Pseudo acid definition

Kinetic theory indicates that equation (32) should apply to this mechanism. Since the extent of protonation as well as the rate constant will vary with the acidity, the sum of protonated and unprotonated substrate concentrations, (Cs + Csh+), must be used. The observed reaction rate will be pseudo-first-order, rate constant k, since the acid medium is in vast excess compared to the substrate. The medium-independent rate constant is k(), and the activity coefficient of the transition state, /, has to be included to allow equation of concentrations and activities.145 We can use the antilogarithmic definition of h0 in equation (33) and the definition of Ksh+ in equation (34) ... 

With the object, therefore, of definitely establishing the configuration of tropine and of pseudo-tropine, we have conducted experiments on the resolution of these bases, and some of their derivatives, by fractionally crystallising their salts with certain optically active acids. It may at once be stated that the results of these experiments point to the conclusion that both the bases in question are internally compensated compounds. The relation between them must, therefore, be of the nature of a cis-trans-isomerism, as concluded by Willstatter. (loc. cit.). Attempts were made to racemise tropine by heating the latter at high temperatures with hydrochloric acid, but these were unsuccessful. Source Barrowcliff 1909... 

According to Wilhelm Ostwald, acid-base indicators are weak acids or bases which, when undissociated, exhibit a color different from that of their ionic forms. Hantzsch and others have shown that the color change is not due to ionization, but rather results from a structural change. The explanation of Ostwald, however, is most suitable for purposes of elucidating the behavior of indicators at various hydrogen ion concentrations. We shall return in Chapter Seven to a comparison of the views of Ostwald and Hantzsch. It will then be found advisable to revise the definition of Ostwald as follows Indicators are weak acids and bases of which the ionogenic form possesses a color and constitution different from the color and structure of the pseudo or normal form. 

The alkaline hydrolysis of phthalate diesters has been fit to the Taft-Pavelich equation (Eq. 9). Dimethyl phthalate (DMP) hydrolyzes to phthalic acid (PA) in two steps DMP + H20->MMP + CH30H and MMP + H20- PA + CH30H. The first step is about 12 times faster than the second, and nearly all the diester is converted to the monoester before product PA is formed. Other diesters are assumed to behave similarly. An LFER was obtained from rate measurements on five phthalate esters (Wolfe et al., 1980b). The reaction constants, p and S, were determined by multiple regression analysis of the measured rate constants and reported values of cr and Es for the alkyl substituents. The fitted intercept compares favorably with the measured rate constant (log kOH = — 1.16 0.02) for the dimethyl ester (for which a and s = 0 by definition). Calculated half-lives under pseudo-first-order conditions (pH 8.0, 30°C) range from about 4 months for DMP to over 100 years for di-2-ethylhexyl phthalate. 

An exception to the definition for pseudo poly(amino acids) as previously established is a polymer synthesized by Chen et al. [31,32], because its backbone is comprised of lysine alternating with an isophthaloyl group and lacks nonamide linkages (Table 12.2). Hydrophobicity of the polymer is increased by conjugating ethanol or hydro-phobic amino acids, such as valine, leucine, and phenylalanine, as protecting groups on the carboxyl terminal of lysine via carbodiimide chemistry. This protected lysine is then copolymerized with isophthaloyl chloride via single-phase polymerization in the presence of a base (Table 12.2) [32]. 

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