1,8-Diazabicyclo(5.4.0)undec-7-ene
Chemical compound
From Wikipedia, the free encyclopedia
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]
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| Names | |
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| Preferred IUPAC name
2,3,4,6,7,8,9,10-Octahydropyrimido[1,2-a]azepine | |
| Other names
DBU, Diazabicycloundecene | |
| Identifiers | |
3D model (JSmol) |
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| ChemSpider | |
| ECHA InfoCard | 100.027.013 |
| EC Number |
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PubChem CID |
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| UNII | |
CompTox Dashboard (EPA) |
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| Properties | |
| C9H16N2 | |
| Molar mass | 152.241 g·molâ1 |
| Appearance | Colorless liquid |
| Density | 1.018 g/mL liquid[citation needed] |
| Melting point | â70 °C (â94 °F; 203 K) |
| Boiling point | 261 °C (502 °F; 534 K) (1 atm), 80 to 83 °C (0.6 mmHg) |
| 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: | |
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| Danger | |
| H301, H302, H312, H314, H412 | |
| 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).
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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.
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.[citation needed]
- 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]