ChemInform Abstract: Pyrroles from Ketoximes and Acetylene. Part 39. Influence of the Nature of the Alkali Metal Cation and the Solvent on the Reaction Rate in the System MOH‐DMSO.
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Abstract The reaction of acetophenone oxime (I) with acetylene (II) in an alkaline medium to give 2‐phenylpyrrole (III) and 2‐phenyl‐1‐vinylpyrrole (IV) is studied in detail.Keywords:
Acetylene
Pentoxide
Vanadium Oxide
Alkaline earth metal
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An infrared study of adsorbed acetylenes has revealed several features of the nature and orientation of the adsorbed species. Acetylene, deuteroacetylene, methyl acetylene, and dimethyl acetylene are strongly chemisorbed at room temperature on alumina. Weak chemisorption also occurs with acetylene, deuteroacetylene, and methyl acetylene. The strongly held acetylene is held normal to the surface, while the weakly held acetylene is held parallel to the surface. Similar effects occur with methyl acetylene, all of the strongly held molecules being attached to the surface by the acetylenic end. Both the strongly and weakly adsorbed dimethyl acetylene is adsorbed parallel to the surface. The sites responsible for the strong chemisorption of dimethyl acetylene are different from those active in the strong chemisorption of acetylene. With silica, no strong chemisorption occurred at room temperature for either acetylene or dimethyl acetylene. For both adsorbents, the interaction between the OD (and OH) groups of the surface and the adsorbates has been studied. Exchange takes place between the highest frequency OH groups on alumina and the strongly adsorbed C2D2. An OD group at the expected frequency was observed after the exchange had taken place. The remaining two types of OH groups on alumina did not appear to interact with the strongly held species, but only with the weakly held species. With dimethyl acetylene, the silica OD groups interacted to much the same degree as did the two lower frequency alumina OD groups.
Acetylene
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1) The catalytic hydrogenation of acetylene was investigated by Pd-Alumina under various conditions. 2) The hydrogenation of acetylene proceeds in two distinct steps. The first step consists of the reduction and polymerization of acetylene, and the second step the reduction of ethylene to ethane. The second reaction starts after all of the acetylene is reduced to ethylene, and is indicated by a sudden increase in the rate of hydrogenation. 3) The results indicate that acetylene is strongly adsorbed on the surface of the catalyst and the inhibition of the hydrogenation by acetylene is pronounced. 4) It was found that the final products of the hydrogenation can be made wholly into ethylene or ethane and that the highest yield of ethylene is obtained possibly, when acetylene content is small, by avoiding the polymerization of acetylene.
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A pilot plant was launched and the modes of acetylene hydrogenation on cobalt catalysts were worked out. It has been found that the modified 7% Co/ SiAl cobalt catalyst is active in the process of hydrogenating acetylene into ethylene. Optimal conditions of acetylene hydrogenation on 7% Co/ SiAl catalyst were determined. The effects of temperature, space velocity and the ratio of initial components in the hydrogenation of acetylene to ethylene were investigated. The textural characteristics of cobalt catalysts before and after the hydrogenation of acetylene were investigated by the SEM method. The structure of cobalt catalysts after the hydrogenation of acetylene does not lose catalytic activity and selectivity. It has been found that catalyst samples have channels of different sizes, flaky particles and fibers located in the gaps between large aggregates are also present on the surface. The optimum temperature was 180 ° C in the hydrogenation of acetylene into ethylene at conversion 73.0%. Conversion of acetylene increases to 81.2% when temperature rises to 200°C, acetylene conversion decreases to 68% with further temperature exceeding to 220°C. Acetylene conversion again increases from 68 to 73.6% at 140°C in the ratio of acetylene to hydrogen 1:2. The selectivity of the catalyst 7%Co/SiAl to ethylene was studied depending on the temperature in the acetylene hydrogenation reaction. The selectivity to ethylene decreases with increasing temperature, since an increase in temperature activates side reactions.
Acetylene
Space velocity
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The purification process of acetylene and the principle of removing methyl acetylene, 1,3-butadiene, allene and other higher alkynes from acetylene were introduced, and the factors influencing the purification process were analyzed. Based on the analysis, the measures for controlling the level of higher alkynes in acetylene were proposed and implemented, which ensured that the acetylene purification unit could run in high load, long period and stable operation.
Acetylene
Allene
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Acetylene
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Alkaline earth metal
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Acetylene
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Journal of the Chemical Society Faraday Transactions 1 Physical Chemistry in Condensed Phases (1977)
Studies have been made of the kinetics of the hydrogenation of mixtures containing 2 % of acetylene in ethylene on an alumina supported palladium catalyst in a static system. Information has been obtained about the nature of the selectivity of the reaction of acetylene. Detailed analyses of the kinetics have been made as the ratio of the pressure of acetylene to ethylene decreases and subsequently as the remaining hydrogen is used up.The poisoning action of carbon monoxide, which selectively inhibits the hydrogenation of ethylene, has also been studied.Tracer studies using carbon-13 labelled acetylene, light ethylene and hydrogen with analysis by combined gas chromatography-mass spectrometry, have shown unambiguously that ethane produced from the hydrogenation of a mixture of acetylene in ethylene comes predominantly from the ethylene.The reaction between acetylene, ethylene and deuterium gives a greater understanding of the surface processes involved and produces ethane which is mainly [2H2]ethane.It is postulated that two types of site exist on the surface, type X which hydrogenates both acetylene and ethylene and on which acetylene is adsorbed ∼2200 times more strongly than ethylene at 293 K and type Y which is easily poisoned by carbon monoxide and can hydrogenate ethylene even in the presence of acetylene.
Acetylene
Palladium catalyst
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Brønsted–Lowry acid–base theory
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