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Phenylacetylene is a prototypical terminal acetylene, undergoing many reactions expected of that functional group. It undergoes semi hydrogenation over Lindlar catalyst to give styrene . In the presence of base and copper(II) salts, it undergoes oxidative coupling to give diphenylbutadiyne . [ 6 ]
It is advised to check the references for photos of reaction results. [1] Reagent testers might show the colour of the desired substance while not showing a different colour for a more dangerous additive. [ 2 ]
Hofmann Isonitrile synthesis, Carbylamine reaction; Hofmann product; Hofmann rearrangement; Hofmann–Löffler reaction, Löffler–Freytag reaction, Hofmann–Löffler–Freytag reaction; Hofmann–Martius rearrangement; Hofmann's rule; Hofmann–Sand reaction; Homo rearrangement of steroids; Hooker reaction; Horner–Wadsworth–Emmons ...
Yet another method involves the coupling of iodobenzene and the copper salt of phenylacetylene in the Castro-Stephens coupling. The related Sonogashira coupling involves the coupling of iodobenzene and phenylacetylene. Diphenylacetylene is a planar molecule. The central C≡C distance is 119.8 picometers. [1]
The Hay coupling is variant of the Glaser coupling. It relies on the TMEDA complex of copper(I) chloride to activate the terminal alkyne. Oxygen (air) is used in the Hay variant to oxidize catalytic amounts of Cu(I) to Cu(II) throughout the reaction, as opposed to a stoichiometric amount of Cu(II) used in the Eglington variant. [7]
An alkyne trimerisation is a [2+2+2] cycloaddition reaction in which three alkyne units (C≡C) react to form a benzene ring. The reaction requires a metal catalyst. The process is of historic interest as well as being applicable to organic synthesis. [1] Being a cycloaddition reaction, it has high atom economy.
Figure 6:Reaction Coordinate Diagrams showing reactions with 0, 1 and 2 intermediates: The double-headed arrow shows the first, second and third step in each reaction coordinate diagram. In all three of these reactions the first step is the slow step because the activation energy from the reactants to the transition state is the highest.
Phenylacetylene was proven to form Pd monoacetylide complex D as well as Pd bisacetylide complex F under mild reaction conditions. Both activated species, namely complexes B and F , are involved in the transmetallation step, forming complex C and regenerating D .