Structures and Properties of trans‐1,3,3,3‐Tetrafluoro‐ propene (HFO‐1234ze) and 2,3,3,3‐Tetrafluoropropene (HFO‐1234yf) Refrigerants

The refrigerant trans‐1,3,3,3‐tetrafluoropropene (HFO‐1234ze) is used as a replacement for former cooling agents that have been phased‐out due to their global warming potential or ozone depleting potential. Although it is used on a large scale, only a few vibrational data and no structural data of HFO‐1234ze are known. We report structure determinations based on low‐temperature single‐crystal X‐ray diffraction data as well as gas‐phase diffraction data of HFO‐1234ze and HFO‐1234yf (2,3,3,3‐tetrafluoropropene). Furthermore, vibrational spectra of HFO‐1234ze in all phases are described. The results are discussed together with quantum‐chemical calculations on the PBE0/cc‐pVTZ level of theory. Combustion experiments of HFO‐1234ze show carbonyl difluoride, carbon dioxide and hydrogen fluoride to be the main combustion products. The structures of two tetrafluoropropenes have been elucidated in the solid state and in the gas phase. Combustion experiments prove the flammability of the refrigerant HFO‐1234ze and the formation of hazardous gases.