Carbonyl halides of the Group 6 transition metals. VI. Complexes with Bis(diphenylphosphino)methane

1968 ◽  
Vol 21 (5) ◽  
pp. 1143 ◽  
Author(s):  
MW Anker ◽  
R Colton ◽  
IB Tomkins
Keyword(s):  
Molecular Weight ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Transition Metals ◽  
Monodentate Ligand ◽  
Monomeric Complex ◽  
Group 6 ◽  
Nuclear Magnetic

Complexes of the type MX2(CO)2 diphos2 [M = Mo, W; X = Cl, Br; diphos = bis(diphenylphosphino)methane] have been prepared and characterized. The complexes are neutral, diamagnetic, seven-coordinate species with one of the diphosphine molecules acting as a monodentate ligand. Nuclear magnetic resonance, conductance, and molecular weight studies support this view. The monomeric complex MoBr2(CO)3 diphos has also been prepared.

scholarly journals Cleavage of the Graft Bonds in PVDF–g–St Films by Boiling Xylene Extraction and the Determination of the Molecular Weight of the Graft Chains

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1098 ◽  
Author(s):  
Chen ◽  
Seko
Keyword(s):  
Molecular Weight ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Thermal Degradation ◽  
Gel Permeation Chromatography ◽  
Extraction Time ◽  
Gel Permeation ◽  
Irradiation Graft ◽  
Nuclear Magnetic

To determine the molecular weight of graft chains in grafted films, the polystyrene graft chains of PVDF–g–St films synthesized by a pre-irradiation graft method are cleaved and separated by boiling xylene extraction. The analysis of the extracted material and the residual films by FTIR, nuclear magnetic resonance (NMR), and gel permeation chromatography (GPC) analyses indicates that most graft chains are removed from the PVDF–g–St films within 72 h of extraction time. Furthermore, the molecular weight of the residual films decreases quickly within 8 h of extraction and then remains virtually unchanged up to 72 h after extraction time. The degradation is due to the cleavage of graft bonds, which is mainly driven by the thermal degradation and the swelling of graft chains in solution. This allows determination of the molecular weight of graft chains by GPC analysis of the extracted material. The results indicate that the PVDF–g–St prepared in this study has the structure where one or two graft chains hang from each PVDF backbone.

Structural studies of the capsular polysaccharide from Haemophilus pleuropneumoniae serotype 2

1987 ◽  
Vol 65 (5) ◽  
pp. 414-422 ◽  
Author(s):  
Eleonora Altman ◽  
Jean-Robert Brisson ◽  
Malcolm B. Perry
Keyword(s):  
Molecular Weight ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
High Molecular Weight ◽  
Capsular Polysaccharide ◽  
Structural Studies ◽  
High Molecular Weight Polymer ◽  
Molecular Weight Polymer ◽  
Structure Formula ◽  
Nuclear Magnetic

The capsular polysaccharide of Haemophilus pleuropneumoniae serotype 2 (ATCC 27089) is composed of D-glucose (two parts), D-galactose (one part), glycerol (one part), and phosphate (one part). Hydrolysis, dephosphorylation, methylation, enzymic studies, and 1H and 13C nuclear magnetic resonance experiments showed that the polysaccharide is a high molecular weight polymer of a tetrasaccharide repeating units, linked by monophosphate diester and having the following structure:[Formula: see text]

The high molecular weight polyphloroglucinols of the marine brown alga Fucusvesiculosus L. 1H and 13C nuclear magnetic resonance spectroscopy

1985 ◽  
Vol 63 (2) ◽  
pp. 304-313 ◽  
Author(s):  
A. Gavin McInnes ◽  
Mark A. Ragan ◽  
Donald G. Smith ◽  
John A. Walter
Keyword(s):  
Molecular Weight ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Nuclear Magnetic Resonance Spectroscopy ◽  
High Molecular Weight ◽  
Resonance Spectroscopy ◽  
13C Nuclear Magnetic Resonance ◽  
Before And After ◽  
Nuclear Magnetic

1H and 13C nuclear magnetic resonance spectroscopy of the high-molecular-weight (> 104) polyphenol fraction from Fucusvesiculosus, before and after acetylation or methylation, demonstrates that it is composed of phloroglucinol units (48.9 ± 3.5%) and 2,2′,4,4′,6,6′-hexahydroxybiphenyl, 2,2′,2″,4,4′,4″,6,6′,6″-nonahydroxy-1,1′:3′1″-terphenyl, and related quater-and polyphenyl groups (together, 51.1 ± 3.5%) linked by ether bonds, each bond involving the carbinol and methine carbons of different units and the formal loss of a molecule of hydrogen. The polymer is highly branched, with ca. 20 – 22% of the constituent units being chain termini; there is no evidence for large rings of units. Approximately 5 – 10% of the phloroglucinol and 54 – 82% of the directly bonded units occur on the exterior of the molecule, whereas the interior backbone consists predominantly of ether-linked phloroglucinol units.

Reaction of glyoxal at the ortho position of phenols. Synthesis of 5a,10b-dihydrobenzofuro[2,3-b]benzofurans and 2-(3-benzofuranyl)phenols

1967 ◽  
Vol 45 (15) ◽  
pp. 1777-1784 ◽  
Author(s):  
E. C. M. Coxworth
Keyword(s):  
Molecular Weight ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Ortho Position ◽  
Acidic Media ◽  
Nuclear Magnetic Resonance Spectra ◽  
Acid Catalyzed ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

The acid-catalyzed reaction of glyoxal at the ortho position of phenols has been shown to yield, as initial products, substituted 5a,10b-dihydrobenzofuro[2,3-b]benzofurans, such structures being indicated by the nuclear magnetic resonance spectra, and confirmed in several cases by synthesis via an unambiguous route. At higher temperatures in acidic media, and in the absence of glyoxal, these initial products were converted into the corresponding 2-(3-benzofuranyl)phenols. When glyoxal was present in acidic media, the 2-(3-benzofuranyl)phenols reacted further to give unidentified products of appreciably higher molecular weight.

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