Polyesters based on 2,5-disubstituted furans in various states of reduction

Abstract

2-5-Furan dicarboxylic acid, 1a, was synthesized from mucic acid and 5-hydroxymethyl-2-furaldehyde, 1e, was synthesized from sucrose. These materials were used to synthesize compounds 1b, 1c, 1d, 1f and 1g. The 2,5-disubstituted dihydrofurans 2a-c, 3a-c, 4a-b and the 2,5-disubstituted tetrahydrofurans 5a-f and 6a-d were prepared in addition to 2,4-dioxo-3,8-dioxabicyclo[3.2.1]octane and 2-oxo-3,8-dioxabicyclo[3.2.1]octane.

The reduction of 1a with dissolving metals was examined. The reduction systems which were employed were sodium amalgam in water or deuterium oxide and sodium, potassium, calcium or lithium in liquid ammonia in the presence of absolute ethanol. In the absence of a proton source 1a, 2a, 3a, and 4a were treated with sodium in liquid ammonia. the isomerization of 2a, 3a or 4a with sodium amide in liquid ammonia was examine as was the isomerization of 2a in aqueous sodium hydroxide or by sodium deuteroxide in deuterium oxide. A mechanism for the dissolving metal reduction of 1a was suggested.

Polyesters were prepared by reacting 1b with 1,6-hexane diol; 1d with 1c; 1d with a mixture of 2c and 3c; 1d with 5c; and 1d with 2,2'-bis(4-hydroxyphenyl)propane. Other polyesters were synthesized by reacting 5b with ethylene glycol; 5d with 5c; 5d with 6c; 6d with 5c; and 6d with 6c. The above processes were performed by employing melt-transesterification, interfacial or solution polymerization techniques. In addition, polyesters were prepared by the catalytic decomposition of ethylene carbonate in the presence of 2,4-dioxo-3,8-dioxabicyclo[3.2.1]octane and by the ring-opening polymerization of 2-oxo-3,8-dioxabicyclo[3.2.1]octane. The above polymers exhibited intrinsic viscosities in chloroform at 25° which varied from 0.006 to 0.5. The lower molecular weight polyesters were found to be sticky, semi-solids while the higher molecular weight polyesters were fibrous and film-forming. The thermal properties of the polymers were examined by differential scanning calorimetry.