Dual Pathways in the Solvolyses of Phenyl Chlorothioformate

Evaluation of Electronic Effects in the Solvolyses of p‐Methylphenyl and p‐Chlorophenyl Chlorothionoformate Esters

“…In 100% EtOH at 25.0 °C, the rates of solvolysis for substrates 1-8 are 3.15 ± 0.04 × 10 -5 s -1 [27], 260 ± 3 × 10 -5 s -1 [25], 1.00 ± 0.02 × 10 -5 s -1 [27], 6.73 ± 0.15 × 10 -5 s -1 [28], 1740 × 10 -5 s -1 (estimated from specific rates at lower temperature) [49], 1.51 ± 0.17 × 10 -5 s -1 , 15.9 ± 1.0 × 10 -5 s -1 , and 11.9 ± 1.1 × 10 -5 s -1 [40], respectively. For compounds 1-5 and 8 , a tetrahedral A-E transition state is proposed for their ethanolyses [25,27,28,40,49].…”

“…For compounds 1-5 and 8 , a tetrahedral A-E transition state is proposed for their ethanolyses [25,27,28,40,49]. The rate order in pure ethanol of k 5 ≫ k 2 ≫ k 7 > k 8 > k 4 > k 1 > k 6 > k 3 reveals that the rate of the dithio ester is the slowest.…”

“…We compare the experimental rate data of 6 and 7 and their correlation results obtained using the two-term Grunwald-Winstein equation (equation 1) to those previously published [9, 25-28, 40, 49-51] for compounds 1-5 and 8 .…”

“…For 4 in the more nucleophilic solvents we obtained [28] l = 1.74, m = 0.48, l/m = 3.63, and, l =0.62, m = 0.92, and l/m = 0.67 in the highly ionizing fluoroalcohol mixtures. On the other hand, for PhOCSCl ( 1 ), an l value of 1.88, an m value of 0.56, and an l/m ratio of 3.36 was obtained [26,27] in nucleophilic solvents favoring the stepwise addition-elimination pathway (Scheme 1), and an l value of 0.34, an m value of 0.93 and an l/m ratio of 0.37 was obtained in the highly ionizing solvents suggesting a dissociative S N 1 mechanism (Scheme 2) with moderate rear-side nucleophilic solvation of the developing carbocation.…”

Application of the Extended Grunwald-Winstein Equation to Solvolyses of n-Propyl Chloroformate

“…Although both the N T and Y X scales are based on standard systems involving substitution reaction at an sp 3 -hybridized carbon [3,4], the scales have also been used with considerable success in the correlation analyses of solvolysis reactions of substrates which have attack at the sp 2 -hybridized carbon of acyl halides [5][6][7] and chloroformate esters [8][9][10][11][12][13][14][15], at the phosphorus atom of phosphorochloridate esters [16,17] or amides [18], and at the sulfur atom of arenesulfonyl chlorides [19].…”