Question

CONTEXT

So we did an Sn1 reaction in chem lab to convert t-butyl alcohol to t-butyl chloride by the following reaction

C4H10O + HCl --> C4H9Cl + H2O

We did this by mixing the HCl and the t-butyl alcohol in a separatory funnel, then we collected the organic layer that formed and vacuum distilled the product.

QUESTIONS

What is something that could cause a low yield in this experiment? we got a 26% yield, I was thinking maybe heating up the distillation apparatus too quickly would cause some of our low boiling material to be left behind or leaving some of the product behind in the separatory funnel  but I wasn't sure what else

What could we tell about the purity of our product from the boiling point? I thought boiling point wasn't really a distinguishing factor, but then again since the reagents have different boiling points maybe getting a BP of t-butyl chloride close to the literature value would be a good thing, I'm just not sure if any side products could have been produced from the reaction that might have had similar boiling points

Why would a lower range boiling point be achieved? We got 50.0-50.2 for the bp, the lit says anywhere between 50-52. Could the reduced pressure in the distillation apparatus have caused a decrease in the BP range?

Thanks, let me know if I need to explain anything further!

Answer 1

Question 1.

The reason for getting a low yield is that there is an elimination reaction (E1) occurring simultaneously to form isobutylene or 2-methylpropene.

Question 2.

The purity of the SN1 reaction product, i.e. t-butyl chloride is less because it is low boiling, evaporates quickly and while condensing gets lot of impurities either from the walls of the flask or from the atmosphere.

Question 3.

As you guessed, the lower boiling point of the SN1 produce (t-butyl chloride) may be due to the reduced pressure.