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ResultsTable 1. Time vs. Concentration of t-butyl bromideTime (min)Volume NaOH used (mL)[t-buBr] (M)0*- 0.445151.90.35303.30.28454.80.2056060.145907.30.081208.30.03∞8.90*The concentration of t-butyl bromide at time = 0 was determined by finding the concentrationof HBr at time = ∞as shown in Equation 2 using 8.9 mL of NaOH. 015304560759010512000.050.10.150.22.214.171.1240.40.450.5Time vs. [t-buBr]Time (minutes)[t-buBr] (M)3
Solvolysis of t-butyl bromide Georgetown University Figure 2. Plot of time versus concentration of t-butyl bromide is shown. 0153045607590105120-4-3.5-3-2.5-2-1.5-1-0.50f(x) = - 0.02x - 0.68R² = 0.98Time vs. ln[t-buBr]Time (minutes)ln[t-buBr] Figure 3. Plot of time versus natural log of concentration of t-butyl bromide and its line of bestfit are shown. As shown in Figure 3, the data indicated a rate constant of 0.0221 min-1for the reaction in75% isopropanol in water mixture. Discussion4
Solvolysis of t-butyl bromide Georgetown University The solvolysis of t-butyl bromide was determined to be a first order reaction as the data were fit well by a linear plot (R2= 0.98353) (Figure 3). This consequentially confirmed that the solvolysis of t-butyl bromide is an SN1 reaction. In a concurrent experiment where 80% isopropanol in water mixture was used, the data indicated a rate constant of 0.015 min-1. This meant that the reaction proceeded faster in 75% isopropanol in water mixture because the mixture contained higher proportion of the polar water. This is consistent with the prediction thatmore polar solvent is more effective in stabilizing the carbocation and halide ion in the intermediate stage. According to the Hammond Postulate, lowering the energy of intermediates will lower the energy of the transition state because the transition state is close to the intermediates in energy. This will in turn lower the activation energy, and the reaction would proceed faster. This effect of solvent polarity on solvolysis of alkyl halides was also shown in