How Chemists Activate Carboxylic Acids

Dissolving sutures, such as dexon and poly(dioxanone) (PDS), are S3mthetic polymers that are now routinely used in surgery. The many ester groups they contain are slowly hydrolyzed to small molecules that are then metabolized to compounds easily excreted by the body. Patients no longer have to undergo a second medical procedure to remove the sutures that was required when traditional suture materials were used. 

Depending on their structures, these synthetic sutures lose 50% of their strength after two to three weeks and are completely absorbed within three to six months. 

One of the two polymers used for sutures shown in the box on Dissolving Sutures loses 50% of its strength in two weeks, and the other loses that much strength in three weeks. Which suture material lasts longer  

One way organic chemists activate carboxylic acids is by converting them into acyl chlorides, the most reactive of the carboxylic acid derivatives. A carboxylic acid can be converted into an acyl chloride by being heated either with thionyl chloride (SOCI2) or with phosphorus trichloride (PCI3). 

These reagents convert the leaving group of a carboxylic acid into a better leaving group than the chloride ion. 

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