Reactions of ethanoic acid

The reaction of ethanoic acid and phosphorus pentachloride may be written ... 

Fig. Equilibrium acid-base reaction of ethanoic acid with water.

A colourless crystalline compound, CHaCOONa, which is known as the anhydrous salt (r.d. 1.52 m.p. 324°C) or the trihydrate (r.d. 1.45 loses water at 58°C). Both forms are soluble in water and in ethoxyethane, and slightly soluble in ethanol. The compound maybe prepared by the reaction of ethanoic acid (acetic acid) with sodium carbonate or with sodium hydroxide. Because it is a salt of a strong base... 

An example of Equation (8.9) is the series of reactions of ethanoic acid with carboxylate anions (Equation (8.9a)) ... 

In contrast, the condensation reaction of ethanoic acid and ethanol to produce ethyl etha-noate at 25°C gives a mixture of reactants and products at equihbrium, and the amount of product is much less than 100%. 

Some organic reactions have very large equilibrium constants, large negative values of and are quantitative. However, many reactions have much smaller equilibrium constants and correspondingly smaller AG° values. For example, the esterification reaction of ethanoic acid and ethanol has an equilibrium constant of 4 and = —1.7 kj mole" at 298 K. 

Carboxylic acids display the typical reactions of all acids due to the presence of excess H+(aq) ions in their aqueous solutions (see page 307). For example, they react with bases to form a salt plus water. Their salts are called carboxylates. The carboxylate salt formed by the reaction of ethanoic acid with sodium hydroxide is called sodium ethanoate, CHjCOO Nah... 

Cobalt(II) is also easily oxidised in the presence of the nitrite ion NO2 as ligand. Thus, if excess sodium nitrite is added to a cobalt(II) salt in presence of ethanoic acid (a strong acid would decompose the nitrite, p. 244), the following reaction occurs ... 

Notice that for ethanoic acid, and any other weak acid, the arrow ( ) tells us that the dissociation is an equilibrium process. The position of the equilibrium lies well over to the left-hand side so there will be very few hydrogen ions and ethanoate ions present at equilibrium compared with the much larger number of ethanoic acid molecules. We can also say that the value of the equilibrium constant, K, for this reaction is much less than 1. 

Write a general expression for the acid dissociation constant of the following reaction, a dissociation of ethanoic acid ... 

Suppose a water solution was made up initially to be 0.01 M in methyl bromide and 1.0M in sodium ethanoate at 50°. In water, the SN2 rate constant for reaction of hydroxide ion with methyl bromide at 50° is 30 X 10-4 liter mole-1 sec-1, whereas that of ethanoate ion at 50° is 1.0 x 10-4 liter mole-1 sec-1. The ionization constant of ethanoic acid at 50° is 1.8 x 10-5. In the following, neglect the rates of the reactions of methyl bromide with water or ethanoic acid and any further reactions of ethanoate ... 

Explain why the reaction fails, and indicate the products you actually expect to form on heating a mixture of ethanoic acid and ferf-butyl alcohol with sulfuric acid as... 

An electroactive species may not be initially present in solution, but may be formed by a reaction of the bulk solution species. This class of electrochemical mechanism is described as a CE mechanism in the Testa and Reinmuth notation. An example of a CE mechanism involves the reduction of ethanoic acid in aqueous solutions, in which protons released by the acid in (46) are reduced reversibly in (47) at the electrode surface (see for example Vielstich and John, 1960a,b Daniele et al., 1996). 

When the reactants and the catalyst are in the same physical state the catalyst is called a homogeneous catalyst e.g. concentrated sulfuric acid speeds up the reaction between ethanoic acid and ethanol to form the ester, ethyl ethanoate. Manganese(IV) oxide catalyses the thermal decomposition of potassium chlorate(V) to give oxygen. 

In an empirical approach to chemical kinetics, what would be the simplest mathematical way of representing the information obtained by Marcellin Berthelot and Pean de St Gilles for the reaction between ethanoic acid and ethanol ... 

The species A (aq) in equation (16.4) is referred to as the conjugate base of the acid AH(aq). This is because the A (aq) ion acts like a base in that it accepts a proton from H30" (aq) in the reverse of reaction (16.4). For example, the conjugate base of ethanoic acid is the ethanoate ion CH3COO (aq). 

In a typical example of an esterification reaction, glacial ethanoic acid is heated with ethanol in the presence of concentrated sulfuric acid, which acts as the catalyst. The sweet-smelling ester ethyl ethanoate is formed ... 

I) CH3COOH(aq) + H20(l) — CH3C00 (aq) + H30 (aq) As more hydronium ions are mopped up byOH-(aq) ions in the neutraiisation reaction, more ethanoic acid molecuies ionize. The titration voiumes are then identicai with those of a strong acid. 

II) The members ofthe first two pairs are strong acids and strong bases. The CHsCOOH-NaOH pair contains a weak acid and most of its moiecuies must first ionize before neutraiization can take piace. The ionization process is endothermic and reduces the overaii amount of heat given out in the reaction between ethanoic acid and sodium hydroxide. 

Under vigorous conditions strong oxidizing agents such as chromic acid and permanganate attack alkanes, but the reaction is of little synthetic use for usually mixtures of products are obtained in low yield. The reaction was traditionally used in the Kuhn-Roth estimation of the number of methyl groups in an unknown compound. This depends on the fact that a methyl group is rarely oxidized (the relative rates of oxidation of primary, secondary and tertiary C—H bonds are 1 110 7000) and hence the amount of ethanoic acid formed can be quantified. 

Sulfuric acid is not really an organic acid, but it is useful for comparative purposes because it represents the simplest analogy (like comparing water and methanol). A comparison of sulfonic acids with carboxylic acids—all organic molecules—leads to a more realistic idea of relative acid strength. The pK for acetic acid (ethanoic acid, MeCOOH) is 4.76 (see Table 6.1) and the pK for methanesulfonic acid (MeS020H) is -1.9. The reaction of methanesulfonic acid... 

The pKg values given for all organic molecules in this chapter are based on their reaction in water, which means that water is the base in those reactions. If a different solvent is used, the pK is different. If another base is added to the water solution, the pK may be different. Remember that acid strength depends on the strength of the base, which influences the position of the equilibrium and Kg. In the reaction of acetic acid (ethanoic acid, 18) and water, the conjugate acid is HgO+ and the conjugate base is the acetate anion (24). In this reaction, water reacts as the base, but water is also the solvent and it has a profound effect on the course of the reaction. 

The nitronium ion (NO2), generated as indicated earlier from the action of sulfuric acid (H2SO4) on nitric acid (HONO2)(Scheme 6.83), introduced in the form of nitronium tetrafluoroborate (N02 BF4) or formed in situ from the reaction of nitric acid (HONO2) with ethanoic anhydride (acetic anhydride [(CH3CO)2]) (Equation 6.102) also reacts with napththalene (Table 6.13, example 2) to give substitution at both C-1 (C-a) and C-2 (C-P) as... 

The sixth item in Table 9.6 illustrates the reaction between ketene (CH2=C=0) and ethanoic acid (acetic acid,CH3C02H). As shown in Equation 9.99,ketene (CH2=C=0) can be prepared by the dehydration of ethanoic acid (acetic acid, CH3CO2H), and the isolation of ketene is complicated because of its ready dimerization to diketene (4-methylideneoxacyclobutane-2-one). 

A reaction mixture is set up in a sealed flasks and left for 48 hours at 25°C to reach equilibrium. Samples can then be taken from the flask and titrated with alkali to find the concentration of ethanoic acid present at equilibrium (Figure 7.22). 

The correct argument is as follows. The addition of water decreases the concentrations of ethanoic acid molecules, ethanoate ions and hydrogen ions. Two of these species are on the right side of the equation and only one on the left a shift to the right is more effective at restoring the original concentrations of molecules and ions than a shift to the left. The decrease in concentration reduces the rate of the backward reaction to a greater extent than the forward reaction. 

If 1,00 mole of ethyl ethanoate is mixed with 1.00 mole of water and the reaction is allowed to reach equilibrium at a particular temperature, then 0.30 moles of ethanoic acid is found in the equilibrium mixture. 

We need to fill in the gaps in the second line by applying the stoichiometry built into the equation. It is important to note that the coefficients in the equation are all T. The reaction has proceeded to produce 0.30 moles of ethanoic acid, and the molar ratio of ethanoic acid and ethanol is 1 1. This means that the amount of ethanol in the equilibrium mixture is also 0.30 moles. 

The equihbiia that govern the reactions of weak acids or bases in aqueous solution will resist attempts to change them. This is known as Le Chateliei s principle. For example, the dissociation of ethanoic acid obeys the equation ... 

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