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  • 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
  • Aldaric acid
  • Carbohydrate in which carboxylic acid functions are present at both ends of the chain. Aldaric acids are typically prepared by oxidation of aldoses with nitric acid
  • Aldehyde
  • Compound of the type FIG
  • Alditol
  • The polyol obtained on reduction of the carbonyl group of a carbohydrate
  • Aldol addition
  • Nucleophilic addition of an aldehyde or ketone enolate to the carbonyl group of an aldehyde or ketone enolate to the carbonyl group of an aldehyde or a ketone. The most typical case involves two molecules of an aldehyde, and is usually catalyzed by bases. FIG
  • Aldol condensation
  • When an aldol addition is carried out so that the β-hydroxy aldehyde or ketone dehydrates under the conditions of its formation, the product is described as arising by an aldol condensation. FIG
Department of Chemistry & Chemical Biology