acid–base catalysis

      acceleration of a chemical reaction by the addition of an acid or a base, the acid or base itself not being consumed in the reaction. The catalytic reaction may be acid-specific (acid catalysis), as in the case of decomposition of the sugar sucrose into glucose and fructose in sulfuric acid; or base-specific (base catalysis), as in the addition of hydrogen cyanide to aldehydes and ketones in the presence of sodium hydroxide. Many reactions are catalyzed by both acids and bases.

      The mechanism of acid- and base-catalyzed reactions is explained in terms of the Brønsted–Lowry (Brønsted–Lowry theory) concept of acids and bases as one in which there is an initial transfer of protons from an acidic catalyst to the reactant or from the reactant to a basic catalyst. In terms of the Lewis theory of acids and bases, the reaction entails sharing of an electron pair donated by a base catalyst or accepted by an acid catalyst.

      Acid catalysis is employed in a large number of industrial reactions, among them the conversion of petroleum hydrocarbons (hydrocarbon) to gasoline and related products. Such reactions include decomposition of high-molecular-weight hydrocarbons (cracking) using alumina–silica catalysts (Brønsted–Lowry acids), polymerization of unsaturated hydrocarbons using sulfuric acid or hydrogen fluoride (Brønsted–Lowry acids), and isomerization of aliphatic hydrocarbons using aluminum chloride (a Lewis acid).

      Among industrial applications of base-catalyzed reactions is the reaction of diisocyanates with polyfunctional alcohols in the presence of amines, used in the manufacture of polyurethane foams.

* * *


Universalium. 2010.

Look at other dictionaries:

  • acid-base catalysis — rūgštinė bazinė katalizė statusas T sritis chemija apibrėžtis Katalizė, kurios katalizatorius yra H⁺ arba OH⁻ jonai. atitikmenys: angl. acid base catalysis rus. кислотно основной катализ …   Chemijos terminų aiškinamasis žodynas

  • acid–base reaction — ▪ chemistry Introduction       a type of chemical process typified by the exchange of one or more hydrogen ions, H+, between species that may be neutral (molecules, such as water, H2O; or acetic acid, CH3CO2H) or electrically charged (ions, such… …   Universalium

  • catalysis — catalytic /kat l it ik/, adj., n. catalytical, adj. catalytically, adv. /keuh tal euh sis/, n., pl. catalyses / seez /. 1. Chem. the causing or accelerating of a chemical change by the addition of a catalyst. 2. an action between two or more… …   Universalium

  • Catalysis — Catalyst redirects here. For other uses, see Catalyst (disambiguation). Solid heterogeneous catalysts such as in automobile catalytic converters are plated on structures designed to maximize their surface area …   Wikipedia

  • Acid catalysis — In acid catalysis and base catalysis a chemical reaction is catalyzed by an acid or a base. The acid is often the proton and the base is often a hydroxyl ion. Typical reactions catalysed by proton transfer are esterfications and aldol reactions.… …   Wikipedia

  • Acid — This article is about acids in chemistry. For the drug, see Lysergic acid diethylamide. For other uses, see Acid (disambiguation). Acidity redirects here. For the novelette, see Acidity (Novelette). Acids and Bases …   Wikipedia

  • acid — acidly, adv. acidness, n. /as id/, n. 1. Chem. a compound usually having a sour taste and capable of neutralizing alkalis and reddening blue litmus paper, containing hydrogen that can be replaced by a metal or an electropositive group to form a… …   Universalium

  • base — base1 /bays/, n., adj., v., based, basing. n. 1. the bottom support of anything; that on which a thing stands or rests: a metal base for the table. 2. a fundamental principle or groundwork; foundation; basis: the base of needed reforms. 3. the… …   Universalium

  • Enzyme catalysis — is the catalysis of chemical reactions by specialized proteins known as enzymes. Catalysis of biochemical reactions in the cell is vital due to the very low reaction rates of the uncatalysed reactions. The mechanism of enzyme catalysis is similar …   Wikipedia

  • amino acid — Biochem. any of a class of organic compounds that contains at least one amino group, NH2, and one carboxyl group, COOH: the alpha amino acids, RCH(NH2)COOH, are the building blocks from which proteins are constructed. Cf. essential amino acid.… …   Universalium

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.