Fresh coff ee, I Show how to calculate the two probabilities given in Example 9.8.
Chapter 19 notes: Carboxylic Acids Nomenclature Find longest carbon chain including –COOH. Replace the last -e with –oic Acid. If there are two present, replace the –e with –dioc Acid If –COOH is bonded to a ring, add carboxylic acid placing it in the 1 position and omitting the 1 in the name. Tip: Common names also exist, however, it is more important to know the IUPC name as either name is correct on the exam (in Dr. Friebe’s class.) Because IUPC is systematic, it is easier to derive the name from a structure rather than memorizing common names. Another instructor may want you to know both, so keep that in mind Metal salts change –ic to –ate. Properties Carboxylic acids are s2 hybridized, and are trigonal planar with 120˚ bond angles They have dipole-dipole and hydrogen bonding interactions They form dimers (dashed lines=H-bonds): Very polar High melting points and boiling points Soluble in organic solvents and in water when there are less than or equal to 5 carbons. If there are more than 5 carbons, the nonpolar portion makes the molecule insoluble in water. Preparation Prepared using oxidation reactions Use one of these 1˚ Alcohol: reagents in the presence of 2 S4 and water Alkyl Benzene (methyl group can also be CH R or2CHR ): 2 Alkyne Oxidative cleavage: Bronsted-Lowry Acid-Base reactions and nucleophile reactions Reaction with a base Reaction with a strong acid (2 pathways) First pathway the acid attacks the double bond, and is preferred because it is resonance stabilized. Second pathway is possible where the acid attacks the OH group. Reactions with a nucleophile Inductive effect Electron withdrawing groups make protons more acidic Electron donating groups make protons more acidic More stable conjugate base => more acidic proton Benzoic acid is less acidic with activating groups because electrons are donated to benzene ring. More negative group closer to the positive proton holds the proton tighter. Deactivating groups mare benzoic acid more acidic because they withdraw electrons from the ring. More positively charged ring means the positively charged proton can leave more easily.