Coupling agents, carboxylated

At one time these were the only commercially important non-silane coupling agents. Supplied by du Pont under the Volan tradename, they are coordination complexes of carboxylic acids with chromium(III) chlorides. Hydrolysis of the... 

A series of thiol and selenolesters can be prepared from carboxylic acids and the coupling agents CDI, oxalyldiimidazole, or oxalylditriazole via the corresponding carboxylic acid azolides (Tables 3-7 and 3-9). 

Figure 5 Schematic of the attachment of coupling agent to a filler particle. X = Cl, OCHj, carboxyl M = Si, Ti, Zr R = long-chain alkyls or oligomers that contain grafted polar groups, e.g., amides and carboxyl.

Another highly effect chain extender is trimellitic anhydride (TMA) which gives rise to branching of the PET structure. Note that the multifunctional epoxies (see Table 14.2) react quickly with the terminal carboxylic acid groups of PET but can also react with the film former and the silane coupling agent on glass fibre reinforcements. 

In 2001, De Luca and GiacomeUi " reported a new simple and high-yielding one-flask synthesis of Weinreb amides from carboxylic acids and A-protected amino acids that uses different 1,3,5-triazine derivatives (such as 236) as the coupling agents (Scheme 104). The method allows the preparation of Weinreb amides 237 and hydroxamates as O-benzyl and 0-silyl hydroxamates that can be easily transformed into hydroxamic acids. 

Figure 13.6. Activation of carboxylates by uronium salts [5,10,17,18,84,96], X leaving group. Table 13.6. Preparation of amides using uronium salts as coupling agents.

Amine and carboxyl functional coupling agents are recommended for both nylon and cellulosic materials. The amine groups of APDMSB can react with the carbonyl functionality and the carboxyl end groups of nylon, and with the hydroxyl groups of cellulose. The carboxyl groups of FA react with the nylon... 

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