Acid-base behavior in aprotic organic solvents

Abstract

Butyl hydroperoxide and deuteroperoxide. Deuterium isotope effects on hydrogen bonding by Br0nsted acids 40 4.3. Hydrogen-bonded ion pairs 41 4.3.1. Conductance 41 a. Walden's work 42 b. Wynne-Jones' postulate 42 c. Investigations of Kraus, Fuoss, and associates... 43 d. Summary 45 4.3.2. Dielectric constants 46 a. Dielectric polarization of substituted ammonium picrates and halides in benzene 46 b. Dielectric polarization of other acid-base complexes in benzene 47 4.3.3. CoUigative properties 49 a. Cryoscopy 50 Page b. The differential vapor pressure (DVP) method... 51 104 4.5.6. Homoconjugation of other organic and inorganic acids a. Perchloric acid 105 b. Other acids 105 4.5.7. Heteroconjugate anions 105 a. Chemical behavior 105 b. Physical measurements 108 4.6. Concluding discussion of hydrogen bonding 112 4.6.1. Definition of a hydrogen bond. Systems which form hydrogen bonds 112 4.6.2! Some recent concepts of hydrogen bonding 113 5. Acidity and basicity scales in aprotic organic solvents... 114 5.1. Early attempts to determine relative acidities 114 5.2. Log Kbha scales of acidity and basicity 115 5.3. Methods used in determining values of log A^bha 116 5.4. Tables of log ^bha, and AS obtained using aprotic solvents 118 5.4.1. Aromatic and substituted aromatic hydrocarbons 118 a. Benzene 118 b. Anisole and chlorobenzene 126 5.4.3. Carbon tetrachloride 126 5.4.4. Chloroform 128 5.4.5. Miscellaneous aprotic solvents 129 6. Acid-base titrations in completely aprotic solvents 133 6.1. Introduction 133 6.2. Titrations with indicator dyes in completely aprotic solvents 133 6.3. Instrumental procedures for detecting end-points in completely aprotic solvents 133 6.3.1. Conductance titrations 133 iv Contents -Continued Page 6.3.2. Dielectrometric titrations 133 6.3.3. Photometric titrations 134 6.3.4. Thermometric titrations 135 6.3.5. Titrations by the DVP method 135 6.3.6. Cryoscopic titrations 135 6.3.7. Other possible instrumental procedures 135 a. Refractive index 135 b. Density 135 c. Optical rotation 135 6.4. Reference acids and bases for aprotic organic solvents 135 6.4.1. Acids 135 a. Hydrogen chloride 135

1,n-Radical ions. Photosensitized (electron transfer) and electrochemical oxidation of 1,1,2,2-tetraphenylcyclopropane

“…the same factors that are important in aqueous media). However, it is clear that relative pK,,'s in aprotic solvents are very much attenuated, relative to those values measured in water (28). Most of this difference is a result of the heat of transfer of the proton from water to acetonitrile.…”

“…These results are rationalized by considering the effect of the solvent polarity on the strength of the acid (or it's conjugate base) (28). The dielectric constant of binary solvent mixtures of carbon tetrachloride and acetonitrile as a function of mole frac- homoconjugate ion formation, (A-H--A)-, and, in the case of 5, the p K R , , are also important.…”

Conductimetric titrations of symmetrical aliphatic dicarboxylic acids in solvents pyridine and pyridine–benzene mixtures

“…Since titration curves up to first end-point show that the conductivity increases smoothly, there should be no intermolecular hydrogen bonds (11). Otherwise maxima at the half-neutralization points would appear before the first end-points (13)(14)(15)(16). Figure 1 further shows that the first end-points of acids having up to four methylene groups are very sharp; while those of acids having five to eight methylene groups are less sharp.…”

Glycosylidene Carbenes part 26. The intramolecular F…︁HO hydrogen bond of 1,3‐diaxial 3‐fluorocyclohexanols

“…(dd, 'J(C,F) = 23.3),69.06 (dd, 'J(C,F) = 21.8, C(I), C(5));64.54 (d, C(2)); 62.73 (d, C(4)); 37.10 ( t . CH,); 24.50 ( I , CH,); 22.41 ( t , CH,); 13.98(4.…”