Chapter 8: Carboxylic Acids Flashcards
carboxylic acid
caontin both an carbonyl group and a hydroxyl group, they are always terminal groups
nomenclature
adding the suffic -oic acdi to the parent root
methanoi acid
formic acid
ethanoic acid
acetic acid
propanoic acid
propionic acid
cyclic carboxylic acid
suffic carboxylic acid after the the cycloalkane
dicarboxylic acid
Have a carboxylic acid group on each end of the molecule, are common biological systems. they have the suffix -dioic acid
salts of carboxylic acid
begginign with cation followed by the name of the acid with the ending -oate replacing -oic acid
dimers
paris of molecules connected by two hydrogen bonds
substituints affect aciity?
Substituent on carbon atoms near carboxyl group influence anion stability and therefore affect acidity.
Electron withdrawing groups (-NO2) increase acidity. Electron donating groups destabilize the negative charge, decreasing the acidity (-NH2).
dicarboxylic hydrogen acidity
Dicarboxylic acids are more acidic than the analogous monocarboxylic acids. When one proton is removed from the molecule, the carboxylate anion is formed, resulting in an immediate decrease in the acidity. The second proton is actually less acidic than the analogous proton of a monocarboxylic acid.
acidity
Hydroxyl hydrogen of carboxylic acid is quite acidic. The negative charge that remains after the hydrogen is removed Is stabilized through resonance. There acidities due to resonance stabilization and can be enhanced by the addition of electronegative group or greater ability to delocalize charge.
The more stable the conjugate base is, the easier it is for the proton to leave, and thus the stronger the acid.
Nucleophilic acyl substitution
Existence of a Living Group in carboxylic acids and their derivatives. In this case, after opening the carbonyl via nucleophilic attack and forming a tetrahedral intermediate, the carbonyl can reform, thereby kicking off the leaving group.
betha-dicarboxylic acid
Each carboxylic acid is positioned on the beta carbon of the other, There are two carboxylic acids separated by a single carbon. High acidity of the Alpha hydrogen is located on the carbon between the two carboxyl groups.
synthesis of carboxylic acid
Carboxylic acids can be prepared via oxidation of aldehyde and primary alcohols. The oxidation is often a dichromate salt (Na2Cr2O or K2Cr2O7), chromium trioxide (CrO3) or potassium permanganate (KMnO4).
Secondary and tertiary alcohol cannot be oxidized to carboxylic acids because they already have at least two bonds to other carbons.
amides
Carboxylic acids can be converted into amides if the incoming nucleophile is ammonia (NH4) or an amide. Named by replacing the -oic acid suffix with -amide in the name of the parent carboxylic acid. Any alkyl groups on the nitrogen are placed at the beginning of the name with the prefix N-. Amides that are cyclic, are called lactams, and are named by replacing -oic acid with -lactam.
Acyl derivatives
encompasses all molecules with a carboxylic acid derived carbonyl including carboxylic acid, amides, esters, anhydrides and others.
esters
Are a hybrid between a carboxylic acid and an ether (ROR’). Esterification is a condensation reaction with water as a side product. The carbonyl oxygen can be protonated, which enhances the polarity of the bond, therefore placing additional positive charge on the carbonyl carbon and increasing its susceptibility to nucleophilic attack.
Esters that are cyclic are called lactones. Are named by replacing -oic acid with -lactone.
anhydrides
Anhydrides can be formed by the condensation of two carboxylic acids. They are named by replacing the acid at the end of the name of the parent carboxylic acid with anhydride.
reduction
carboxylic acids can be reduced to primary alcohols by the use of lithium aluminum hydride (LiAlH4). A gentler reducing agent like sodium borohtdride (NaBh4) is not strong enough to reduce carboxylic acids.
saponification
Long chain carboxylic acids react with sodium or potassium hydroxide, a salt is formed. This process is called saponification. It is how SOAP is formed. Soap molecules arrange themselves into spherical structure called micelles. The polar head interacts with the hydrophilic environment, The nonpolar tails are oriented towards the interior of the micelle.
decarboxylation
Describes the complete loss of the carboxyl group as carbon dioxide. The carboxyl group is lost and replaced with hydrogen. The enol that is initially formed from the destruction of the ring tautomerises to the more stable keto form.
