Substituent Effects on the Acetyl Group Conformation and the Carbonyl Frequency in Acetophenones

The fundamental carbonyl stretching frequencies for o-, m-, and p-substituted acetophenones in dilute CCl4 solution are correlated with the electrophilic substituent constant σ+ by the expression vc=o (cm−1) = 11.53σ+ + 1691.5 (n = 27, correlation coefficient = 0.988, standard deviation = 1.2 cm−1). The frequencies of carbonyl groups trans to an o-substituent follow this correlation, assuming σo+ ≈ σp+, while those oriented cis to the substituent generally do not. Deviations from this correlation are interpreted in terms of dipole–dipole interactions, steric hindrance to planarity, intramolecular hydrogen bonding, and non-additivity of σ+ values for some combinations of substituents. The carbonyl frequencies for singly m- and p-substituted acetophenones are also correlated with the polar and resonance components of σ+ by the expression vc=o (cm−1) = 15.66σI + 10.99σR+ + 1689.8 (n = 13, correlation coefficient = 0.981, standard deviation = 0.9 cm−1). Thus the sensitivity of the carbonyl frequency to the polar effect is greater than to the resonance effect. In ω-substituted acetophenones no precise correlation with polar substituent constants is observed.

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Beziehungen zwischen Rotationsisomerie, Wasserstoffbrücken-Bindung und Substituenteneffekten der organischen Chemie / Relations between Rotational Isomerism, Hydrogen Bonding, and Substituent Effects in Organic Chemistry

Zeitschrift für Naturforschung B ◽

10.1515/znb-1972-0615 ◽

1972 ◽

Vol 27 (6) ◽

pp. 663-674 ◽

Cited By ~ 4

Author(s):

Gotthard H. Krause ◽

Herbert Hoyer

Keyword(s):

Hydrogen Bonding ◽

Substituent Effects ◽

Intramolecular Hydrogen Bonding ◽

Rotational Isomerism ◽

Proton Acceptor ◽

Single Bond ◽

Free Enthalpy ◽

Acceptor Group ◽

Intramolecular Hydrogen ◽

Derivatives Of

The change of free enthalpy involved in intramolecular hydrogen bonding is smaller if the proton acceptor group can rotate round a single bond, as compared to proton acceptor groups which are fixed in a position optimal for hydrogen bonding. Also, the free enthalpy change is altered when the rotation of the proton acceptor is sterically restricted. This is demonstrated by comparing the absorptions of carbonyl stretching vibrations in the infrared spectra of certain compounds showing rotational isomerism. In the present study derivatives of 5-hydroxy-2,2-dimethyl-6-carbomethoxychromanone- (4), 3-nitrosalicylaldehyde and 3-nitro-2-hydroxy-acetophenones substituted in the position 5 and 6 are examined.

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A Study of Transmission Effects of Sulfonyl and Carbonyl Groups

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19950841 ◽

1995 ◽

Vol 60 (5) ◽

pp. 841-850 ◽

Cited By ~ 2

Author(s):

Miroslav Ludwig ◽

Patrik Pařík ◽

Jiří Kulhánek

Keyword(s):

Latent Variables ◽

Dissociation Constants ◽

Substituent Effects ◽

Principal Component ◽

Carbonyl Groups ◽

H Nmr ◽

Deviation Analysis ◽

Substituent Constants ◽

The Difference ◽

Latent Structures

Seventeen p-substituted N-phenylsulfonylbenzamides of general formulas XC6H4SO2NHCOC6H5 and C6H5SO2NHCOC6H4X have been synthesized and their structure has been confirmed by elemental analysis and 1H NMR spectra. The dissociation constants of all the compounds have been measured by potentiometric titration in methanol, acetonitrile, dimethylformamide, dimethyl sulfoxide, and pyridine. The obtained pKHA values have been correlated with three sets of Hammett substituent constants using simple or double linear regression. The solvent and substituent effects are discussed on the basis of experimental results, and the difference between the substituent effects from sulfonamide and benzamide sections is evaluated. It has been found that due to the extensive delocalization of negative charge in the conjugated base the transmission effects of carbonyl and sulfonyl groups on the transmission of substituent effect are roughly the same. The experimental data have been interpreted by the methods with latent variables: the principal component analysis (PCA), the conjugated deviation analysis (CDA), and the method of projection to latent structures (PLS). The results obtained by these procedures were similar.

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Substituent effects of nitro group in cyclic compounds

Structural Chemistry ◽

10.1007/s11224-020-01612-x ◽

2020 ◽

Vol 32 (1) ◽

pp. 179-203 ◽

Cited By ~ 1

Author(s):

Anna Jezuita ◽

Krzysztof Ejsmont ◽

Halina Szatylowicz

Keyword(s):

Nitro Group ◽

System Analysis ◽

Inductive Effect ◽

Resonance Effect ◽

Substituent Effects ◽

Electron Delocalization ◽

High Electron ◽

Aromatic Character ◽

Substituent Constants ◽

Cyclic Compounds

AbstractNumerous studies on nitro group properties are associated with its high electron-withdrawing ability, by means of both resonance and inductive effect. The substituent effect of the nitro group may be well described using either traditional substituent constants or characteristics based on quantum chemistry, i.e., cSAR, SESE, and pEDA/sEDA models. Interestingly, the cSAR descriptor allows to describe the electron-attracting properties of the nitro group regardless of the position and the type of system. Analysis of classical and reverse substituent effects of the nitro group in various systems indicates strong pi-electron interactions with electron-donating substituents due to the resonance effect. This significantly affects the pi-electron delocalization of the aromatic ring decreasing the aromatic character, evidenced clearly by HOMA values. Use of the pEDA/sEDA model allows to measure the population of electrons transferred from the ring to the nitro group.

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NMR of Enaminones Part 3—1H,13C and17O NMR Spectroscopic Studies of Acyclic and CyclicN-Aryl Enaminones: Substituent Effects and Intramolecular Hydrogen Bonding

Magnetic Resonance in Chemistry ◽

10.1002/(sici)1097-458x(199705)35:5<311::aid-omr94>3.0.co;2-m ◽

1997 ◽

Vol 35 (5) ◽

pp. 311-322 ◽

Cited By ~ 29

Author(s):

Jin-Cong Zhuo

Keyword(s):

Hydrogen Bonding ◽

Substituent Effects ◽

Intramolecular Hydrogen Bonding ◽

Spectroscopic Studies ◽

Intramolecular Hydrogen

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EFFECT OF INTRAMOLECULAR HYDROGEN BONDING ON IONIZATION CONSTANTS OF SUBSTITUTED SALICYLIC ACIDS

Canadian Journal of Chemistry ◽

10.1139/v66-188 ◽

1966 ◽

Vol 44 (11) ◽

pp. 1261-1269 ◽

Cited By ~ 25

Author(s):

G. E. Dunn ◽

Fei-lin Kung

Keyword(s):

Hydrogen Bond ◽

Hydrogen Bonding ◽

Spectrophotometric Method ◽

Chelate Ring ◽

Substituent Effects ◽

Intramolecular Hydrogen Bonding ◽

Ionization Constants ◽

Intramolecular Hydrogen ◽

Hammett Relationship ◽

Salicylic Acids

Ionization constants at 25 °C have been determined by a spectrophotometric method for 17 substituted salicylic acids. These have been fitted to the simple Hammett relationship and to the extended one proposed by Jaffe, which takes into account the transmission of substituent effects by the o-hydroxy group. The results with Jaffe's equation show that substituent effects on acidity are transmitted only slightly, if at all, through the intramolecular hydrogen bond of a chelate ring. Possible interpretations of the results are discussed.

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