CHAPTER NINETEEN Carboxylic Acids FIGURE 19. 4 Elec- trostatic potential maps of (a) acetic acid and (b)acetate ion. The negative between both oxygen etate ion 121 pm -12 CHIC CH3CO OH 125pm For many years, resonance in carboxylate ions was emphasized when explaining the acidity of carboxylic acids. Recently, however, it has been suggested that the induc their relative contributions may be a matter of debate, both play major roles. though tive effect of the carbonyl group may be more important. It seems clear that, even though 19.5 SALTS OF CARBOXYLIC ACIDS In the presence of strong bases such as sodium hydroxide, carboxylic acids are neutral ized rapidly and quantitatively boxylic Hydroxide (stronger (stronger (weaker(weaker base) PROBLEM 19.3 Write an ionic equation for the reaction of acetic acid with each of the following, and specify whether the equilibrium favors starting materials or pre (a) Sodium ethoxide ( d) Sodium acetylide (b )Potassium tert-butoxide (e) potassium nitrate SAMPLE SOLUTION (a) This is an acid-base reaction ethoxide ion is the base CH3CO2H CH3CH2O CH3CO2 CH3CH2OH Acetic acid Ethoxide ion Acetate ion Ethanol (stronger acid) (st The position of equilibrium lies well to the right. Ethanol, with a Ka of 10-16 (pka 16), is a much weaker acid than acetic acid Back Forward Main MenuToc Study Guide ToC Student o MHHE WebsiteFor many years, resonance in carboxylate ions was emphasized when explaining the acidity of carboxylic acids. Recently, however, it has been suggested that the induc￾tive effect of the carbonyl group may be more important. It seems clear that, even though their relative contributions may be a matter of debate, both play major roles. 19.5 SALTS OF CARBOXYLIC ACIDS In the presence of strong bases such as sodium hydroxide, carboxylic acids are neutral￾ized rapidly and quantitatively: PROBLEM 19.3 Write an ionic equation for the reaction of acetic acid with each of the following, and specify whether the equilibrium favors starting materials or products: (a) Sodium ethoxide (d) Sodium acetylide (b) Potassium tert-butoxide (e) Potassium nitrate (c) Sodium bromide (f) Lithium amide SAMPLE SOLUTION (a) This is an acid–base reaction; ethoxide ion is the base. The position of equilibrium lies well to the right. Ethanol, with a Ka of 1016 (pKa16), is a much weaker acid than acetic acid. CH3CO2H Acetic acid (stronger acid) CH3CH2OH Ethanol (weaker acid) CH3CH2O Ethoxide ion (stronger base) CH3CO2 Acetate ion (weaker base) RC H O O Carboxylic acid (stronger acid) OH Hydroxide ion (stronger base) K  1011 RC O O Carboxylate ion (weaker base) H OH Water (weaker acid) NH4 CH3C OH O 121 pm 136 pm CH3C O1/2 O1/2 125 pm 125 pm 742 CHAPTER NINETEEN Carboxylic Acids (a) (b) FIGURE 19.4 Elec￾trostatic potential maps of (a) acetic acid and (b) acetate ion. The negative charge (red) is equally distributed between both oxygens of ac￾etate ion. Back Forward Main Menu TOC Study Guide TOC Student OLC MHHE Website