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Organic Chemistry
Published in Armen S. Casparian, Gergely Sirokman, Ann O. Omollo, Rapid Review of Chemistry for the Life Sciences and Engineering, 2021
Armen S. Casparian, Gergely Sirokman, Ann O. Omollo
Thus, isomers are molecules with the same molecular formula but different structural formulas. There are two types of isomers: constitutional isomers and stereoisomers. Constitutional isomers differ in connectivity while stereoisomers have the same connectivity but different orientation in space.
Applied Chemistry and Physics
Published in Robert A. Burke, Applied Chemistry and Physics, 2020
Prefixes may be added to hydrocarbon compounds. These prefixes indicate the number of what ever the prefix is shown in front of. Di is two, tri is three and tetra is four. Alkanes and alkenes are sometimes found with different structural formulas than the usual straight chains. These are referred to as isomers. An isomer is a compound that has the same molecular formula as the straight chained version, but a different structural formula. This concept is also referred to as branching (Figure 3.47). This has the effect of lowering the boiling point of the material. For example, butane has a boiling point of around 31°F. It can be used as a heating fuel like propane. Butane and propane are stored and used at ambient temperatures. However, with the boiling point of 31°F, the areas in the country where butane could be used in the winter would be limited by the winter time temperatures. If, however, butane is branched to form isobutane, this process lowers the boiling point of butane to around 10°F, making butane more useful as a heating fuel in many colder parts of the country.
Alkanes, Isomers, and Nomenclature
Published in Michael B. Smith, A Q&A Approach to Organic Chemistry, 2020
An isomer is two or more molecules that have the same empirical formula, but the individual atoms are connected in different ways, leading to different molecules. Are there isomers for the formula C3H8?
Enantioselective behavior of environmental chiral pollutants: A comprehensive review
Published in Critical Reviews in Environmental Science and Technology, 2022
Marina Arenas, Julia Martín, Juan Luis Santos, Irene Aparicio, Esteban Alonso
Chiral compounds are mirror–image molecules with at least one chiral, asymmetric or stereogenic center that is bonded to different atoms or groups. A chiral chemical consists of at least one pair of enantiomers or optical isomers that rotate the plane of polarized light in opposite directions, but showing similar physical and chemical properties. One of the ways to term enantiomers is based on the direction they rotate the plane of polarized light, being termed levorotatory (L) and dextrorotatory (D), respectively. Alternatively, a minus sign (-) can be used for counterclockwise rotating molecules and a plus sign (+) used for clockwise rotating molecules (Challener, 2001). Additionally, E1 and E2 are used when the direction of the rotation is unknown and they refer to the first and last eluted enantiomers, respectively. The Cahn, Ingold and Prelog system for naming enantiomers assigns an R (rectus) or S (sinister) descriptor to each chiral center. The atoms or groups bonded to the chiral center are ranking according to the priority of each group (Cahn et al., 1956).