|
|
This is only a preview of the paper
Click here to register and get the full text.
Existing members click here to login
|
|
|
Introduction
The technique of Palladium-catalyzed carbonylation can be used to produce many polymeric systems when coupled with phenols and aromatic amines or iodides. ... Palladium-catalyzed carbonylations create an alternative route to producing polymers. This paper will discuss the formation of aramids, poly(imide-amides), polyesters, triflates, polyimides, and poly(benzoxazoles) by the technique of palladium-catalyzed carbonylation.
Amides and Esters
The formation of amides and esters by the palladium-catalyzed carbonylation and the coupling reactions of aromatic amines and halides were first studied in 1974 (1). ... The next step involves the insertion of carbon monoxide into the aryl-palladium bond. ... However, many approaches have been made to use the carbonylation chemistry to form polyimides. ... The final attempt involved combining the carbonylation technique with the traditional procedure to perform ring closing on poly(amide-esters). The bis(0-iodoesters) reacted with diamines and carbon monoxide with a palladium catalyst present. This poly(amide-esters) turned out to be unstable in the conditions of the reaction and cyclized in the presence of base which gave the imidized polymer found in equation 3. ... Aramids were the first class of polymers to be produced using palladium-catalyzed carbonylation and condensation reactions. It was believed that aryldibromides and aromatic diamines would react under 1 atm carbon monoxide with a palladium catalyst, a tertiary base and phosphine ligands. ... The use of diiodinated aromatics made it possible for the formation of a variety of aramids (6 ). ... It is also stated that usually when involving the esterification of aryl bromides with palladium, carbon monoxide and an alcohol, the oxidative addition is the rate-limiting step.
Approximate Word count = 1246
Approximate Pages = 5
(250 words per page double spaced)
|
|
|
|
|
|