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Chemicals from Olefin Hydrocarbons
Published in James G. Speight, Handbook of Petrochemical Processes, 2019
In the first half of the 20th century, acetylene was the most important of all starting materials for organic synthesis. Acetylene is a colorless, combustible gas with a distinctive odor. When acetylene is liquefied, compressed, heated, or mixed with air, it becomes highly explosive. As a result, special precautions are required during its production and handling. The most common use of acetylene is as a raw material for the production of various organic chemicals including 1,4-butanediol, which is widely used in the preparation of polyurethane and polyester plastics. The second most common use is as the fuel component in oxy-acetylene welding and metal cutting. Some commercially useful acetylene compounds include acetylene black, which is used in certain dry-cell batteries, and acetylenic alcohols, which are used in the synthesis of vitamins.
Fire Hazards of Materials and Their Control
Published in Peter M. Bochnak, Fire Loss Control, 2020
Acetylene is widely used as a raw material in the chemical industry in acetylenic chemistry and also in welding and cutting. Chemically pure acetylene is colorless and odorless, with an ignition temperature of 571°F (299°C), a wide flammable range of 2.5% to 81%, and a vapor density of 0.9. Decomposition of acetylene occurs at 15 psi without the presence of air, evolving hydrogen and carbon with explosive force if ignited. As a consequence, acetylene generators are operated at below this figure. The sensitivity of acetylene to explosion is resolved in cylinders by dissolving compressed acetylene in acetone with a special porous filler.
N-Heterocyclic carbene-Pd(II)-PPh3 complexes as a new highly efficient catalyst system for the Sonogashira cross-coupling reaction: Synthesis, characterization and biological activities
Published in Journal of Coordination Chemistry, 2018
L. Boubakri, L. Mansour, A. H. Harrath, I. Özdemir, S. Yaşar, N. Hamdi
We proposed a plausible mechanism for the copper-free Sonogashira cross-coupling reaction catalyzed by [Pd(NHC)(PPh3)] (3a–h). The Pd(0) species could be generated readily from the reaction of [Pd(NHC)(PPh3)] with solvents, substrates, etc. [54–56], followed by the oxidative addition of palladium(0) with arylbromides to form intermediate 1. The phenylacetylene is not able to deprotonate, therefore, the replacement between intermediate 1 and phenylacetylene occurred to afford intermediate 2. Furthermore, in this catalytic process, the base KOtBu abstracts the acetylenic proton of the terminal alkyne, thereby enhancing the coordination of phenylacetylene ligand to the metal and liberation of HBr [57]. Finally, the reductive elimination of intermediate 3 took place to regenerate the active Pd(0) species and give the desired product. The suggested mechanism according to the above explanations is shown in Scheme 3.
Performance, combustion and emission analysis of internal combustion engines fuelled with acetylene – a review
Published in International Journal of Ambient Energy, 2022
Sumit Sharma, Dilip Sharma, Shyam Lal Soni, Digambar Singh, Amit Jhalani
Acetylene is an explosive and colourless gas with a distinctive odour. As a result, special safeties are necessary during their production, handling, and burning. The generally acetylene has been used as a raw material for the production of various organic chemicals, which are widely used in the preparation of polyester and polyurethane plastics. It is being used as the fuel component in metal cutting and oxy-acetylene welding. Some commercially useful acetylene compounds such as acetylenic alcohols, which are used in the synthesis of vitamins and acetylene black, which is used in certain dry-cell batteries. Presently, acetylene is being used in I.C. Engines.
Pd@GO/Fe3O4/PAA/DCA: a novel magnetic heterogeneous catalyst for promoting the Sonogashira cross-coupling reaction
Published in Journal of Coordination Chemistry, 2019
Mansoureh Daraie, Majid M. Heravi, Shaghayegh Sadat Kazemi
A plausible reaction mechanism is proposed in Scheme 3. In accordance with this suggested mechanistic pathway, initially [Pd(0)L2] is oxidatively added to the aryl or vinyl halide. Then, a reversible coordination of the alkyne occurs, generating an alkyne–Pd(II) complex where the acetylenic proton is removed by the base along with coordination of the acetylene ligand to the metal. This [Pd(II)R1(C[tbond]CR2)L2] complex releases the cross-coupled product by reductive elimination regenerating the catalyst species [Pd(0)L2].