ChemInform Abstract: CHEMISTRY OF REACTIVE LIGNIN INTERMEDIATES. II. ADDITION REACTIONS OF VINYL-SUBSTITUTED QUINONE METHIDES IN AQUEOUS SOLUTION

1976 ◽  
Vol 7 (6) ◽  
pp. no-no
Author(s):  
JACQUELINE HEMMINGSON ◽  
GORDON LEARY
Keyword(s):  
Aqueous Solution ◽  
Addition Reactions ◽  
Quinone Methides

scholarly journals Cover Feature: para -Quinone Methides as Acceptors in 1,6-Nucleophilic Conjugate Addition Reactions for the Synthesis of Structurally Diverse Molecules (Eur. J. Org. Chem. 18/2020)

2020 ◽  
Vol 2020 (18) ◽  
pp. 2642-2642
Author(s):  
Carolina G. S. Lima ◽  
Fernanda P. Pauli ◽  
Dora C. S. Costa ◽  
Acácio S. de Souza ◽  
Luana S. M. Forezi ◽  
...  
Keyword(s):  
Conjugate Addition ◽  
Addition Reactions ◽  
Quinone Methides

scholarly journals Carbonyl Addition Reactions: Factors Affecting the Hydrate–Hemiacetal and Hemiacetal–Acetal Equilibrium Constants

1975 ◽  
Vol 53 (6) ◽  
pp. 898-906 ◽  
Author(s):  
J. Peter Guthrie
Keyword(s):  
Aqueous Solution ◽  
Carbonyl Compounds ◽  
Equilibrium Constants ◽  
Substituent Effects ◽  
Steric Effects ◽  
Addition Reactions ◽  
Free Energies ◽  
Electronic Effects ◽  
Factors Affecting ◽  
Analogous Formula

Equilibrium constants for hydrate–hemiacetal interconversion in aqueous solution at 25° have been measured for four fluorinated carbonyl compounds: compound, alcohol, K4 (M−1): CF3CHO, C2H5OH, 2.3; CF3COCH3, CH3OH, 1.0; CF3COPh, CH3OH, 3.5; CF3COCF3, CH3OH, 0.14. These values, combined with values from the literature, permit an examination of substituent effects upon the equilibrium constant for[Formula: see text]The free energy change for this process, corrected for symmetry and steric effects, follows the equation[Formula: see text]Thus electronic effects upon this equilibrium are generally small and in fact are often smaller than steric effects.This analysis permits and justifies the calculation of free energies of formation of [Formula: see text] compounds from the (more generally measurable) free energies of formation of the analogous [Formula: see text] compounds.

para -Quinone Methides as Acceptors in 1,6-Nucleophilic Conjugate Addition Reactions for the Synthesis of Structurally Diverse Molecules

2020 ◽  
Vol 2020 (18) ◽  
pp. 2650-2692 ◽  
Author(s):  
Carolina G. S. Lima ◽  
Fernanda P. Pauli ◽  
Dora C. S. Costa ◽  
Acácio S. de Souza ◽  
Luana S. M. Forezi ◽  
...  
Keyword(s):  
Conjugate Addition ◽  
Addition Reactions ◽  
Quinone Methides

scholarly journals Thermodynamics of ester and orthoester formation from trifluoroacetic acid

1976 ◽  
Vol 54 (2) ◽  
pp. 202-209 ◽  
Author(s):  
J. Peter Guthrie
Keyword(s):  
Aqueous Solution ◽  
Free Energy ◽  
Equilibrium Constant ◽  
Trifluoroacetic Acid ◽  
Sodium Methoxide ◽  
Standard Free Energy ◽  
Steric Effects ◽  
Addition Reactions ◽  
Free Energies ◽  
Acetic Acids

The equilibrium constant for the addition of sodium methoxide to methyl trifluoroacetate, in methanol as solvent, has been measured by 19F nmr, and is 7 M−1. From this was calculated an equilibrium constant, 2 × 10−4 M−1, for addition of methanol to the ester. The equilibrium constant for formation of methyl trifluoroacetate in aqueous solutions is 0.06 M−1. These results, with literature data, permit calculation of the free energies of formation in aqueous solution of orthotrifluoroacetic acid and its mono-, di-, and trimethyl esters. These in turn permit calculation of the standard free energy changes for addition of water and methanol to trifluoroacetic acid and its methyl ester. These combined with the analogous values for formic and acetic acids permit evaluation of ρ* values for these addition reactions. Linear plots are obtained if correction is made for steric effects, and the ρ* values are somewhat larger, 2.1–2.9, than was observed for the analogous carbonyl addition reactions.

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