:1,8-Diazabicyclo(5.4.0)undec-7-ene
{{short description|Chemical compound}}
{{correct title|reason=bracket|title=1,8-Diazabicyclo[5.4.0]undec-7-ene}}
{{chembox
| Watchedfields = changed
| verifiedrevid = 477206737
| Name = 1,8-Diazabicyclo[5.4.0]undec-7-ene
| ImageFile = DBU.svg
| ImageName =
| ImageFile1 = DBU-3D-balls.png
| ImageAlt1 = DBU molecule
| PIN = 2,3,4,6,7,8,9,10-Octahydropyrimido[1,2-a]azepine
| OtherNames = DBU, Diazabicycloundecene
|Section1={{Chembox Identifiers
| SMILES = N\2=C1\N(CCCCC1)CCC/2
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 73246
| InChI = 1/C9H16N2/c1-2-5-9-10-6-4-8-11(9)7-3-1/h1-8H2
| InChIKey = GQHTUMJGOHRCHB-UHFFFAOYAM
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/C9H16N2/c1-2-5-9-10-6-4-8-11(9)7-3-1/h1-8H2
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = GQHTUMJGOHRCHB-UHFFFAOYSA-N
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo = 6674-22-2
| PubChem = 81184
| EC_number = 229-713-7
| UNII = H1ILJ6IBUX
| RTECS =
}}
|Section2={{Chembox Properties
| C=9|H=16|N=2
| Appearance = Colorless liquid
| Density = 1.018 g/mL liquid{{Citation needed|date=May 2025}}
| Solubility = ethers, alcohols
| MeltingPtC = -70
| BoilingPtC = 261
| BoilingPt_notes = (1 atm),
80 to 83 °C (0.6 mmHg)
| pKa = 13.5±1.5{{cite journal | author = Kaupmees, K. | author2 = Trummal, A. | author3 = Leito, I. | title = Basicities of Strong Bases in Water: A Computational Study | journal = Croat. Chem. Acta | year = 2014 | volume = 87 | issue = 4 | pages = 385–395 | doi = 10.5562/cca2472 | doi-access = free }} (pK{{sub|a}} of conjugate acid in water); 24.34{{cite journal | author = Kaljurand, I. | author2 = Kütt, A. | author3 = Sooväli, L. | author4 = Rodima, T. | author5 = Mäemets, V. | author6 = Leito, I. | author7 = Koppel, I. A. | title = Extension of the Self-Consistent Spectrophotometric Basicity Scale in Acetonitrile to a Full Span of 28 pKa Units: Unification of Different Basicity Scales | journal = J. Org. Chem. | year = 2005 | volume = 70 | issue = 3 | pages = 1019–1028 | doi = 10.1021/jo048252w | pmid=15675863}} (pK{{sub|a}} of conjugate acid in acetonitrile)
| Viscosity =
}}
|Section7={{Chembox Hazards
| ExternalSDS =
| MainHazards =
| FlashPtC = 119.9
| GHSPictograms = {{GHS05}}{{GHS06}}{{GHS07}}
| GHSSignalWord = Danger
| HPhrases = {{H-phrases|301|302|312|314|412}}
| PPhrases = {{P-phrases|260|264|270|273|280|301+310|301+312|301+330+331|302+352|303+361+353|304+340|305+351+338|310|312|321|322|330|363|405|501}}
}}
|Section8={{Chembox Related
| OtherCompounds =
}}
}}
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.{{cite journal|doi=10.1055/s-2004-815436|title=DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) - A Nucleophillic Base|journal=Synlett|issue=3|pages=574–575|year=2004|last1=Ghosh|first1=Nandita|doi-access=free}}
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.{{cite patent|country=CN|number=101279973|status=patent|title=Preparation of 1,8-diazabicyclo[5.4.0]undec-7-ene|inventor=Bi Zuowen, Gao Hongbin, Cao Hongbo, Wang Xiaomei, Liu Change, Xu Qin, Zhang Zonghua|assign=Shandong Xinhua Wanbo Chemical|gdate=2010-06-02}}
Occurrence
Although all commercially available DBU is produced synthetically, it may also be isolated from the sea sponge Niphates digitalis.{{cite journal|author1=E. L. Regalado|author2=Judith Mendiola|author3=Abilio Laguna|author4=Clara Nogueiras|author5=Olivier P Thomas|journal=Nat. Prod. Commun.|year=2010|volume=5|title=Polar alkaloids from the Caribbean marine sponge Niphates digitalis|issue=8 |pages=1187–1190 |pmid= 20839615}} 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.{{cite journal | last1=Parviainen | first1=Arno | last2=King | first2=Alistair W. T. | last3=Mutikainen | first3=Ilpo | last4=Hummel | first4=Michael | last5=Selg | first5=Christoph | last6=Hauru | first6=Lauri K. J. | last7=Sixta | first7=Herbert | last8=Kilpeläinen | first8=Ilkka | title=Predicting Cellulose Solvating Capabilities of Acid–Base Conjugate Ionic Liquids | journal=ChemSusChem | volume=6 | issue=11 | date=2013 | issn=1864-5631 | doi=10.1002/cssc.201300143 | pages=2161–2169| pmid=24106149 | bibcode=2013ChSCh...6.2161P }} Lewis acids also attach to the same nitrogen.{{cite journal | last1=Romero | first1=Erik A. | last2=Zhao | first2=Tianxiang | last3=Nakano | first3=Ryo | last4=Hu | first4=Xingbang | last5=Wu | first5=Youting | last6=Jazzar | first6=Rodolphe | last7=Bertrand | first7=Guy | title=Tandem copper hydride–Lewis pair catalysed reduction of carbon dioxide into formate with dihydrogen | journal=Nature Catalysis | volume=1 | issue=10 | date=2018-10-01 | issn=2520-1158 | doi=10.1038/s41929-018-0140-3 | pages=743–747}}
- As a catalyst, for example as a curing agent for epoxy resins and polyurethane.{{citation needed|date=May 2025}}
- In the separation of fullerenes in conjunction with trimethylbenzene. It reacts with C70 and higher fullerenes, but not with C60.
- As a dehydrohalogenation agent.{{cite book |doi=10.1002/047084289X.rd011.pub2 |chapter=1,8-Diazabicyclo[5.4.0]undec-7-ene |title=Encyclopedia of Reagents for Organic Synthesis |date=2006 |last1=Savoca |first1=Ann C. |last2=Urgaonkar |first2=Sameer |isbn=0-471-93623-5 }}
- 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.{{Cite web |date=2022 |title=Novatio Silfix Primer SDS |url=https://novatio.com/storage/files/87eab6b0-ac1a-4e81-87d8-af8743c9fd11/silfix-primer-sds-en-220714.pdf |archive-url=https://web.archive.org/web/20250516111927/https://novatio.com/storage/files/87eab6b0-ac1a-4e81-87d8-af8743c9fd11/silfix-primer-sds-en-220714.pdf |archive-date=2025-05-16 |access-date=2025-05-16 |website=novatio.com |language=}}