Phthalate-free, what does it actually mean??

Although the term phthalate-free is getting more airplay every day there seems to be some confusion what actually phthalate-free means. I will try to provide a simple and clear description. We are talking about plasticizers and chemically these are mostly esters. An ester is nothing more than an acid reacting with alcohol creating an ester and water. Acid + Alcohol = Ester + Water. The chemical name of the plasticizer/ ester is based on the type of alcohol and acid. For instance the reaction of 2ethylhexanol with adipic acid gives the ester called di-2-ethylhexyl adipate (and water). This product is mainly known in the market as DOA: di-octyl adipate. I will not go deeper into this funny name change, there are good reasons for this but let’s not make it too complicated.
The main point is that the acid is giving the ester the last part of its name. If you use adipic acid the ester will be an adipate. If you use citric acid, the ester will be a citrate.
The name phthalates is having the same background. 
In order to produce DOP (di-octyl phthalate) you will need 2ethylhexanol and phthalic anhydride. Phthalic anhydride is the anhydride of phthalic acid. The anhydride is used because it is reacting quicker than the acid. Bottom line is that in the end phthalic acid is giving the last part of the chemical name.
DOP is a phthalate because it is made from phthalic anhydride (which comes from phthalic acid). Products likes DINP and DIDP are phthalates because phthalic anhydride is used as raw material.
When a plasticizer is phthalate-free this basically means it is not produced from phthalic anhydride. All esters which are not based on phthalic anhydride can be considered phthalate-free.
One important note I have to make on purity. It can happen that small parts of phthalic anhydride for instance can end up in raw materials and consequently in the production process which can lead to the production of phthalates as a co-product.  This can be limited to such levels that one can still speak of phthalate-free.
To make it a bit more complicated we need to look how phthalic anhydride is produced. Phthalic anhydride is produced by oxidation of ortho-xylene. To be 100% chemically correct we should actually speak of ortho-phthalates instead of phthalates.
So (ortho-) phthalates are those esters produced from phthalic anhydride. Phthalate free are those esters based on other acids which do not contain significant impurities of phthalic anhydride.
This is off course a simplified story but I hope it makes clear what I understand under phthalate-free.

2 Comments to Phthalate-free, what does it actually mean??

  1. Rana's Gravatar Rana
    2013-06-10 at 07:52 | Permalink

    i need to how can I make phthalates product to be phthalates free. in the other word I need to know if any PU product has the phthalates then how can I make it phthalates free. is there any chemical what can be use to make my PU product phthalates free??

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