13C NMR study of substituted quinone methides. 2- and 2,6-substituted fuchsones

1981 ◽  
Vol 46 (8) ◽  
pp. 1775-1787 ◽  
Author(s):  
Antonín Lyčka ◽  
Dobroslav Šnobl ◽  
Bohumír Koutek ◽  
Libuše Pavlíčková ◽  
Milan Souček
Keyword(s):  
13C Nmr ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Coupling Constants ◽  
Quinone Methides ◽  
Nmr Study ◽  
Related Compounds

Carbon-13 chemical shifts and 1J(CH) coupling constants for 11 fuchsones of the types I and II in deuteriochloroform are reported. The assignments are based on an analysis of proton coupled and proton decoupled spectra and on the analogy to chemical shifts of some structuraly related compounds. Satisfactory Swain-Lupton F and R correlations which were found for most of 13C chemical shifts afforded values for percent resonance contributions to transmission of substituent effects as follows, C(1), 19%; C(3), 71%; C(7), 43%. Some alternative correlations for other similar systems e.g. quinones and tropones are also given.

13C NMR study of 7,7-disubstituted quinone methides

1981 ◽  
Vol 46 (9) ◽  
pp. 2083-2090 ◽  
Author(s):  
Antonín Lyčka ◽  
Dobroslav Šnobl ◽  
Bohumír Koutek ◽  
Libuše Pavlíčková ◽  
Milan Souček
Keyword(s):  
Double Bond ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Exocyclic Double Bond ◽  
Carbonyl Carbon Atom ◽  
Resonance Contribution ◽  
Carbonyl Carbon ◽  
Quinone Methides ◽  
Total Transmission ◽  
Nmr Study

Carbon-13 chemical shift assignments for nine 7,7-disubstituted 2,6-ditert-butylquinone methides of the types III-VI are reported. The 13C shifts of the exocyclic double bond carbon atoms are extraordinarily sensitive to C(7) substitution, viz. ΔδC(7) = 82.4 ppm and ΔδC(4) = 56.7 ppm on going from the dimethylamino to the cyano substituent. In contrast, electronic properties of the substituents are only weakly expressed on the carbonyl carbon atom. Satisfactory Swain-Lupton correlations were found for C(1), C(2) and C(4) chemical shifts yielding more than 50% of resonance contribution to the total transmission of substituent effects. Intercorrelations between the exocyclic double bond carbon chemical shifts of quinone methides and of identically substituted fulvenes as well as styrenes are also presented.

13C NMR study of tetrosides and their derivatives

1980 ◽  
Vol 45 (10) ◽  
pp. 2779-2783 ◽  
Author(s):  
Jiří Urban ◽  
Miroslav Marek ◽  
Jiří Jarý ◽  
Petr Sedmera
Keyword(s):  
13C Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Direct Coupling ◽  
Coupling Constants ◽  
Anomeric Configuration ◽  
Nmr Study ◽  
C Nmr

13C NMR spectra of 23 tetrose derivatives were assigned. The C(1) resonates below 103 ppm with compounds having cis-arranged substituents at C(1) and C(2) and above 106 ppm with compounds having trans-arrangement. The carbon-13 chemical shifts are mainly influenced by the 1,2-interaction. The magnitudes of direct coupling constants 1J(C(1), H) cannot be used for the determination of the anomeric configuration.

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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