Reaction Anion Addition

Mattson AE, Bharadwaj AR, Zuhl AM, Scheldt KA (2006a) Thiazolium-catalyzed additions of acylsilanes a general strategy for acyl anion addition reactions. J Org Chem 71 5715-5724... 

In addition, the use of thiazolium catalyzed processes to prepare conq)ounds which are the result of an acyl anion addition reaction have shown utility in synthetic organic chemistry. The benzoin condensation (21-24) and the Stetter reaction (25-27) represent two of the most powerful exan5>les of these types of transformations (Figure 2.). 

It may be shown that My, > M (x > x ). The averages are equal only for a monodisperse polymer, where aU of the chains are exactly the same length. The ratio My,IM = Xy/x is known as the polydispersity index, PI. PI is a measure of the breadth of the molecular weight distribution. A monodisperse sample would have a PI of 1.0, but typical values range from about 1.02 for carefully fractionated polymers synthesized by anionic addition reactions to over 50 for some commercial polymers. 

The a-alkyl cyanoacrylate super glues ( one drop holds 5000 lbs ) are now a familiar part of the consumer market. Originally, the monomers had extremely low viscosities and so could crawl into narrow crevices and wet the adherend surfaces rapidly. On the other hand, they would not fill gaps and were absorbed into porous adherends, giving poor bonds. Newer versions are available with higher viscosities to overcome these drawbacks. Cyanoacrylates can polymerize in seconds by an anionic addition reaction believed initiated by hydroxyl ions from water adsorbed on the adherend surfaces ... 

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