Carboxylic acids are organic acids characterized by the presence of a carboxyl group, which has the formula -C(=O)OH, usually written -COOH or -CO₂H. An organic acid is an Organic compound with Acidic properties Carboxyl group or CO2H is a Functional group present in Amino acids and Carboxylic acids Its structure is composed of one carbon atom attached A chemical formula is a way of expressing information about the Atoms that constitute a particular Chemical compound, and how the relationship between those atoms changes ^[1] Carboxylic acids are Brønsted-Lowry acids — they are proton donors. Salts and anions of carboxylic acids are called carboxylates. Salt is a Dietary mineral composed primarily of Sodium chloride that is essential for Animal life but toxic to most land plants An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge

The simplest series of carboxylic acids are the alkanoic acids, R-COOH, where R is a hydrogen or an alkyl group. Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 An alkyl is a Univalent radical consisting of Carbon and Hydrogen atoms arranged in a chain In Organic chemistry, functional groups are specific groups of Atoms within Molecules that are responsible for the characteristic Chemical reactions Compounds may also have two or more carboxylic acid groups per molecule.

Contents 1 Physical properties 1.1 Stability of the acid 1.2 Stability of the conjugate base 2 Spectroscopy 3 Sources 4 Synthesis 5 Reactions 6 Nomenclature and examples 7 See also 8 References 9 External links

Physical properties

Carboxylic acids are polar, and form hydrogen bonds with each other. A dimer is a Chemical or Biological entity consisting of two subunits called Monomers which are held together by either Intramolecular forces "Polar molecule" and "Non-polar" redirect here A hydrogen bond results from a Dipole-dipole force between an Electronegative atom and a Hydrogen atom bonded to Nitrogen, Oxygen At high temperatures, in vapor phase, carboxylic acids usually exist as dimeric pairs. Lower carboxylic acids (1 to 4 carbons) are miscible with water, whereas higher carboxylic acids are very much less-soluble due to the increasing hydrophobic nature of the alkyl chain. They tend to be rather soluble in less-polar solvents such as ethers and alcohols. ^[2]

Carboxylic acids are widespread in nature and are typically weak acids, meaning that they only partially dissociate into H⁺ cations and RCOO⁻ anions in aqueous solution. A weak acid is an Acid that does not completely donate all of its hydrogens when dissolved in water Dissociation in Chemistry and Biochemistry is a general process in which ionic compounds ( complexes, Molecules, or Salts) separate An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge Water ( H2[[oxygen O]] H OH) is the most abundant Molecule on Earth 's surface composing of about 70% of the Earth's surface as For example, at room temperature, only 0. 02 % of all acetic acid molecules are dissociated in water. Acetic acid, also known as ethanoic acid, is an organic chemical compound, giving Vinegar its sour taste

Since the carboxylic acids are weak acids, in water, both forms exist in an equilibrium:

RCOOH ↔ RCOO⁻ + H⁺

The acidity of carboxylic acids can be explained by either the stability of the acid or the stability of the conjugate base using inductive effects or resonance effects. Within the Brønsted - Lowry ( protonic) theory of acids and bases, a conjugate acid is the acid member HX of a pair of two compounds that transform The inductive effect in Chemistry is an experimentally observable effect of the transmission of charge through a chain of Atoms in a Molecule Resonance in Chemistry is a theory used to represent and model certain types of non-classical Molecular structures Resonance is a key component

Stability of the acid

Using inductive effects, the acidity of carboxylic acids can be rationalized by the two electronegative oxygen atoms distorting the electron clouds surrounding the O-H bond, weakening it. " Electronegativity " is the opposite of " Electropositivity," which describes an element's ability to donate electrons Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the The weak O-H bond causes the acid molecule to be less stable, and causing the hydrogen atom to be labile, thus it dissociates easily to give the H⁺ ion. Since the acid is unstable, the equilibrium will lie on the right. In a Chemical process, chemical equilibrium is the state in which the chemical activities or Concentrations of the reactants and products have no net change

Additional electronegative atoms or groups, such as chlorine or hydroxyl, substituted on the R-group have a similar, though lesser effect. The presence of these groups increases the acidity through inductive effects. The inductive effect in Chemistry is an experimentally observable effect of the transmission of charge through a chain of Atoms in a Molecule For example, trichloroacetic acid (three -Cl groups) is a stronger acid than lactic acid (one -OH group), which in turn is stronger than acetic acid (no electronegative constituent). Trichloroacetic acid (also known as trichloroethanoic acid) is an analogue of Acetic acid in which the three Hydrogen atoms of the Methyl Lactic acid ( IUPAC Systematic name: 2-hydroxypropanoic acid) also known as milk acid, is a Chemical compound that plays a role

Stability of the conjugate base

The acidity of a carboxylic acid can also be explained by resonance effects. Resonance in Chemistry is a theory used to represent and model certain types of non-classical Molecular structures Resonance is a key component The result of the dissociation of a carboxylic acid is a resonance stabilized product in which the negative charge is shared (delocalized) between the two oxygen atoms. Each of the carbon-oxygen bonds has what is called a partial double-bond characteristic. Since the conjugate base is stabilized, the above equilibrium lies on the right.

Spectroscopy

Carboxylic acids are most readily identified as such by infrared spectrometry. Infrared spectroscopy (IR spectroscopy is the subset of Spectroscopy that deals with the Infrared region of the Electromagnetic spectrum. They exhibit a sharp C=O stretch between 1680 and 1725 cm⁻¹, and the characteristic O-H stretch of the carboxyl group appears as a broad peak in the 2500 to 3000 cm⁻¹ region. ^[2]

In ¹H NMR spectrometry, the hydroxyl hydrogen appears in the 10-13 ppm region, though it is often either broadened or not observed due to exchange with any traces of water.

Sources

Lower straight-chain aliphatic carboxylic acids, as well as those of even carbon number up to C₁₈, are commercially available. In Organic chemistry, compounds composed of Carbon and Hydrogen are divided into two classes Aromatic compounds which contain Benzene rings For example, acetic acid is produced by methanol carbonylation with carbon monoxide, whereas long chain carboxylic acids are obtained by the hydrolysis of triglycerides obtained from plant or animal oils. Methanol, also known as methyl alcohol, carbinol, wood alcohol, wood naphtha or wood spirits, is a Chemical compound Carbonylation refers to reactions that introduce Carbon monoxide into organic and inorganic substrates Carbon monoxide, with the chemical formula CO is a colorless odorless tasteless yet highly toxic Gas. (more properly known as, TAG or triacylglyceride) is Glyceride in which the Glycerol is Esterified with three Fatty acids It is the

Vinegar, a dilute solution of acetic acid, is biologically produced from the fermentation of ethanol. Fermentation is the process of deriving energy from the oxidation of organic compounds such as carbohydrates using an endogenous electron acceptor which is It is used in food and beverages, but is not used in industry.

Synthesis

• Carboxylic acids can be produced by oxidation of primary alcohols and aldehydes with strong oxidants such as Potassium Dichromate, Jones reagent, potassium permanganate, or sodium chlorite. Organic reductions or organic oxidations or organic redox reactions are Redox reactions that take place with Organic compounds In Organic In Chemistry, an alcohol is any Organic compound in which a Hydroxyl group ( - O[[hydrogen H]]) is bound to a Carbon An aldehyde is an organic compound containing a terminal Carbonyl group. Potassium dichromate, K2Cr2O7 is a common inorganic chemical reagent most commonly used as an Oxidizing agent in various laboratory The Jones oxidation is a Chemical reaction described as the Chromic acid oxidation of primary and secondary Alcohols to Carboxylic acids Potassium permanganate is the Chemical compound K[[manganese Mn]] O 4 Sodium chlorite is a chemical compound used in the manufacture of Paper.
• They may also be produced by the oxidative cleavage of olefins by ozonolysis, potassium permanganate, or potassium dichromate. In Organic chemistry, an alkene, olefin, or olefine is an unsaturated Chemical compound containing at least one Carbon Ozonolysis is the cleavage of an Alkene or Alkyne with Ozone to form Organic compounds in which the multiple Carbon-carbon bond has Potassium permanganate is the Chemical compound K[[manganese Mn]] O 4 Potassium dichromate, K2Cr2O7 is a common inorganic chemical reagent most commonly used as an Oxidizing agent in various laboratory In particular, any alkyl group on a benzene ring will be fully oxidized to a carboxylic acid, regardless of its chain length. This is the basis for the industrial synthesis of benzoic acid from toluene. Benzoic acid, C7H6O2 (or C6H5COOH is a colorless crystalline solid and the simplest Aromatic Carboxylic acid Toluene, also known as methylbenzene or phenylmethane, is a clear water -insoluble liquid with the typical smell of Paint thinners redolent of
• Carboxylic acids can also be obtained by the hydrolysis of nitriles, esters, or amides, with the addition of acid or base. A nitrile is any Organic compound which has a - C ≡ N Functional group. Esters are a class of Chemical compounds and Functional groups Esters consist of an inorganic or organic Acid in which at least In Chemistry, an amide is one of three kinds of Compounds (sometimes called acid amide the organic Functional group characterized
• They can also be prepared from the action of a Grignard reagent on carbon dioxide, though this method is not used in industry. The Grignard reaction, named for the French chemist François Auguste Victor Grignard, is an organometallic Chemical reaction in which Alkyl - Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single

Carboxylic acids may also form from the following reactions:

• Disproportionation of an aldehyde in the Cannizzaro reaction
• Rearrangement of diketones in the benzilic acid rearrangement
• Halogenation followed by hydrolysis of methyl ketones in the haloform reaction
• Hydroformylation of an alkene followed by hydrolysis in the Koch reaction
• Less-common reactions involving the generation of benzoic acids are the von Richter reaction from nitrobenzenes and the Kolbe-Schmitt reaction from phenols. An aldehyde is an organic compound containing a terminal Carbonyl group. The Cannizzaro reaction, named after its discoverer Stanislao Cannizzaro, is a Chemical reaction that involves the base -induced Disproportionation The benzilic acid rearrangement is the Rearrangement reaction of Benzil with Potassium hydroxide to benzilic acid The haloform reaction is a chemical reaction where a haloform (CHX3 where X is a Halogen) is produced by the exhaustive Halogenation of a methyl Ketone The Koch reaction is an Organic reaction for the Organic synthesis of certain tertiary Carboxylic acids from an Alkene, Carbon monoxide The von Richter reaction is the Chemical reaction of Aromatic Nitro compounds with Potassium cyanide giving Carboxylation ortho to The Kolbe-Schmitt reaction / Kolbe process (named after Adolph Wilhelm Hermann Kolbe and Rudolf Schmitt) is a Carboxylation Chemical reaction Phenol, is a toxic colourless Crystalline Solid with a sweet tarry odor commonly referred to as a "hospital smell"

Reactions

• Carboxylic acids react with bases to form carboxylate salts, in which the hydrogen of the hydroxyl (-OH) group is replaced with a metal cation. In Chemistry, a base is most commonly thought of as an aqueous substance that can accept Protons This refers to the Brønsted-Lowry theory of acids and An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge Thus, acetic acid found in vinegar reacts with sodium bicarbonate (baking soda) to form sodium acetate, carbon dioxide, and water:

CH₃COOH + NaHCO₃ → CH₃COONa + CO₂ + H₂O

• Carboxylic acids also react with alcohols and amines to give esters and amides. Sodium bicarbonate or sodium hydrogen carbonate is the Chemical compound with the formula NaHCO3 Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single In Chemistry, an alcohol is any Organic compound in which a Hydroxyl group ( - O[[hydrogen H]]) is bound to a Carbon Amines are Organic compounds and Functional groups that contain a basic Nitrogen Atom with a Lone pair. Esters are a class of Chemical compounds and Functional groups Esters consist of an inorganic or organic Acid in which at least In Chemistry, an amide is one of three kinds of Compounds (sometimes called acid amide the organic Functional group characterized Like other alcohols and phenols, the hydroxyl group on carboxylic acids may be replaced with a chlorine atom using thionyl chloride to give acyl chlorides. Phenol, is a toxic colourless Crystalline Solid with a sweet tarry odor commonly referred to as a "hospital smell" Thionyl chloride (or thionyl dichloride) is an Inorganic compound with the formula S[[Oxygen O]] Cl 2 In Organic chemistry, an acyl chloride (or acid chloride) is an Organic compound which is a reactive derivative of a Carboxylic acid.

• As with all carbonyl compounds, the protons on the α-carbon are labile due to keto-enol tautomerization. The alpha carbon in Organic chemistry refers to the first carbon that attaches to a Functional group (the carbon is attached at the first or alpha position Thus the α-carbon is easily halogenated in the Hell-Volhard-Zelinsky halogenation. The Hell-Volhard-Zelinsky halogenation reaction halogenates Carboxylic acids at the α Carbon.

• The Arndt-Eistert synthesis inserts an α-methylene group into a carboxylic acid. The Arndt-Eistert synthesis is a series of Chemical reactions designed to convert a Carboxylic acid to a higher carboxylic acid homologue (ie
• The Curtius rearrangement converts carboxylic acids to isocyanates. The Curtius rearrangement (or Curtius reaction or Curtius degradation) as first defined by Theodor Curtius, is a Chemical reaction that involves Isocyanate is the Functional group of atoms &ndashN=C=O (1 Nitrogen, 1 Carbon, 1 Oxygen) not to be confused with the Cyanate
• The Schmidt reaction converts carboxylic acids to amines. The Schmidt reaction is an Organic reaction involving alkyl migration over the Carbon to Nitrogen Chemical bond in an Azide with expulsion Amines are Organic compounds and Functional groups that contain a basic Nitrogen Atom with a Lone pair.
• Carboxylic acids are decarboxylated in the Hunsdiecker reaction. The Hunsdiecker reaction (also called the Borodin reaction after Alexander Borodin) is the Organic reaction of Silver salts of Carboxylic acids
• The Dakin-West reaction converts an amino acid to the corresponding amino ketone. The Dakin-West reaction is a Chemical reaction that transforms an Amino-acid into an Amino - Ketone using a Acid anhydride and a base
• In the Barbier-Wieland degradation (1912), the alpha-methylene group in an aliphatic carboxylic acid is removed in a sequence of reaction steps, effectively a chain-shortening ^{[3] [4]}.
• The addition of a carboxyl group to a compound is known as carboxylation; the removal of one is decarboxylation. Enzymes that catalyze these reactions are known as carboxylases (EC 6. Enzymes are Biomolecules that catalyze ( ie increase the rates of Chemical reactions Almost all enzymes are Proteins Carboxylation in Chemistry is a Chemical reaction in which a Carboxylic acid group is introduced in a Substrate. This article is about the Enzyme Commission codes For the European Commission system for coding chemicals see EC-No. 4. 1) and decarboxylases (EC 4. Carboxy-lyases, also known as decarboxylases, are carbon-carbon Lyases that add or remove a Carboxyl group from Organic compounds These 1. 1).

Nomenclature and examples

The carboxylate anion R-COO^– is usually named with the suffix -ate, so acetic acid, for example, becomes acetate ion. A carboxylate anion is an Ion with Negative charge that contains the group -COO&minus In IUPAC nomenclature, carboxylic acids have an -oic acid suffix (e. IUPAC Nomenclature is a system of naming Chemical compounds and of describing the science of Chemistry in general g. , octadecanoic acid). In common nomenclature, the suffix is usually -ic acid (e. g. , stearic acid). Stearic acid (first syllable rhymes with either bear or gear) ( IUPAC Systematic name: octadecanoic acid) is a saturated

Straight-Chained, Saturated Carboxylic Acids

Carbon atoms	Common name	IUPAC name	Chemical formula	Common location or use
1	Formic acid	Methanoic acid	HCOOH	Insect stings
2	Acetic acid	Ethanoic acid	CH3COOH	Vinegar
3	Propionic acid	Propanoic acid	CH3CH2COOH
4	Butyric acid	Butanoic acid	CH3(CH2)2COOH	Rancid butter
5	Valeric acid	Pentanoic acid	CH3(CH2)3COOH	Valerian
6	Caproic acid	Hexanoic acid	CH3(CH2)4COOH
7	Enanthic acid	Heptanoic acid	CH3(CH2)5COOH
8	Caprylic acid	Octanoic acid	CH3(CH2)6COOH	Coconuts and breast milk
9	Pelargonic acid	Nonanoic acid	CH3(CH2)7COOH	Pelargonium
10	Capric acid	Decanoic acid	CH3(CH2)8COOH
12	Lauric acid	Dodecanoic acid	CH3(CH2)10COOH	Coconut oil
16	Palmitic acid	Hexadecanoic acid	CH3(CH2)14COOH	Palm oil
18	Stearic acid	Octadecanoic acid	CH3(CH2)16COOH	Some waxes, soaps, and oils

Other carboxylic acids include:

• Short-chain unsaturated monocarboxylic acids
  • Acrylic acid (2-propenoic acid) – CH₂=CHCOOH, used in polymer synthesis
• Fatty acids – medium to long-chain saturated and unsaturated monocarboxylic acids, with even number of carbons
  • Docosahexaenoic acid – nutritional supplement
  • Eicosapentaenoic acid – nutritional supplement

• Amino acids – the building blocks of proteins

• Keto acids – acids of biochemical significance that contain a ketone group
  • Pyruvic acid
  • Acetoacetic acid

• Aromatic carboxylic acids
  • Benzoic acid – C₆H₅COOH; sodium benzoate, the sodium salt of benzoic acid is used as a food preservative
  • Salicylic acid – found in many skin care products

• Dicarboxylic acids – containing two carboxyl groups
  • Aldaric acid – a family of sugar acids
  • Oxalic acid – found in many foods
  • Malonic acid
  • Malic acid – found in apples
  • Succinic acid – a component of the citric acid cycle
  • Glutaric acid
  • Adipic acid – the monomer used to produce nylon

• Tricarboxylic acids – containing three carboxyl groups
  • Citric acid – found in citrus fruits
  • Isocitric acid
  • Aconitic acid
  • Propane-1,2,3-tricarboxylic acid (tricarballylic acid, carballylic acid)
• Alpha hydroxy acids – containing a hydroxy group
  • Lactic acid (2-hydroxypropanoic acid) – found in sour milk

See also

• Acid anhydride
• Acid chloride
• Amide
• Ester

References

External links

• Carboxylic acids pH and titration - freeware for calculations, data analysis, simulation, and distribution diagram generation

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