In organic chemistry, an amide ( or or, also known as an organic amide or a carboxamide, is a compound with the general formula RC NR′R″, where R, R', and R″ represent organic groups or hydrogen atoms. The amide group is called a peptide bond when it is part of the main chain of a protein, and an isopeptide bond when it occurs in a side chain, such as in the amino acids asparagine and glutamine. It can be viewed as a derivative of a carboxylic acid RC OH with the hydroxyl group –OH replaced by an amine group −NR′R″; or, equivalently, an acyl group RC − joined to an amine group.
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 R−COOH or R−CO2H, with R referring to the alkyl, alkenyl, aryl, or other group. Carboxylic acids occur widely. Important examples include the amino acids and fatty acids. Deprotonation of a carboxylic acid gives a carboxylate anion.
An ester is a chemical compound derived from an oxoacid in which at least one –OH hydroxyl group is replaced by an –O– alkyl (alkoxy) group, as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides are fatty acid esters of glycerol; they are important in biology, being one of the main classes of lipids and comprising the bulk of animal fats and vegetable oils.
Hydrolysis is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile.
An acyl group is a moiety derived by the removal of one or more hydroxyl groups from an oxoacid, including inorganic acids. It contains a double-bonded oxygen atom and an alkyl group (R-C=O). In organic chemistry, the acyl group is usually derived from a carboxylic acid, in which case it has the formula RCO–, where R represents an alkyl group that is linked to the carbon atom of the group by a single bond. Although the term is almost always applied to organic compounds, acyl groups can in principle be derived from other types of acids such as sulfonic acids and phosphonic acids. In the most common arrangement, acyl groups are attached to a larger molecular fragment, in which case the carbon and oxygen atoms are linked by a double bond.
In organic chemistry, an imino acid is any molecule that contains both imine (>C=NH) and carboxyl functional groups.
A diol is a chemical compound containing two hydroxyl groups. An aliphatic diol is also called a glycol. This pairing of functional groups is pervasive, and many subcategories have been identified.
An imine is a functional group or organic compound containing a carbon–nitrogen double bond. The nitrogen atom can be attached to a hydrogen or an organic group (R). The carbon atom has two additional single bonds. Imines are common in synthetic and naturally occurring compounds and they participate in many reactions.
An acyl halide is a chemical compound derived from an oxoacid by replacing a hydroxyl group with a halide group.
Tautomers are structural isomers of chemical compounds that readily interconvert. The chemical reaction interconverting the two is called tautomerization. This conversion commonly results from the relocation of a hydrogen atom within the compound. The phenomenon of tautomerization is called tautomerism, also called desmotropism. Tautomerism is for example relevant to the behavior of amino acids and nucleic acids, two of the fundamental building blocks of life.
Solvolysis is a type of nucleophilic substitution (SN1/SN2) or elimination where the nucleophile is a solvent molecule. Characteristic of SN1 reactions, solvolysis of a chiral reactant affords the racemate. Sometimes however, the stereochemical course is complicated by intimate ion pairs, whereby the leaving anion remains close to the carbocation, effectively shielding it from an attack by the nucleophile. Particularly fast reactions can occur by neighbour group participation, with nonclassical ions as intermediates or transition states.
An organic acid anhydride is an acid anhydride that is an organic compound. An acid anhydride is a compound that has two acyl groups bonded to the same oxygen atom. A common type of organic acid anhydride is a carboxylic anhydride, where the parent acid is a carboxylic acid, the formula of the anhydride being (RC(O))2O. Symmetrical acid anhydrides of this type are named by replacing the word acid in the name of the parent carboxylic acid by the word anhydride. Thus, (CH3CO)2O is called acetic anhydride. Mixed (or unsymmetrical) acid anhydrides, such as acetic formic anhydride (see below), are known, whereby reaction occurs between two different carboxylic acids. Nomenclature of unsymmetrical acid anhydrides list the names of both of the reacted carboxylic acids before the word "anhydride" (for example, the dehydration reaction between benzoic acid and propanoic acid would yield "benzoic propanoic anhydride").
In chemistry, disproportionation, sometimes called dismutation, is a redox reaction in which one compound of intermediate oxidation state converts to two compounds, one of higher and one of lower oxidation states. More generally, the term can be applied to any desymmetrizing reaction of the following type: 2 A → A' + A", regardless of whether it is a redox or some other type of process.
Amidines are organic compounds with the functional group RC(NR)NR2, where the R groups can be the same or different. They are the imine derivatives of amides (RC(O)NR2). The simplest amidine is formamidine, HC(=NH)NH2.
In organic chemistry a halohydrin is a functional group in which a halogen and a hydroxyl are bonded to adjacent carbon atoms, which otherwise bear only hydrogen or hydrocarbyl groups. The term only applies to saturated motifs, as such compounds like 2-chlorophenol would not normally be considered halohydrins. Megatons of some chlorohydrins, e.g. propylene chlorohydrin, are produced annually as precursors to polymers.
An oxyacid, oxoacid, or ternary acid is an acid that contains oxygen. Specifically, it is a compound that contains hydrogen, oxygen, and at least one other element, with at least one hydrogen atom bonded to oxygen that can dissociate to produce the H+ cation and the anion of the acid.
A nitronate (IUPAC: azinate) in organic chemistry is a functional group with the general structure R1R2C=NO−
2. It is the anion of nitronic acid (sometimes also called an aci, or an azinic acid), a tautomeric form of a nitro compound. Just as ketones and aldehydes can exist in equilibrium with their enol tautomer, nitro compounds exist in equilibrium with their nitronate tautomer under basic conditions. In practice they are formed by the deprotonation of the α-carbon, the pka of which is typically around 17.
In chemical nomenclature, nor- is a prefix to name a structural analog that can be derived from a parent compound by the removal of one carbon atom along with the accompanying hydrogen atoms. The nor-compound can be derived by removal of a CH
3, CH
2, or CH group, or of a C atom. The "nor-" prefix also includes the elimination of a methylene bridge in a cyclic parent compound, followed by ring contraction.. The terms desmethyl- or demethyl- are synonyms of "nor-".
A reductone is a special class of organic compounds. They are enediols with a carbonyl group adjacent to the enediol group, i.e. RC(OH)=C(OH)-C(O)R. The enediol structure is stabilized by the resonance resulting from the tautomerism with the adjacent carbonyl. Therefore, the chemical equilibrium produces mainly the enediol form rather than the keto form.
A descriptor is in chemical nomenclature a prefix placed before the systematic substance name, which describes the configuration or the stereochemistry of the molecule. Some listed descriptors are only of historical interest and should not be used in publications anymore as they do not correspond with the modern recommendations of the IUPAC. Stereodescriptors are often used in combination with locants to clearly identify a chemical structure unambiguously.
