Carboxylate

Carboxylate-resonance-hybrid

Acrylate-ion-3D-balls

Carboxylate-resonance-2D

Ester-from-carboxylate-and-alkyl-halide-2D-skeletal

Reaction of carboxylic acids reduction - part two

Carboxylate is an ion consisting of a carbon atom double-bonded to an oxygen atom and single-bonded to a hydroxyl group, making it a negatively charged version of a carboxylic acid group (-COOH). The formula for a carboxylate ion is typically written as R-COO^−, where R represents the alkyl group attached to the carboxylate functionality. Carboxylates are the conjugate bases of carboxylic acids and form when a carboxylic acid donates a proton (H^+), resulting in a resonance-stabilized anion.

Properties

Carboxylates are characterized by their high solubility in water, due to their ability to form hydrogen bonds with water molecules. This property is crucial for the solubility of amino acids and proteins in biological systems. The resonance stabilization of the carboxylate ion makes it less reactive than many other anions, contributing to the relative stability of carboxylic acids in nature.

Synthesis

Carboxylates can be synthesized through several methods, including the direct deprotonation of carboxylic acids. This can be achieved by treating a carboxylic acid with a strong base, such as sodium hydroxide (NaOH) or potassium hydroxide (KOH), resulting in the formation of a sodium or potassium carboxylate salt, respectively.

Another common method for synthesizing carboxylates is through the saponification of esters. In this reaction, an ester reacts with a base, leading to the formation of a carboxylate and an alcohol.

Applications

Carboxylates have a wide range of applications in various industries. In the soap industry, the carboxylate ion is responsible for the soap's cleaning action. Soaps are typically sodium or potassium salts of fatty acids, which are long-chain carboxylic acids. The carboxylate end of the soap molecule is hydrophilic (water-attracting), while the hydrocarbon tail is hydrophobic (water-repelling), allowing soaps to emulsify oils and grease in water.

In biology, carboxylates play a critical role in the Krebs cycle (also known as the citric acid cycle), a series of chemical reactions used by all aerobic organisms to generate energy through the oxidation of acetate derived from carbohydrates, fats, and proteins into carbon dioxide. Carboxylates such as citrate and malate are key intermediates in this cycle.

Carboxylates are also used as preservatives, due to their ability to inhibit microbial growth, and as plasticizers in the production of plastics, where they increase the flexibility of the material.

Environmental Impact

Carboxylates derived from biodegradable sources are considered environmentally friendly due to their ability to be broken down by microorganisms. However, synthetic carboxylates, particularly those used as plasticizers, can pose environmental risks if not properly managed, as they may not readily degrade and can accumulate in the environment.

See Also

• Carboxylic acid
• Ester
• Soap
• Krebs cycle