reactivity

(noun)

Relative susceptibility to chemical reaction.

Related Terms

Examples of reactivity in the following topics:

  • Reactive Intermediates

  • Synthesis of Addition Polymers

    • Many of these addition reactions are known to proceed in a stepwise fashion by way of reactive intermediates, and this is the mechanism followed by most polymerizations.
    • Radical Polymerization The initiator is a radical, and the propagating site of reactivity (*) is a carbon radical.
    • Cationic Polymerization The initiator is an acid, and the propagating site of reactivity (*) is a carbocation.
    • Anionic Polymerization The initiator is a nucleophile, and the propagating site of reactivity (*) is a carbanion.
    • Coordination Catalytic Polymerization The initiator is a transition metal complex, and the propagating site of reactivity (*) is a terminal catalytic complex.

  • Solvent Effects

    • Solvation of nucleophilic anions markedly influences their reactivity.
    • These solvated species are more stable and less reactive than the unsolvated "naked" anions.
    • Thus, for reaction in DMSO solution we observe the following reactivity order:

  • Addition Copolymerization

    • Most direct copolymerizations of equimolar mixtures of different monomers give statistical copolymers, or if one monomer is much more reactive a nearly homopolymer of that monomer.
    • In cases where the relative reactivities are different, the copolymer composition can sometimes be controlled by continuous introduction of a biased mixture of monomers into the reaction.
    • Formation of alternating copolymers is favored when the monomers have different polar substituents (e.g. one electron withdrawing and the other electron donating), and both have similar reactivities toward radicals.

  • Acyl Group Substitution

    • Different carboxylic acid derivatives have very different reactivities, acyl chlorides and bromides being the most reactive and amides the least reactive, as noted in the following qualitatively ordered list.
    • The change in reactivity is dramatic.
    • Reactivity: acyl halides > anhydrides >> esters ≈ acids >> amides
    • Thus, acyl chlorides (Y = Cl) are the most reactive of the derivatives.
    • Finally, anhydrides and esters have intermediate reactivities, with anhydrides being more reactive than esters.

  • Properties of Alkenes

    • Due to the presence of a double bond in their carbon skeletons, alkenes are more reactive than their related alkanes.
    • The sigma bond has similar properties to those found in alkanes, while the pi bond is more reactive.
    • Alkenes are more reactive than their related alkanes due to the relative instability of the double bond.

  • The Halogens (Group 17)

    • The halogens are a series of highly reactive, nonmetal elements from Group 17 of the periodic table.
    • The halogens, as a group, are extremely reactive.
    • However, due to their extremely high reactivity (electronegativity), they are not found in their elemental form in any natural environment on Earth.
    • Fluorine is one of the most reactive elements in existence, attacking otherwise inert materials, such as glass, and forming compounds with the heavier noble gases.
    • The high reactivity of fluorine also means that once it does react with something, it bonds with it so strongly that the resulting molecule is very inert and non-reactive to anything else.

  • Reactions of Simple Organometallic Compounds

    • The electropositive nature of the metal atom or group is an important factor influencing the reactivity of these reagents.
    • The carbon-magnesium bond of Grignard reagents is about 20% ionic, and they have proven to be somewhat less reactive.
    • Alkylmercury and lead compounds are the least reactive commonly studied organometallics.
    • Dialkylmercury compounds are much less reactive, and can be mixed with water or alcohol without change.
    • These serve as a reminder that oxidative conditions should be avoided when using reactive organometallic compounds.

  • Main Group Organometallic Compounds

    • Depending on the reduction potential of the metal, the reactivity of organometallic compounds varies markedly, the most reactive requiring low to moderate temperatures and inert conditions (atmosphere and solvents) for preparation and use.
    • In general, the reactivity parallels the ionic character of the carbon-metal bond, which may be estimated from the proton and carbon chemical shifts of methyl derivatives.
    • All these metals have strong or moderate negative reduction potentials, with lithium and magnesium being the most reactive.
    • Halide reactivity increases in the order: Cl < Br < I.
    • Simple alkyl derivatives of all three kinds are pyrophoric (burn spontaneously on exposure to air) and react with water to generate the corresponding alkane (RH); however, the zinc compounds are distinctly less reactive in other respects.

  • Introduction to Chemical Reactivity

    • Other compounds may also be involved, and common reactive partners (reagents) may be identified.