510 CARBOXYLIC ACIDS (g) A carboxylic acid function is attached as a substituent on a seven-membered ring. The com- olic acid CO,H (h) The aromatic ring is named as a substituent attached to the eight-carbon carboxylic acid Numbering of the chain begins with the carboxyl group CHCH -CH(CH2)CO2H 6-Phenyloctanoic acid 19.15(a) Carboxylic acids are the most acidic class of organic compounds containing only the elements C, H, and O. The order of decreasing acidity is Acetic acid CHaCO, H 18×10-5 Ethanol CH3,OH Ethane H3 CH3 ≈1 (b) Here again, the carboxylic acid is the strongest acid and the hydrocarbon the weakest Benzoic acid CH,CO, H 6.7X 10-5 Benzyl alcohol CBH CH,OH 16-18 C6H6 ≈43 (c) Propanedioic acid is a stronger acid than propanoic acid because the electron-withdrawing effect of one carboxyl group enhances the ionization of the other. Propanedial is a 1,3-dicar- bonyl compound that yields a stabilized enolate; it is more acidic than 1, 3-propanediol. Propanedioic acid HO, CCH, CO, H 14×10-3 Propanoic acid CHa CH,CO, H 1.3×10-5 ≈10 1, 3-Propanediol HOCH,CH, CH,OH 10 ≈16 (d) Trifluoromethanesulfonic acid is by far the strongest acid in the group. It is structurally related to sulfuric acid, but its three fluorine substituents make it much stronger. Fluorine substituents Back Forward Main Menu TOC Study Guide Toc Student OLC MHHE Website(g) A carboxylic acid function is attached as a substituent on a seven-membered ring. The com￾pound is cycloheptanecarboxylic acid. (h) The aromatic ring is named as a substituent attached to the eight-carbon carboxylic acid. Numbering of the chain begins with the carboxyl group. 19.15 (a) Carboxylic acids are the most acidic class of organic compounds containing only the elements C, H, and O. The order of decreasing acidity is Ka pKa Acetic acid CH3CO2H 1.8  105 4.7 Ethanol CH3CH2OH 1016 16 Ethane CH3CH3 1046 46 (b) Here again, the carboxylic acid is the strongest acid and the hydrocarbon the weakest: Ka pKa Benzoic acid C6H5CO2H 6.7  105 4.2 Benzyl alcohol C6H5CH2OH 1016–1018 16–18 Benzene C6H6 1043 43 (c) Propanedioic acid is a stronger acid than propanoic acid because the electron-withdrawing effect of one carboxyl group enhances the ionization of the other. Propanedial is a 1,3-dicar￾bonyl compound that yields a stabilized enolate; it is more acidic than 1,3-propanediol. Ka pKa Propanedioic acid HO2CCH2CO2H 1.4  103 2.9 Propanoic acid CH3CH2CO2H 1.3  105 4.9 Propanedial O?CHCH2CH?O 109 9 1,3-Propanediol HOCH2CH2CH2OH 1016 16 (d) Trifluoromethanesulfonic acid is by far the strongest acid in the group. It is structurally related to sulfuric acid, but its three fluorine substituents make it much stronger. Fluorine substituents 6-Phenyloctanoic acid CH(CH2)4CO2H CH2CH3 CO2H 510 CARBOXYLIC ACIDS __ __ __ Back Forward Main Menu TOC Study Guide TOC Student OLC MHHE Website