The Proton–Proton and Proton–Carbon-13 Spin–Spin Coupling Constants in 1,3-Dioxole and Bis-1,3-dioxolyl. Conformational Dependence

Abstract

. Can. J. Chem. 53, 2734Chem. 53, (1975.The carbon-13 satellite peaks in the proton magnetic resonance spectra of 1,3-dioxole and bis-1,3-dioxolyl are analyzed under single and double resonance conditions to yield the signs and magnitudes of proton-proton coupling constants over three, four, and five bonds, and of protonxarbon-13 coupling constants over one, two, and three bonds. The conformational behavior of bis-1,3-dioxolyl contrasts sharply with that of analogous sym-tetrasubstituted ethane derivatives. It is indicated that the two-bond proton-carbon-13 coupling in the ethanic fragment can be used for conformational analysis in a manner similar to vicinal proton-proton couplings. The vicinal three-bond protonxarbon-13 couplings are given for dihedral angles of 180 and 120" and their relative magnitudes are as expected from a Karplus relationship. The two-bond protonxarbon-13 coupling in the olefinic fragment is, at 20.0 Hz, the largest coupling known for such a bond.TED SCHAEFER, KALVIN CHUM, DAVID MCKINNON et M. S. CHAUHAN. Can. J. Chern. 53,2734Chern. 53, (1975.On a analysk les pics satellites causes par le 13C dans les spectres r.m.p. du dioxole et du bis-dioxolyl-1,3; utilisant des conditions de resonance simple et de resonance double, on a pu determiner le signe et I'amplitude des constantes de couplage proton-proton sur trois, quatre et cinq liens et les constantes de couplage proton-13C sur un, deux et trois liens. Le comportement conformationnel du bis-dioxolyl-1,3 est en opposition flagrante avec celui de dCrives analogues de 1'Cthane tetrasubstituk d'une facon symktrique. I1 ressort de ces travaux que le couplage proton-13C sur deux liens de la fraction Cthane pourrait &re utilise pour des besoins conformationnels de la mCme maniere que les couplages proton-proton vicinaux. On donne les couplages vicinaux proton-13C sur trois liens pour des angles dikdres de 180 et 120' et leurs amplitudes relatives correspondent a ce que I'on peut attendre a partir d'une relation de Karplus. Le couplage proton-13C sur deux liens du fragment olCfinique est de 20.0 Hz qui est la valeur la plus ClevCe connue pour un tel couplage.[Traduit par le journal]

Karplus-Type Equations for 1J(X−Y) in Molecules HmX−YHn: (X, Y = N, O, P, S)

“…The A−X−Y−B dihedral angle is determined by the orientation of A and B, but the coupling constants that depend on θ are not limited to 3 J (A−B), because 2 J (X−B), 2 J (A−Y), or even 1 J (X−Y) is possible. It is this last coupling constant 1 J (X−Y) that is the focus of this Letter.…”

The structure and purity of a reference dye standard used for quantification of C.I. Solvent Red 164 in fuels

“…To further study the purity of NIST SRM 2037 the intensities of the impurity resonances were compared to the one-bond 1 H-13 C Jcouplings (w160 Hz) due to naturally abundant carbon-13 in the 6.8-9.3 ppm region [19,20]. Since the natural abundance of 13 C is w1.1% and the concentration of NIST SRM is 2.89 mM, the integrated intensity of the 13 C-satellite resonances corresponds to a concentration of 0.015 mM.…”