Why Does Polymerisation Occur in Diols?

[jsmith613]

why does
HO-R-OH
(where R is an alkyl group) polymerise?
i.e: with itself?

 

[chemisttree]

How many carbons in that "alkyl" group?

 

[MrSid]

How many carbons in that "alkyl" group?

This extremely important, since only the simplest case of the diols existing on the same carbon are readily polymerized to poly acetals (geminal diol). The simplest is polyformaldehyde, a white powder that is poorly soluble in water with reaction to depolymerize to a formaldehyde solution.

One can envision under acidic conditions and with removal of H2O to drive the reaction, that poly ethers can be made for other alkyls of longer than one methylene (vicinal diols and greater intervening methylenes). For the shorter alkyls, (2,3,4, and 5 intervening methylenes), dimers, trimers, and the monomer can cyclize and remove intermediates (volatile under the conditions of reaction heat and H2O removal) needed to make longer polymers so complex mixtures result.

 

[chemisttree]

That's why I asked the question. Geminal diols behave very differently than other diols.