p-n-Octadecyloxybenzoic acid
- Formula: C25H42O3
- Molecular weight: 390.5992
- IUPAC Standard InChI: InChI=1S/C25H42O3/c1-2-3-4-5-6-7-8-9-10-11-12-13-14-15-16-17-22-28-24-20-18-23(19-21-24)25(26)27/h18-21H,2-17,22H2,1H3,(H,26,27)
- IUPAC Standard InChIKey: TZEWVAHWYIHCEC-UHFFFAOYSA-N
- CAS Registry Number: 15872-50-1
- Chemical structure:
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Condensed phase thermochemistry data
Go To: Top, Phase change data, References, Notes
Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
Data compiled by: Eugene S. Domalski and Elizabeth D. Hearing
Constant pressure heat capacity of solid
| Cp,solid (cal/mol*K) | Temperature (K) | Reference | Comment |
|---|---|---|---|
| 34.7 | 320. | Ikeda and Hatakeyama, 1976 | T = 320 to 420 K. Value is unsmoothed experimental datum for c,I phase. |
Phase change data
Go To: Top, Condensed phase thermochemistry data, References, Notes
Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
Data compiled as indicated in comments:
TRC - Thermodynamics Research Center, NIST Boulder Laboratories, Chris Muzny director
DH - Eugene S. Domalski and Elizabeth D. Hearing
| Quantity | Value | Units | Method | Reference | Comment |
|---|---|---|---|---|---|
| Tfus | 378. | K | N/A | Herbert, 1967 | Smectic liquid crystal phase; Uncertainty assigned by TRC = 1. K; TRC |
Temperature of phase transition
| Ttrs (K) | Initial Phase | Final Phase | Reference | Comment |
|---|---|---|---|---|
| 342.5 | crystaline, III, c,III | liquid, smectic transition temperature | Ikeda and Hatakeyama, 1976 | DH |
Enthalpy of phase transition
| ΔHtrs (kcal/mol) | Temperature (K) | Initial Phase | Final Phase | Reference | Comment |
|---|---|---|---|---|---|
| 16.085 | 379.5 | crystaline, I | liquid | Ikeda and Hatakeyama, 1976 | DH |
| 9.2973 | 371.0 | crystaline, II | liquid | Ikeda and Hatakeyama, 1976 | DH |
| 3.1788 | 408.5 | liquid | liquid | Ikeda and Hatakeyama, 1976 | DH |
Entropy of phase transition
| ΔStrs (cal/mol*K) | Temperature (K) | Initial Phase | Final Phase | Reference | Comment |
|---|---|---|---|---|---|
| 42.3 | 379.5 | crystaline, I, c,I | liquid, smectic transition | Ikeda and Hatakeyama, 1976 | DH |
| 25.1 | 371.0 | crystaline, II, c,II | liquid, smectic transition | Ikeda and Hatakeyama, 1976 | DH |
| 7.9 | 408.5 | liquid, Smectic | liquid, isotropic | Ikeda and Hatakeyama, 1976 | DH |
References
Go To: Top, Condensed phase thermochemistry data, Phase change data, Notes
Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
Ikeda and Hatakeyama, 1976
Ikeda, M.; Hatakeyama, T.,
Thermal studies on the phase transition of p-n-Octadecyloxybenzoic acid (Part I),
Mol. Cryst. Liq. Cryst., 1976, 33, 201-212. [all data]
Herbert, 1967
Herbert, A.J.,
Transition temperatures and transition energies of the p-n-alkoxy benzoic acids, from n-propyl to n-octadecyl,
Trans. Faraday Soc., 1967, 63, 555, https://doi.org/10.1039/tf9676300555
. [all data]
Notes
Go To: Top, Condensed phase thermochemistry data, Phase change data, References
- Symbols used in this document:
Cp,solid Constant pressure heat capacity of solid Tfus Fusion (melting) point Ttrs Temperature of phase transition ΔHtrs Enthalpy of phase transition ΔStrs Entropy of phase transition - Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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