Heat capacities between the temperatures 10 K and 445 K for 2,4-dimethylpyrrole and barriers to methyl-group rotation in the solid state for 2,4- and 2,5-dimethylpyrrolea,b
✍ Scribed by R.D. Chirico; I.A. Hossenlopp; B.E. Gammon; S.E. Knipmeyer; W.V. Steele
- Publisher
- Elsevier Science
- Year
- 1994
- Tongue
- English
- Weight
- 361 KB
- Volume
- 26
- Category
- Article
- ISSN
- 0021-9614
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✦ Synopsis
Heat capacities and enthalpy increments between the temperatures (T=10 \mathrm{~K}) and (445 \mathrm{~K}) were determined for 2,4-dimethylpyrrole by adiabatic calorimetry. (Chemical Abstract registry number ([625-82-1]).) The triple-point temperature and enthalpy of fusion are reported, and enthalpies and entropies relative to those of the crystals at (T \rightarrow 0) were derived. No crystal-tocrystal phase transitions or anomalies were observed. Heat capacities for the supercooled liquid were determined between the glass transition and triple-point temperatures. Barriers to methylgroup rotation in the solid state for 2,4-dimethylpyrrole and 2,5-dimethylpyrrole were estimated by comparison of the heat capacities of the crystals for 2,4-dimethylpyrrole with literature values for 2,5 -dimethylpyrrole.