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Kinetic and Mechanistic Insights into the Pathway Leading to Cyclic Crystalline Phosphorus Ylide Formation in the Presence of 3-Chloropentane-2,4-dione: Theoretical and Stopped-Flow Approaches

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  • Contract grant sponsor: University of Sistan and Baluchestan.

  • Supporting Information is available in the online issue at www.wileyonlinelibrary.com.

Correspondence to: Sayyed Mostafa Habibi-Khorassani; e-mail: smhabibikhorassani@yahoo.com.

ABSTRACT

In this work, three speculative mechanisms of the reaction between triphenylphosphine and dimethyl acetylendicarboxylate in the presence of 3-chloropentane-2,4-dione were energetically and thermodynamically developed using quantum mechanical calculations and were profoundly compared with stopped-flow and UV spectrophotometry approaches. The third speculative mechanism that led to the five-membered ring structure was experimentally and theoretically favorable. The five-membered ring structure of product was characterized by X-ray crystallographic data. Also, steps 1 and 2 of the third mechanism were determined as fast and rate-determining steps, respectively. The experimental kinetic evidence of the formation and decay of intermediate in steps 1 and 2 (fast and rate-determining steps, respectively) was compatible with theoretical data. Experimental kinetic data were recognized for overall reaction along with activation parameters for fast and rate-determining steps of the reaction. Theoretical kinetic data (k and Ea) and activation parameters (ΔG, ΔS, and ΔH) were calculated for each step and overall reactions.

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