Why Does Polymerisation Occur in Diols?

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HO-R-OH, where R represents an alkyl group, can polymerize due to the unique behavior of geminal diols compared to other diols. The polymerization is particularly effective when the diols are on the same carbon, leading to the formation of polyformaldehyde, which is a white powder with limited water solubility and can depolymerize back into a formaldehyde solution. Under acidic conditions and with the removal of water, polyethers can be synthesized from vicinal diols with longer alkyl chains, which include more than one methylene group. However, for shorter alkyls with 2 to 5 intervening methylenes, the reaction tends to yield complex mixtures of dimers, trimers, and cyclized monomers due to the volatility of intermediates formed during the reaction. This complexity arises because geminal diols exhibit distinct reactivity compared to other diols, significantly influencing the polymerization process.
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why does
HO-R-OH
(where R is an alkyl group) polymerise?
i.e: with itself?
 
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How many carbons in that "alkyl" group?
 
chemisttree said:
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.
 
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That's why I asked the question. Geminal diols behave very differently than other diols.
 

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