Contribution to the structure of aluminium caprolactamate based on the study of infrared and proton magnetic resonance spectra

1979 ◽  
Vol 44 (9) ◽  
pp. 2772-2779 ◽  
Author(s):  
Otomar Kříž ◽  
Bohuslav Čásenský
Keyword(s):  
Magnetic Resonance ◽  
Low Temperature ◽  
Oxygen Atom ◽  
Proton Magnetic Resonance ◽  
Nmr Spectra ◽  
Membered Ring ◽  
Aluminium Atom ◽  
Molecular Weights ◽  
H Nmr

Aluminium caprolactamate (I) was prepared by the reaction of ε-caprolactam with isopropyliminoalane (II) in benzene. IR and 1H-NMR spectra of I in various solvents are described as well as low-temperature 1H-NMR spectra in hexane and dichlormethane. On the basis of these results together with the determination of molecular weights, structural arrangement was proposed for the dimer of I containing an eight-membered ring formed by two -O-C-N-bridges between aluminium atoms and two caprolactam ligands on each aluminium atom bonded through oxygen atom of carbonyl.

Conformations of Chlorophylls a and a′ and their Magnesium-Free Derivatives as Revealed by Circular Dichroism and Proton Magnetic Resonance

1981 ◽  
Vol 36 (8) ◽  
pp. 1000-1009 ◽  
Author(s):  
Paavo H. Hynninen ◽  
Gunnel Sievers
Keyword(s):  
Circular Dichroism ◽  
Magnetic Resonance ◽  
Electronic Absorption ◽  
Proton Magnetic Resonance ◽  
Nmr Spectra ◽  
Cd Spectra ◽  
Steric Strain ◽  
Methyl Group ◽  
H Nmr ◽  
Circular Dichroïsm

Abstract The electronic absorption (UV/VIS), circular dichroism (CD) and proton magnetic resonance (1H NMR) spectra have been recorded for C-10 epimeric chlorophylls a and a′, pheophytins a and a′ as well as pheophorbides a and a′. Although the epimers in each pair showed virtually identical UV/VIS spectra, their CD spectra were profoundly different and exhibited opposite signs at most wavelengths in the UV region. The differences were interpreted as arising, in part, from different C-10 configurations, and, in part, from conformational alterations induced by the steric strain in the crowded periphery of the macrocycle. The conformational alterations were also clearly indicated by the 1H NMR Δδ-values observed for the α,β and δ methine protons, the C-10 protons and most methyl group protons of the epimers in each pair. This was considered to imply changes in the geometry of the whole macrocycle. The Δδ-values were larger for the Mg-free epimers than for the chlorophyll epimers, which shows that the central Mg-atom makes the macrocycle more rigid. Correlations between the signs of the CD bands and configurations are discussed.

Aliphatic diazo compounds. XII. The synthesis of 5-endo-hetero-atom-substituted 3-diazo-2-norbornanones and the proton magnetic resonance spectra of these diazo ketones and their precursors

1979 ◽  
Vol 57 (13) ◽  
pp. 1656-1667 ◽  
Author(s):  
Peter Yates ◽  
Gordon F. Hambly
Keyword(s):  
Magnetic Resonance ◽  
Long Range ◽  
Proton Magnetic Resonance ◽  
Nmr Spectra ◽  
Steric Effect ◽  
Diazo Compounds ◽  
Lower Field ◽  
Methyl Group ◽  
H Nmr ◽  
Basic Alumina

Treatment of 6-endo-acetoxy-5,5-dimethyl-2,3-norbornanedione (6) with tosylhydrazine gives the 2-tosylhydrazone (7), which is converted to 5-endo-acetoxy-3-diazo-6,6-dimethyl-2-norbornanone (1) by basic alumina; the exclusive formation of the 2-tosylhydrazone is ascribed to the smaller steric effect of the endo C-6 acetoxyl relative to the endo C-5 methyl group. The 6-endo-methoxy analogue of 6, 17, and the related 6-endo-chloro- and 6-endo-bromo-1,5,5-trimethyl-2,3-norbornanediones (23 and 26) are similarly converted to the corresponding α-diazo ketones 2–4. The 1H nmr spectra of the diazo ketones 1–4 have their C-1 bridgehead proton signals shifted to higher field relative to the corresponding bridgehead proton signals of the related α-diketones, whereas the C-4 bridgehead proton signals of 1 and 2 are shifted to lower field in relation to the corresponding α-diketone signals. The 1H nmr spectra of the α-diketones show an unusual long range coupling (4J ≥ 1 Hz) between the C-4 bridgehead protons and the exo C-6 protons that is significantly smaller or absent in the spectra of the related diazo ketones and monoketones. In all of these types of compound an endo-methoxyl or -acetoxyl group at C-5(6) shifts the exo and endo C-6(5) methyl signals to lower and higher field, respectively, whereas an endo-halo substituent at C-5(6) shifts both the exo and endo C-6(5) methyl signals to lower field.

Zur Thermodynamik der hydrophoben Wechselwirkung; die Systeme Wasser + Glycin+ Harnstoff und Wasser + Alanin+ Harnstoff bei 25 °C / Thermodynamics of Hydrophobie Interaction in the Systems Water + Glycin + Urea and Water + Alanin + Urea at 25 °C

1973 ◽  
Vol 28 (9-10) ◽  
pp. 533-554 ◽  
Author(s):  
Lothar Rafflenbeul ◽  
Wa-Ming Pang ◽  
Hansjürgen Schönert ◽  
Klaus Haberle
Keyword(s):  
Amino Acid ◽  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Pressure Measurements ◽  
Free Enthalpy ◽  
Heat Of Dilution ◽  
Ternary Solutions ◽  
Vapor Pressure Measurements ◽  
Calorimetric Determination

Abstract Isopiestic vapor pressure measurements and calorimetric determination of the heat of dilution have been performed and evaluated with respect to enthalpy, entropy and free enthalpy in the ternary solutions water+ glycin+ urea and water+ alanin + urea. The free enthalpy of transfer for the process: Amino acid from water to water+ urea, which can be derived from these measurements, does not agree with the value calculated from solubility measurements. The reason for this discrepancy and the values of entropy and enthalpy in terms of hydrophobic interaction are discussed. Supplementary measurements of the proton magnetic resonance in these solutions are included.

The solution conformation of prostacyclin as determined by high field proton magnetic resonance techniques

1980 ◽  
Vol 58 (10) ◽  
pp. 974-983 ◽  
Author(s):  
George Kotovych ◽  
Gerdy H. M. Aarts ◽  
Tom T. Nakashima ◽  
Glen Bigam
Keyword(s):  
Magnetic Resonance ◽  
Correlation Time ◽  
Proton Magnetic Resonance ◽  
Double Resonance ◽  
Relaxation Times ◽  
Segmental Motion ◽  
Solution Conformation ◽  
Nmr Spectrum ◽  
H Nmr ◽  
The Difference

The proton magnetic resonance (1H nmr) spectrum at 400 MHz of prostacyclin at pH 10.4 in glycine buffer has been completely analyzed utilizing homonuclear double resonance, inversion recovery, and difference nOe experiments. The spectral analysis shows that the two protons at C-4 are non-equivalent even though they are removed from the asymmetric centres at C-8 and C-9 by five bonds. The difference nOe measurements verify the configuration at C-5.Proton longitudinal relaxation times (T1) were measured at 400 and 200 MHz. From the T1 frequency dependence, effective rotational correlation times ranging from 2.3 × 10−10 to 3.0 × 10−10 s were calculated for H-5, H-9, H-11, and H-15. This indicates that the portion of the molecule encompassed by these protons has a longer correlation time than is observed for the C-2 and the C-17 to C-19 protons, for which the average correlation time is 1.2 × 10−10 s. Hence the aliphatic side chains have more segmental motion.

Magnetic resonance imaging (1H) and spectroscopy (1H, 31P) of growing chicken embryos

1993 ◽  
Vol 73 (4) ◽  
pp. 953-965 ◽  
Author(s):  
A. Lirette ◽  
Z. Liu ◽  
D. C. Crober ◽  
R. A. Towner ◽  
U. M. Oehler ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Magnetic Resonance ◽  
Nmr Spectra ◽  
Surface Coil ◽  
Nmr Imaging ◽  
Chicken Embryos ◽  
H Nmr ◽  
Imaging And Spectroscopy ◽  
Two Peaks

Nuclear magnetic resonance (NMR) imaging and spectroscopy techniques were used to observe in vivo anatomical and metabolite changes, respectively, in developing chicken embryos. Proton (1H) NMR images of the eggs revealed major changes in yolk shape from day 2 to day 6. Embryos were visible from day 6 to hatching, and good embryonic anatomical images were obtained. Two peaks were observed from 1H-NMR spectroscopy of fertilized eggs: one for lipid methylene protons, and one for water protons. Water peak to lipid peak ratios did not vary significantly (P > 0.05) from day 2 to day 21 of incubation. Localized 31P-NMR spectra of developing embryos were obtained with either a 31P surface coil or a double-tuned 31P/1H volume coil. The surface-coil method gave a greater signal to noise ratio by a factor of four. The 31P-NMR spectra indicated two peaks at day 2; these were attributed to phosphomonoesters and phosphodiesters. The three peaks characteristic of ATP appeared on day 11 and increased in size until hatching. From day 19, phosphocreatine was detectable. There appeared to be a good correlation between 31P-metabolite changes detected by in vivo 31P-NMR spectroscopy and literature values for biochemical analyses of developing chicken embryos. The advantage in using NMR imaging and spectroscopy techniques is that anatomical and metabolic changes can be obtained in vivo, non-invasively and repeatedly as an embryo develops. Key words: NMR, MRI, embryo, poultry

A 19F nuclear magnetic resonance study of the conjugate Brönsted-Lewis superacid HSO3F-SbF5. Part 1

1999 ◽  
Vol 77 (11) ◽  
pp. 1869-1886 ◽  
Author(s):  
Dingliang Zhang ◽  
Markus Heubes ◽  
Gerhard Hägele ◽  
Friedhelm Aubke
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nmr Spectra ◽  
Nuclear Magnetic Resonance Study ◽  
Magnetic Resonance Study ◽  
Formation Reaction ◽  
H Nmr ◽  
Acid Conjugate ◽  
Nmr Methods ◽  
Cis And Trans

The Brönsted-Lewis superacid HSO3F-SbF5 or "magic acid" is re-investigated by modern 19F NMR methods over a wide concentration range. The system is found to be considerably more complex than had been assumed previously. A total of 13 different anions are identified of which only five have previously been identified in magic acid. With increasing SbF5 contents the concentration of monomeric anions like [SbF6]-, [SbF5(SO3F)]-, cis- and trans-[SbF4(SO3F)2]-, and mer-[SbF3(SO3F)3]- gradually decreases. Except for [Sb2F11]-, which is present in very small concentrations only, the formation of oligomers involves exclusively μ-fluorosulfato bridges. In addition to donor (SO3F)- and acceptor (SbF5) complex formation to give [SbF5(SO3F)]- and possibly ligand redistribution, the solvolysis of SbF5 or SbF4(SO3F) in HSO3F appears to be the principal formation reaction for polyfluorosulfatofluoroantimonate(V) anions. In glass (NMR tubes) the solvolysis product HF is converted to the oxonium ion [H3O]+, which has previously been identified by 1H NMR and structurally characterized as [H3O][Sb2F11] by us.Key words: magic acid, conjugate superacid, fluorosulfuric acid, 19F NMR spectra.

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