Article

Abstract

The formate ester of benzoin (1) and the methyl ethers of benzoin and anisoin (2, 3) have been converted separately under thermal gas-phase conditions cleanly into 1,2-diarylethanone and have given, respectively, the following Arrhenius log A (s -1 ) and E a (kJ mol -1 ): 10.11 and 132.0, 11.29 and 173.0, and 11.85 and 151.1. A plausible mechanism is suggested to account for these transformations based on the kinetics and products of reaction.Résumé : Opérant en phase gazeuse thermique, on a transformé proprement l'ester formique de la benzoïne (1) ainsi que les éthers méthyliques de la benzoïne et de l'anisoïne (2 et 3) en 1,2-diaryléthanones; les valeurs pour le log A d'Arrhenius (s -1 ) et pour E a (kJ mol -1 ) sont respectivement les suivantes: 10,11 et 132,0; 11,29 et 173,0; 11,85 et 151,1. Pour expliquer ces transformations, on suggère un mécanisme plausible qui tient compte de la cinétique et de la nature des produits formés.

Kinetics and mechanism of gas‐phase pyrolysis of N‐aryl‐3‐oxobutanamide ketoanilides, their 2‐arylhydrazono derivatives, and related compounds

“…The kinetic data on the pyrolysis of compounds (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14) are summarized in Table I. The reactions followed first-order kinetics.…”

“…The coefficients for these two correlations are 0.99 and 1.00, respectively. To facilitate comparison, the rate constants (k, s −1 ) of thermolysis at 450 K of compounds (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14) are compiled in Figure 2. The figure also includes the rate constants at 600 K reported earlier for six related diketone and cyano analogues (15)(16)(17)(18)(19)(20) [2,16].…”

“…2). The substi-tuted 2-arylhydrazono ketoanilides (5)(6)(7)(8) are less reactive than the unsubstituted analogues (1-4) by factors ≥1.4 × 10 3 . Unsubstituted pentane-2,4-dione (15) is, on the other hand, ca.…”

Gas‐phase elimination reactions of 4‐arylideneimino‐2‐cyanoethyl‐1,2,4‐triazol‐3(2H)‐ones, their thione analogues and 2‐glucosyl‐1,2,4‐triazole‐3(2H)‐thiones: a kinetic and mechanistic study

“…Electrophilic substitutions of asymmetric heterocyclic urea and thiourea derivatives [represented here by 1,2,4-triazol-3(2H)-ones and their thione derivatives] are known to give mixtures of different regioisomeric products. 2 This usually leads to tedious separation and identification. Therefore, we were interested in gaining a detailed understanding of the kinetics and thermal behavior of 2-substituted 1,2,4triazol-3(4H)-ones and their thiones as potential starting material for the protection of N-2 in these triazoles in order to assist in regioselective substitution at other nitrogen sites in the ring.…”

Gas-phase pyrolysis of 2-heteroaromatic-1-dimethylaminoethylenes: Kinetic and mechanistic study

“…In conjunction with our recent interest in adopting the environmentally friendly gas-phase technique in synthetic organic chemistry, we have previously reported on the utility of this technique for synthesis of substituted nitriles [6,7], ketones [8], and functionally substituted heteroaromatics. In the present article we report results of our efforts aimed at utilizing the same technique for syntheses of condensed pyridines utilizing the readily obtainable compounds (1-6) as starting materials [9] (See Scheme 1 for compound structures).…”