5-lactone melting temperature

Figure 11.9. Glass transition temperatures of polystyrene bloek, Tg.ps, and melting temperatures of e-eapro-lactone bloek, T for e-eaprolactone-styrene dibloek eopolymer plastieized with variable amounts of DOP (( )ps = (weight of PS)/(total weight of PS and DOP)). [Data from Nojima S Tanaka H Rohadi A Sasaki S, Polymer, 39, Nos. 8-9, 1998, p. 1727-34.]...

Above its melt temperature of 245° C, the polymer decomposes to pivalo-lactone, and then further to isobutylene and carbon dioxide. Consequently, heating must occur as rapidly as possible in processing the polymer to molded articles, films, or fibers. In addition, nucleating agents have to be added to the polymer. The processing difficulties are presumably why the polymer has not been commercialized even though the mechanical properties are good. 

Solid lactones or cyclic carbonates form linear hydroxy amides upon reaction with gaseous ammonia, methylamine, or ethylamine. For example, the compounds 277a-c and (ketonized) 279a-c are quantitatively formed at 0 °C and room temperature, respectively, without melting [12] (Scheme 39). 

S-lactone (Note 1) is added slowly with vigorous stirring. During the addition, the temperature should be kept below 65°. After an hour in the ice bath, the solution is kept at room temperature for 24 hours and is then poured into 1 1. of water and stirred until the hydrolysis of the acetic anhydride is complete (about an hour). The mixture is placed in a refrigerator until the product crystallizes completely (Note 2). The crude material is removed by filtration and washed with a small amount of ice water. The 2,3,4,6-tetra-O-acetyl-D-gluconic acid monohydrate thus obtained melts at 113-117°. The yield is 79-84 g. (74-79%). 

The melt condensation of acid and hydroxyl functional group normally requires exact stoichiometry, elevated temperature, and a long reaction cycle. Such a route would not be possible to utilize to produce block polymers from lactones and other vinyl monomers. However, a rather facile route leading to polyester formation can be realized by the ring-opening polymerization of lactones as seen from the scheme ... 

The cyclopentanoid lactone (Ci0H 6O2) was first investigated with the crystal at room temperature.64 The crystal has a relatively low melting... 

Polycaprolactone (PCL) is obtained by ring-opening polymerization of the six-membered lactone, e-caprolactone (Figure 30.4f), which yields a semicrystalline polymer with a melting point of 59°C-64°C and a glass transition temperature of 60°C with great organic solvent solubility. Anionic, cationic, coordination, or radical polymerization routes are all applicable for synthesis. " " " ... 

In such cases the enantiomeric excess is crystallized with a higher purity than that of in the initial composition, in a certain range of temperature. For example, the common intermediate of the synthesis of several prostaglandines is a lactone (PGL). Its enantiomeric mixtures (eeo) can be enriched by crystallization (eesoUd) from melt, while the racemic ratio (liquid residue, eeuquid) can be recovered for repeated resolution.20... 

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