Density 752 kg/m³ | Appearance Colorless liquid | |
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Related amines Related compounds | ||
Triisopropylamine is an organic chemical compound consisting of three isopropyl groups bound to a central nitrogen atom. As a hindered tertiary amine, it can be used as a non-nucleophilic base and as a stabilizer for polymers; however, its applications are limited by its relatively high cost and difficult synthesis.
Contents
Structure
Triisopropylamine is notable as being the most sterically crowded amine currently known. The even more crowded tri-tert-butyl-amine (tBu3N) has never been successfully synthesized, although the existence of 2,2,4,4-Tetramethyl-3-t-butyl-pentane-3-ol (tBu3COH) implies that it may be possible.
In the early 1990s, theoretical studies and electron diffraction analysis of the 3D structure of the molecule, in the gas phase or in non-polar solvents, indicated that the bonds between the nitrogen atom and the three carbon atoms were nearly coplanar in the ground state, instead of forming a trigonal pyramid as in simpler amines. The average C-N-C angle was claimed to be 119.2°, much closer to the 120° of the flat configuration than to the 111.8° of trimethylamine. This peculiarity was attributed to steric hindrance by the bulky isopropyl radicals. However, in 1998 X-ray diffraction analysis of the crystallized solid showed that the C3N core is actually pyramidal, with the N atom lying approximately 0.28 Å off the carbons' plane (whereas in trimethylamine the distance is about 0.45 Å). However the researchers could not rule out the crystal field effect as the cause of the asymmetry.
The C-C-C planes of the isopropyl groups are slightly tilted (about 5°) relative to the threefold symmetry axis of the C3N core.
Preparation
Steric effects make triisopropylamine difficult to synthesise and unlike less hindered tertiary amines (such as triethylamine) it cannot be produced by the alkylation of ammonia with alcohol; attempts to do so stall at diisopropylamine. It can be prepared from diisopropylamine by a procedure developed by Bock and others: