Lewis base


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Lewis base

[′lü·əs ‚bās]
(chemistry)
A substance that can donate an electron pair; examples are the hydroxide ion, OH-, and ammonia, NH3.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
The number of Lewis base sites (pK = -0.29) increases compared with saponite in Sap7.
For most carbocationic polymerizations of a vinyl ether produced using a Lewis Acid coinitiator, such as ethylaluminum sesquichloride, an appropriate concentration of Lewis base is needed to obtain a living polymerization.
Halogen bonding is directly related to electron donation of lewis bases to halogen atoms and can be defined as the non- covalent interaction of halogens with halogens or lewis bases [14-16].
The procedure is based on molecules called Lewis bases, which carry a lone pair of electrons and can bond with so-called Lewis acids to make a molecule called an adduct.
Interfacial shear strengths for the fibers in PPS and epoxy matrices, summarized in Table 2, show that the plasma treatment produced a significant increase in bond strength with the PPS resin, presumably a Lewis base. The plasma treatment had no such effect with the epoxy resin.
Initially, in order to determine optimal polymerization reaction conditions, the influences of catalyst quantity, Lewis base quantity, and monomer concentration on the inherent viscosity of the polymer were examined by the Friedel-Crafts acylation of IPC with a mixture of 70 mol% BPOBBP and 30 mol% DPODPS in DCE using anhydrous aluminum chloride as a catalyst and NMP as a Lewis base and the results are listed in Table 1.
wherein [M.sup.I] and [M.sup.II] are metals; T is nitrogen or phosphorus; P is a carbon, nitrogen or phosphorus atom; groups [R.sup.1], [R.sup.2] and [R.sup.3] may be linked to each other; Y is a divalent bridging group; X, [X.sup.1] and [X.sup.2] are anionic ligand groups with certain exceptions; D is a neutral Lewis base ligand; and s, o, k, i, ii, p, m, a, b, c, d, e, t and y are numbers as further described in the claims.
The technique uses the Lewis acid tris(pentafluorophenyl) borane and the Lewis base tetramethylpiperidine that have been modified to be too large to get close enough to form an adduct (Lewis bases, which carry a lone pair of electrons, can bond with Lewis acids to form molecules called adducts).
They found that a water molecule will bind between two aluminum sites in a cluster as long as one of the sites behaves like a Lewis acid, a positively charged center that wants to accept an electron, and the other behaves like a Lewis base, a negatively charged center that wants to give away an electron.
They have been stationed at Fort Lewis base in Washington State since February for a two-month cross-service exercise.
A negative Huggins interaction parameter and excellent miscibility are expected because that MMA-MAAM copolymer is a Lewis base while MMA-MAA copolymer is a Lewis acid.

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