ch. 20 Flashcards
What hybridization is the carbonyl carbon in carboxylic acids?
Sp2
Are carboxylic acids weaker or stronger than mineral acids?
weaker
Why do carboxylic acids dissociate more than alcohols?
the carboxylate ions are stablized by resonance
What is the pKa of carboxylic acids?
Approximately 5
What makes carboxylic acids more acidic?
Being substituted by EWG lowering the pKa and stabilizing the carboxylate ions.
What makes a carboxylic acid less acidic?
Being substituted by EDG raising the pKa and destabilizing the carboxylate ions.
Henderson-Hasselbalch Equation
pH = pK_a + log10([A^-] / [HA])
What pH causes carboxylic acids to entirely dissociate?
pH= 7.3; exist as carboxylate anions
Methods of synthesis of carboxylic acids?
Oxidation of alkylbenzenes, oxidation of primary alcohols/aldehydes, reaction of Grignard reagents with CO2 (carboxylation), and hydrolysis of nitriles
General reactions of carboxylic acids?
Loss of acidic proton, nucleophilic acyl substitution at the carbonyl group, substitution of the alpha carbon, and reduction.
Nitriles are prepared by what type of reactions?
SN2 reaction of alkyl halide with cyanide ion or dehydration of an amide
Reactions of nitriles
hydrolysis to carboxylic acids, reduction to primary amines, and reaction with Grignard reagents to yield ketones
Acids IR absorption?
2500-3300 cm O-H bond and 1710-1760 cm C=O
Nitriles IR absorption?
2250 cm
Acids CNMR and HNMR absorption?
165-185 and 12