Diethyl -muconate

Photopolymerization of the crystals was carried out in a sealed Pyrex ampule under irradiation of UV light using a high-pressure mercury lamp (Toshiba SHL-100-2, 100 W) at a distance of 10 cm. A typical polymerization procedure is described below. Monomer diethyl c ,cA-muconate 1 (200 mg, 1.0 mmol) was placed in an ample, which was then evacuated on a vacuum line. After irradiation, polymer was isolated by removal of the unreacted monomer with chloroform (20 mL) for 5-10 h at room temperature. Photopolymerization was also carried out by direct exposure to sunlight. 

Tashiro, K., Kamae, T., Kobayashi, M., Matsumoto, A., Yokoi, K. and Aoki, S. (1999) Structural change in the topochemical solid-state polymerization process of diethyl ds.cis-muconate crystal. 1. Investigation of polymerization process by means of X-ray diffraction, infrared/ raman spectra, and DSC. Macromolecules, 32, 2449-2454. 

Oxepan and other oxygen- or nitrogen-containing saturated heterocycles can be prepared in high yield by the dehydrative coupling of aamino-alcohols, using diethyl azodicarboxylate and triphenylphosphine. The synthetically useful oxepin-2,7-diones (muconic acid anhydrides) can be conveniently prepared by the oxidation of ortho-henzoquinones with w-chloroperoxybenzoic acid. °... 

We show an example of the case of poly(l,4- diethyl c/s,cis-muconate). We prepare a single crystal of 1,4-diethyl cw,cw-muconate from the solution and irradiate with the X-ray beam for the structure analysis of the monomer and the polymer. Since the structural changes occur rapidly during the polymerization reaction, that is, on a time scale of several tens of minutes under the X-ray irradiation, fast acquisition of the X-ray reflections is necessary for accurate structural analysis. A CCD camera makes it possible to collect about 6(XX) reflections in 13 minutes [130]. 

Figure 5.29 Time dependence of Raman and X-ray data measured in the photoinduced solid-state polymerization reaction of diethyl cA,cA-muconate single crystal [133].

Figure 5.30 Illustration of the structural change in the photoinduced solid-state polymerization reaction of diethyl cw,cw-muconate single crystal [133]. The polymer segments generated during the course of the reaction are under tension due to the interactions with the surrounding monomer molecules (b). This tensile stress working on the short polymer chain segments becomes weaker and disappears when the polymer chains become longer and their number is increased in the crystal lattice (c).

Figure 5.28 Molecular shapes of poly (diethyl cw.cw-muconate) and the corresponding monomers in the crystal lattice [130]. (See text for full caption.)...

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