Related Experiment Video
Updated: May 23, 2026

High-Temperature and High-Pressure In situ Magic Angle Spinning Nuclear Magnetic Resonance Spectroscopy
Published on: October 9, 2020
In situ high-pressure and high-temperature experiments on n-heptane
Erwei Qiao1, Haifei Zheng, Changxing Long
1Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China.
Abstract:
The Raman spectroscopy of n-heptane was investigated in a moissanite anvil cell at ambient temperatures and a diamond anvil cell under pressures of up to ~2000 MPa and at temperature range from 298 to 588 K. The results show that at room temperature the vibration modes, assigned to the symmetric and antisymmetric stretching of CH(3) and CH(2) stretching, shifted to higher frequency according to quasi-linearity with increasing pressure, and a liquid-solid phase transition occurred at near 1150 MPa. The high-temperature solidus line of n-heptane follows a quadratic function of P = 0.00737T(2) + 5.27977T - 1195.76556. Upon phase change, fitting the experimental data obtained in the temperature range of 183∼412 K to the Clausius-Clapeyron equation allows one to define the thermodynamic parameters of n-heptane of dP/dT = 0.01474T + 5.27977.
Related Concept Videos
¹H NMR of Conformationally Flexible Molecules: Variable-Temperature NMR
Mass Spectrometry: Branched Alkane Fragmentation
Reduction of Benzene to Cyclohexane: Catalytic Hydrogenation
¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
Mass Spectrometry: Long-Chain Alkane Fragmentation
Combustion Energy: A Measure of Stability in Alkanes and Cycloalkanes
Alkanes undergo combustion in the presence of excess oxygen and high-temperature conditions to give carbon dioxide and water. A combustion reaction is the energy source in natural gas, liquified petroleum gas (LPG), fuel oil, gasoline, diesel fuel, and...

