Is Adipoyl Chloride A Polymer

by Terry McMillan

Do you realize this:

1. That some students consider Adipoyl Chloride a "renowned" chemical with less than 500 scientific citations?

2. That there are various other polymerization reactions known as "polymerization without free radical formation" where some type of activation agent is required?

Allow me to explain. (I started my search for the name Adipoyl Chloride for you because the discovery by Bell and Leeb (1963) of free radical adipoyl formation using fatty acids as initiators is a well-known advance in polymerization chemistry.)

Many years ago the polymer science community discovered that the polymerization or condensation of fatty acids proceeds much faster and more efficiently than most polymer chemists had previously realized. This was attributed to the rapid decomposition of the acid and the formation of radicals upon injection into the reaction. This very basic reaction is known as "free radical polymerization," and the starting point of its development was taken from an earlier discovery by Bell and Leeb in the case of ethyl acrylate. However, we are already a long way beyond that discovery. As a matter of fact, only about a quarter of the total known number of alkyl groups to be polymerized are already formed within the molecules when the acrylate monomers are used as starting materials. Thus, in the case of acrylate monomers, the acrylate esters, alone or in admixture, are the starting points for free radical polymerization.

The radical polymerization of a wide variety of other monomers has already been extensively developed in the chemical industry and is well established, thus it is understandable that it has become popular as a high capacity process for obtaining polymers like alkyl and acrylates. (For example, to prepare trimethylol propane we employ the same process.) The current biggest concern about the use of free radical polymerization for polymers is the formation of dormant polymerization products and the associated formation of unwanted polymer products during polymer product upgrading. This can eventually result in a failure or a contamination of the polymer product which may itself present safety hazards.