Send Orders for Reprints to reprints@benthamscience.ae Current Organocatalysis, 2018, 5, 1-11 1 RESEARCH ARTICLE 2213-3372/18 $58.00+.00 © 2018 Bentham Science Publishers Kinetics and a Mechanistic Elucidation of Triphenylarsine as a Catalyst on One-Pot Reaction for the Formation of Dialkyl-2(2- Oxobenzo [d] Oxazol- 3(2H)- yl) Fumarate Marjan Hashemi-Shahri, Sayyed Mostafa Habibi-Khorassani and Mehdi Shahraki * Department of Chemistry, Faculty of Science, University of Sistan and Baluchestan, P.O. Box 98135-674, Zahedan, Iran Abstract: Background: Phosphorus ylides have less nucleophilic and are more stable than arsenic ylides. Due to less interactions of p-carbon orbital with d-arsenic orbital, arsenic ylides react more than phosphorus ylides in the same reactions. Kinetics and a mechanistic investigation of many reac- tions with TPP have been reported earlier. Herein, we have reported the kinetic results obtained by UV-vis spectrophotometry technique from the reactions between dialkyl acetylenedicarboxylate (DMAD, DEAD and DTAD), triphenylarsine (TPA) as a catalyst and N-H heterocyclic compounds. Methods: A kinetic study was followed for the present reaction using the UV-vis spectrophotometry method. 0.3 mL aliquot of 10 -2 M solution of reactants 1 and 3 were pipetted into a quartz spectropho- tometer cell, then 0.3 mL aliquot of 5×10 -2 M solution of reactant 2 was added to the mixture accord- ing to the stoichiometry of each reactant in the overall reaction. During the whole reaction time, the reaction was supervised by recording scans of the entire spectra at 25 °C. The wavelength of 290 nm was chosen to follow the kinetics studies. Results: The reaction followed second-order kinetics and the partial order with respect to dialkyl acethylenedicarboxylates 1 and N-H heterocycle 3 compounds was one and one. . The fourth step (k4) of the proposed mechanism was recognized as the rate-determining step. This is logical, because in step4 (k4), a tiny protic solvent such as methanol is able to rapid the rate of proton-transfer through a hard non- linear arrangement of TS4 from C1 towards C2. Both steric and inductive effects of differ- ent alkyl groups within the structure of dialkyl acetylenedicarboxylates (which participate in the first step1 (k1) of the reaction mechanism) had a significant role on the reduction of the reaction rate, be- cause kobs depends on (k1). Conclusion: An electron withdrawing substituent group on the second ring of 5-chloro-2- benzoxazolinione speeds up the rate of reaction, opposite the way of 2-benzoxazolinione alone. The magnitude of ∆H ǂ is larger than T∆S ǂ , so the reactions are enthalpy- controlled. The large and very positive values of ∆S ǂ imply that all reactions have dissociative process. In the case of triphenylarsine (TPA), kinetics and reaction mechanism was different from triphenylphosphine (TPP) in a similar re- actions. A R T I C L E H I S T O R Y Received: April 14, 2018 Revised: July 13, 2018 Accepted: August 01, 2018 DOI: 10.2174/2213337205666180807102109 Keywords: Dialkyl acetylenedicarboxylates derivative, kinetics, mechanism, N-H heterocycle compound, triphenylarsine. 1. INTRODUCTION The compounds containing a N-vinyl group are interesting intermediates for various transformations. These are important bulding blocks in the synthesis of polymers [1, 2], natural product analogs [3], catalysts, ion- exchangers, polymeric dyes [4], agriculture chemicals and pharmaceutics [5], which have applications in metal separation and polar compound extraction [6]. 2-Benzoxazolinone (I) is a heterocyclic *Address correspondence to this author at the Department of Chemistry, Faculty of Science, University of Sistan and Baluchestan, P.O. Box 98135- 674, Zahedan, Iran; Tel: +989155413826; E-mail: mehdishahraki@chem.usb.ac.ir compound comprised of a benzene ring which is fused to a five- membered ring containing oxygen and nitrogen as the hetro atoms. The numbering of 2-benzoxazolinone is derived from the parent benzoxazole which is shown as the following structure (II). Prior to 1936, chemical abstracts employed the numbering system shown as structure (III). Under this system, structure (I) was referred to as benzoxazolone rather than as 1-benzoxazolinone. Frequently, in chemical literature which originated before 1900, O-oxycarbanil and carbonyl- O-aminophenol were used to designate (I). Benzoxazolinones have been investigated extensively primarily for their medi- cinal value as central nervous system (CNS) depressants which exhibit analgesic, antipyretic [7-13], anticonvulsant [14], hypnotic, curdiotonic [15, 16], antiulcer [17], antineo-