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Trapp mixture

The Trapp mixture is a specific mixture of organic solvents that allows chemical reactions to take place at very low temperatures. It is made up of THF:diethyl ether:pentane in a 4:4:1 ratio which remains liquid down to −110 °C and the same solvents in a 4:1:1 ratio remain a liquid down to −120 °C. This solvent system retains a low viscosity until just before freezing and it allows a lower temperature reaction than pure THF, which melts at −108.4 °C. An illustrative application of Trapp solvent is the preparation of vinyllithium by lithium halogen exchange from vinyl bromide and tert-butyllithium. The low temperatures suppress the reaction of the strongly basic organolithium reagent with the THF.

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Jul 13, 2026
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The Trapp mixture is a specific mixture of organic solvents that allows chemical reactions to take place at very low temperatures.1 It is made up of THF:diethyl ether:pentane in a 4:4:1 ratio which remains liquid down to −110 °C and the same solvents in a 4:1:1 ratio remain a liquid down to −120 °C. This solvent system retains a low viscosity until just before freezing and it allows a lower temperature reaction than pure THF, which melts at −108.4 °C. An illustrative application of Trapp solvent is the preparation of vinyllithium by lithium halogen exchange from vinyl bromide and tert-butyllithium.2 The low temperatures suppress the reaction of the strongly basic organolithium reagent with the THF.

References

References

  1. G. Köbrich; H. Trapp (February 1966). "Darstellung und thermische Stabilität von 1-Chlor-2.2-diaryl-vinyllithium-Verbindungen ('The formation and thermal stability of 1-chloro-2,2-diaryl-vinyl lithium compounds')". Chem. Ber. 99 (2): 680. doi:10.1002/cber.19660990243. Retrieved 10 March 2024.
  2. Eric K. Eisenhart; Bernard Bessieres (17 September 2007). ""Vinyllithium"". e-EROS Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rv015.pub2. Retrieved 10 March 2024.