Hexahydro-1,3,5-triazine

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Structure of a trisubstituted hexahydrotriazine 1,3,5-triazanes.svg
Structure of a trisubstituted hexahydrotriazine

In chemistry, hexahydro-1,3,5-triazine is a class of heterocyclic compounds with the formula (CH2NR)3. Known as aldehyde ammonias, these compounds characteristically crystallize with water. They are reduced derivatives of 1,3,5-triazine, which have the formula (CHN)3, a family of aromatic heterocycles.

Contents

They are also called triazacyclohexanes or TACH's, but this acronym is also applied to cis,cis-1,3,5-triaminocyclohexane.

Preparation

N,N',N''-trisubstituted hexahydro-1,3,5-triazines arise from the condensation of a primary amine and formaldehyde as illustrated by the route to 1,3,5-trimethyl-1,3,5-triazacyclohexane:

3 CH2O + 3 H2NMe → (CH2NMe)3 + 3 H2O

The C-substituted derivatives are obtained by reaction of aldehydes and ammonia: [1]

3 RCHO + 3 NH3 → (RCHNH)3 + 3 H2O

1-Alkanolamines are intermediates in these condensation reactions. [2]

RDX, an explosive, is a hexahydro-1,3,5-triazine. RDX.svg
RDX, an explosive, is a hexahydro-1,3,5-triazine.

The parent hexahydro-1,3,5-triazine (CH2NH)3 has been detected as an intermediate in the condensation of formaldehyde and ammonia. This reaction affords hexamethylene tetraamine. [3] The N-substituted derivatives are more stable. These

Representative model reaction using N,N-dimethyl-p-phenylene diamine (1.1) and stoichiometric paraformaldehyde. Hemiaminal 1.2 is an intermediate to hexahydrotriazine 1.3. 1,3,5-hexahydro-1,3,5-triazine synthesis.png
Representative model reaction using N,N-dimethyl-p-phenylene diamine (1.1) and stoichiometric paraformaldehyde. Hemiaminal 1.2 is an intermediate to hexahydrotriazine 1.3.

The N,N',N"-triacyltriazines are trizines with acyl groups attached to the three nitrogen centers of the ring. These triacyltriazines arise from the reaction of hexamethylene tetraamine with acid chlorides or the condensation of amides with formaldehyde. [4]

Structure

Unlike the parent triazines, the hexahydro derivatives are conformationally flexible. [5]

Structure of (Me3TACH)ScCl3 viewed down the three-fold symmetry axis (color scheme: blue = N, green = Cl, gray = C). JASWUW.png
Structure of (Me3TACH)ScCl3 viewed down the three-fold symmetry axis (color scheme: blue = N, green = Cl, gray = C).

Trimers of isocyanates are sometimes labeled as 2,4,6-trioxohexahydro-1,3,5-triazines. They have the formula (RNC(O))3 and based on the isocyanuric (trione) tautomer of cyanuric acid.

The N,N',N"-hexahydro-1,3,5-triazines function as tridentate ligands, which are called TACH (triazacyclohexanes). Examples include Mo(CO)3[(CH2)3(NMe)3] formed from the TACH ligand and molybdenum hexacarbonyl. [7]

Hexahydro-1,3,5-triazine polymers have also been synthesized. [2]

References

  1. ↑ Nielsen, Arnold T.; Atkins, Ronald L.; Moore, Donald W.; Scott, Robert; Mallory, Daniel; LaBerge, Jeanne M. (1973). "Structure and chemistry of the aldehyde ammonias. 1-Amino-1-alkanols, 2,4,6-trialkyl-1,3,5-hexahydrotriazines, and N,N-dialkylidene-1,1-diaminoalkanes". J. Org. Chem. 38 (19): 3288–3295. doi:10.1021/jo00959a010.
  2. 1 2 3 Garcia, J. M.; Jones, G. O.; Virwani, K.; McCloskey, B. D.; Boday, D. J.; Ter Huurne, G. M.; Horn, H. W.; Coady, D. J.; Bintaleb, A. M.; Alabdulrahman, A. M. S.; Alsewailem, F.; Almegren, H. A. A.; Hedrick, J. L. (2014). "Recyclable, Strong Thermosets and Organogels via Paraformaldehyde Condensation with Diamines". Science. 344 (6185): 732–5. Bibcode:2014Sci...344..732G. doi:10.1126/science.1251484. PMID   24833389. S2CID   28090009.
  3. ↑ Richmond, H. H.; Myers, G. S.; Wright, George F. (1948). "The Reaction between Formaldehyde and Ammonia". Journal of the American Chemical Society. 70 (11): 3659–3664. Bibcode:1948JAChS..70.3659R. doi:10.1021/ja01191a034. PMID   18102916.
  4. ↑ Teeters, W. O.; Gradsten, M. A. (1950). "Hexahydro-1,3,5-tripropionyl-s-triazine". Organic Syntheses. 30: 51. doi:10.15227/orgsyn.030.0051.
  5. ↑ Jewett, J. G., Breeyear, J. J., Brown, J. H., Bushweller, C. H. (2000). "Stereodynamics of 1,3,5-Trialkyl-1,3,5-triazacyclohexanes: 1H and 13C Dynamic NMR Studies. Solvent Effects. Ab Initio and Molecular Mechanics Calculations". J. Am. Chem. Soc. 122 (2): 308. Bibcode:2000JAChS.122..308J. doi:10.1021/ja990760d.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  6. ↑ Tredget, Cara S.; Lawrence, Sally C.; Ward, Benjamin D.; Howe, Robert G.; Cowley, Andrew R.; Mountford, Philip (2005). "A Family of Scandium and Yttrium Tris((trimethylsilyl)methyl) Complexes with Neutral N3 Donor Ligands". Organometallics. 24 (13): 3136–3148. doi:10.1021/om050209r.
  7. ↑ "Organometallic Reagents". Inorganic Syntheses. Vol. 35. 2010. p. 109. doi:10.1002/9780470651568.ch6. ISBN   978-0-471-68255-4.
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