intramolecular

(noun)

Refers to interactions within a molecule.

Related Terms

  • bond
  • bonding orbital
  • covalent bond
  • ionic bond
  • intermolecular forces

Examples of intramolecular in the following topics:

  • Cyclization by Intramolecular Addition Reactions

    • If a radical is joined to a double bond by a chain of three or more carbons intramolecular addition generates a ring.
  • Ene Reactions

    • This is the same bond bookkeeping change exhibited by electrocyclic reactions, but no rings are formed or broken in an ene reaction unless it is intramolecular.
    • The following examples illustrate some typical ene reactions, with equation 3 being an intramolecular ene reaction.
    • This is the case for reactions 1 and 2, which proceed under milder conditions than 3, despite the latter's intramolecular nature.
    • Because this is an intramolecular ene reaction a new ring is formed.
  • Reactions of Alkylidene Complexes

    • Equation # 5 shows a sequence involving epoxide alkylation, followed by an intramolecular trans-esterification analog.
  • The Payne Rearrangement

    • Epoxy alcohols undergo reversible intramolecular epoxide opening reactions known as the Payne rearrangement.
  • Multistep Transformations

    • The resulting diketone, in its cis-fused configuration, then undergoes an intramolecular Michael reaction, forming a new five-membered ring (note the colored bond).
  • Cascade Reaction Sequences

    • In many cases carbon-carbon bond construction has been enhanced by sequences of intramolecular events termed tandem, domino or cascade reactions.
    • The second example shows an intramolecular hetero Diels-Alder cycloaddition, followed by bonding of the resulting immonium cation to a pendant tri-substituted double bond (an aza-Prins reaction).
    • The first example above is an interesting case of an acid catalyzed cascade of intramolecular epoxide openings, involving oxygen nucleophiles.
    • In this case the resulting allenic system is part of a conjugated diene, and undergoes an intramolecular Diels-Alder cycloaddition.
  • Irreversible Substitution Reactions

    • The last example (reaction #4) is an interesting case of intramolecular alkylation of an enolate anion.
    • It is the rapid intramolecular nature of the alkylation that allows these unfavorable conditions to be used.
    • Although conformer II of the enolate anion could generate a stable five-membered ring by an intramolecular SN2 reaction, assuming proper orientation of the α and γ' carbon atoms, the concentration of this ideally coiled structure will be very low.
    • Ring closures to four, five, six and seven-membered are also possible by intramolecular enolate alkylation, as illustrated by the following example.
  • Three-Membered Rings

    • Many examples of intramolecular interactions, such as example 10, have been documented.
    • An interesting regioselectivity in the intramolecular ring-opening reactions of disubstituted epoxides having a pendant γ-hydroxy substituent has been noted.
  • Rearrangements of Cationic Oxygen

    • Once the peracid has added to the carbonyl group, the rearrangement may be facilitated by an intramolecular hydrogen bond, in the manner depicted in brackets on the right.
    • Peracid exchange with peracetic acid leads to an intramolecular Baeyer-Villiger reaction by way of the bicyclic acylperoxide drawn in brackets.
  • Carbonyl Compounds

    • The second illustrates the intramolecular variant.
    • Three intramolecular type I reactions, all proceeding by way of biradical intermediates, demonstrate the variety of products that may be formed by hydrogen transfer disproportionation and/or ring closure.
    • The cyclic transition states for such intramolecular hydrogen transfer usually include five or six, and occasionally seven atoms.
    • These reactions all begin by an intramolecular hydrogen atom abstraction, similar to the intermolecular abstraction in the reductive dimerization of benzophenone.
    • In hydrocarbon solvents intramolecular hydrogen transfer back to carbon is common, reducing the quantum yield of these products by over 50%.
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