Chemical Forums

Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: snorkack on June 08, 2017, 04:51:11 PM

Title: Polycarbonate stability
Post by: snorkack on June 08, 2017, 04:51:11 PM

No, not polymeric carbonates. Polycarbonates with a functional group.

Compounds with structure
R-O-CO-OH
are labile towards easy elimination of CO₂:
R-O-CO-OH :rarrow:R-OH+CO₂2
But the mechanism relies on mobility of H. Carbonate esters are not so labile. The reaction
R-O-CO-O-R´ :rarrow:R-O-R´+CO₂ is not easy.
Now, there are attested dicarbonates, like dimethyl dicarbonate:
Me-O-CO-O-CO-O-Me
and tricarbonates, like di-tert-buthyl-tricarbonate:
tBu-O-CO-O-CO-O-CO-O-tBu
So... how easily and by which mechanisms do they eliminate CO₂?
After all, CO₂ is a stable molecular gas and solid. It does not spontaneously polymerize to linear chains like SO₃ does.
How many CO₂ units can suitable end groups force to stay put in a linear polymer? Do any tetracarbonates exist, how do they decay and under which conditions?