10477-70-0Relevant academic research and scientific papers
Access to "friedel-Crafts-Restricted" tert -alkyl aromatics by activation/methylation of tertiary benzylic alcohols
Hartsel, Joshua A.,Craft, Derek T.,Chen, Qiao-Hong,Ma, Ming,Carlier, Paul R.
, p. 3127 - 3133 (2012/05/20)
Herein we describe a two-step protocol to prepare m-tert-alkylbenzenes. The appropriate tertiary benzylic alcohols are activated with SOCl2 or concentrated HCl and then treated with trimethylaluminum, affording the desired products in 68-97% yields (22 examples). This reaction sequence is successful in the presence of a variety of functional groups, including acid-sensitive and Lewis-basic groups. In addition to t-Bu groups, 1,1-dimethylpropyl and 1-ethyl-1-methylpropyl groups can also be installed using this method.
Electronic properties of the nitrone substituent. Stabilization of benzylic carbocations
Creary, Xavier,Hartandi, Kresna
, p. 97 - 102 (2007/10/03)
The nitrone substituent CH=N(O) t-Bu is electron-withdrawing with a Taft σI value of 0.20. It also retards the solvolysis rate of a cumyl chloride when placed in the meta-position (σ = 0.20). However, CH=N(O) t-Bu becomes weakly cation stabilizing when placed in the para-position of a cumyl cation (σ+ = -0.04). This weak cation stabilization is a result of a conjugative interaction which delocalizes charge and offsets the inductive effect of the nitrone. When the nitrone is placed in the para-position, but then twisted out of conjugation with the aromatic ring by incorporation of flanking 3,5-dimethyl groups, it again retards solvolysis rates. Computational studies (B3LYP/6-31G*) show that the nitrone substituent stabilizes a para-substituted benzyl cation relative to the meta-substituted analog by a conjugative interaction. However, the calculated stabilization greatly overestimates the cation stabilization seen in solvolytic reactions. Copyright
The Electronic Effect of the Phenylazo and t-Butylazo Groups
Byrne, Christopher J.,Happer, Duncan A. R.,Hartshorn, Michael P.,Powell, H. Kipton J.
, p. 1649 - 1654 (2007/10/02)
Hammett ?p+-values for arylazo and t-butylazo groups have been determined by measurements of the kinetics of solvolysis of the appropriately substituted arylpropan-2-yl chlorides.They have been found to be considerably more positive than expected and differ significantly from earlier estimates based on the rates of electrophilic attack on azobenzene.An interpretation of the discrepancy has been advanced based on the differing orientations of the azo linkage with respect to the aromatic ring in the transition state.The introduction of methyl groups into positions ortho to the phenylazo and t-butylazo substituents causes a change in character from -I, -R to -I, +R.This is true not only for the solvolysis reaction but also for benzoic acid ionisation.
