The Competitive Reaction of Nucleophiles in the Butanol Series Revisited

An improved procedure for the study of the competitive reaction of nucleophiles in the butanol series is described. Starting with 1-butanol, 2-butanol and 2-methyl-2-propanol, the relative nucleophilicities of chloride and bromide ions during a nucleophilic substitution reaction are examined by automated 1H-NMR spectroscopy instead of the usual gas chromatography. While the reaction time, purification and extraction procedures were slightly modified and simplified to accommodate a large laboratory group (60 students); the data acquisition time was shortened considerably by use of the 1H-NMR method. Furthermore, the cost of the experiment per student was reduced significantly.