Drago equation

As regards their chemical meaning, the two terms of the Drago equation (formally the electrostatic and the covalent term) might reflect the d-interaction and the n-interaction also. However, the experimental data are indicative of the former explanation. 

Acid-base interactions introduction D E PACKHAM Relation to work of adhesion, Drago equation... 

They made use of the Drago Equation (3.2) to characterise a series of particulate inorganic materials, e.g., ferric oxide, silica and titania, and ascribed E and C constants to their surfaces. 

Drago and co-workers have correlated a large body of enthalpies of adduct formation in Lewis acid-base systems, including some solvents as reactants, with this four-parameter equation ... 

Drago and coworkers have also calculated the enthalpy values for the formation of many complexes or hydrogen bonds by NMR and calorimetric techniques. For example, in a series of phenols or t-BuOH, they observed the IR frequency shifts (Avqh) of the hydroxyl compounds and found that a linear relationship exists between bases and individual acids. In Table 7 shows some AH values calculated by equation 2, and Avqh values of t-BuOH" " while in Table 8 frequency data Avq of various substituted phenols and the AH values are given. 

Eaq and Caq are the tendency of acid A and base B to undergo ionic and covalent bonding, respectively. Equation (2) resembles that proposed by Drago et al. (18) to model heats of complex formation of acids and bases in solvents of low dielectric constant. Only Lewis acids of ionic radius greater than 1.0 A obey Eq. (2). For all smaller Lewis acids, a third pair of parameters has to be introduced ... 

Hydrogen bonding is a special type of acid-base interaction (see Chapter 9). Probably the most important equation relating hydrogen bond strengths is the equation known as the Drago four-parameter equation,... 

Table 9.7 Acid and Base Parameters for Use in the Drago Four-Parameter Equation.

The double-scale four-parameter enthalpic equation proposed in 1965 (54) and successfully developed by Drago et al seems to be the best tool so far available for correlating and predicting the formation enthalpies of Lewis adducts in the gas phase or, if really necessary, in solution. 

R. S. Drago, B. B. Way land. A Double-Scale Equation for Correlating Enthalpies of Lewis Acid-Base Interactions. J. Am. Chem. Soc. 1965, 87, 3571-3577. 

Double Heck reaction, 42 494 Double layer interface, 30 223-225 Double nucleophilic displacement, capped cyclodextrin, 32 437 Double-pulse method, 38 31 Double recognition models, 32 451 52 Doublet mechanisms, 30 43, 45, 47 Drago parameters, 38 212 Drougard-Decrooq equation, 30 345, 356, 371 Dry evaporation, perovskite preparation, 36 246-247... 

Pearson (2) and Drago and Weyland 38) proposed a two-parameter equation for the equilibrium constant K for the reaction between A and B... 

The TiF4 and Pr 2NH, Et2NH, py or NMe3 systems have been shown to be quite complex by Drago and coworkers.45 For example, in TiF4-rich solutions in acetone, high conductance has been explained by equation (10). 

A somewhat similar oxidation of terminal alkenes to methyl ketone and alcohol by 02 in the presence of Co(salMDPT) [salMDPT = bis(salicylideneiminopropyl)methylamine] and in ethanol solvent has recently been reported by Drago and coworkers (equation 244).560 Only terminal alkenes were found to be reactive with this catalytic system. The reaction is alcohol dependent and occurs in ethanol and methanol but not in t-butyl or isopropyl alcohols. The alcohol is concomitantly oxidized during the reaction, and may act as a coreducing agent and/or favor the formation of cobalt hydride. This oxidation might occur according to the mechanism of equation (243). 

At present the dye techniques are very useful and economical but are somewhat approximate. Advances in use of indicator dyes for measuring surface acidity and basicity may be expected to include a two-parameter measure of acid or base strength similar to the E and C equation of Drago, and the use of fluorescent indicators for colored solids. 

A graph similar to Figure 7 resulted with adsorption of tri-ethylamine onto the same iron oxide, with AHa< s=-13.1 Kcal/mole and Tm corresponding to 167 A2. Using Drago s values of Cg and Eg for triethylamine.il.09 and 0.99 respectively jin units of (Kcal/mole)V2>we can write equation (5) as ... 

A four-parameter equation for predicting the calorimetric enthalpies of acid-base interactions, —Ai/ab, in neutral solvents, proposed by Drago et al. [146], with spectroscopically determined shifts of the OH stretching frequency of phenol when interacting with a variety of bases of dilute solutions in carbon tetrachloride and tetrachloroethylene. 

Doan and Drago [153,154] have reported an extended work that Eq. (61) include the spectral shifts obtained from the LSERs approach. They showed that a four-parameter equation for a general set of electron donors (acceptors), in which the specific interaction or spectral shift with an electron acceptor (donors) can be fit by LSERs. 

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