-3
$\begingroup$

European REACH regulation for registration of chemical substances has an own definition of a polymer according to this regulation.

I've noticed the following problem.

I want to discuss here only the chemical aspects.

Can glycerol in substituted natural fats be a monomer according to European REACH Regulation?

Let's assume a fat obtained from animals, plants or fishes as industrial raw material (means a mixture of different triglycerides) that is substituted with a functional group (e. g. acetylated, hydroxylated, oxidated, sulfated or sulfited fat), e.g. at the double bonds of the unsaturated triglycerides or at the hydroxyl groups of castor oil. (See e.g. Wikipedia for the structure formulas of such triglycerides.)

REACH Regulation (1907/2006/EU), May 8 2023, states:
"For the purposes of this Regulation:

  1. polymer: means a substance consisting of molecules characterised by the sequence of one or more types of monomer units. Such molecules must be distributed over a range of molecular weights wherein differences in the molecular weight are primarily attributable to differences in the number of monomer units. A polymer comprises the following:

(a) a simple weight majority of molecules containing at least three monomer units which are cova-lently bound to at least one other monomer unit or other reactant;

(b) less than a simple weight majority of molecules of the same molecular weight.

In the context of this definition a ‘monomer unit’ means the reacted form of a monomer substance in a polymer;

  1. monomer: means a substance which is capable of forming covalent bonds with a sequence of additional like or unlike molecules under the conditions of the relevant polymer-forming reaction used for the particular process"

Let's assume paragraph 5 is fulfilled for the mixture of differently substituted different triglycerides of the considered natural fat.

My question is:
Can glycerol meet the definition of a monomer according to paragraph 6?

If we synthesize the triglycerides starting with the reaction between the fatty acids and the substituent, glycerol is a monomer according to paragraph 6: glycerol is capable of forming covalent bonds with the sequence that consists of the substituent and the fatty acid.

But if we synthesize the triglycerides starting with the reaction between glycerol and the fatty acids, glycerol isn't capable of forming covalent bonds with a sequence of further molecules in the polymer formation reaction.

That means, if the mixture is a polymer according to REACH or not depends on the order of the synthesis steps in this case.

Am I right?

I found that there are gaps in the REACH polymer definition. I want to see if I'm right or looking for counterarguments.

$\endgroup$
0

1 Answer 1

1
$\begingroup$
  1. polymer: means a substance consisting of molecules characterised by the sequence of one or more types of monomer units. Such molecules must be distributed over a range of molecular weights wherein differences in the molecular weight are primarily attributable to differences in the number of monomer units. …

This

  • … are primarily attributable to differences in the number of monomer units …

rules out triglycerides – substituted or not – from being a polymer.

  1. monomer: means a substance which is capable of forming covalent bonds with a sequence of additional like or unlike molecules under the conditions of the relevant polymer-forming reaction used for the particular process"

And this

  • … under the conditions of the relevant polymer-forming reaction used for the particular process …

rules out glycerol from being a monomer as there is no polymer.


REACH aside, purely from a chemical point of view and in context of eventually substituted triglycerides, very few chemists would consider such triglyceride as a polymer and glycerol as a monomer.

$\endgroup$
7
  • $\begingroup$ As you consider glycerol as a monomer and as there is just a single glycerol unit.... // You would not consider as a PE/PET polymer a compound with just 1 ethylene, ethyleneglycol or TF acid unit. $\endgroup$
    – Poutnik
    Jun 30, 2023 at 8:29
  • $\begingroup$ You would not consider as a PE/PET polymer a compound with just 1 ethylene, ethyleneglycol or TF acid unit. // Ethene, or ethylene diradical are not PE. 1 Ethyleneglycol esterified with 2 terephthalic acids, or vice versa, are not PET. $\endgroup$
    – Poutnik
    Jun 30, 2023 at 8:35
  • $\begingroup$ Not substituted triglycerides are not REACH polymers, as I understand the wording. // The best choice would be asking REACH about interpretation. A asking B "What does C mean by X?" may not provide a satisfactory nor reliable answer. A should ask C. $\endgroup$
    – Poutnik
    Jun 30, 2023 at 8:52
  • $\begingroup$ Non-substitued triglyceride mixtures and your short-PE/PET example with only 3 molecule units aren't REACH polymers because at least 3 monomer units are necessary which are covalently bound to at least one other molecule unit. We need at least 4 molecule units. Let's assume your PE/PET copolymer with 4 molecule units. The problem remains that a monomer must be capable of forming covalent bonds with a sequence of further molecule units. If a molecule unit is a monomer depends on the order of the polymer forming steps. A molecule is a monomer only if there is already a molecule sequence. $\endgroup$
    – IV_
    Jun 30, 2023 at 9:17
  • $\begingroup$ Could you please correct your answer to be suitable and remove some of your many comments? $\endgroup$
    – IV_
    Jun 30, 2023 at 9:21

Not the answer you're looking for? Browse other questions tagged or ask your own question.