Preface

Theoretical Models and Experimental Data for Reactions between Water and Protonated Alcohols: Substitution and Elimination Mechanisms

“…The protonated alcohols, ROH 2 , were generated by proton transfer to the corresponding alcohols under chemical ionization 3 C tradisjonelt forklares med at ùkt metylsubstitusjon paÊ a-karbonet reduserer reaksjonshastigheten for S N 2-reaksjoner grunnet ùkt sterisk hindring. For R (CH 3 ) 2 CH og (CH 3 ) 3 C finner ogsaÊ eliminasjon sted, og de teoretiske beregningene viser at en forside-angrep nukleofil substitusjonsmekanisme ogsaÊ konkurrerer med bakside-angrep S N 2.…”

“…This TS is lower in energy than the products, CH 2 CH 2 (12) and (H 2 O) 2 H (11), and may in principle allow the two water molecules to interchange before completion of the elimination pathway, or before an alternative course of events in which one water molecule is lost. In the latter case the net outcome is substitution if the so-formed [CH 2 CH 2 ]´´´[H 3 O ] species isomerizes to protonated ethanol. Upon closer inspection it turns out that this gives rise to a substitution reaction with retention of configuration at the carbon centre.…”

Preparation of phenazine N5,N10-dioxides: Effects of benzofuroxan substituents in the outcome of their expansion reaction with phenolates

“…Because "throughconjugation" could be operative in the expansion processes, the correlations between σ p -and σ p + substituent constants and the proportion of the 7-isomer were analyzed. 34 For the amine derivatives the substituent resonance-electron-withdrawing effects (expressed as σ p _ ) did not correlate adequately to the proportion of the 7-isomers as did σ p constants (r= -0.8463, s= 0.3300, p= 0.0336). For the hydroxyl-derivatives, improvements in the statistical parameters were obtained in the correlation between σ p -and the 7-isomer proportions (r= -0.8610, s= 0.3151, p= 0.0276).…”

Kinetics and Mechanism of the Anilinolysis of Aryl Ethyl Isothiocyanophosphates in Acetonitrile

“…with the conventional criteria, where nonlinear free energy correlation of the concave downward plot is diagnostic of a rate-limiting step change from bond breaking with weakly basic nucleophiles to bond formation with strongly basic nucleophiles. [11][12][13][14][15][16][17][18][19][20] In this mechanism for anilines with high pK a values, k -a << k b , meaning that the k a step is the ratedetermining step, i.e., k H(D) = k a with smaller Brönsted coefficients β X in Eq. (3).…”