Triisopropylamine

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Triisopropylamine
Skeletal formula of triisopropylamine
Identifiers
CAS number 3424-21-3 YesY
PubChem 61924
ChemSpider 55785 N
UNII Y67CF9Z56L YesY
EC number 222-317-5
Jmol-3D images Image 1
Properties
Molecular formula C9H21N
Molar mass 143.27 g mol−1
Appearance Colorless liquid
Odor Ichtyal, ammoniacal
Density 0.752 g/cm3
Boiling point 47 °C (117 °F; 320 K) at 1.9 kPa
Related compounds
Related amines
Related compounds
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
Infobox references

Triisopropylamine is an organic chemical compound consisting of three isopropyl groups bound to a central nitrogen atom.[1][2] 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.

Structure[edit]

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.[3][4] The average C-N-C angle was claimed to be 119.2°,[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.[5]

The C-C-C planes of the isopropyl groups are slightly tilted (about 5°) relative to the threefold symmetry axis of the C3N core.[3][5][6]

Preparation[edit]

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:[2]

Preparation of triisopropylamine.png

References[edit]

  1. ^ G. Graner, E. Hirota, T. Iijima, K. Kuchitsu, D. A. Ramsay, J. Vogt and N. Vogt (2003), C9H21N, Triisopropylamine. In Molecules Containing Five or More Carbon Atoms, volume 25D of the series Landolt-Börnstein - Group II Molecules and Radicals. Springer-Verlag. ISBN 978-3-540-42860-2; DOI 10.1007/10735542_789.
  2. ^ a b c Hans Bock, Ilka Goebel, Zdenek Havlas, Siegfried Liedle, Heinz Oberhammer (1991). "Triisopropylamine: A Sterically Overcrowded Molecule with a Flattened NC3 Pyramid and a "p-Type" Nitrogen Electron Pair". Angew. Chem. Int. Ed. 30 (2): 187–190. doi:10.1002/anie.199101871. 
  3. ^ a b Arthur M. Halpern, B. R. Ramachandran (1992). "Photophysics of a sterically crowded tertiary-saturated amine: triisopropylamine". J. Phys. Chem. 96 (24): 9832–9839. doi:10.1021/j100203a047. 
  4. ^ Christoph Kölmel, Christian Ochsenfeld and Reinhart Ahlrichs (1992). "An ab initio investigation of structure and inversion barrier of triisopropylamine and related amines and phosphines". Theoretical Chemistry Accounts: Theory, Computation, and Modeling (Theoretica Chimica Acta) 82 (3–4). 
  5. ^ a b Boese, R.; Bläser, D.; Antipin, M. Y.; Chaplinski, V.; de Meijere, A. (1998). "Non-planar structures of Et3N and Pri3N: a contradiction between the X-ray, and NMR and electron diffraction data for Pri3N". Chem. Commun. (7): 781–782. doi:10.1039/a708399h. 
  6. ^ Yang M, Albrecht-Schmitt T, Cammarata V, Livant P, Makhanu DS, Sykora R, and Zhu W (2009). "Trialkylamines more planar at nitrogen than triisopropylamine in the solid state". J. Org. Chem. 74 (7): 2671–8. doi:10.1021/jo802086h. PMID 19323571.