Fluoroform

Structural formula
General
Surname	Fluoroform
other names	Trifluoromethane Fluoryl HFC-23 TRIGON 300 Freon 23 Freon R23 Genetron-23 R23 FC 23 FE-13
Molecular formula	CHF 3
Brief description	colorless gas with an ethereal odor
External identifiers / databases
CAS number 75-46-7 EC number 200-872-4 ECHA InfoCard 100,000,794 PubChem 6373 ChemSpider 21106179 Wikidata Q410612
properties
Molar mass	70.01 g mol −1
Physical state	gaseous
density	1.46 g cm −3 (liquid at boiling point)  3.15 g l −1 (0 ° C)
Melting point	−155.2 ° C
boiling point	−82.2 ° C
Vapor pressure	2.51 M Pa (0 ° C) 3.26 MPa (10 ° C) 4.18 MPa (20 ° C)
solubility	bad in water (1 g l −1 )
Dipole moment	1.65150 D (5.509 · 10 -30  C  ·  m )
safety instructions
GHS labeling of hazardous substances Caution H and P phrases H: 280 P: 403
Global warming potential	13856 (based on 100 years)
Thermodynamic properties
ΔH f 0	−695.4 kJ / mol
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Fluoroform ( empirical formula CHF ₃ ) is a colorless, non-toxic and non-flammable inert gas with a slight ethereal odor. Due to its structure (CHX ₃ ) it is homologous to chloroform , bromoform and iodoform and named analogously.

presentation

Fluoroform (HFC-23) is a by-product of the production of chlorodifluoromethane , which is a basic product for the production of Teflon . In the laboratory it can be obtained from iodoform and mercury (I) fluoride , or from chloroform and hydrofluoric acid :

${\displaystyle \mathrm {CHI_{3}+3\ HgF\longrightarrow \ CHF_{3}+3\ HgI} }$

${\displaystyle \mathrm {CHCl_{3}+3\ HF\longrightarrow \ CHF_{3}+3\ HCl} }$

properties

Fluoroform is inert. It only reacts with strongly oxidizing reagents.

use

CHF ₃ is used as an extinguishing agent and refrigerant as well as a process gas for dry etching . In organic synthesis, the compound can be used as a reagent for difluoromethylation reactions . These reactions proceed via the difluorocarbene CF ₂ as an intermediate.

environment

Since fluoroform contains neither chlorine nor bromine, it does not attack the ozone layer . The atmosphere currently contains about 200,000 tons of fluoroform. As a greenhouse gas, it is about 14,000 times as powerful as carbon dioxide . For this reason, fluoroform is named in the Kyoto Protocol as a “hydrogen-containing fluorocarbon”, the emission of which must be reduced.

According to the two main producers, China and India, the greenhouse gas HFC-23 should hardly be released into the atmosphere by 2017. In fact, atmospheric researchers led by the University of Bristol have measured record values. As the international team reported in January 2020, however, emissions continued to rise and had reached a record level in 2018.

Trading in emission rights for HFC-23

This substance hit the headlines in 2010 when , according to the television magazine Monitor, research into climate certificates , which can be sold after reducing emissions, was tricked: In exchange for savings mainly by Indian and Chinese chemical plants in the production of fluoroform (HFC -23), German coal-fired power plant operators bought the opportunity to produce significantly more carbon dioxide . This was determined by tracking the fluctuating levels of emissions from HFC-23.

In August 2015 it became known that trickery had also been carried out in connection with HFC-23 emission levels in Russia around 2011. With state tolerance, plants were operated more inefficiently in one year with increased emissions of greenhouse gas, in order to achieve revenues from the pollution certificate trade in the following year through normal economic operation. The EU had already banned trading in HFC-23 certificates before 2013. For the Paris climate agreement, experts and the German Federal Environment Ministry were hoping for international control when selecting projects.

Substitute for refrigeration technology

R-469A , a mixture of R-744 and R-410A , is a climate-friendly substitute. The CO ₂ equivalent (GWP) of R-469A is 1357, less than a tenth of the CO ₂ equivalent of R-23 (GWP of 14800). This means that this refrigerant has unlimited approval in accordance with EU regulation 517/2014. This regulation allows gases with CO ₂ equivalents over 2500 in stationary industrial refrigeration systems only for applications below −50 ° C.

Precautions

The gas should not be inhaled as it can cause respiratory failure. A narcotic effect occurs from around 20 percent by volume in the breath (see safety data sheet ). According to NFPA and ISO application standards, the NOAEL is 30 percent by volume.

literature

• Fred Pearce: Grim surprise - News of a powerful greenhouse gas came too late for Kyoto . In: New Scientist . No. 2120 , February 1998 ( newscientist.com ).

Individual evidence

1. ↑ ^{a b c d e f g h i j k} Entry on trifluoromethane in the GESTIS substance database of the IFA , accessed on February 18, 2017(JavaScript required) .
2. ↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Dipole Moments, pp. 9-58.
3. ↑ G. Myhre, D. Shindell et al .: Climate Change 2013: The Physical Science Basis . Working Group I contribution to the IPCC Fifth Assessment Report. Ed .: Intergovernmental Panel on Climate Change . 2013, Chapter 8: Anthropogenic and Natural Radiative Forcing, pp. 24-39; Table 8.SM.16 ( PDF ).
4. ↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Standard Thermodynamic Properties of Chemical Substances, pp. 5-19.
5. ↑ G. Brauer (Ed.), Handbook of Preparative Inorganic Chemistry 2nd ed., Vol. 1, Academic Press 1963, pp. 204-5.
6. ↑ Patent EP0907402 : Method of removing, from a stream of gas, fluorinated compounds which contribute to destruction of the ozone layer and / or changes in climate, and use of the method. Published on May 23, 2001 , inventors: Walter Holzinger, Eckard Kopatzki, Karl Markert, Christoph Scholz. ‌
7. ↑ ^{a b} Köckinger, M .; Ciaglia, T .; Bersier, M .; Hanselmann, P .; Gutmann, B .; Cap, CO: Utilization of fluoroform for difluoromethylation in continuous flow: a concise synthesis of α-difluoromethyl-amino acids in Green Chem. 2018, doi : 10.1039 / C7GC02913F , open access .
8. ↑ Gutmann, B .; Koeckinger, M .; Glotz, G .; Ciaglia, T .; Slama, E .; Zadravec, M .; Pfanner, S .; Maier, MC; Gruber-Wölfler, H .; Cap, CO: Design and 3D printing of a stainless steel reactor for continuous difluoromethylations using fluoroform in React. Chem. Eng. 2 (2017) 919-927, doi : 10.1039 / c7re00176b , open access .
9. ↑ Dr. Anke Sauter: Further increase in strong greenhouse gas measured . Press release from Goethe University Frankfurt am Main, January 24, 2020 (accessed on January 28, 2020)
   
10. ↑ Climate trade instead of climate change: Is climate protection becoming a farce? (PDF; 70 kB) Monitor No. 610 from August 19, 2010.
11. ↑ Covered by the highest circles: Millions swindled with climate tricks , orf.at, August 25, 2015. Retrieved August 25, 2015.
12. ↑ Climate Protection - Printing Money in the Greenhouse , sueddeutsche.de, August 24, 2015. Retrieved August 25, 2015.
13. ↑ Lambert Schneider, Anja Kollmuss: Perverse effects of carbon markets on HFC-23 and SF6 abatement projects in Russia . In: Nature Climate Change . tape 5 , no. 12 , 2015, p. 1061-1063 , doi : 10.1038 / nclimate2772 .
14. ↑ ^{a b} Regulation (EU) no. 517/2014 Regulation (EU) no. 517/2014 of the European Parliament and of the Council of 16 April 2014 fluorinated greenhouse gases and repealing Regulation (EC) no. 842/2006 retrieved on February 25, 2020