Kinetics and mechanism of gas‐phase pyrolysis of ylides. Part 3.1 Thermal reactivity of α‐carbonyl‐ and thiocarbonyl‐stabilized methylenetriphenylphosphoranes |
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Authors: | Rasha F Al‐Bashir Nouria A Al‐Awadi Osman M E El‐Dusouqui |
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Institution: | 1. Applied Science Department, College of Technological Studies, Public Authority for Applied Education and Training, Kuwait;2. Chemistry Department, Kuwait University, Safat 13060, Kuwait |
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Abstract: | Fourteen ketone/thione‐stabilized triphenylphosphonium methylides were subjected to conventional gas‐phase and flash vacuum pyrolysis (FVP). The kinetics of the first‐order thermal gas‐phase reactions of all these compounds were investigated over 360–653 K temperature range. The values of the Arrhenius log A and energy of activation of these ylides averaged 11.52 ± 0.34 s?1 and 133.20 ± 3.14 kJ mol?1, respectively. The products of sealed‐tube (static) and FVP were analyzed and compared. A mechanism is proposed to account for the products of reaction. The rate constants k (s?1)] of the substrates at 500 K were calculated and used to substantiate the proposed mechanism of pyrolysis, and to rationalize the thermal gas‐phase reactivities of the ylides under study. Copyright © 2010 John Wiley & Sons, Ltd. |
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Keywords: | gas‐phase kinetics mechanism pyrolysis ylides |
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