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.
1,4-Dichlorobenzene (1,4-DCB, p-DCB, or para-dichlorobenzene, sometimes abbreviated as PDCB or para) is an aryl chloride and isomer of dichlorobenzene with the formula C6H4Cl2. This colorless solid has a strong odor. The molecule consists of a benzene ring with two chlorine atoms (replacing hydrogen atoms) on opposing sites of the ring.
Tetrachloroethylene, also known under the systematic name tetrachloroethene, or perchloroethylene, and abbreviations such as "perc", and "PCE", is a chlorocarbon with the formula Cl2C=CCl2. It is a colorless liquid widely used for dry cleaning of fabrics, hence it is sometimes called "dry-cleaning fluid". It also has its uses as an effective automotive brake cleaner. It has a mild sweet, sharp odor, detectable by most people at a concentration of 50 ppm.
Carotenoids are yellow, orange, and red organic pigments that are produced by plants and algae, as well as several bacteria, archaea, and fungi. Carotenoids give the characteristic color to pumpkins, carrots, parsnips, corn, tomatoes, canaries, flamingos, salmon, lobster, shrimp, and daffodils. Over 1,100 identified carotenoids can be further categorized into two classes – xanthophylls and carotenes.
The organic compound 1,1,1-trichloroethane, also known as methyl chloroform and chlorothene, is a chloroalkane with the chemical formula CH3CCl3. It is an isomer of 1,1,2-trichloroethane. This colorless, sweet-smelling liquid was once produced industrially in large quantities for use as a solvent. It is regulated by the Montreal Protocol as an ozone-depleting substance and its use is being rapidly phased out.
Pentane is an organic compound with the formula C5H12—that is, an alkane with five carbon atoms. The term may refer to any of three structural isomers, or to a mixture of them: in the IUPAC nomenclature, however, pentane means exclusively the n-pentane isomer, in which case pentanes refers to a mixture of them; the other two are called isopentane (methylbutane) and neopentane (dimethylpropane). Cyclopentane is not an isomer of pentane because it has only 10 hydrogen atoms where pentane has 12.
IARC group 3 substances, chemical mixtures and exposure circumstances are those that can not be classified in regard to their carcinogenicity to humans by the International Agency for Research on Cancer (IARC). This category is used most commonly for agents, mixtures and exposure circumstances for which the level of evidence of carcinogenicity is inadequate in humans and inadequate or limited in experimental animals. Exceptionally, agents (mixtures) for which the evidence of carcinogenicity is inadequate in humans, but sufficient in experimental animals may be placed in this category when there is strong evidence that the mechanism of carcinogenicity in experimental animals does not operate in humans. Agents, mixtures and exposure circumstances that do not fall into any other group are also placed in this category.
Cyclodecapentaene or [10]annulene is an annulene with molecular formula C10H10. This organic compound is a conjugated 10 pi electron cyclic system and according to Huckel's rule it should display aromaticity. It is not aromatic, however, because various types of ring strain destabilize an all-planar geometry.
1,1-Dichloroethane is a chlorinated hydrocarbon. It is a colorless oily liquid with a chloroform-like odor. It is not easily soluble in water, but miscible with most organic solvents.
Organohalide respiration (OHR) (previously named halorespiration or dehalorespiration) is the use of halogenated compounds as terminal electron acceptors in anaerobic respiration. Organohalide respiration can play a part in microbial biodegradation. The most common substrates are chlorinated aliphatics (PCE, TCE, chloroform) and chlorinated phenols. Organohalide-respiring bacteria are highly diverse. This trait is found in some Campylobacterota, Thermodesulfobacteriota, Chloroflexota (green nonsulfur bacteria), low G+C gram positive Clostridia, and ultramicrobacteria.
1,1-Dichloroethylene, commonly called vinylidene chloride or 1,1-DCE, is an organochloride with the molecular formula CHClCl2CH3. It is a colorless liquid with a sharp odor. Like most chlorocarbons, it is poorly soluble in water but soluble in organic solvents. 1,1-DCE was the precursor to the original clingwrap, Saran, for food, but this application has been phased out.
A dichlorodifluoroethylene is one of three compounds with the chemical formula C
2Cl
2F
2. Dichlorodifluoroethylenes are colourless gases, and are some of the simplest chlorodifluoroalkenes.
1,2-Dichlorobenzene, or orthodichlorobenzene (ODCB), is an aryl chloride and isomer of dichlorobenzene with the formula C6H4Cl2. This colourless liquid is poorly soluble in water but miscible with most organic solvents. It is a derivative of benzene, consisting of two adjacent chlorine atoms.
1,1,2,2-tetrachloroethane (TeCA), also known by the brand names Bonoform, Cellon and Westron, is an organic compound. It is colorless liquid and has a sweet odor. It is used as an industrial solvent and as a separation agent. TeCA is toxic and it can be inhaled, consumed or absorbed through the skin. After exposure, nausea, dizziness or even liver damage may occur.
1,1'-Azobis-1,2,3-triazole is a moderately explosive but comparatively stable chemical compound which contains a long continuous chain of nitrogen atoms, with an unbroken chain of eight nitrogen atoms cyclised into two 1,2,3-triazole rings. It is stable up to 194 °C. The compound exhibits cis–trans isomerism at the central azo group: the trans isomer is more stable and is yellow, while the cis isomer is less stable and is blue. The two rings are aromatic and form a conjugated system with the azo linkage. This chromophore allows the trans compound to be isomerised to the cis when treated with an appropriate wavelength of ultraviolet light.
Pentachloroethane is a chemical compound of chlorine, hydrogen, and carbon with the chemical formula C2HCl5. It is a colourless non-flammable liquid that is used as a solvent for oil and grease, in metal cleaning, and in the separation of coal from impurities.
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.
1,2-Difluoroethylene, also known as 1,2-difluoroethene, is an organofluoride with the molecular formula C2H2F2. It can exist as either of two geometric isomers, cis-1,2-difluoroethylene or trans-1,2-difluoroethylene.
An indenofluorene (IF) is any of five hydrocarbons with formula C
20H
12, whose carbon skeleton is a sequence of five fused rings with 6, 5, 6, 5, and 6 carbon atoms; an arrangement that can be described as the fusion of an indene core and a fluorene core.
cis-1,2-Bis(diphenylphosphino)ethylene (dppv) is an organophosphorus compound with the formula C2H2(PPh2)2 (Ph = C6H5). Both the cis and trans isomers are known, but the cis isomer is of primary interest. Classified as a diphosphine ligand, it is a bidentate ligand in coordination chemistry. For example it gives rise to the complex Ni(dppv)2 and the coordination polymer [Ni(dppv)]n. As a chelating ligand, dppv is very similar to 1,2-bis(diphenylphosphino)benzene.
