Substituent effects in naphthalene. II. The strengths of the 4, 5, 6, 7, and 8-substituted 2-naphthoic acids

The apparent pKa values of 44 substituted 2-naphthoic acids, six substituted 1-naphthoic acids, and the unsubstituted naphthoic acids have been determined for 50% v/v aqueous ethanol at 25�. The ΔpK values are examined in terms of Dewar and Grisdale's simple expression for aromatic substituent effects. This expression proves to be fairly satisfactory, but takes no account of substituent dipole orientation, secondary resonance effects, nor π-inductive effects. A survey of the naphthoic acid strengths demonstrates the importance of these factors. In particular, unambiguous evidence for the important role played by direct electrostatic interactions is obtained.

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Reactions of aryl diazonium salts and arylazo alkyl ethers. III. Substituent effects in the ionization of anti-arylazo ethyl ethers in ethanol

Australian Journal of Chemistry ◽

10.1071/ch9781519 ◽

1978 ◽

Vol 31 (7) ◽

pp. 1519 ◽

Cited By ~ 4

Author(s):

TJ Broxton

Keyword(s):

Substituent Effects ◽

Parameter Analysis ◽

Diazonium Salts ◽

Resonance Effects ◽

Inductive Effects ◽

Alkyl Ethers

A dual substituent parameter analysis of substituent effects on the ionization of anti-arylazo ethyl ethers in ethanol shows that the reaction is affected primarily by inductive effects. The reaction is insensitive to resonance effects and an explanation for this behaviour is offered.

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The substituent effects on the 13c chemical shifts of the azomethine carbon atom of n-(phenyl substituted) salycilaldimines

Journal of the Serbian Chemical Society ◽

10.2298/jsc120319033d ◽

2012 ◽

Vol 77 (8) ◽

pp. 993-1001

Author(s):

Sasa Drmanic ◽

Aleksandar Marinkovic ◽

Jasmina Nikolic ◽

Bratislav Jovanovic

Keyword(s):

Carbon Atom ◽

Schiff Bases ◽

13C Nmr ◽

Chemical Shifts ◽

Substituent Effects ◽

13C Chemical Shifts ◽

Resonance Effects ◽

Inductive Effects ◽

Substituent Constants ◽

Significant Resonance

The Hammett correlations between 13C-NMR chemical shifts of the azomethine carbon atom and the corresponding substituent constants for thirtheen Schiff bases were established. Successful correlation of the chemical shifts with electrophilic substituent constants ?+ indicate significant resonance interaction of the substituents on the aniline ring with the azomethine carbon atom in the examined series of imines. The demand for electrons in the investigated compounds was compared to that of the N-benzylidenanilines and N-(phenyl substituted) pyridinealdimines. The way of transmission of the substituent effects was discussed and they are separated into resonance and inductive effects. Inductive effects prevail over resonance effects.

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Substituent Effects on the Basicity of ortho-, meta- and para-substituted N1,N1-Dimethyl-N2-phenylformamidines in Ethanol and in Water

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19920113 ◽

1992 ◽

Vol 57 (1) ◽

pp. 113-118

Author(s):

Ewa Daniela Raczyńska

Keyword(s):

Quantitative Analysis ◽

Aqueous Ethanol ◽

Substituent Effects ◽

Amino Group

The relative δpKa values of ortho-, meta-, and para-substituted N1,N1-dimethyl-N2-phenylformamidines obtained in 95.6% aqueous ethanol have been compared with those in water. The comparison shows only some differences in the ortho substituent effects. The meta and para substituent effects in ethanol are not very different from those in water. Quantitative analysis of the experimental δpKa values based on the Taft equation has led to separation of the total electromeric effects into the inductive and mesomeric effects. As compared to the amino group in anilines, the formamidine group is more sensitive to the transmission of the inductive than the mesomeric effects.

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Kinetic study of hydrolysis of benzoates. part xxvii. ortho substituent effect in alkaline hydrolysis of phenyl esters of substituted benzoic acids in aqueous Bu4NBr

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc2008019 ◽

2009 ◽

Vol 74 (1) ◽

pp. 29-42 ◽

Cited By ~ 9

Author(s):

Vilve Nummert ◽

Mare Piirsalu ◽

Signe Vahur ◽

Oksana Travnikova ◽

Ilmar A. Koppel

Keyword(s):

Alkaline Hydrolysis ◽

Rate Constants ◽

Pure Water ◽

Substituent Effects ◽

Benzoic Acids ◽

Resonance Effects ◽

The Media ◽

Substituted Benzoic Acids ◽

Hydrolysis Of ◽

Ortho Substituent

The second-order rate constants k (in dm3 mol–1 s–1) for alkaline hydrolysis of phenyl esters of meta-, para- and ortho-substituted benzoic acids, X-C6H4CO2C6H5, have been measured spectrophotometrically in aqueous 0.5 and 2.25 M Bu4NBr at 25 °C. The substituent effects for para and meta derivatives were described using the Hammett relationship. For the ortho derivatives the Charton equation was used. For ortho-substituted esters two steric scales were involved: the EsB and the Charton steric (υ) constants. When going from pure water to aqueous 0.5 and 2.25 M Bu4NBr, the meta and para polar effects, the ortho inductive and resonance effects in alkaline hydrolysis of phenyl esters of substituted benzoic acids, became stronger nearly to the same extent as found for alkaline hydrolysis of C6H5CO2C6H4-X. The steric term of ortho-substituted esters was almost independent of the media considered. The rate constants of alkaline hydrolysis of ortho-, meta- and para-substituted phenyl benzoates (X-C6H4CO2C6H5, C6H5CO2C6H4-X) and alkyl benzoates, C6H5CO2R, in water, 0.5 and 2.25 M Bu4NBr were correlated with the corresponding IR stretching frequencies of carbonyl group, (ΔνCO)X.

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Additions and Corrections - Substituent Effects. VII. The19F Nuclear Magnetic Resonance Spectra of Substituted 1- and 2-Fluoronaphthalenes

Journal of the American Chemical Society ◽

10.1021/ja00987a604 ◽

1967 ◽

Vol 89 (11) ◽

pp. 2799-2799

Author(s):

W. Adcock ◽

M. J . S. Dewar

Keyword(s):

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

Substituent Effects ◽

Nuclear Magnetic Resonance Spectra ◽

Substituted 1 ◽

Magnetic Resonance Spectra ◽

Nuclear Magnetic

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Transmission of substituent effects in heterocyclic systems. Application of molecular orbital parameters to the solvolysis of 4-substituted 1-(2-furyl)ethyl systems

The Journal of Organic Chemistry ◽

10.1021/jo00981a023 ◽

1972 ◽

Vol 37 (16) ◽

pp. 2623-2625 ◽

Cited By ~ 4

Author(s):

Donald S. Noyce ◽

Hernan J. Pavez

Keyword(s):

Molecular Orbital ◽

Substituent Effects ◽

Orbital Parameters ◽

Substituted 1

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Effects of substituents on the 1H-NMR chemical shifts of 3-methylene-2-substituted-1, 4-pentadienes

Journal of the Serbian Chemical Society ◽

10.2298/jsc0307525v ◽

2003 ◽

Vol 68 (7) ◽

pp. 525-534 ◽

Cited By ~ 1

Author(s):

Natasa Valentic ◽

Gordana Uscumlic

Keyword(s):

Chemical Shifts ◽

Substituent Effects ◽

Electronic Effects ◽

Resonance Effects ◽

Charge Densities ◽

Linear Free Energy ◽

Energy Relationships ◽

Consistent Picture ◽

Vinyl Group ◽

Proton Chemical Shifts

The principle of linear free energy relationships was applied to the 1H chemical shifts of the ?-vinyl proton atoms of 3-methylene-2-substituted-1,4-pentadienes. The correlations of the proton chemical shifts with Swain and Lupton substituent parameters provide a mutually consistent picture of the electronic effects in these compounds. The overall pattern of proton chemical shifts can be largely accounted for by a model of substituent effects based on field, resonance and ? polarization effects. Owing to the particular geometric arrangement of the vinyl group in 3-methylene-2-substituted-1,4-pentadienes, the ?-vinyl protons HB and HC have different sensitivities to polar and resonance effects. The different sensitivities of the 1H chemical shifts to resonance effects reveals some effects not predicted by the model outlined above. Evidence is presented that demonstrates that both the 1H and 13C chemical shifts for these compounds reflect their ground-state charge densities.

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