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  • 1,2 Addition
  • Addition of reagents of the type X-Y to conjugated dienes in which X and Y add to adjacent doubly bonded carbons FIG
  • 1,3-Diaxial repulsion
  • Repulsive forces between axial substituents on the same side of a cyclohexane ring.
  • 1,4 Addition
  • Addition of reagents of the type X-Y to conjugated dienes in which X and Y add to the termini to diene system (see conjugated addition) FIG
  • 13C NMR
  • Nuclear magnetic resonance spectroscopy in which the environments of individual carbon atoms are examined via their mass-13 isotope.
  • 18-Electron rule
  • The number of ligands that can be attached to a transition metal are such that the sum of the electrons brought by the ligands plus the valence electrons of the metal equal 18
  • Absolute configuration
  • The three-dimensional arrangement of atoms or groups at a chirality center typically defined by and R or S notation
  • Absorbance
  • In UV-VIS spectroscopy, the value of log10(I0/I), where I0 is the intensity of the incident radiation and I is the intensity of the beam after it has passed through the sample.
  • Acetal
  • Product of the reaction of an aldehyde or a ketone with two moles of an alcohol according to the equation
  • Acetoacetic ester synthesis
  • A synthetic method for the preparation of ketones in which alkylation of the enolate of ethyl acetoacetate fig is the key carbon-carbon bond-forming step
  • Acetyl coenzyme A
  • A thioester abbreviated as FIG that acts as the source of acetyl groups in biosynthetic processes involving acetate
  • Acetylene
  • The simplest alkyne, FIG
  • Achiral
  • Opposite of chiral. An achiral object is super-imposable on its mirror image
  • Acid
  • According to the Arrhenius definition, a substance that ionizes in water to produce protons. According to the BrØnsted-Lowry definition, a substance that donates a proton to some other substance. According to the Lewis definition, an electron-pair acceptor.
  • Acid anhydride
  • Compund of the type FIG Both R groups are usually the same, although they need not always be.
  • Acidity constant Ka
  • Equilibrium constant for dissociation of an acid: FIG
  • Activating substituent
  • A group that when present in place of a hydrogen causes a particular reaction to occur faster. Term is most often applied to substituents that increase the rate of electrophilic aromatic substitution.
  • Activation energy
  • The minimum energy that a reacting system must possess above its most stable state in order to undergo a chemical or structural change.
  • Active site
  • The region of an enzyme at which the substrate is bound.
  • Acyl cation
  • Synonymous with acylium ion
  • Acyl chloride
  • Compound of the type FIG R may be alkyl or aryl
  • Acyl group
  • The group FIG  R may be alkyl or aryl
  • Acyl transfer
  • A nucleophilic acyl substitution. A reaction in which one type of carboxylic acid derivative is converted to another.
  • Acylation
  • Reaction in which an acyl group becomes attached to some structural unit in a molecule. Examples include the Friedel-Crafts acylation and the conversion of amines to amides.
  • Acylium ion
  • The cation FIG
  • Addition
  • Reaction in which a reagent X-Y adds to a multiple bond so that X become attached to one of the carbons of the multiple bond and Y to the other.
  • Addition polymer
  • A polymer formed by addition reactions of monomers
  • Addition-elimination mechanism
  • Two-stage mechanism for nucleophilic aromatic substitution. In the addition stage, the nucleophile adds to the carbon that bears the leaving group. In the elimination stage, the leaving group is expelled. FIG
  • Adenosine 5'-triphosphate (ATP)
  • The main energy-storing compound in all living organisms. FIG
  • Alcohol
  • Compound of the type ROH
  • Alcohol dehydrogenase
  • Enzyme in the liver that catalyzes the oxidation of alcohols to aldehydes and ketones
Department of Chemistry & Chemical Biology