Of substituted acetic acid

Figure 16. Nonisokinetic dependence of calorimetric AH on AG° for ionization of substituted acetic acids (75), actual regression line (full straight line) and lines transferred from the aH° versus AS° plot (broken lines).

Concerted acid-base catalysed enolizations of a range of simple aldehydes and ketones have been measured in water at 25 °C, using a range of substituted acetic acid-acetate buffers.The buffer plots yield rate constants for acid (A a) and base ( b) catalytic terms in the normal way at low buffer concentrations. Extension up to higher concentrations (as far as [total buffer] = 2 m, typically) yields the third-order term ( ab) via upward curvature of the plots. While ab does not have a simple correlation with either k or b, it does correlate with their product, i.e. 

Table 3.2 Acidities of Substituted Acetic Acids X-CH2CO2H...

Synthesis of substituted acetic acids via acetoacetic ester Acetoacetic ester, an ester formed by the self-condensation of ethyl acetate via a Claisen condensation, has the following structure ... 

Synthesis of substituted acetic acid via malonic ester Malonic ester is an ester formed by reacting an alcohol with malonic acid (propanedicarboxylic acid). Following is the structure of diethyl malonate ... 

Synthesis of substituted acetic acids via acetoacetic ester... 146 Synthesis of substituted acetic acid via malonic ester. .. 150 a halo acids, a hydroxy acids, and a, (3 unsaturated acids.. .153... 

Malonic Ester Synthesis of Substituted Acetic Acids... 

The TLSER methodology has been successfully applied to develop correlation equations for a wide variety of solvent-dependent properties and processes [350, 364-369]. Some examples are the characterization of other solvent polarity, acidity, and basicity scales [364], the acidities of substituted acetic acids in various solvents [365], the basicities of substituted dimethylamines in various solvents [366], the decarboxylation kinetics of 3-carboxybenzisoxazole [367], the C=0 stretching frequencies of substituted pyrrolidin-2-ones [368], and gas-water distribution coefficients [369]. 

Many investigators have attempted to isolate mercury derivatives from aceto-acetie ester, but the results have been so varied that no reliance can be placed on any of the early work on this compound. Kharasch and Staveley, however, have obtained definite results by heating mercury salts of substituted acetic acids in vacuo, e.g, di-method and diethyl aceto-acetic acids when dried and heated in vacuo at 90 C. evolve carbon dioxide, and the mercury becomes bound to the carbon atoms which were formerly attached to the carboxyl groups —... 

These Oi values of Taft and Lewis were used as a basis set by Charton [Charton, 1963 Charton, 1964] with the aim of obtaining a large number of inductive constants. Acid dissociation constants of substituted acetic acids (XCH2COOH) in water were correlated with Oi constants of the basis set at temperatures from 5° to 50°C in terms of the equation ... 

The Taft steric constant Es was proposed as a measure of steric effects that a substituent X exerts on the acid-catalyzed hydrolytic rate of esters of substituted acetic acids XCH2COOR [Taft, 1952], The basic assumption is that the effect of X on acid hydrolysis is purely steric, as the reaction constant q for acid hydrolysis of substituted esters is close to zero. 

Provided there is no resonance transmission in the effect of substituents on the dissociation of acetic acids (as would be expected) then the linear equation indicates that the transmission of the effect of the meta substituent does not involve resonance either. The correlation shows that provides a useful secondary definition of Oi. This relationship is a Class II free energy correlation between the dissociation of substituted acetic acids and weZa-substituted benzoic acids. 

Reaction (3.11) (Sn2) Reaction (3.12) (SN1) Acid strength of substituted acetic acids... 

As shown in scheme 16, the nature of substituted acetic acid which esterifies the secondary hydroxyl depends on the target structure. 

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