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

The correct title of this article is 1,8-Diazabicyclo[5.4.0]undec-7-ene. The substitution of any brackets is due to technical restrictions.

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
Preferred 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
EC Number	229-713-7
PubChem CID	81184
UNII	H1ILJ6IBUX
CompTox Dashboard (EPA)	DTXSID2049424
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	152.241 g·mol−1
Appearance	Colorless liquid
Density	1.018 g/mL liquid[citation needed]
Melting point	−70 °C (−94 °F; 203 K)
Boiling point	261 °C (502 °F; 534 K) (1 atm), 80 to 83 °C (0.6 mmHg)
Solubility in water	ethers, alcohols
Acidity (pKa)	13.5±1.5[1] (pKa of conjugate acid in water); 24.34[2] (pKa of conjugate acid in acetonitrile)
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H301, H302, H312, H314, H412
Precautionary statements	P260, P264, P270, P273, P280, P301+P310, P301+P312, P301+P330+P331, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, 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). Y verify (what is YN ?) Infobox references

Synthesis

DBU can be synthesised in three steps from caprolactam and acrylonitrile. First, the nitrile undergoes an addition reaction at the caprolactam nitrogen, producing N-(2-cyanoethyl)-caprolactam. This is then hydrogenated to N-aminopropyl-caprolactam, followed by an intramolecular carbonyl condensation to form the imine. Water is removed by fractional distillation.^[4]

Occurrence

Although all commercially available DBU is produced synthetically, it may also be isolated from the sea sponge Niphates digitalis.^[5] The biosynthesis of DBU has been proposed to begin with adipaldehyde and 1,3-diaminopropane.

Proposed pathway for the biosynthesis of DBU in sponges.^[5]

Applications

DBU is used:

• As a reagent in organic chemistry, where DBU is used as a ligand and base. As a base, protonation occurs at the imine nitrogen.^[6] Lewis acids also attach to the same nitrogen.^[7]
• As a catalyst, for example as a curing agent for epoxy resins and polyurethane.^{[citation needed]}
• In the separation of fullerenes in conjunction with trimethylbenzene. It reacts with C₇₀ and higher fullerenes, but not with C₆₀.
• As a dehydrohalogenation agent.^[8]
• In surface activation products (primers) for low-surface energy plastics and elastomers (such as PTFE, HDPE, PP, and silicone rubber), where DBU raises the surface energy enough for adhesives (such as cyanoacrylate and contact cement) to bond to these otherwise inert, non-stick materials.^[9]

See also

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