In organic chemistry, phenols, sometimes called phenolics, are a class of chemical compounds consisting of one or more hydroxyl groups (−OH) bonded directly to an aromatic hydrocarbon group. The simplest is phenol, C
6H
5OH. Phenolic compounds are classified as simple phenols or polyphenols based on the number of phenol units in the molecule.
In organic chemistry, the Diels–Alder reaction is a chemical reaction between a conjugated diene and a substituted alkene, commonly termed the dienophile, to form a substituted cyclohexene derivative. It is the prototypical example of a pericyclic reaction with a concerted mechanism. More specifically, it is classified as a thermally-allowed [4+2] cycloaddition with Woodward–Hoffmann symbol [π4s + π2s]. It was first described by Otto Diels and Kurt Alder in 1928. For the discovery of this reaction, they were awarded the Nobel Prize in Chemistry in 1950. Through the simultaneous construction of two new carbon–carbon bonds, the Diels–Alder reaction provides a reliable way to form six-membered rings with good control over the regio- and stereochemical outcomes. Consequently, it has served as a powerful and widely applied tool for the introduction of chemical complexity in the synthesis of natural products and new materials. The underlying concept has also been applied to π-systems involving heteroatoms, such as carbonyls and imines, which furnish the corresponding heterocycles; this variant is known as the hetero-Diels–Alder reaction. The reaction has also been generalized to other ring sizes, although none of these generalizations have matched the formation of six-membered rings in terms of scope or versatility. Because of the negative values of ΔH° and ΔS° for a typical Diels–Alder reaction, the microscopic reverse of a Diels–Alder reaction becomes favorable at high temperatures, although this is of synthetic importance for only a limited range of Diels-Alder adducts, generally with some special structural features; this reverse reaction is known as the retro-Diels–Alder reaction.
The Claisen rearrangement is a powerful carbon–carbon bond-forming chemical reaction discovered by Rainer Ludwig Claisen. The heating of an allyl vinyl ether will initiate a [3,3]-sigmatropic rearrangement to give a γ,δ-unsaturated carbonyl, driven by exergonically favored carbonyl CO bond formation.
The Bodroux–Chichibabin aldehyde synthesis is a chemical reaction whereby a Grignard reagent is converted to an aldehyde one carbon longer.
Clemmensen reduction is a chemical reaction described as a reduction of ketones or aldehydes to alkanes using zinc amalgam and concentrated hydrochloric acid (HCl). This reaction is named after Erik Christian Clemmensen, a Danish-American chemist.
The Knorr pyrrole synthesis is a widely used chemical reaction that synthesizes substituted pyrroles (3). The method involves the reaction of an α-amino-ketone (1) and a compound containing an electron-withdrawing group α to a carbonyl group (2).
The Feist–Benary synthesis is an organic reaction between α-halo ketones and β-dicarbonyl compounds to produce substituted furan compounds. This condensation reaction is catalyzed by amines such as ammonia and pyridine. The first step in the ring synthesis is related to the Knoevenagel condensation. In the second step the enolate displaces an alkyl halogen in a nucleophilic aliphatic substitution.
The Niementowski quinoline synthesis is the chemical reaction of anthranilic acids and ketones to form γ-hydroxyquinoline derivatives.
The Rosenmund reduction is a hydrogenation process in which an acyl chloride is selectively reduced to an aldehyde. The reaction was named after Karl Wilhelm Rosenmund, who first reported it in 1918.
Elemicin is a phenylpropene, a natural organic compound, and is a constituent of several plant species' essential oils.
Hexacene is an aromatic compound consisting of six linearly-fused benzene rings. It is a blue-green, air-stable solid with low solubility.
Bis(benzene)chromium is the organometallic compound with the formula Cr(η6-C6H6)2. It is sometimes called dibenzenechromium. The compound played an important role in the development of sandwich compounds in organometallic chemistry and is the prototypical complex containing two arene ligands.
The Wurtz–Fittig reaction is the chemical reaction of an aryl halide, alkyl halides, and sodium metal to give substituted aromatic compounds. Following the work of Charles Adolphe Wurtz on the sodium-induced coupling of alkyl halides, Wilhelm Rudolph Fittig extended the approach to the coupling of an alkyl halide with an aryl halide. This modification of the Wurtz reaction is considered a separate process and is named for both scientists.
Thiazyl fluoride, NSF, is a colourless, pungent gas at room temperature and condenses to a pale yellow liquid at 0.4 °C. Along with thiazyl trifluoride, NSF3, it is an important precursor to sulfur-nitrogen-fluorine compounds. It is notable for its extreme hygroscopicity.
Organochromium chemistry is a branch of organometallic chemistry that deals with organic compounds containing a chromium to carbon bond and their reactions. The field is of some relevance to organic synthesis. The relevant oxidation states for organochromium complexes encompass the entire range of possible oxidation states from –4 (d10) in Na4[Cr–IV(CO)4] to +6 (d0) in oxo-alkyl complexes like Cp*CrVI(=O)2Me.
In organosulfur chemistry, a sulfenyl chloride is a functional group with the connectivity R−S−Cl, where R is alkyl or aryl. Sulfenyl chlorides are reactive compounds that behave as sources of RS+. They are used in the formation of RS−N and RS−O bonds. According to IUPAC nomenclature they are named as alkyl thiohypochlorites, i.e. esters of thiohypochlorous acid.
Zethrene (dibenzo[de,mn]naphthacene) is a polycyclic aromatic hydrocarbon consisting of two phenalene units fused together. According to Clar's rule, the two exterior naphthalene units are truly aromatic and the two central double bonds are not aromatic at all. For this reason the compound is of some interest to academic research. Zethrene has a deep-red color and it is light sensitive - complete decomposition under a sunlight lamp occurs within 12 hours. The melting point is 262 °C.
Roland Heinrich Scholl was a Swiss chemist who taught at various European universities. Among his most notable achievements are the synthesis of coronene, the co-development of the Bally-Scholl synthesis, and various discoveries about polycyclic aromatic hydrocarbons.
N,N,N′,N′-Tetramethylformamidinium chloride is the simplest representative of quaternary formamidinium cations of the general formula [R2N−CH=NR2]+ with a chloride as a counterion in which all hydrogen atoms of the protonated formamidine [HC(=NH2)NH2]+ are replaced by methyl groups.
The Fiesselmann thiophene synthesis is a name reaction in organic chemistry that allows for the generation of 3-hydroxy-2-thiophenecarboxylic acid derivatives from α,β-acetylenic esters with thioglycolic acid and its derivatives under the presence of a base. The reaction was developed by Hans Fiesselmann in the 1950s.
