization ◽  
Complete Assignment

Reactions between arachno-4-NB8H13 and Lewis bases L in dichloromethane or without solvent generate the previously unreported series of arachno compounds exo-6-L-arachno-4-NB8H11, where L = pyridine (py), quinoline (quin), isoquinoline (i-quin), urotropine (uro), and MeCN. These are characterized by mass spectrometry together with 11B and 1H NMR spectroscopy. The NMR results permit complete assignment of all resonances and thence permit comparison with the structurally similar compounds exo-6-L-arachno-4-EB8H10 (for E = CH2 or S).

Solid-State Carbon-13 NMR Studies of Vulcanized Elastomers. VII. Sulfur-Vulcanized Cis-1,4 Polybutadiene at 75.5 Mhz

1989 ◽  
Vol 62 (5) ◽  
pp. 908-927 ◽  
Author(s):  
R. S. Clough ◽  
J. L. Koenig
Keyword(s):  
Solid State ◽  
Nmr Spectroscopy ◽  
Chemical Shifts ◽  
Chemical Information ◽  
Chemical Probes ◽  
Nmr Studies ◽  
Nmr Characterization ◽  
The Individual ◽  
Insight Into

Abstract Solid-state C-13 NMR spectroscopy provides a wealth of chemical information concerning sulfur-vulcanized cis-l,4-polybutadiene. New resonances which appear upon curing have chemical shifts which are expected for crosslink and cyclic structures. The DEPT experiment with MAS worked well for the polybutadiene vulcanizate in the solid state. DEPT is very useful as an aid in the assignment of structures to resonances. The new resonances can be assigned to more than one type of structure given only chemical shift and DEPT information. Swelling measurements indicate the majority of the resonances are due to cyclics. Further work involving C-13 NMR characterization of polybutadiene vulcanizates treated with chemical probes and vulcanizates cured with organic accelerators should provide insight into the specific structures responsible for the individual resonances.

RAFT Polymerization of Styrene Using Dithioester with Anthracene Z Group as Chain Transfer Agent

e-Polymers ◽  
2007 ◽  
Vol 7 (1) ◽  
Author(s):  
Zhou Nianchen ◽  
Zhu Jian ◽  
Zhang Zhengbiao ◽  
Zhu Xiulin
Keyword(s):  
Raft Polymerization ◽  
Controlled Radical Polymerization ◽  
Polymer Chains ◽  
Chain Extension ◽  
Enhanced Fluorescence ◽  
H Nmr ◽  
Nmr Characterization ◽  
Raft Agent ◽  
Living Controlled Radical Polymerization

AbstractA novel dithioester, bearing anthracene as Z group, benzyl anthracene-10-carbodithioate (BAC) was successfully synthesized and used as the RAFT agent for the RAFT polymerizations of styrene (St). The results indicated that the polymerization presented the characteristics of “living”/controlled radical polymerization. 1H NMR characterization of obtained polystyrene confirmed that most of the polymer chains were end-capped by the anthracene moiety. The successful chain extension experiment further demonstrated the “living” character of the polymer. The fluorescence investigation of the polymers contained an anthrancene moiety of BAC in the chain end expressed enhanced fluorescence property than that of BAC in CHCl3 solution.

Sulphur–nitrogen anions: 14N and 15N NMR investigations of the deprotonation of cyclic sulphur imides and sulphur–ammonia solutions

1992 ◽  
Vol 70 (3) ◽  
pp. 710-718 ◽  
Author(s):  
T. Chivers ◽  
K. J. Schmidt
Keyword(s):  
Nmr Spectroscopy ◽  
Sodium Azide ◽  
Liquid Ammonia ◽  
Molar Ratio ◽  
15N Nmr ◽  
Molar Ratios ◽  
Nmr Data ◽  
Nmr Characterization

The following systems have been investigated by 14N and (or)15N NMR spectroscopy: (a) the deprotonation of S7NH by n-BuLi, (b) solutions of S8, S7NH, 1,3- and 1,4-S6(NH)2, and K2SN2 in liquid ammonia, (c) the reaction of sodium azide with sulphur in hexamethylphosphoramide (HMPA), (d) the reactions of S7NH and S4(NH)4 with potassium amide in liquid ammonia in various molar ratios, and (e) the reaction of (NSCl)3 with potassium amide (1:6 molar ratio) in liquid ammonia. These investigations have provided an NMR characterization of the thermally unstable S7N− (δ15N ca. −324 ppm) and S2N2H− ions (δ14N + 7 and −149 ppm, 1J(14N−1H) 36 Hz, 1J(15N−H) 55 Hz, 2J(15N-15N) 2.2 Hz) in liquid ammonia, demonstrated the existence of S7N−, in addition to SSNSS−, as the major nitrogen-containing ingredient of sulphur–ammonia solutions (SAS), and confirmed the formation of the SSNSS−, but not S7N−, from the reaction of sodium azide and sulphur in HMPA. Consistent with previous chemical investigations, the NMR data show that the S7N− and S2N2H− ions are thermally unstable with respect to the formation of SSNSS− and S3N3−, respectively, in solution. Solutions of S4(NH)4/4KNH2 or (NSCl)3/6KNH2 show the same two 14N or 15N NMR resonances at ca. +97 and −108 ppm as a solution of NSN2− in liquid ammonia. Keywords: sulphur–nitrogen anions, nitrogen NMR, liquid ammonia.

Vanadia Gel Synthesis via Peroxovanadate Precursors. 1. In Situ Laser Raman and51V NMR Characterization of the Gelation Process

2000 ◽  
Vol 104 (49) ◽  
pp. 11622-11631 ◽  
Author(s):  
Craig J. Fontenot ◽  
Jerzy W. Wiench ◽  
M. Pruski ◽  
G. L. Schrader
Keyword(s):  
Gelation Process ◽  
Laser Raman ◽  
Nmr Characterization

Revisiting the iridacycle-catalyzed hydrosilylation of enolizable imines

2018 ◽  
Vol 8 (24) ◽  
pp. 6316-6329
Author(s):  
Jorge Pèrez-Miqueo ◽  
Virginia San Nacianceno ◽  
F. Borja Urquiola ◽  
Zoraida Freixa
Keyword(s):  
Nmr Spectroscopy ◽  
H Nmr

In situ1H NMR spectroscopy reveals a cascade mechanism for the hydrosilylation of enolizable imines catalyzed by iridium(iii) metallacycles.

In-depth NMR and IR study of the proton transfer equilibrium between [{(MeC(CH2PPh2)3}Ru(CO)H2] and hexafluoroisopropanol

2001 ◽  
Vol 79 (5-6) ◽  
pp. 479-489 ◽  
Author(s):  
Vladimir I Bakhmutov ◽  
Ekaterina V Bakhmutova ◽  
Natalia V Belkova ◽  
Claudio Bianchini ◽  
Lina M Epstein ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Ir Spectroscopy ◽  
Proton Transfer ◽  
Proton Transfer Reaction ◽  
Proton Donor ◽  
Strong Hydrogen Bond ◽  
Nmr Study ◽  
Ir Study

The (carbonyl)dihydride complex [(triphos)Ru(CO)H2] (2) has been synthesized by reaction of the ruthenate [(triphos)RuH3]K (triphos = MeC(CH2PPh2)3) with ethanol saturated with CO. A single crystal X-ray analysis and IR and NMR experiments have shown that 2 adopts in both the solid state and solution an octahedral coordination geometry with a facial triphos ligand, two cis terminal hydrides, and a terminal carbonyl. The reaction of hexafluoro-2-propanol (HFIP) with 2 has been studied in CH2Cl2 solution by IR and NMR spectroscopy. The proton donor interacts with a terminal hydride of 2 forming a rather strong hydrogen bond. The resulting H-bonded adduct [{(triphos)Ru(CO)(H)H}···{HOCH(CF3)2}] (2a) has fully been characterized by in situ NMR and IR techniques. Compound 2a is in equilibrium with the nonclassical η2-H2 complex [(triphos)Ru(CO)H(H2)]+ (2b), which can independently be prepared by protonation of 2 with a strong protic acid at low temperature. Unequivocal characterization of the dihydrogen complex (2b) has been achieved by a multifaceted spectroscopic investigation (Tobs1min = 0.005 s (200 MHz), JH,D [Formula: see text] 30 Hz, DQCC = 78.3 kHz). A combined IR and NMR study of the proton transfer reaction involving 2 and HFIP in CH2Cl2 to give, first, the H-bonded adduct (2a) and, then, the dihydrogen complex (2b) has demonstrated that all these species are in equilibrium in the temperature range from 190 to 260 K. The thermodynamic parameters for the formation of 2a have independently been determined by NMR and IR methods, while those for the formation of 2b have been obtained by IR spectroscopy. An energetic profile for the reaction sequence 2 [Formula: see text] 2a [Formula: see text] 2b is proposed and discussed.Key words: hydrides, hydrogen bonding, ruthenium, IR spectroscopy, NMR spectroscopy.

scholarly journals In-Situ X-Ray Characterization of Fiber Structure during Melt Spinning

2008 ◽  
Vol 3 (3) ◽  
pp. 155892500800300 ◽  
Author(s):  
Michael S. Ellison ◽  
Paulo E. Lopes ◽  
William T. Pennington
Keyword(s):  
Melt Spinning ◽  
Simultaneous Detection ◽  
Polymer Melt ◽  
Polymer Chains ◽  
Degree Of Crystallinity ◽  
Structure Evolution ◽  
X Ray ◽  
Spinning Process

The properties of a polymer are strongly influenced by its morphology. In the case of fibers from semi-crystalline polymers this consists of the degree of crystallinity, the spacing and alignment of the crystalline regions, and molecular orientation of the polymer chains in the amorphous regions. Information on crystallinity and orientation can be obtained from X-ray analysis. In-situ X-ray characterization of a polymer during the melt spinning process is a major source of information about the effects of material characteristics and processing conditions upon structure evolution along the spinline, and the final structure and properties of the end product. We have recently designed and installed an X-ray system capable of in-situ analysis during polymer melt spinning. To the best of our knowledge this system is unique in its capabilities for the simultaneous detection of wide angle and small angle X-ray scattering (WAXS and SAXS, respectively), its use of a conventional laboratory radiation source, its vertical mobility along the spinline, and its ability to simulate a semi-industrial environment. Setup, operation and demonstration of the capabilities of this system is presented herein as applied to the characterization of the melt spinning of isotactic poly(propylene). Crystallinity and crystalline orientation calculated from WAXS patterns, and lamellar long period calculated from SAXS patterns, were obtained during melt spinning of the polymer along the spinline.

Synthesis and characterization of a new (phthalocyani-nato)bis(carboxylate) silicon(IV) compound with increased solubility

2002 ◽  
Vol 06 (03) ◽  
pp. 198-202 ◽  
Author(s):  
José L. Sosa-Sánchez ◽  
Alberto Galindo ◽  
Dino Gnecco ◽  
Sylvain Bernès ◽  
George R. Fern ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Structure Determination ◽  
Spectroscopic Characterization ◽  
X Ray Diffraction ◽  
H Nmr ◽  
Axial Ligands ◽  
Nmr Characterization ◽  
Soluble Silicon ◽  
Soluble Material

The synthesis and spectroscopic characterization of a new soluble silicon(IV) phthalocyanine complex is presented. The compound shows an increased solubility compared to its SiPcCl 2 precursor and this allowed solution 1 H NMR characterization. The assignment of the 1 H NMR signals for the axial ligands is greatly facilitated due to the anisotropic high ring current effects from the macrocycle. In addition, good quality crystals were grown from this more soluble material for molecular structure determination by single-crystal X-ray diffraction analysis. The molecular structure determination shows that the complex crystallizes in a non-centrosymmetric space group due to the inherent chirality of the naproxene ligands. Bond lengths and angles fit well to other analogous compounds previously reported.

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