Carboxylate in the context of "Zwitterion"

In organic chemistry, a functional group is any substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions regardless of the rest of the molecule's composition. This enables systematic prediction of chemical reactions and behavior of chemical compounds and the design of chemical synthesis. The reactivity of a functional group can be modified by other functional groups nearby. Functional group interconversion can be used in retrosynthetic analysis to plan organic synthesis.

A functional group is a group of atoms in a molecule with distinctive chemical properties, regardless of the other atoms in the molecule. The atoms in a functional group are linked to each other and to the rest of the molecule by covalent bonds. For repeating units of polymers, functional groups attach to their nonpolar core of carbon atoms and thus add chemical character to carbon chains. Functional groups can also be charged, e.g. in carboxylate salts (−COO), which turns the molecule into a polyatomic ion or a complex ion. Functional groups binding to a central atom in a coordination complex are called ligands. Complexation and solvation are also caused by specific interactions of functional groups. In the common rule of thumb "like dissolves like", it is the shared or mutually well-interacting functional groups which give rise to solubility. For example, sugar dissolves in water because both share the hydroxyl functional group (−OH) and hydroxyls interact strongly with each other. Plus, when functional groups are more electronegative than atoms they attach to, the functional groups will become polar, and the otherwise nonpolar molecules containing these functional groups become polar and so become soluble in some aqueous environment.

A detergent is a formulated and commercially sold product for cleaning that contains surfactants plus other components. Detergents comprise surfactants as main functional components to remove hydrophobic grease or dirt by dispersing them in water. They often further comprise water (to facilitate application), builders (to soften water), enzymes (for breaking down proteins, fats, or starches), and dyes or fragrances (to improve the user's sensory experience).

Common surfactants used in detergents are alkylbenzene sulfonates, which are soap-like compounds that are more soluble than soap in hard water, because the polar sulfonate is less likely than the polar carboxylate of soap to bind to calcium and other ions found in hard water.

Saponification is a process of cleaving esters into carboxylate salts and alcohols by the action of aqueous alkali. Typically aqueous sodium hydroxide solutions are used. It is an important type of alkaline hydrolysis. When the carboxylate is a long chain, its salt is called a soap. The saponification of ethyl acetate gives sodium acetate and ethanol:

In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group (−C(=O)−OH) attached to an R-group. The general formula of a carboxylic acid is often written as R−COOH or R−CO₂H, sometimes as R−C(O)OH with R referring to an organyl group (e.g., alkyl, alkenyl, aryl), or hydrogen, or other groups. Carboxylic acids occur widely. Important examples include the amino acids and fatty acids. Deprotonation of a carboxylic acid gives a carboxylate anion.

Cholesteryl esters are a type of dietary lipid and are ester derivatives of cholesterol. The ester bond is formed between the carboxylate group of a fatty acid and the hydroxyl group of cholesterol. Cholesteryl esters have a lower solubility in water due to their increased hydrophobicity. Esters are formed by replacing at least one –OH (hydroxyl) group with an –O–alkyl (alkoxy) group. They are hydrolyzed by pancreatic enzymes, such as cholesterol esterase, to produce cholesterol and free fatty acids. They are associated with atherosclerosis.

Cholesteryl esters are found in human brains as lipid droplets which store and transport cholesterol. Increased levels of cholesteryl esters have been found in certain parts of the brain of people with Huntington's disease. Higher concentrations of cholesteryl esters have been found in the caudate and putamen, but not the cerebellum, of people with Huntington disease compared with levels in controls. Increase in cholesteryl esters has also been found in other neurological disorders like multiple sclerosis and Alzheimer's disease.