MCAT CARS Strategy Course Trial Session - Tuesday at 8PM ET! Reserve Spot

MCAT CARS Strategy Course Trial Session - Tuesday at 8PM ET!
Reserve Spot

MCAT Content / Carboxylic Acids / Carboxylic Acids Description


Topic: Carboxylic Acids

Carboxylic acids (-COOH) are functional groups composed of one carbonyl and one hydroxyl group.

A carboxyl group (COOH) is a functional group consisting of a carbonyl group (C=O) with a hydroxyl group (O-H) attached to the same carbon atom. Carboxyl groups have the formula -C(=O)OH, usually written as -COOH or CO2H. Carboxylic acids are a class of molecules which are characterized by the presence of one carboxyl group. As proton donors, carboxylic acids are characterized as Brønsted-Lowry acids. Acids with two or more carboxylic groups are called dicarboxylic, tricarboxylic, etc. Salts and esters of carboxylic acids are called carboxylates. Carboxylate ions are resonance-stabilized. This increased stability leads to increased acidity compared to that of alcohols. Generally, in IUPAC nomenclature, carboxylic acids have an “-oic acid” suffix, although “-ic acid” is the suffix most commonly used.

When naming compounds with a carboxylic acid group present, it is appropriate to replace the ending (the -e, for example) with -oic acid. The acidity of the carboxylic acid comes from the ability to donate the proton on the -OH substituent.

Physical Properties
Due to the strong hydrogen-bonding, two important factors with carboxylic acids are that they have a high boiling point but are also soluble in water and other organic solvents such as toluene and ethanol. Carboxylic acids are also highly reactive to two factors: the two electron-rich oxygens in the carbonyl and alcohol portion of the functional group, and the electron-poor carbon between the carbonyl alcohol group, which is a desirable attack location for nucleophiles.

Practice Questions

Khan Academy

MCAT Official Prep (AAMC)

Official Guide C/P Section Passage 3 Question 10

Chemistry Question Pack Question 15

Key Points

• Carboxylic acids are used as precursors to form other compounds such as esters, aldehydes, and ketones.

• Carboxylic acids can exhibit hydrogen bonding with themselves, especially in non-polar solvents; this leads to increased stabilization of the compounds and elevates their boiling points.

• Since they contain both hydroxyl and carbonyl functional groups, carboxylic acids participate in hydrogen bonding as both hydrogen acceptors and hydrogen donors.

• Compounds with a carboxylic acid group present adopt the suffix -oic acid in their nomenclature.

• Carboxylic acids have a high boiling point and have an easily reactive electron-poor carbon.

Key Terms

Brønsted-Lowry acids: A chemical species that donates one or more hydrogen ions in a reaction.

Carbonyl: Group containing double-bonded carbon and oxygen, written as C=O.

Alcohol: Group containing a hydroxyl, written as -OH.

Ester: A compound most often formed by the condensation of an alcohol and an acid, with elimination of water. It contains the functional group C=O joined via carbon to another oxygen atom.

Nitrile: Any of a class of organic compounds containing a cyano functional group (-C≡N).

Olefin: Any of a class of unsaturated, open-chain hydrocarbons such as ethylene; an alkene with only one carbon-carbon double bond.

Billing Information
We had trouble validating your card. It's possible your card provider is preventing us from charging the card. Please contact your card provider or customer support.
{{ cardForm.errors.get('number') }}
{{ registerForm.errors.get('zip') }}
{{ registerForm.errors.get('coupon') }}
Tax: {{ taxAmount(selectedPlan) | currency spark.currencySymbol }}

Total Price Including Tax: {{ priceWithTax(selectedPlan) | currency spark.currencySymbol }} / {{ selectedPlan.interval | capitalize }}