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  • Deactivating substituent
  • A group that when present in place of hydrogen causes a particular reaction to occur more slowly. The term is most often applied to the effect of substituent on the rate of electrophilic aromatic substitution.
  • debye
  • A unit of electrical dipole moment.
  • Debye unit (D)
  • Unit customarily used for measure dipole moments : EQUATION
  • Decarboxylation
  • Reaction of the type RCO2H -> RH + CO2, in which carbon dioxide is lost from a carboxylic acid. Decarboxylation normally occurs readily only when the carboxylic acid is a 1,3-dicarboxylic acid or a β-keto acid.
  • Decoupling
  • In NMR spectroscopy, any process that destroys the coupling of nuclear spins between two nuclei. Two types of decoupling are employed in 13C NMR spectroscopy. Broadband decoupling removes all the 1H-13C couplings; off-resonance decoupling removes all 1H-13C couplings except those between directly bonded atoms.
  • Dehydration
  • Removal of H and OH from adjacent atoms. The term is most commonly employed in the preparation of alkenes by heating alcohols in the presence of an acid catalyst. 1,2- 1,3- 1,4-Dehydrobenzene
  • Dehydrogenation
  • Elimination in which H2 is lost from adjacent atoms. The term is most commonly encountered in the industrial preparation of ethylene from ethane, propene from propane, 1,3-butadiene from butane, and styrene from ethylbenzene.
  • Dehydrohalogenation
  • Reaction in which and alkyl halide on being treated with a base such as sodium ethoxide, is converted to an alkene by loss of a proton from one carbon and the halogen from the adjacent carbon.
  • Delocalization
  • Association of an electron with more than one atom. The simplest example is the shared electron pair (covalent) bond. Delocalization is important in conjugated π electron systems, where an electron may be associated with several carbon atoms
  • Delocalization energy
  • synonymous with resonance energy.
  • Deoxy sugar
  • A carbohydrate in which one of the hydroxyl groups has been replaced by a hydrogen
  • DEPT
  • Abbreviation for ­distortionless enhancement of polarization transfer. DEPT is an NMR technique that reveals the number of hydrogens directly attached to a carbon responsible for a particular signal
  • Detergents
  • substances that clean by micellar action. Although the term usually refers to a synthetic detergent, soaps are also detergents.
  • Deuterium isotope effect
  • The difference in a property, usually reaction rate, that results when one or more atoms of 1H in a compound are replaced by 2H.
  • Diastereomers
  • Stereoisomers that are not enantiomers – stereoisomers that are not mirror images of one another.
  • Diastereotopic
  • Describing two atoms or groups in a molecule that are attached to the same atom but are in stereochemically different environments that are not mirror images of each other. The two protons shown in bold in H2C=CHCl, for example, are diastereotopic. One is cis to chlorine, the other is trans.
  • Diazonium ion
  • Ion of the type R-N+=N:. aryl diazonium ions are formed by treatment of primary aromatic amines with nitrous acid. They are extremely useful in the preparation of aryl halides, phenols, and aryl cyanides.
  • Diazotization
  • The reaction by which a primary amine is converted to the corresponding diazonium ion by nitrosation.
  • Dieckmann cyclization
  • An intramolecular version of the Claisen condensation.
  • Dielectric constant
  • A measure of the ability of a material to disperse the force of attraction between oppositely charged particles. The symbol for dielectric constant is ϵ.
  • Diels-Alder reaction
  • Conjugate addition of an alkene to a conjugated diene to give a cyclohexane derivative. Diels-Alder reactions are extremely useful in synthesis.
  • Dienophile
  • The alkene that adds to the diene in a Diels-Alder reaction.
  • Dihydroxylation
  • Reaction or sequence of reactions in which an alkene is converted to a vicinal diol.
  • Dimer
  • molecule formed by the combination of two identical molecules
  • Diol
  • A compound with two alcohol functional groups
  • Dipeptide
  • A compound in which two α-amino acids are linked by an amide bond between the amino group of one and the carboxyl group of the other: FIG
  • Dipole moment
  • Product of the attractive force between two opposite charges and the distance between them. Dipole moment has the symbol µ and is measure in Debye units (D).
  • Dipole-Dipole attractive force
  • A force of attraction between oppositely polarized atoms
  • Dipole/induced-dipole force
  • A force of attraction that results when a species with a permanent dipole induces a complementary dipole in a second species.
  • Direct addition
  • Synonymous with 1,2-addition.
Department of Chemistry & Chemical Biology