Comparison of Crystal Structure between Low- and High-Temperature Phases of Diethyl (Z,Z)-muconate. A Trial to Investigate the Reasons Why the Solid-State Polymerization Reaction Is Ceased at Low Temperature
| Autor: | Shinsuke Nakamoto, Akikazu Matsumoto, Kohji Tashiro, Seishi Saragai, Toshiya Kamae, Takashi Tsubouchi |
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| Rok vydání: | 2001 |
| Předmět: | |
| Zdroj: | Polymer Journal. 33:199-203 |
| ISSN: | 1349-0540 0032-3896 |
| DOI: | 10.1295/polymj.33.199 |
| Popis: | Diethyl (Z,Z)-muconate (EMU) shows the topotactic polymerization reaction in the solid-state by an irradiation of light. This reaction occurs quite rapidly at room temperature but reduces its rate gradually at lower temperature and does not occur at all below −45°C, where the 1st-order phase transition occurs. In order to clarify the reasons why the reaction is ceased in the low-temperature phase, the X-Ray structural analysis was made at −80°C by using an imaging plate system. The molecular packing structure was found to be slightly different from that at room temperature. If the reactivity is affected quite sensitively by such a slight difference in packing structure, we have to say that the solid-state polymerization of EMU can be induced for the first time when the molecular packing mode satisfies the quite narrow and limited geometrical condition. But, this idea is difficult to be accepted at the present stage judging from the small structural difference between the two phases. As seen typically for the case of polydiacetylenes, the solid-state polymerization or in more general the topochemical reactions had been discussed so far in terms of such packing geometry as the inter-atomic distance, the molecular orientation in the crystal lattice, etc. But this rule is considered to be too simple to interpret the remarkable difference in the polymerization reactivity at high- and low-temperatures of EMU. In other words, this example of EMU brings up a very important warning about the conventionally-made discussion on the factors governing the solid-state polymerization reaction. |
| Databáze: | OpenAIRE |
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