Enthalpies of transfer of transition states in the Menshutkin reaction from a polar protic to a dipolar aprotic solvent

Abstract

lit.17 bp 109-111°( 3 mm)]; vmxx 1682 cm"1; nmr 0.6-2.0 (m, 9 ), 1.7 (d, J = 7.0 Hz, 3 H), 3.33 (m, 1 H), and 7.35 and 7.96 (m, 5 H each).B. Phenyl l-Phenyl-2-hexyl Ketone .-Treatment of the enolate 3 with benzyl chloride followed by work-up as described above produced phenyl l-phenyl-2-hexyl ketone (for yields see

Computational Study of Reactivity and Transition Structures in Nucleophilic Substitutions on Benzyl Bromides

“…[34,35] The X substituents of the compounds used in the calculations and in the kinetic measurements of the various reactions are given in Figures 8 and 9, while structural parameters of the TSs 11 are plotted in Figures 1-4 and additional structural data are listed in Table S3 in the Supporting Information. Scheme 2.…”

Effects of substituents on activation parameters in SN2 reactions at aliphatic carbon in solution

“…All details of the statistical parameters of these equations for the reactions of compounds 1 – 11 with nucleophiles 12 – 22 are given in Table S1 of the supporting information. The rate constants and the ρ values were published earlier 19, 28, 35, 43, 58–69. References are given in Tables 1 and S1.…”

“…From the temperature-dependent rate data [19,28,35,43,[58][59][60][61][62][63][64][65][66][67][68][69] the Eyring plots were generated by plotting log(k/T) versus 1/T and the enthalpy and entropy of activation, DH 6 ¼ , DS 6 ¼ , were determined for the reactions of alkyl, alkenyl and alkynyl benzenesulfonate derivatives 1-4, N-methyl pyridinium salt 5, N-chloroacetyl arylamines 6, benzyl halides 7-10 and allyl bromide 11 with charged 16, 20, 21 and uncharged nucleophiles 12-15, 17-19, 22 in protic and aprotic solvents (Scheme 2). The DH 6 ¼ , DS 6 ¼ and DG 6 ¼ activation parameters obtained were used by Eqns (1)-(3) to establish the dDH 6 ¼ , dDS 6 ¼ and dDG 6 ¼ reaction constants (Table 1).…”

“…The rate constants and the r values were published earlier. [19,28,35,43,[58][59][60][61][62][63][64][65][66][67][68][69] References are given in Tables 1 and S1. Table S1 contains the parameters of Eqns (1)-(3) for the reactions of compounds 1-11 with nucleophiles 12-22.…”

79Br NMR spectroscopy as a practical tool for kinetic analysis

“…The Menschutkin reaction of each of the substituted benzyl bromides 1a-e with pyridine 2 to give the corresponding benzylpyridinium bromides 3a-e (Scheme 1) is representative of the substitution process in which bromide is produced. [15] It also offers the advantages of being readily followed using 1 H NMR spectroscopy and that variation of the substituent on the bromides 1a-e allows tuning of the rate of the reaction in order to test the scope of this spectroscopic method. The elimination of hydrogen bromide from the dibromide 4 to give the ester bromides 5 and 6 (Scheme 2) [16] and the conversion of the dibromoketone 7 to the corresponding chalcone 8 (Scheme 3) [17] are examples of elimination processes.…”