1,8-Diazabicyclo(5.4.0)undec-7-ene

1,8-Diazabicyclo[5.4.0]undec-7-ene, or more commonly DBU, is a chemical compound and belongs to the class of amidine compounds. It is used in organic synthesis as a catalyst, a complexing ligand, and a non-nucleophilic base.[3]

1,8-Diazabicyclo[5.4.0]undec-7-ene
Names
IUPAC name
2,3,4,6,7,8,9,10-octahydropyrimido[1,2-a]azepine
Other names
DBU,Diazabicycloundecene
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.027.013
EC Number
  • 229-713-7
UNII
Properties
C9H16N2
Molar mass 152.241 g·mol−1
Appearance Colorless liquid
Density 1.018 g/mL liquid
Melting point −70 °C (−94 °F; 203 K)
Boiling point 80 to 83 °C (176 to 181 °F; 353 to 356 K) (0.6 mmHg); 261 °C (1 atm)
Acidity (pKa) 13.5±1.5[1] (pKa of conjugate acid in water); 24.34[2] (pKa of conjugate acid in acetonitrile)
Hazards
GHS pictograms
GHS Signal word Danger
H301, H302, H312, H314, H318, H412
P260, P264, P270, P273, P280, P301+310, P301+312, P301+330+331, P302+352, P303+361+353, P304+340, P305+351+338, P310, P312, P321, P322, P330, P363, P405, P501
Flash point 119.9 °C (247.8 °F; 393.0 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Occurrence

Although all commercially available DBU is produced synthetically, it can also be isolated from the sea sponge Niphates digitalis.[4] The biosynthesis of DBU has been proposed to begin with 1,6-hexanedial and 1,3-diaminopropane.[4]

Hypothetical pathway of DBU production in sponges

Uses

As a reagent in organic chemistry, DBU is used as a catalyst, a complexing ligand, and a non-nucleophilic base. It is also used as a curing agent for epoxy. It is used in fullerene purification with trimethylbenzene (it reacts with C70 and higher fullerenes, but not to C60 fullerenes); and it is also used as a catalyst in polyurethane production. It has a strong catalyst effect for the reactions of alicyclic and aliphatic isocyanates. It also exhibited its dual character (base and nucleophile) in the synthesis of aryl- and styryl-terminal acetylenes.

See also

References
  1. Kaupmees, K.; Trummal, A.; Leito, I. (2014). "Basicities of Strong Bases in Water: A Computational Study". Croat. Chem. Acta. 87 (4): 385–395. doi:10.5562/cca2472.
  2. Kaljurand, I.; Kütt, A.; Sooväli, L.; Rodima, T.; Mäemets, V.; Leito, I.; Koppel, I. A. (2005). "Extension of the Self-Consistent Spectrophotometric Basicity Scale in Acetonitrile to a Full Span of 28 pKa Units: Unification of Different Basicity Scales". J. Org. Chem. 70 (3): 1019–1028. doi:10.1021/jo048252w. PMID 15675863.
  3. Ghosh, Nandita (2004). "DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) - A Nucleophillic Base". Synlett (3): 574–575. doi:10.1055/s-2004-815436.
  4. Regalado, E.L. et al., Nat. Prod. Commun., 2010, 5, 1187- 1190
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