What Is Eglinton Coupling Reaction?
The oxidative coupling reaction of terminal alkynes in pyridine in the presence of stoichiometric copper (II) salts is used to synthesize symmetrical and cyclic diynes. Related reactions are Glaser coupling, Hay coupling (using catalytic copper salts) and Cadiot-Chodkiewicz coupling (synthesis of asymmetrical diynes). The reaction conditions of Glaser coupling require that the generated copper acetylene intermediate must be oxidized with oxygen to obtain the desired product. Eglinton coupling is one of the improved methods for this harsh condition.
Copper (II) salts are used in the reaction instead of copper (I) salts, such as copper acetate. And the copper salt is quantitative and non-catalytic, so it is no longer necessary to re-oxidize with oxygen. The base is mostly pyridine or other nitrogen-containing organic bases.
Fig 1. Eglinton coupling reaction and its mechanism. [1]
Application Examples of Eglinton Coupling
- Example 1: Jiaqiang Li et al. used the Eglinton coupling reaction template to achieve the synthesis of ultra-thin β-graphene (β-GDY)-like films, which is a promising material for electronic device applications. In detail, the monomer tetraethynylethylene (TEE) is added to a reactor containing dichloromethane (DCM), pyridine, toluene, copper acetate (Cu(OAc)2) and single-layer graphene (SLG) supported on a SiO2/Si plate. The four terminal acetylenic groups on TEE are highly reactive and easily chemically coupled with each other to form a uniform carbon network structure on the graphene surface, thereby obtaining a carbon film containing β-GDY with a thickness of about 1.5 nm on the SiO2/Si substrate. [2]
- Example 2: Yoshito Tobe et al. reported a facile intramolecular cyclization method in the oxidative coupling of alkynes at the 1,3 positions of the benzene ring. Specifically, the oxidative coupling of ethynyl propylene to the 1,3,5 positions of the benzene nucleus 3b did not give a cage-like dimer 2, but instead gave a dimer 4 with a strained [1 2] metacyclic aromatic diphenyl tetrayne system. [3]
Fig 2. Synthetic examples via Eglinton coupling reaction.
Related Products
| CAS No. | Structure | Product | Inquiry |
| 142-30-3 |  | 2,5-Dimethyl-3-hexyne-2,5-diol | Inquiry |
| 1002-28-4 |  | 3-Hexyn-1-ol | Inquiry |
| 78628-80-5 |  | Terbinafine hydrochloride | Inquiry |
| 126764-17-8 |  | 1-Chloro-6,6-dimethyl-5-hept-2-en-4-ino | Inquiry |
| 55314-57-3 |  | ETHYL 2-PENTYNOATE | Inquiry |
| 622-76-4 |  | 1-Phenyl-1-butyne | Inquiry |
| 14916-80-4 |  | 3-Octyn-1-ol | Inquiry |
| 5663-96-7 |  | 2-Octynoic acid | Inquiry |
| 287471-30-1 |  | 1-Chloro-6,6-dimethyl-2-hepten-4-yne | Inquiry |
| 5963-77-9 |  | 2-Pentynoic acid | Inquiry |
| 764-60-3 |  | 2-Hexyn-1-ol | Inquiry |
| 78629-20-6 |  | 3-Hydroxy-6,6-Dimethyl-1-Heptene-4-Yne | Inquiry |
References
- Eglinton, G. et al. Proc. Chem. Soc. 1957,350.
- Li, Jiaqiang, et al. ACS applied materials & interfaces, 2018, 11(3), 2734-2739.
- Tobe, Yoshito, et al. The Journal of Organic Chemistry, 2003, 68(8), 3330-3332.
