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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 ]
The table is color-coded to show the chemical groupings. Small symbols pack in additional information: solid/liquid/gas, the color of an element, common in the human body, common in the earth's crust, magnetic metals, noble metals, radioactive, and rare or never found in nature.
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.
For example, an UAA with an azide side group provides convenient access for cycloalkynes to proteins tagged with this "AHA" unnatural amino acid. [54] In another example, "CpK" has a side group including a cyclopropane alpha to an amide bond that serves as a reaction partner to tetrazine in an inverse diels-alder reaction. [55]
The Sandmeyer reaction is an example of a radical-nucleophilic aromatic substitution (S RN Ar). The radical mechanism of the Sandmeyer reaction is supported by the detection of biaryl byproducts. [8]
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]
It is a member of the diyne chemical class and can be made via the Glaser coupling of phenylacetylene [2] However, a variety of other synthesis methods have been developed. [3] [4] Diphenylbutadiyne forms a variety of metal-alkyne complexes. One example is the organonickel complex (C 5 H 5 Ni) 4 C 4 (C 6 H 5) 2. [5]
These reactions invariably involve metal-acetylide intermediates. This reaction was discovered by chemist John Ulric Nef in 1899 while experimenting with reactions of elemental sodium, phenylacetylene, and acetophenone. [3] [4] For this reason, the reaction is sometimes referred to as Nef synthesis.