# How would you measure the rate of this SN1 reaction?

I am performing the following $\mathrm{S_N1}$ reaction:

$$\ce{t-BuOH + HCl -> t-BuCl + H2O}$$

I would also like to measure the rate of this reaction, but I cannot seem to find a way. I initially envisaged measuring the rate by using an indicator to tell when the conc. $\ce{HCl}$ had been used up.

However, I do not believe the reaction has gone to completion, thus why, when using my method of using an indicator, the indicator never changed colour, due to leftover acid - also Clayden's Organic Chemistry [1, p. 348] cites a 90% yield, presumably meaning not all of the acid reacts.

The reaction should take 20 minutes [1] at room temperature and so I don't think I can measure the rate by looking measuring a change in temperature. I do not know how else I could measure the rate.

1. Clayden, J.; Greeves, N.; Warren, S. G. Organic Chemistry, 2nd ed.; Oxford University Press: Oxford; New York, 2012. ISBN 978-0-19-927029-3.
• Measure the pH, and just measure the initial rate. – DHMO Jan 12 '17 at 17:29
• As the reaction is very slow you could measure IR spectrum vs time, preferably using total reflection ( ATR) method. – porphyrin Jan 12 '17 at 20:58
• Side-question: terminology-wise, should this reaction be considered an SN1 reaction or an acid-base reaction? Can a reaction be both? – Don_S Mar 14 '17 at 10:29
• @Don_S The mechanism by which it occurs is SN1, therefore, I would consider it to be an SN1 reaction – Saul McShane Mar 14 '17 at 20:25
• You can sample aliquots and use NMR or GC to compare peaks of your starting materials to products. – Zhe Jul 12 '17 at 12:18