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

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
CAS Number	6674-22-2 Y
3D model (JSmol)	Interactive image
ChemSpider	73246 Y
ECHA InfoCard	100.027.013
InChI InChI=1S/C9H16N2/c1-2-5-9-10-6-4-8-11(9)7-3-1/h1-8H2 Y Key: GQHTUMJGOHRCHB-UHFFFAOYSA-N Y InChI=1/C9H16N2/c1-2-5-9-10-6-4-8-11(9)7-3-1/h1-8H2 Key: GQHTUMJGOHRCHB-UHFFFAOYAM
SMILES N\2=C1\N(CCCCC1)CCC/2
Properties
Chemical formula	C9H16N2
Molar mass	152.24 g/mol
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
R-phrases (outdated)	R22 R34
S-phrases (outdated)	S24 S25
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

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.

Occurrence

Although all DBU is produced synthetically, it can also be isolated from the sea sponge Niphates digitalis.^[3] The biosynthesis of DBU has been proposed to begin with 1,8-octanedial (suberic aldehyde) and 1,3-diaminopropane.^[3]

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- & styryl- terminal acetylenes.

See also

• 1,5-Diazabicyclo[4.3.0]non-5-ene
• DABCO

References

1. ↑ Kaupmees, K.; Trummal, A.; Leito, I. (2014). "Basicities of Strong Bases in Water: A Computational Study". Croat. Chem. Acta. 87: 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: 1019–1028. PMID 15675863. doi:10.1021/jo048252w. 
3. 1 2 Regalado, E.L. et al., Nat. Prod. Commun., 2010, 5, 1187- 1190