15N NMR spectra of wyosine (Y-nucleoside) triacetate and its 7-methyl congener. Chemical shifts and15N,1H coupling constants

1988 ◽  
Vol 26 (5) ◽  
pp. 435-438 ◽  
Author(s):  
C. Glemarec ◽  
G. Remaud ◽  
J. Chattopadhyaya
Keyword(s):  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
15N Nmr

1H, 13C and 15N NMR Spectra of Coupling Products of Benzenediazonium Salts with Aliphatic Nitro Compounds and Study of Their E/Z Isomerism

1996 ◽  
Vol 61 (4) ◽  
pp. 589-596 ◽  
Author(s):  
Antonín Lyčka
Keyword(s):  
Dimethyl Sulfoxide ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Nitro Compounds ◽  
Coupling Constants ◽  
15N Nmr ◽  
Geometrical Isomers ◽  
Sodium Salts ◽  
Aliphatic Nitro Compounds ◽  
Tautomeric Forms

The 1H, 13C and 15N NMR spectra have been measured of coupling products of benzenediazonium salts with nitromethane, nitroethane, 1-nitropropane, 2-nitroethanol and of their sodium salts, and the chemical shifts have been unambiguously assigned. The coupling products have been found to exist only in their hydrazone tautomeric forms. Stereospecific behaviour of the coupling constants 2J(15N,1H) and 2J(15N,13C) in the 15N isotopomers and NOESY have been used to differentiate between the E and Z geometrical isomers. The above-mentioned compounds exist as Z isomers in deuteriochloroform and predominantly (>95%) as E isomers in dimethyl sulfoxide, while the sodium salts are present only as E isomers in dimethyl sulfoxide.

13C and 15N NMR spectra of 3-methyl-1-phenylpyrazole-4,5-dione 4-(4'-substituted phenyl)hydrazones

1987 ◽  
Vol 52 (3) ◽  
pp. 727-735 ◽  
Author(s):  
Antonín Lyčka ◽  
Tibor Liptaj ◽  
Josef Jirman
Keyword(s):  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
15N Nmr ◽  
Substituent Constants ◽  
Phenyl Hydrazones

13C and 15N NMR spectra have been measured of eleven 3-methyl-1-phenylpyrazole-4,5-dione 4-(4'-substituted phenyl)hydrazones (I). The 13C chemical shifts of the non-substituted compound I have been assigned with the use of the 1J(13C, 13C) coupling constants obtained from the 1D-INADEQUATE spectrum. The greatest changes in chemical shifts of the compounds I connected with the substituent at 4'-position have been observed for the nitrogen atoms Nα, Nβ, N2 and carbon C(4). These substitution chemical shifts have been correlated with the substituent constants by means of the equations SCS = ρ1σ1 + ρRσR + const., where σR means one of the values σR0, σRBA, σR-, or σR+. The best correlations have been obtained for the combinations Nα - σRBA, Nβ - σR-, N2 - σR0, and C(4) - σR0. The 15N substituent chemical shifts of the nitrogen atoms Nα and Nβ of compounds I have been compared with the analogous values of 4-substituted trans-azobenzenes.

Some Applications of Ultrahigh Resolution 15N NMR Spectroscopy

1998 ◽  
Vol 53 (4) ◽  
pp. 411-415 ◽  
Author(s):  
Bernd Wrackmeyer ◽  
Ēriks Kupče
Keyword(s):  
Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Absolute Magnitude ◽  
Natural Abundance ◽  
Coupling Constants ◽  
15N Nmr ◽  
Ultrahigh Resolution ◽  
Tert Butyl ◽  
15N Nmr Spectroscopy

Abstract Ultrahigh resolution 15N NMR spectra were measured for two nitroalkanes (MeNO2 la, tBuNO2 1c), two isocyanates (tBuNCO 2c, Me3SiNCO 2d), four isothiocyanates (MeNCS 3a, EtNCS 3b, tBuNCS 3c, Me3SiNCS 3d), one carbodiimide (Me3SiNCNSiMe3 4d), one keteneimine [Me3SiNCC(SiMe3)2 5d], two sulphinyl imides (tBuNSO 6c, Me3SiNSO 6d), and N-tert-butyl-pyrrole 7c, in order to determine coupling constants J(15N ,I3C) and isotope induced chemical shifts 1∆12/13C (15N) at the natural abundance of the isotopes. The values 1∆12/13C (15N) can be separated into two groups, one dealing with NC single and another one with NC double bonds. In each group (with few exceptions), the values 1∆12/13C (15N) become more negative with a decrease in the absolute magnitude of l1J(l5N ,13C)l. The corresponding values 1∆14/15N (13C) show a sim ilar behaviour. However, N-substituted pyrroles appear to be exceptional in this respect.

13C and 15N NMR spectra of oximes prepared by nitrosation of activated methylene group

1990 ◽  
Vol 55 (1) ◽  
pp. 136-146 ◽  
Author(s):  
Josef Jirman ◽  
Antonín Lyčka ◽  
Miroslav Ludwig
Keyword(s):  
Dimethyl Sulfoxide ◽  
Ethyl Acetoacetate ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
15N Nmr ◽  
Carbonyl Groups ◽  
Nmr Chemical Shifts ◽  
Methylene Group ◽  
C Nmr

15N and 13C NMR spectra have been measured of the compounds type XC(=NOH)Y, where X, Y = COCH3, CN, COOR, CONHR, and X +Y = C6H4(CO)2. The (E)-(Z) isomerism at the C=NOH bond has been studied by means of 15N labelling and stereospecific behaviour of the 2J(15N, 13C) coupling constants. The nitrosation of methyl cyanoacetate gives specifically the respective (E)-oxime, whereas that of acetoacetanilide gives the (Z)-isomer. The nitrosation of ethyl acetoacetate gives both (E)- and (Z)-oximes in a ratio of ca 1:10; the (E)-isomer is less stable and is transformed into the (Z)-isomer. The applicability of the 1J(13C, 13C) coupling constants and lanthanoid shift reagents to the study of (E)-(Z) isomerism of oximes with geminal carbonyl groups has also been verified. The 15N NMR chemical shifts of the oximes studied correlate with their respective pKa values measured in dimethyl sulfoxide according to the equation pKa = -0.11δ15N + 13.44.

scholarly journals 15N—NMR-Spektroskopie bei Stickstoffwasserstoffsäure und Chlorazid / 15N NMR Spectroscopy at Hydrazoic Acid and Chlorine Azide

1978 ◽  
Vol 33 (9) ◽  
pp. 993-996 ◽  
Author(s):  
Joachim Müller
Keyword(s):  
Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
15N Nmr ◽  
Hydrazoic Acid ◽  
15N Nmr Spectroscopy

The 15N NMR spectra of HN3 and CIN3 solutions were recorded under triply labelled conditions. The chemical shifts and coupling constants are discussed with respect to the structure and in relation to other isoelectronic compounds.

13C and 15N NMR study of azo-hydrazone tautomerism in azo dyes containing amino or acetamido groups

1983 ◽  
Vol 48 (11) ◽  
pp. 3104-3111 ◽  
Author(s):  
Antonín Lyčka
Keyword(s):  
Temperature Dependence ◽  
Isotope Effect ◽  
Azo Dyes ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
15N Nmr ◽  
Nmr Study ◽  
Hydrazone Form

13C and 15N NMR spectra of ten model azo dyes containing NH2 or NHCOCH3 group in ortho- or para-position to the phenylazo group on benzene, naphthalene and anthracene skeleton were measured. A negligible content of the hydrazone form in these compounds follows from the 13C and 15N chemical shifts and from a slight temperature dependence of the 15N chemical shifts and 1J(15N15N) coupling constants. The 15N isotope effect Δδ (15N) = 0.1 ppm was observed and the values of 1J(15N15N) = 15.6 ± 0.3 Hz were found with compounds double labelled by 15N.

13C and 15N NMR studies of 2,3,4-pentanetrione 3-phenylhydrazone, dimethyl 2-phenylhydrazonopropanedioate and ethyl 2-phenylhydrazono-3-oxobutanoate

1980 ◽  
Vol 45 (12) ◽  
pp. 3354-3359 ◽  
Author(s):  
Antonín Lyčka
Keyword(s):  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
15N Nmr ◽  
Nmr Studies ◽  
Carbon And Nitrogen

The 13C AND 15N NMR spectra of 2,3,4-pentanetrione 3-phenylhydrazone, dimethyl 2-phenylhydrazonopropanedioate and ethyl 2-phenylhydrazono-3-oxobutanoate have been measured in deuteriochloroform at 30 °C. The carbon and nitrogen signals have been assigned, and the chemical shifts and coupling constants 1J(CH) have been determined. Ethyl 2-phenylhydrazono-3-oxobutanoate has been measured first as the (E) isomer and then as a mixture of the (E) and (Z) isomers. This compound has also been prepared with one or two 15N atoms enabling determination of absolute values of the coupling constants nJ(15N13C) and 1J(15N15N), respectively.

Carbon-13 and nitrogen-14 NMR spectra of 1-(substituted phenyl)pyridinium salts

1980 ◽  
Vol 45 (10) ◽  
pp. 2766-2771 ◽  
Author(s):  
Antonín Lyčka
Keyword(s):  
Heavy Water ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Pyridinium Salts ◽  
Nmr Signals ◽  
C Nmr

The 13C and 14N NMR spectra of 1M solutions of 1-(substituted phenyl)pyridinium salts (4-CH3, 4-OCH3, H, 4-Cl, 4-Br, 4-I, 3-NO2, 4-NO2, 2,4-(NO2)2 (the 13C NMR only)) have been measured in heavy water at 30 °C. The 13C and 14N chemical shifts, the 1J(CH) coupling constants, some 3J(CH) coupling constants, and values of half-widths Δ 1/2 of the 14N NMR signals are given. The 13C chemical shifts of C(4) correlate with the σ0 constants (δC(4) = (1.79 ± 0.097) σ0 + (147.67 ± 0.041)), whereas no correlation of the nitrogen chemical shifts with the σ constants has been found. The half-widths Δ 1/2 correlate with the σ0 constants (Δ 1/2 = (76.2 ± 4.9) σ0 + (106.4 ± 2.2)) except for 1-phenylpyridinium chloride.

The High Resolution NMR Spectra of Pesticides. II. The DDT-Type Compounds

1969 ◽  
Vol 52 (5) ◽  
pp. 1074-1092 ◽  
Author(s):  
L H Keith ◽  
A L Alford ◽  
A W Garrison
Keyword(s):  
Nuclear Magnetic Resonance ◽  
High Resolution ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Aromatic Rings ◽  
Nuclear Magnetic Resonance Spectra ◽  
High Resolution Nmr ◽  
Related Compounds ◽  
Deshielding Effect

Abstract The high resolution nuclear magnetic resonance spectra of the DDT class of pesticides and related compounds are discussed, including a study of the resonances of the aromatic protons as they are affected by various substiluents. The CCl3 moiety on the α-carbon strongly deshields the ortho protons on the aromatic rings, and this deshielding effect is greatly enhanced by substitution of a chlorine ortho rather than para on the aromatic ring. These deshielding effects are explained by a consideration of the electronegativity of the substituents and the stereochemistry of the molecule. The chemical shifts and coupling constants are tabulated.

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