Transmission of substituent effects in heterocyclic systems. Solvolysis of some substituted 1-(3-benzofuryl)ethanol derivatives

1972 ◽  
Vol 37 (26) ◽  
pp. 4311-4315 ◽  
Author(s):  
Donald S. Noyce ◽  
Richard W. Nichols
Keyword(s):  
Substituent Effects ◽  
Substituted 1

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

1965 ◽  
Vol 18 (9) ◽  
pp. 1365 ◽  
Author(s):  
PR Wells ◽  
W Adcock
Keyword(s):  
Electrostatic Interactions ◽  
Aqueous Ethanol ◽  
Substituent Effects ◽  
Simple Expression ◽  
Dipole Orientation ◽  
Aromatic Substituent ◽  
Resonance Effects ◽  
Naphthoic Acid ◽  
Inductive Effects ◽  
Substituted 1

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.

Acid-Base Properties of Substituted Naphthoic Acids in Nonaqueous Media

1997 ◽  
Vol 62 (11) ◽  
pp. 1737-1746 ◽  
Author(s):  
Patrik Pařík ◽  
Miroslav Ludwig
Keyword(s):  
Experimental Data ◽  
Linear Regression ◽  
Latent Variables ◽  
Latent Variable ◽  
Dissociation Constants ◽  
Substituent Effects ◽  
Acid Base ◽  
Nonaqueous Media ◽  
Substituent Constants ◽  
Substituted 1

Thirteen substituted 1-naphthoic acids have been prepared and their dissociation constants, along with those of twenty-five substituted 2-naphthoic acids, have been measured potentiometrically in methanol, N,N-dimethylformamide, pyridine, and acetonitrile. The pKHA values obtained have been treated by linear regression using four sets of substituent constants. The experimental data have also been interpreted by statistical methods using latent variables. The first latent variable calculated by these methods can be used as a new set of substituent constants for describing substituent effects in naphthalene skeleton.

Kinetic and thermodynamic control of pseudobase formation from C-3 substituted 1-methylquinolinium cations

1984 ◽  
Vol 62 (7) ◽  
pp. 1301-1307 ◽  
Author(s):  
John W. Bunting ◽  
Norman P. Fitzgerald
Keyword(s):  
Aqueous Solutions ◽  
Rate Constants ◽  
Kinetic Data ◽  
Mixing Time ◽  
Equilibrium Constants ◽  
Substituent Effects ◽  
Stopped Flow ◽  
Thermodynamic Control ◽  
Preferred Species ◽  
Substituted 1

The kinetic and thermodynamic control of pseudobase formation from 3-W-1-methylquinolinium cations has been studied for a variety of substituents (W). Spectral data indicate that, in both aqueous and methanolic solution, the C-2 pseudobases predominate at equilibrium for W = H and Br, while the C-4 pseudobases are the thermodynamically preferred species for W = CONH2, CO2CH3, CN, and NO2. Stopped-flow studies indicate that in all cases the C-2 pseudobases are the kineticallycontrolled products upon basification of the aqueous solutions of these cations. Equilibrium constants (pKR+) have been measured for pseudobase formation at both C-2 and C-4 for each W in all cases where they are experimentally accessible. Substituent effects upon [Formula: see text] correlate with σm for W, while [Formula: see text] depends upon σp−. These substituent effects allow the prediction of [Formula: see text] and [Formula: see text] for the 1-methylquinolinium cation. Rates of C-2 to C-4 pseudobase equilibration have been measured in all cases where the latter species is thermodynamically more stable. These kinetic data allow the evaluation of rate constants for C-4 pseudobase equilibration with each cation. In all cases except W = CN, C-2 pseudobase formation is complete within the mixing time of the stopped-flow instrument.

Substituent effects in fluoromethylnaphthalenes by 19F nuclear magnetic resonance

1981 ◽  
Vol 59 (17) ◽  
pp. 2642-2649 ◽  
Author(s):  
Elisabeth A. Dixon ◽  
Alfred Fischer ◽  
Frank P. Robinson
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Aromatic Ring ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Resonance Interaction ◽  
Parameter Analysis ◽  
Side Chain ◽  
Temperature Dependent ◽  
Substituted 1 ◽  
Electron Withdrawing Substituents

19F substituent chemical shifts (SCS) are reported for a series of twenty-one 3- and 4-substituted 1-fluoromethylnaphthalenes. The fluoromethylnaphthalenes exhibit an inverse SCS dependence: electron-withdrawing substituents produce upfield shifts. The results correlate well with SCS values previously reported for substituted benzyl fluorides. Hammett correlations are poor with conjugatively electron-withdrawing substituents exhibiting weaker than expected effects in the 3-position and stronger than expected effects in the 4-position. Dual substituent parameter analysis confirms the enhanced substituent–aromatic ring resonance interaction when the substituent is in the 4-position (ρR/ρI = 2). There is no evidence for enhanced resonance interaction between fluoromethyl side-chain and aromatic ring. The 19F chemical shift of 1-fluoromethylnaphthalene is markedly temperature dependent.

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