Preferred controlling agents for the electrophilic polymerization reaction are organic Lewis bases
such as DMF, DMAc and NMP.
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.
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.
This is because that MAAM, a Lewis base
unit, could form hydrogen bond with Lewis acid of MAA unit and the formed hydrogen bond has much higher bond energy than that formed between MAAM and MMA or MAA and MMA.
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.
This product acts as a powerful Lewis base
and has a high catalytic effect.
The new class of CSPs is based on the modification of zirconia through the use of Lewis base
Often, alkali metal alkoxides are also used in conjunction with Lewis base
modifiers to achieve even higher vinyl contents (ref.
The nitrogen analog of this heterocycle (bipytidine) is a commonly employed chelating Lewis base
, which reacts with Lewis acidic metals and other species.
3)2] in the presence of a Lewis base
, L, affords trans-Cp*W(NO)(H)[(CH.