lar mass = 263 g mol-1) but is branched and forms a number
of 5 member rings as it wraps itself around a metal atom.
The structure of GLDA, as it is informally known, is shown
below, with its glutamic acid base shown in red.
Perhaps most importantly, GLDA has been positioned
as being “natural”—composed of one molecule of glutamic
acid and two molecules of acetic acid (vinegar).
There are other new chelants which have been introduced over the last 20 years. None has yet assumed the
dominance in the marketplace that would attract the attention of people with rats to sacrifice. Many are based on the
a-aminocarboxylate architecture. Most do not take advantage of being positioned as “natural,” perhaps leaving them
vulnerable to unwanted attention.
Consider the case of iminodisuccinic acid (IDS). It is a
branched molecule with the ability to form a couple of five-member rings. The molecular mass is a little high (249 g
mol-1) and two of the carboxylates are positioned such that
seven-member rings form. Its structure, shown below, is not
entirely ideal, but it is an acceptable chelant.
IDS has no doubt been named to reflect the manufac-
turing process by which it is made. As such, it sounds like a
“chemical,” which frequently equates in the public mind to
“toxic beyond belief.”
There is no reason that IDS could not be positioned as
a “natural” chelant as well. Shown below is aspartic acid, a
natural amino acid. Clearly, iminodisuccinate incorporates the
asparate structure, shown in red. If IDS were to be referred
to by its alternate, and perfectly legitimate, name of aspar-
tic acid N-succinic acid, it’s now “natural!” It is composed of
a natural amino acid and succinic acid, also available from
Who knows? If we had enacted this strategy a generation ago, NTA may have escaped the regulator’s wrath. As a
“natural” molecule, we would have focused on its excellent
degradability and lack of accumulation in the environment.
As nitrilotriacetic acid, it was treated only as a “chemical”
and only its potential for carcinogenicity was considered—
even to the point of performing tests employing wildly unrealistic doses.
Imagine if we had named this chelant for the glycine
residue around which it is built, as shown in red in the structures below. Instead of calling it nitrilotriacetic acid, it could
have been named glycine N,N-diacetic acid. It’s the same
molecule, but now it seems more “natural.” It would have
been worth a shot. It has worked before.
It seems unlikely we will regulate away all our detergent builders before I decide to hang up my beakers for the
last time. So far, we have tapped only three of the 20 available natural amino acids. But, I think it might prove useful
to start to include public relations as part of the package of
introducing new molecules. Words are powerful and names
are important. We need to take advantage of this power.
There is really no point in losing the use of a valuable molecule any sooner than has to be the case.