Reactions of alkyl halides with amines to form quaternary ammonium salts have been extensively investigated with respect to steric effect between reactants and the effects of pressure on the reaction (2,j). The rate of the reaction increases with increasing applied pressure on the system, and generally the greater the degree of steric hindrance present, the more pronounced the effect of applied pressure on the reaction rate.
Recently, it was demonstrated that 2,6-di-t-butyl pyridine reacts with methyl iodide only under high pressure (h). Another sterically hindered base, 2,h,6-tri-t-butyl N-methyl aniline (I) did not react with methyl iodide under conventicnal methods. Wenster and coworkers have attempted to prepare 2,h,6-tri-t-butyl N,Ndimethyl aniline from I by nine different methylation procedures, e.g.: I, with methyl iodide at 200ยฐC In a sealed tube, with dimethyl sulfate at l@OCC and with sodium amide-methyl iodide. However, all attempts resulted in no reaction (5).
:Ve wish to report the effect of oressure on the reaction between I and methyl iodide. I reacted with methyl iodide under high uressure ~OCO-5#OC atm. at 1CWC in dioxane solution (or without solvent, using large excess methyl iodide) and produced