Eglinton Reaction
The Eglinton reaction, named after Geoffrey Eglinton, is a type of coupling reaction in organic chemistry. It involves the oxidative dimerization of terminal acetylene moieties, typically mediated by a copper(II) salt such as cupric acetate (Cu(OAc)2)[1][2][6]. This reaction is a variant of the Glaser coupling reaction[1][6].
The general process of the Eglinton reaction can be described as follows:
- The terminal alkyne is deprotonated and then oxidized by copper(II) to form the alkynyl copper species[4].
- Two terminal alkynes are coupled together in the presence of the copper(II) salt[1].
The reaction is usually fast, clean, and tolerates mild reaction conditions. The solvent of choice is typically a 1:1 methanolic pyridine mixture, but other solvents can also be used[4].
The Eglinton reaction has been widely employed in the synthesis of cyclic compounds and other complex organic molecules[4]. For example, in 1882, Adolf von Baeyer used the method to prepare 1,4-bis(2-nitrophenyl)butadiyne, en route to indigo dye[1].
Despite its wide use, the exact mechanism governing this reaction is not completely understood[4].
Citations:
[1] https://en.wikipedia.org/wiki/Glaser_coupling
[2] https://www.sciencedirect.com/topics/chemistry/eglinton-coupling
[3] https://www.youtube.com/watch?v=QeTblcpAVO4
[4] https://diposit.ub.edu/dspace/bitstream/2445/170586/1/667369.pdf
[5] https://www.youtube.com/watch?v=w8NYkwk4pvY
[6] https://link.springer.com/chapter/10.1007/978-3-662-05336-2_97