Cis–trans isomerism, also known as geometric isomerism, describes certain arrangements of atoms within molecules. The prefixes "cis" and "trans" are from Latin: "this side of" and "the other side of", respectively. In the context of chemistry, cis indicates that the functional groups (substituents) are on the same side of some plane, while trans conveys that they are on opposing (transverse) sides. Cis–trans isomers are stereoisomers, that is, pairs of molecules which have the same formula but whose functional groups are in different orientations in three-dimensional space. Cis and trans isomers occur both in organic molecules and in inorganic coordination complexes. Cis and trans descriptors are not used for cases of conformational isomerism where the two geometric forms easily interconvert, such as most open-chain single-bonded structures; instead, the terms "syn" and "anti" are used.
Octane is a hydrocarbon and an alkane with the chemical formula C8H18, and the condensed structural formula CH3(CH2)6CH3. Octane has many structural isomers that differ by the location of branching in the carbon chain. One of these isomers, 2,2,4-trimethylpentane (commonly called iso-octane), is used as one of the standard values in the octane rating scale.
In chemistry, isomerization or isomerisation is the process in which a molecule, polyatomic ion or molecular fragment is transformed into an isomer with a different chemical structure. Enolization is an example of isomerization, as is tautomerization. When the isomerization occurs intramolecularly it may be called a rearrangement reaction.
Diarylethene is the general name of a class of chemical compounds that have aromatic functional groups bonded to each end of a carbon–carbon double bond. The simplest example is stilbene, which has two geometric isomers, E and Z.
Anethole is an organic compound that is widely used as a flavoring substance. It is a derivative of the aromatic compound allylbenzene and occurs widely in the essential oils of plants. It is in the class of phenylpropanoid organic compounds. It contributes a large component of the odor and flavor of anise and fennel, anise myrtle (Myrtaceae), liquorice (Fabaceae), magnolia blossoms, and star anise (Schisandraceae). Closely related to anethole is its isomer estragole, which is abundant in tarragon (Asteraceae) and basil (Lamiaceae), and has a flavor reminiscent of anise. It is a colorless, fragrant, mildly volatile liquid. Anethole is only slightly soluble in water but exhibits high solubility in ethanol. This trait causes certain anise-flavored liqueurs to become opaque when diluted with water; this is called the ouzo effect.
The Ferrier rearrangement is an organic reaction that involves a nucleophilic substitution reaction combined with an allylic shift in a glycal. It was discovered by the carbohydrate chemist Robert J. Ferrier.
Benzothiophene is an aromatic organic compound with a molecular formula C8H6S and an odor similar to naphthalene (mothballs). It occurs naturally as a constituent of petroleum-related deposits such as lignite tar. Benzothiophene has no household use. In addition to benzo[b]thiophene, a second isomer is known: benzo[c]thiophene.
In the study of conformational isomerism, the gauche effect is an atypical situation where a gauche conformation is more stable than the anti conformation (180°).
Indium(III) chloride is the chemical compound with the formula InCl3 which forms a tetrahydrate. This salt is a white, flaky solid with applications in organic synthesis as a Lewis acid. It is also the most available soluble derivative of indium. This is one of three known indium chlorides.
trans-Glutaconic acid is an organic compound with formula HO2CCH=CHCH2CO2H. This dicarboxylic acid exists as a colorless solid and is related to the saturated chemical glutaric acid, HO2CC(CH2)3CO2H. Esters and salts of glutaconic acid are called glutaconates.
2,5-Dimethoxy-3,4-methylenedioxyamphetamine is a lesser-known psychedelic drug of the phenethylamine and amphetamine chemical classes. It was first synthesized by Alexander Shulgin and was described in his book PiHKAL. Shulgin listed the dosage as 30–75 mg and the duration as 6–8 hours. He reported DMMDA as producing LSD-like images, mydriasis, ataxia, and time dilation. DMMDA isn't mentioned much in literature outside PiHKAL unlike 2C-B.
In chemistry, isomers are molecules or polyatomic ions with identical molecular formula – that is, the same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism refers to the existence or possibility of isomers.
The Payne rearrangement is the isomerization, under basic conditions, of 2,3-epoxy alcohols to isomeric 1,2-epoxy alcohols with inversion of configuration. Aza- and thia-Payne rearrangements of aziridines and thiiraniums, respectively, are also known.
1-Methyltryptophan is a chemical compound that is an inhibitor of the tryptophan catabolic enzyme indoleamine 2,3-dioxygenase. It is a chiral compound that can exist as both D- and L-enantiomers.
Cyclopentadienyliron dicarbonyl dimer is an organometallic compound with the formula [(η5-C5H5)Fe(CO)2]2, often abbreviated to Cp2Fe2(CO)4, [CpFe(CO)2]2 or even Fp2, with the colloquial name "fip dimer". It is a dark reddish-purple crystalline solid, which is readily soluble in moderately polar organic solvents such as chloroform and pyridine, but less soluble in carbon tetrachloride and carbon disulfide. Cp2Fe2(CO)4 is insoluble in but stable toward water. Cp2Fe2(CO)4 is reasonably stable to storage under air and serves as a convenient starting material for accessing other Fp (CpFe(CO)2) derivatives (described below).
Sodium hyponitrite is a solid ionic compound with formula Na
2N
2O
2 or (Na+
)2[ON=NO]2−.
1,2-Dimethyldiborane is an organoboron compound with the formula [(CH3)BH2]2. Structurally, it is related to diborane, but with methyl groups replacing terminal hydrides on each boron. It is the dimer of methylborane, CH3BH2, the simplest alkylborane. 1,2-Dimethyldiborane can exist in a cis- and a trans arrangement. 1,2-Dimethyldiborane is an easily condensed, colorless gas that ignites spontaneously in air.
Pipethiaden is a benzothiepin-based drug candidate that was at one time studied as a potential preventive to reduce the frequency of recurrent migraine headaches. It also has some activity as an antihistamine acting mainly at the 5-HT2A and 5HT2C receptors.
In organic chemistry, thienothiophene is any of several compounds consisting of two fused thiophene rings. They have the molecular formula C6H4S2. Three constitutional isomers have been synthesized: thieno[3,2-b]thiophene, thieno[2,3-b]thiophene, and thieno[3,4-b]thiophene. The other isomer features S(IV) and is less stable. Thieno[2,3-b]thiophene was the first member of the series to be isolated. It was obtained in very low yield upon heating citric acid, a source of a six-carbon linear chain, with P4S10. More efficient syntheses of this and the other two stable thienothiophenes involve cyclization reactions of substituted thiophenes.
2,3-Dimethylpentane is an organic compound of carbon and hydrogen with formula C
7H
16, more precisely CH
3–CH(CH
3)–CH(CH
3)–CH
2–CH
3: a molecule of pentane with methyl groups –CH
3 replacing hydrogen atoms on carbon atoms 2 and 3. It is an alkane, a fully saturated hydrocarbon; specifically, one of the isomers of heptane.
