Benzoic acid deprotonation

Step 6 Deprotonation of protonated form of benzoic acid... 

Obtain energies for each ion and for their correspondin precursors benzoic acid,phenol and cyclohexanol). Us this information to calculate the energy for each of the abov deprotonation reactions. (The energy of proton is given left.) Is the trend consistent with the experimental pKa dat (see table at left) Does deprotonation energy parade charge delocalization in these systems Explain ho electron delocalization affects the reactivity of these acidf... 

Explain what happens to (a) the concentration of H,0+ ions in an acetic acid solution when solid sodium acetate is added (b) the percentage deprotonation of benzoic acid in a benzoic acid solution when hydrochloric acid is added (c) the pH of the solution when solid ammonium chloride is added to aqueous ammonia. 

With phenyllithium, the iminophosphoranes of benzoic acid hydrazides 157 can be deprotonated, as shown in Scheme 62.0-Acylation of the amide-enolates 158 affords intermediates 159, which are in turn cyclized by an aza-Wittig reaction to 1,3,4-oxadiazoles 160 (68JA5626). 

The solvent affects the chemical equilibria of reactions. Second-order rate constants and equilibrium constants have been determined for the benzoate ion promoted deprotonation reactions of (m-nitrophenyl)nitromethane, (p-nitrophenyl)nitromethane, and (3,5-dinitrophenyl)nitromethane in methanol solution. The pKa values for the arylnitromethanes in methanol are the following pKa = 10.9, 10.5, and 9.86 for m-nitrophenyl)nitromethane, (p-nitrophenyl)nitromethane, and (3,5-dinitrophenyl)nitro-methane, respectively, relative to benzoic acid (pKa = 9.4). A Bronsted B value of... 

Bromo- and iodoanihnes, -phenols and -benzoic acids are first deprotonated in situ by an excess of the organomagnesinm reagent and then coupled (PdCl2(dppf), 1 mol%, THF, 25 °C, 3 h) with organomagnesium halides, thus avoiding tedious protection-deprotection steps . Iron(in) salts can also serve as appropriate catalysts for varions cross-coupling... 

To find the overall goethite-water distribution coefficient for benzoic acid (HBz), assume that only adsorption of the deprotonated species (benzoate, Bz") is important ... 

B is correct. The benzoic acid will be deprotonated by NaOH, making it soluble in the aqueous layer, The MW of benzoic = 122. 

Use Table 4.2 to find a base that is strong enough to deprotonate benzoic acid but not /,-methy I phenol. Then explain how this base might be used to separate these two compounds in the laboratory. 

Because the pK values of many carboxylic acids are 5, bases that have conjugate acids with pKg values higher than 5 are strong enough to deprotonate them. Thus, acetic acid (pATa = 4.8) and benzoic acid (pA a = 4.2) can be deprotonated with NaOH and NaHC03, as. shown in the following equations. 

O-H deprotonation of arylalkanol (I), benzoic acid (II) and arylalkanoic acid (III) radical cations eventually leads to radical zwitterions where the electron hole is localized on the aromatic system and the negative charge resides on the oxygen atom originally bonded to the acidic proton (Scheme 65). From the radical zwitterions an oxygen centered radical can be formed by intramolecular electron transfer from the side-chain -0 to the aromatic jr-system, whose chemistry will be discussed below. 

There are, therefore, four possible equilibria involved in the deprotonation of amino benzoic acids. Spectroscopic observations indicate that, in fact, the more complex composite situation is closer to reality. 

Computed oxygen Vmin for benzoate anions, computed deprotonation energies and experimental gas phase acidities for benzoic acids, and experimentally derived substituent constants... 

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