Lewis acid complexes of 1,2-diketones and their derivatives. The synthesis of seven-membered rings

The structures and charge distributions of Lewis and complexes of butane-2,3-dione, 1, cyclohexane-1,2-dione, 2, and 2-methoxycyclohex-2-en-1-one, 5, have been investigated by 1H nmr spectroscopy. A 1:1 complex was formed between 1 and SnCl4 which appeared to have a bridged structure. In the case of 2 and 5 both oxygens were again involved in complex formation with TiCl4 or SnCl4. In each case the large downfield shift of the vinyl proton resonance, H3, indicated extensive charge delocalization within the complexes and that these systems can be regarded as complexed α,β-unsaturated enones. The reactions of Lewis acid complexes of 2, 5, and the silyl ethers 2-(trimethylsiloxy)cyclohex-2-en-1-one, and 3-(trimethylsiloxy)-but-3-en-2-one, 11, with butadiene have been investigated. The acyclic enol ether 11 reacted with butadiene in the presence of either TiCl4 or SnCl4 to give products corresponding to both 4C + 3C and 4C + 2C cycloaddition reactions; in all other cases 4C + 2C products only could be isolated.

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Association between halothane and oxygenated solvents by 1H NMR spectroscopy

Canadian Journal of Chemistry ◽

10.1139/v95-175 ◽

1995 ◽

Vol 73 (9) ◽

pp. 1406-1411 ◽

Cited By ~ 8

Author(s):

Marcela Tkadlecová ◽

Jaroslav Havlíček ◽

Vladimír Dohnal

Keyword(s):

Nmr Spectroscopy ◽

Complex Formation ◽

Equilibrium Constants ◽

Solution Model ◽

Methyl Tert Butyl Ether ◽

Ideal Solution ◽

Butyl Ether ◽

Complex Formation Equilibria ◽

H Nmr ◽

Halothane Concentration

Using 1H NMR spectroscopy the complex-formation equilibria between halothane (2-bromo-2-chloro-1,1,1-trifluoroethane) and methyl tert-butyl ether or tetrahydrofuran in various inert solvents (hexane, heptane, decane, cyclohexane) were measured as a function of temperature. For two different association models (ideal solution and athermal solution), assuming only the formation of a 1:1 H-bonded complex, the equilibrium constants and the standard enthalpies of the complex-formation reaction were calculated. The ideal solution model provides values of the equilibrium constant that differ for different inert solvents. The athermal solution model makes this false solvent effect much smaller. For the low halothane concentration used, its dimerization was neglected. This assumption was verified experimentally. Keywords: 1H NMR, association, complex formation, halothane.

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The Basicity of Silylamines and Alkylamines: An Equilibrium Study of the Competitive Borane Adduct Formation

Zeitschrift für Naturforschung B ◽

10.1515/znb-1998-1005 ◽

1998 ◽

Vol 53 (10) ◽

pp. 1103-1108 ◽

Cited By ~ 4

Author(s):

Gerald Huber ◽

Hubert Schmidbaur

Keyword(s):

Nmr Spectroscopy ◽

Lewis Acid ◽

Quantum Chemical ◽

Adduct Formation ◽

Steric Effects ◽

Organic Amine ◽

Acid Base ◽

Equilibrium Study ◽

H Nmr ◽

Equilibrium Reactions

AbstractIn order to investigate the Lewis acid/base chemistry of silylamines in solution, the equilibrium reactions of Me3SiNMe2 / Me3SiNMe2(BH3) and different amines NR3 / amineboranes NR3(BH3) were monitored by 1H NMR spectroscopy in C6D6 and CDCI3 at 60 °C. For the equilibrium of the reference silylamine/-borane and Me3CNMe2 / Me3CNMe2(BH3) values K = 0.35 (AG = 3.1 kJ mol-1) in C6D6 and K = 0.50 (AG = 2.0 kJ mol-1) in CDCl3 have been estimated, showing that both the silylamine and the C/Si-analogous organic amine have very similar donor properties. Small amines like NMe3 proved to be much more powerful donors than the silylamine Me3SiNMe2, whereas bulky amines are less efficient donors, indicating that steric effects play an important role. The formation of BH3 adducts of Me2NSiH3 and (H3Si)3N which could not be followed experimentally owing to the low stability of the products, has been studied by quantum chemical calculations. A comparison with data for Me3N(BH3) shows that the silylamines are poorer donors, but the reason for this remains unclear

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Darstellung und Reaktionen der Oxovanadin(V)-tricarboxylate / Synthesis and Reactions of Oxovanadium(V) Tricarboxylates

Zeitschrift für Naturforschung B ◽

10.1515/znb-1980-0706 ◽

1980 ◽

Vol 35 (7) ◽

pp. 817-823 ◽

Cited By ~ 8

Author(s):

Fritz Preuss ◽

Willi Towae ◽

Joachim Woitschach

Keyword(s):

Nmr Spectroscopy ◽

Carboxylic Acid ◽

Complex Formation ◽

Chemical Reactions ◽

Acid Anhydride ◽

Carboxylate Ligands ◽

H Nmr ◽

Silver Carboxylate ◽

Carboxylic Acid Anhydride

Monomeric oxovanadium(V) tricarboxylates VO(RCOO)3 are prepared by reaction of VOCl3 with an excess of silver carboxylate in CH2Cl2 or by depolymerization of (VO2RCOO)n in carboxylic acid anhydride. Their properties are studied by IR and 1H NMR spectroscopy as well as by chemical reactions such as thermolysis, solvolysis, redistribution and complex formation. The structure of 2,2′-dipyridyl and 1,10-phenanthroline complexes [VO(RCOO)3 · B] (B = C10H8N2, C12H8N2) has been found to be octahedral with meridional arrangement of the carboxylate ligands. Syntheses of Na[VO(CH3COO)4] and Ba[VO2(CH3COO)3] · 2CH3COOH are described

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Conformational study on ribonucleoside O-phosphonylmethyl derivatives by 1H NMR spectroscopy

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19851899 ◽

1985 ◽

Vol 50 (8) ◽

pp. 1899-1905 ◽

Cited By ~ 4

Author(s):

Milena Masojídková ◽

Jaroslav Zajíček ◽

Miloš Buděšínský ◽

Ivan Rosenberg ◽

Antonín Holý

Keyword(s):

Nmr Spectroscopy ◽

1H Nmr ◽

1H Nmr Spectroscopy ◽

Conformational Study ◽

H Nmr ◽

Conformational Properties

Conformational properties of ribonucleoside 5'-O-phosphonylmethyl derivatives have been determined by 1H NMR spectroscopy and compared with those of natural nucleosides and 5'-nucleotides.

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Monitoring the encapsulation of chlorin e6 derivatives into polymer carriers by NMR spectroscopy

Journal of Porphyrins and Phthalocyanines ◽

10.1142/s1088424619501815 ◽

2019 ◽

Vol 23 (11n12) ◽

pp. 1576-1586 ◽

Cited By ~ 1

Author(s):

Sara Pfister ◽

Luca Sauser ◽

Ilche Gjuroski ◽

Julien Furrer ◽

Martina Vermathen

Keyword(s):

Relaxation Time ◽

Nmr Spectroscopy ◽

Core Region ◽

Chlorin E6 ◽

Polypropylene Glycol ◽

Polymer Carriers ◽

H Nmr ◽

Line Shape Analysis ◽

Dynamic Methods ◽

Derivatives Of

The encapsulation of five derivatives of chlorin e6 with different hydrophobicity and aggregation properties into a series of five poloxamer-type triblock copolymer micelles (BCMs) with varying numbers of polyethylene and polypropylene glycol (PEG, PPG) units was monitored using 1H NMR spectroscopy. NMR chemical shift and line shape analysis, as well as dynamic methods including diffusion ordered spectroscopy (DOSY) and T1 and T2 relaxation time measurements of the chlorin and the polymer resonances, proved useful to assess the chlorin–BCM compatibility. The poloxamers had high capability to break up aggregates formed by chlorins up to intermediate hydrophobicity. Physically entrapped chlorins were always localized in the BCM core region. The loading capacity correlated with chlorin polarity for all poloxamers among which those with the lowest number of PPG units were most efficient. DOSY data revealed that relatively weakly aggregating chlorins partition between the aqueous bulk and micellar environment whereas more hydrophobic chlorins are well retained in the BCM core region, rendering these systems more stable. T1 and T2 relaxation time measurements indicated that motional freedom in the BCM core region contributes to encapsulation efficiency. The BCM corona dynamics were rather insensitive towards chlorin entrapment except for the poloxamers with short PEG chains. The presented data demonstrate that 1H NMR spectroscopy is a powerful complementary tool for probing the compatibility of porphyrinic compounds with polymeric carriers such as poloxamer BCMs, which is a prerequisite in the development of stable and highly efficient drug delivery systems suitable for medical applications like photodynamic therapy of tumors.

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Different submicellar solubilization mechanisms revealed by 1H NMR and 2D diffusion ordered spectroscopy (DOSY)

Physical Chemistry Chemical Physics ◽

10.1039/d0cp00429d ◽

2020 ◽

Vol 22 (19) ◽

pp. 11075-11085

Author(s):

Mengjian Wu ◽

Zhaoxia Wu ◽

Shangwu Ding ◽

Zhong Chen ◽

Xiaohong Cui

Keyword(s):

Nmr Spectroscopy ◽

Sodium Dodecyl Sulfate ◽

1H Nmr ◽

Sodium Dodecyl ◽

Butyl Methacrylate ◽

H Nmr ◽

Molecular Scale ◽

Two Systems ◽

Dodecyl Sulfate ◽

Triton X

Different submicellar solubilization mechanisms of two systems, Triton X-100/tetradecane and sodium dodecyl sulfate (SDS)/butyl methacrylate, are revealed on the molecular scale by 1H NMR spectroscopy and 2D diffusion ordered spectroscopy (DOSY).

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Tautomerisation in 1-(4-Methylphenylazo)naphthalen-2-ol and 2-(4-Methylphenylazo)-4-methylphenol: A Crystallographic and 13C{1H}NMR Study

Journal of Chemical Research ◽

10.1177/174751989902300304 ◽

1999 ◽

Vol 23 (3) ◽

pp. 178-179

Author(s):

Wendy I. Cross ◽

Kevin R. Flower ◽

Robin G. Pritchard

Keyword(s):

Acetic Acid ◽

Nmr Spectroscopy ◽

Resonant Frequency ◽

X Ray Diffraction ◽

X Ray ◽

H Nmr ◽

Nmr Study ◽

Acetic Acid Esters ◽

Acid Esters ◽

Equivalent Carbon

The acetic acid esters of 1-(4-methylphenylazo)naphthalen-2-ol 1 and 2-(4-methylphenylazo)-4-methylphenol 3 are prepared and characterised by single crystal X-ray diffraction studies and 13C{1H}NMR spectroscopy; the position of the C(2)13C resonance for the ester is used to predict the position of resonant frequency of the equivalent carbon in the parent alcohols and hence, calculate the position of the azo-hydrazone equilibrium in these compounds.

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3-Hydroxy Retinal, a New Chromophore Identified in Insect Eyes: HPLC Separation and NMR Spectroscopic Identification of the Oxime Forms

Zeitschrift für Naturforschung C ◽

10.1515/znc-1988-5-626 ◽

1988 ◽

Vol 43 (5-6) ◽

pp. 473-475 ◽

Cited By ~ 2

Author(s):

Wolfgang Gärtner ◽

Anette Plangger

Keyword(s):

Nmr Spectroscopy ◽

Separation System ◽

Hplc Separation ◽

H Nmr ◽

Spectroscopic Identification

3-Hydroxy retinal acts as visual chromophore instead of retinal in the eyes of several insect orders. A HPLC separation system of the aldehyde and oxime isomers and their identification by 400 MHz 1H NMR spectroscopy is described.

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Water-soluble β-aminobisulfonate building blocks for pH and Cu2+ indicators

RSC Advances ◽

10.1039/c6ra17791c ◽

2016 ◽

Vol 6 (88) ◽

pp. 84712-84721 ◽

Cited By ~ 5

Author(s):

Maria A. Cardona ◽

Marina Kveder ◽

Ulrich Baisch ◽

Michael R. Probert ◽

David C. Magri

Keyword(s):

Nmr Spectroscopy ◽

Building Blocks ◽

Water Soluble ◽

Visible Absorption ◽

H Nmr ◽

Uv Visible

Two phenyl β-aminobisulfonate ligands characterised by UV-visible absorption, EPR and 1H NMR spectroscopy exhibit evidence for binding with Cu2+ in water and methanol.

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