scholarly journals Synthesis and crystal structures of multifunctional tosylates as basis for star-shaped poly(2-ethyl-2-oxazoline)s

2010 ◽  
Vol 6 ◽  
pp. 773-783 ◽  
Author(s):  
Richard Hoogenboom ◽  
Martin W M Fijten ◽  
Guido Kickelbick ◽  
Ulrich S Schubert
Keyword(s):  
Crystal Structures ◽  
Ring Opening ◽  
Functional Materials ◽  
Diode Array ◽  
X Ray ◽  
H Nmr ◽  
Tosyl Chloride ◽  
Array Detectors ◽  
Polymer Architectures ◽  
Cationic Ring Opening Polymerization

The synthesis of well-defined polymer architectures is of major importance for the development of complex functional materials. In this contribution, we discuss the synthesis of a range of multifunctional star-shaped tosylates as potential initiators for the living cationic ring-opening polymerization (CROP) of 2-oxazolines resulting in star-shaped polymers. The synthesis of the tosylates was performed by esterification of the corresponding alcohols with tosyl chloride. Recrystallization of these tosylate compounds afforded single crystals, and the X-ray crystal structures of di-, tetra- and hexa-tosylates are reported. The use of tetra- and hexa-tosylates, based on (di)pentaerythritol as initiators for the CROP of 2-ethyl-2-oxazoline, resulted in very slow initiation and ill-defined polymers, which is most likely caused by steric hindrance in these initiators. As a consequence, a porphyrin-cored tetra-tosylate initiator was prepared, which yielded a well-defined star-shaped poly(2-ethyl-2-oxazoline) by CROP as demonstrated by SEC with RI, UV and diode-array detectors, as well as by 1H NMR spectroscopy.

Synthesis and characterization of polyvinylmethylsiloxanes by cationic polymerization using a solid green catalyst

e-Polymers ◽  
2017 ◽  
Vol 17 (5) ◽  
pp. 439-448 ◽  
Author(s):  
Djamal Eddine Kherroub ◽  
Mohammed Belbachir ◽  
Saad Lamouri
Keyword(s):  
Ring Opening ◽  
Polymeric Materials ◽  
Synthesis And Characterization ◽  
Green Catalyst ◽  
Characterization Methods ◽  
H Nmr ◽  
New Strategy ◽  
Cationic Ring Opening Polymerization ◽  
C Nmr

AbstractThe present work is devoted to the synthesis and characterization of vinylsiloxane polymers produced by the use of an activated natural catalyst known as Maghnite-H+. The cationic ring opening polymerization of pentavinylpentamethylcyclopentasiloxane (V5D5) made it possible to obtain the desired polymeric materials. Through this study, we have adapted a new strategy of synthesis of a siloxane polymer with relatively high molecular mass, using a solid initiator activated by sulfuric acid, which has enabled us to combine the ecological aspect of synthesis and the effectiveness of the catalyst in this kind of reaction. Structural [infrared (IR), proton and carbon nuclear magnetic resonance (1H NMR and 13C NMR)], thermal differential scanning (DSC) and chromatographic (GPC) characterization methods have allowed the products obtained to be identified and their various properties to be focused on. The kinetic study was made to determine the order of the reaction. The proposed reaction mechanism shows the advantages of Maghnite-H+.

Formation of L‐Threonic Acid from L‐Ascorbic Acid Oxidative Ring Opening and its Coordination to PtII: X‐ray Crystal Structures of [Pt(threonato‐O,O′)(PPh3)2] and [Pt(oxalato)(PPh3)2]

2008 ◽  
Vol 2008 (19) ◽  
pp. 3056-3061 ◽  
Author(s):  
Paola Bergamini ◽  
Elena Marchesi ◽  
Andrea Marchi ◽  
Valerio Bertolasi ◽  
Marco Fogagnolo ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Crystal Structures ◽  
Ring Opening ◽  
X Ray ◽  
Threonic Acid

Pd(II) and Pt(II) Complexes of 1,2-Bis(pyridin-2-yl)ethane-N,N'

1994 ◽  
Vol 49 (6) ◽  
pp. 844-848 ◽  
Author(s):  
A. McFarlane ◽  
J. R. Lusty ◽  
J. J. Fiol ◽  
A. Terrón ◽  
E. Molins ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Spectroscopic Data ◽  
Low Energy ◽  
X Ray ◽  
H Nmr ◽  
Direct Bond ◽  
Structures And Properties ◽  
C Nmr

X-ray crystal structures and properties of the two Pd(II) and Pt(II) complexes [bpeH2][PdCl4] and [Pt(bpe)Cl2], [bpe = 1,2-bis(pyridin-2-yl)ethane] are described and correlated with the IR and 1H NMR/13C NMR spectroscopic data. In the case of the Pt(II) complex, the 1,2-bis(pyridin-2-yl)ethane is bound to the metal by the heterocycle nitrogen atoms but no direct bond is found in the case of the Pd(II) complex. The ligand exhibits low energy geometries in both compounds: the cis-conformation in the Pt(II) complex, and the transconformation in the Pd(II) complex

New polymer architectures by cationic ring-opening polymerization

2000 ◽  
Vol 153 (1) ◽  
pp. 209-216 ◽  
Author(s):  
E.J. Goethals ◽  
M. Dubreuil ◽  
Y. Wang ◽  
I. De Witte ◽  
D. Christova ◽  
...  
Keyword(s):  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Polymer Architectures ◽  
Cationic Ring Opening Polymerization

Novel surface treatment for natural fiber composites

2017 ◽  
Vol 31 (16-19) ◽  
pp. 1744092 ◽  
Author(s):  
Wendy Zhang ◽  
Xiaowen Yuan
Keyword(s):  
Ring Opening ◽  
Natural Fiber ◽  
Fiber Composites ◽  
Proton Nuclear Magnetic Resonance ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Dsc Studies ◽  
Flax Fibers ◽  
H Nmr

Poly(lactide) (PLA) — flax fibers stereocomplex composites were prepared by casting commercial poly(L-lactide) (PLA) and flax-g-poly(D-lactide) (flax-g-PDLA), where flax-g-PDLA was synthesized via ring-opening polymerization. Successful surface grafting was revealed by Proton Nuclear Magnetic Resonance (1H NMR) spectroscopy, wide angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC) studies. DSC results showed that stereocomplex crystallites formed between the PLA matrix and flax-g-PDLA, resulting in good fiber/PLA interfacial adhesion.

Assigning structures to diastereomeric aliphatic α,α'-dibromo ketones

2002 ◽  
Vol 80 (4) ◽  
pp. 413-417 ◽  
Author(s):  
Masood Parvez ◽  
SM Humayan Kabir ◽  
Ted S Sorensen ◽  
Fang Sun ◽  
Brian Watson
Keyword(s):  
Liquid Chromatography ◽  
Key Words ◽  
Crystal Structures ◽  
Chemical Shifts ◽  
Gas Liquid Chromatography ◽  
X Ray ◽  
Nmr Chemical Shifts ◽  
H Nmr ◽  
Dibromo Ketones

X-ray crystal structures are reported for two symmetrical aliphatic α,α'-dibromo ketones: a meso diastereomer of 3,5-dibromo–2,2,6,6-tetramethylheptan-4-one, and a rac isomer of 4,6-dibromo–2,2,3,3,7,7,8,8-octamethylnonan-5-one. Using these secure assignments and a previously confirmed structure for the diastereomers of 2,4-dibromopentan-3-one, we show in this study that gas-liquid chromatography (GLC) retention times (meso > rac) can be used to confidently assign the diastereomers for a range of symmetrical and unsymmetrical aliphatic α,α'-dibromo ketones. 1H NMR chemical shifts for the >CHBr hydrogen(s) can also be corroboratively used for assignment purposes (δracH > δmesoH).Key words: α,α'-dibromo ketones, X-ray crystal structures, GLC retention times, isomer assignment

Synthesis and characterization of [MII(bqb)] (M = Co, Ni, Cu), [N(n-Bu)4][CoIII(bqb)(CN)2], and [N(n-Bu)4][CoIII(bqb)(N3)2] containing deprotonated N,N'-bis(2-quinolinecarboxamide)-1,2-benzene (bqb) – X-ray crystal structures of [NiII(bqb)] and [N(n-Bu)4][CoIII(bqb)(N3)2]

2006 ◽  
Vol 84 (7) ◽  
pp. 971-978 ◽  
Author(s):  
Soria Meghdadi ◽  
Mehdi Amirnasr ◽  
Vratislav Langer ◽  
Alison Zamanpoor
Keyword(s):  
Crystal Structures ◽  
Molecular Structures ◽  
Monoclinic Space Group ◽  
Space Group ◽  
X Ray ◽  
X Ray Crystallography ◽  
H Nmr ◽  
Square Planar ◽  
Distorted Octahedral ◽  
Elemental Analyses

Cobalt(II), nickel(II), copper(II), and two cobalt(III) complexes of a new dianionic ligand, bqb, [H2bqb = N,N'-bis(2-quinolinecarboxamide)-1,2-benzene] have been synthesized and characterized by elemental analyses, IR, and 1H NMR spectroscopy. The crystal and molecular structures of the [Ni(bqb)] (2) and [N(n-Bu)4][CoIII(bqb)(N3)2] (5) complexes were determined by X-ray crystallography. Complex 2 crystallizes in the monoclinic space group C2/c with a distorted square-planar structure including two short Ni–N (1.848 Å) and two long Ni–N (1.958 Å) bonds. The structure consists of sheets formed in the plane parallel to the b axis and diagonal to vectors a and c by intermolecular hydrogen bonds. Complex 5 crystallizes in the monoclinic space group C2 with a distorted octahedral structure. The [N(n-Bu)4]+ ion is disordered at the C3A and C4A atoms of one Bu. The IR and 1H NMR spectra of the complexes are also discussed.Key words: N4-dianionic amido ligand (bqb), (bqb) complexes of Co(II), Ni(II), Cu(II), and Co(III), azide, cyanide, X-ray crystal structures.

Iridium(I) complexes containing bidentate pyrazolylgallate ligands. X-ray crystal structures of [Me2Gapz2]Ir(COD), [Ir(μ-pz)(CO)2]2, and [Ir(μ-3,5-Me2pz)(CO)2]2

1985 ◽  
Vol 63 (3) ◽  
pp. 692-702 ◽  
Author(s):  
Sophia Nussbaum ◽  
Steven J. Rettig ◽  
Alan Storr ◽  
James Trotter
Keyword(s):  
Crystal Structures ◽  
Variable Temperature ◽  
Hydrogenation Reaction ◽  
Synthesis And Characterization ◽  
Nmr Studies ◽  
X Ray ◽  
H Nmr ◽  
Measurable Activity

The synthesis and characterization of a number of Ir(I) complexes incorporating bidentate, chelating, pyrazolylgallate ligands are described. Non-rigidity for some of the complexes in solution has been demonstrated by variable temperature 1H nmr studies. Crystal structures of three complexes, [Me2Gapz2]Ir(COD), [Ir(μ-pz)(CO)2]2, and [Ir(μ-3,5-Me2pz)(CO)2]2 are reported and confirm the expected boat conformations for the six-membered M—(N—N)2—Ir rings (where M = Ir or Ga) in the compounds. One of the complexes studied has exhibited measurable activity as a catalyst in the hydrogenation reaction of cyclohexene.

Synthesis, structure, and properties of the hexagermane Pri3Ge(GePh2)4GePri3

2014 ◽  
Vol 92 (6) ◽  
pp. 533-541 ◽  
Author(s):  
Kimberly D. Roewe ◽  
James A. Golen ◽  
Arnold L. Rheingold ◽  
Charles S. Weinert
Keyword(s):  
Physical Properties ◽  
Crystal Structures ◽  
Ring Opening ◽  
Polarized Light ◽  
Structure And Properties ◽  
Opposite Orientation ◽  
X Ray ◽  
Pale Yellow ◽  
Deep Blue ◽  
Irreversible Oxidation

The synthesis of the hexagermane Pri3Ge(GePh2)4GePri3 was achieved starting from the cyclotetragermane (Ph2Ge)4. Ring-opening of (Ph2Ge)4 with Br2 yielded Br(GePh2)4Br that was converted to H(GePh2)4H, and this material was treated with two equiv. of Pri3GeNMe2 to furnish Pri3Ge(GePh2)4GePri3 via the hydrogermolysis reaction. The X-ray crystal structures of (Ph2Ge)4, Br(GePh2)4Br and Pri3Ge(GePh2)4GePri3 were determined. The hexagermane Pri3Ge(GePh2)4GePri3 represents the longest structurally characterized linear oligogermane reported to date and exhibits physical properties that resemble those of the larger polygermane systems. The hexagermane is luminescent and interacts with polarized light, appearing pale yellow under one orientation of polarized light and deep blue under the opposite orientation. The electrochemistry of Pri3Ge(GePh2)4GePri3 was also explored, and this species exhibits the expected five irreversible oxidation waves.

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