On the Importance of the Aromatic Ring Parameter in Studies of the Solvolyses of Cinnamyl and Cinnamoyl Halides

Abstract

In solvolysis studies using Grunwald-Winstein plots, dispersions were observed for substrates with aromatic rings at the α-carbon. Several examples for the unimolecular solvolysis of monoaryl benzylic derivatives and related diaryl- or naphthyl- substituted derivatives have now been reported, where the application of the aromatic ring parameter (I) removes this dispersion. A recent claim suggesting the presence of an appreciable nucleophilic component to the I scale, has now been shown, in a review of the solvolysis of highly-hindered alkyl halides, to be unlikely to be correct. Attention is now focused on the application of the hI term for the solvolysis of compounds containing a double bond in the vicinity of any developing carbocation. Available specific rates of solvolysis (plus some new values) at 25°C of cinnamyl chloride, cinnamyl bromide, cinnamoyl chloride, p-chlorocinnamoyl chloride, and p-nitrocinnamoyl chloride are analyzed using the simple and extended (including the hI term) Grunwald-Winstein equations.

Effectiveness of Liquid-Liquid Extraction, Solid Phase Extraction, and Headspace Technique for Determination of Some Volatile Water-Soluble Compounds of Rose Aromatic Water

“…In water distillation method, rose aromatic water contains very low amounts of (below 0.1%) essential oil and its main component is phenylethyl alcohol [ 4 , 10 – 16 ]. Double distillation method is used as a traditional method.…”

Detailed analysis for the solvolysis of isopropenyl chloroformate

“…Furthermore, with equation 2 an h value of 0.42 ± 0.15 signified that there was minimal charge dispersion into the aromatic ring during the formation of the thioacylium transition state that was stabilized by intense rear-side nucleophilic solvation (as indicated by the large l value). These sensitivity values are now considered typical [2,7,23,27,29,30,33,34,49,56] for substrates believed to solvolyze with the formation of an acylium or a thioacylium ion in the transition state.…”

“…Also, it was demonstrated [2,12,14,15,18,20,21,23–27] that dual reaction channels occurring simultaneously in a side-by-side fashion are possible in some alkyl and aryl chloroformate esters, and that the highly ionizing aqueous 2,2,2,-trifluoethanol (TFE) and 1,1,1,3,3,3,-hexafluoro-2-propanol (HFIP) mixtures are shown [2,3,6–49,55,56,71–74] to be extremely important for meaningful treatments leading to analyses using the Grunwald-Winstein equations. To probe the possibility of an ionization pathway for 1 , we have raised the temperatures (so that the kinetic runs could be followed within a reasonable time frame) and in Table 1 have included 16 specific rates of solvolysis in six solvents with strong hydrogen bonding (highly ionizing) fluoroalcohol components.…”

Use of Empirical Correlations to Determine Solvent Effects in the Solvolysis of S-Methyl Chlorothioformate

“…In a recent review [27] of 30 highly hindered substrates not having appropriately placed π-electrons, we determined that in such substrates the sometimes positive and sometimes negative h values that Martins observed [26] is an artifact resulting from the multicollinearity that is present between the I values and a linear combination of N T and Y X values [27]. We have also just demonstrated that the I scale is very useful in studies of the solvolyses of compounds containing a double bond in the vicinity of any developing carbocation [28]. $\text{log}\hspace{0.17em}false(k/k_{o}false)=mY+c$ $\text{log}\hspace{0.17em}false(k/k_{o}false)=lN+mY+c$ $\text{log}\hspace{0.17em}false(k/k_{o}false)=\text{italicmY}+hI+c$ $\text{log}\hspace{0.17em}false(k/k_{o}false)=lN+mY+hI+c$…”