The Trapp mixture is a specific
mixture of organic
solvent
A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for ...
s that allows
chemical reaction
A chemical reaction is a process that leads to the IUPAC nomenclature for organic transformations, chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the pos ...
s to take place at very low temperatures. It is made up of
THF
Tetrahydrofuran (THF), or oxolane, is an organic compound with the formula (CH2)4O. The compound is classified as heterocyclic compound, specifically a cyclic ether. It is a colorless, water- miscible organic liquid with low viscosity. It is ...
:
diethyl ether
Diethyl ether, or simply ether, is an organic compound in the ether class with the formula , sometimes abbreviated as (see Pseudoelement symbols). It is a colourless, highly volatile, sweet-smelling ("ethereal odour"), extremely flammable li ...
:
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
Vinyl bromide is a simple vinyl halide. It is a colorless liquid. It is produced from ethylene dibromide. It is mainly used as a comonomer to confer fire retardant properties to acrylate polymers.
Reactions and applications
It reacts with magne ...
and
''tert''-butyllithium.
[Eric K. Eisenhart, Bernard Bessieres "Vinyllithium" e-EROS Encyclopedia of Reagents for Organic Synthesis, 2001. .] The low temperatures suppress the reaction of the strongly basic organolithium reagent with the THF.
References
Solvents
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