Cyclononatrienes vs. dihydroanthracenes

1970 ◽  
Vol 48 (22) ◽  
pp. 3591-3592 ◽  
Author(s):  
Robert R. Fraser ◽  
Adel Juraydini
Keyword(s):  
Coupling Constants ◽  
Mass Spectral ◽  
Geminal Coupling ◽  
Derivatives Of

This paper provides evidence that three compounds previously assumed to be methoxyl derivatives of dihydroanthracenes (1) are actually cyclononatriene derivatives. The revised structural assignments, made on the basis of mass spectral and n.m.r. evidence, remove a previous inconsistency in their n.m.r. properties. The constancy of geminal coupling constants in all three cyclononatrienes is discussed.

Conformational Studies on 1,3-Dioxepanes. Part IV. Applications of Geminal Coupling Constants to Conformational Analysis of 1,3-Dioxepanes

1974 ◽  
Vol 52 (24) ◽  
pp. 4062-4071 ◽  
Author(s):  
T. Bruce Grindley ◽  
Walter A. Szarek
Keyword(s):  
Conformational Analysis ◽  
Coupling Constants ◽  
Conformational Studies ◽  
Vicinal Coupling Constants ◽  
Geminal Coupling ◽  
Derivatives Of ◽  
Acetal Carbon

The magnitude of —OCH2O— group geminal H,H coupling contants, the size of the vicinal coupling constants, and the tenets of conformational analysis were used to establish that in solution the conformation of the 1,3-dioxepane rings in derivatives of 1,3:2,5-di-O-methylenemannitol and 2,5-O-methylenemannitol is predominantly the twist-chair in which the C2 axis passes through the acetal carbon.

Magnetic non-equivalence of fluorine atoms of a trifluoromethyl group

1982 ◽  
Vol 60 (19) ◽  
pp. 2451-2455 ◽  
Author(s):  
Mohsin A. Khan ◽  
Donald F. Tavares ◽  
Arvi Rauk
Keyword(s):  
Methoxy Group ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Trifluoromethyl Group ◽  
Single Bond ◽  
Hindered Rotation ◽  
Geminal Coupling ◽  
Coupling Pattern ◽  
Derivatives Of

The three fluorine atoms of N,N-dialkyl amide and chloride derivatives of 2-methoxy-2-phenyl-3,3,3-trifluoropropanoic acid are magnetically nonequivalent below –60 °C and exhibit a clear ABC coupling pattern from which chemical shifts and geminal coupling constants are readily derived. The chemical shifts span a range of about 10 ppm and the geminal coupling constants average about 110 Hz. A five bond coupling of about 5 Hz is observed between the hydrogens of the methoxy group and one of the nonequivalent fluorine atoms of the trifluoromethyl group. Barriers to the hindered rotation about the single bond to the trifluoromethyl group are in the range 36–46 kJ/mol.

Derivatives of 1-Phenylphthalan, 2-Methyl-1-phenylisoindoline, and 5H-Dibenzo[a,d]cycloheptene Oxides; Synthesis and Conformational Aspects

1971 ◽  
Vol 49 (5) ◽  
pp. 746-754 ◽  
Author(s):  
Robert R. Fraser ◽  
Roger N. Renaud
Keyword(s):  
Chemical Shifts ◽  
Coupling Constants ◽  
Ring Systems ◽  
Geometrical Properties ◽  
Geminal Coupling ◽  
Derivatives Of ◽  
Substituted 1

For the purpose of correlation of chemical shifts and geminal coupling constants with stereochemistry a number of compounds of fixed geometry have been synthesized. These include seven 6-substituted 1-phenylphthalans, five 6-substituted 2-methyl-1-phenylisoindolines, and six 2-substituted 5H-dibenzo-[a,d]cycloheptene oxides. The geometrical properties of the three ring systems are discussed and arguments in favor of a quasi-equatorial epoxide substituent in the latter series are supported by n.O.e. measurements.

scholarly journals Interaction of Fullerenes with Organosilanes in the Ionization Chamber of a Mass Spectrometer under Electron Impact and the Reaction of C60with Tetraphenylsilane in Solution under UV Irradiation

2016 ◽  
Vol 2016 ◽  
pp. 1-9
Author(s):  
Yury I. Lyakhovetsky ◽  
Elena A. Shilova ◽  
Alexandra P. Pleshkova ◽  
Alexander I. Belokon ◽  
Sergey O. Yakushin ◽  
...  
Keyword(s):  
Electron Impact ◽  
Mass Spectrometer ◽  
Uv Irradiation ◽  
Ionization Chamber ◽  
Ion Source ◽  
Organic Radicals ◽  
Mechanistic Study ◽  
Mass Spectral ◽  
Additional Support ◽  
Derivatives Of

C60was shown to react with organosilanes Me4Si, Ph2SiH2, Ph2MeSiH, Ph4Si, andα-naphthylphenylmethylsilane in the electron ionization ion source of a mass spectrometer with the transfer of the corresponding organic radicals (Me, Ph, andα-naphthyl) from the silanes to the fullerene. The reactions were accompanied by hydrogen addition to some products and hydrogen loss from them. C70reacted with Me4Si analogously. A reaction mechanism involving homolytic dissociation of the silanes under electron impact to the corresponding organic radicals, which react further with C60at the surface of the ionization chamber of the mass spectrometer to give the respective adducts, was offered. A mechanistic study of the reaction of C60with Me4Si supported it. No silicon containing derivatives of the fullerenes were found. C60reacted with Ph4Si in solution under UV irradiation in a similar fashion furnishing phenyl derivatives of the fullerene. These results provide an additional support to the hypothesis formulated earlier thatthe homolytic reactive mass spectrometry of fullerenes (the reactions of fullerenes with other species in the ionization chambers of mass spectrometers and their mass spectral monitoring)can predict the reactivity of them toward the same reagents in solution to a significant extent.

Proton spin–spin coupling constants and intramolecular hydrogen bonding in bromine derivatives of 1,3-dihydroxybenzene

1976 ◽  
Vol 54 (14) ◽  
pp. 2228-2230 ◽  
Author(s):  
Ted Schaefer ◽  
J. Brian Rowbotham
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Proton Spin ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Hydroxyl Groups ◽  
Oh Groups ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling ◽  
Derivatives Of

The conformational preferences in CCl4 solution at 32 °C of the hydroxyl groups in bromine derivatives of 1,3-dihydroxybenzene are deduced from the long-range spin–spin coupling constants between hydroxyl protons and ring protons over five bonds. Two hydroxyl groups hydrogen bond to the same bromine substituent in 2-bromo-1,3-dihydroxybenzene but prefer to hydrogen bond to different bromine substituents when available, as in 2,4-dibromo-1,3-dihydroxybenzene. When the OH groups can each choose between two ortho bromine atoms, as in 2,4,6-tribromoresorcinol, they apparently do so in a very nearly statistical manner except that they avoid hydrogen bonding to the common bromine atom.

Nitrogen-15 coupling constants: Geminal coupling,2J(15NH), incis- andtrans-aldonitrones and vicinal coupling,3J(15NH), incis-andtrans-ketimines, oxaziridines and nitrones

1980 ◽  
Vol 14 (6) ◽  
pp. 528-533 ◽  
Author(s):  
Derek R. Boyd ◽  
Michael E. Stubbs ◽  
N. J. Thompson ◽  
Herman J. C. Yeh ◽  
Donald M. Jerina ◽  
...  
Keyword(s):  
Coupling Constants ◽  
Geminal Coupling
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