Question

Consider the above reaction using 25.0 mL of tert-butyl alcohol (d = 0.786 g/mL) with 60.0 mL of concentrated hydrobromic acid (d = 1.49 g/mL, 47.0% HBr). On a separate sheet calculate the theoretical yield in grams and the percent yield for a reaction that produced 26.1 g of tert-butyl bromide. Clearly show the set ups to determine the limiting reactant and other calculations using proper units and significant figures. Consult your textbook for the following TWO synthesis. Keep in mind that conc. HCl and conc. HBr will NOT give good yields of alkyl halides by the reaction with primary and secondary alcohols. Give the balanced equation to prepare chlorocyclohexane in good yield from cyclohexanol. Give the balanced equation for the preparation in good yield of 1-bromopentane from 1-pentanol. The reverse of the reaction you performed in the lab can also occur. Under the proper conditions, tertiary alkyl halides may undergo a hydrolysis reaction to form an alcohol and a hydrogen halide. Complete and balance the following equation. (Remember the General II experiment?)

Answer 1

Answer:

Theoretical yield: 36,3g

Percent yield: 71,9%

Explanation:

The reaction of tert-butyl alcohol with hydrobromic acid to produce tert-butyl bromide is a 1:1 reaction.

Moles of tert-butyl alcohol in 25,0 mL are:

25,0mL × (0,786g / mL) × (1mol / 74,12g) = 0,265 moles of tert-butyl alcohol

Moles of hydrobromic acid are:

60,0mL× 47,0% × (1,49g / mL) × (1mol / 80,91g) = 0,519 moles of HBr

As moles of tert-butyl alcohol are less than moles of HBr, limiting reactant is tert-butyl alcohol.

Theoretical yield of tert-butyl bromide in grams is:

0,265 moles × (137,02g / 1mol) = 36,3g

Percent yield:

26,1g / 36,3g × 100 = 71,9%

The reactions are in the image.

There are many ways to produce alkyl halides from primary and secondary alcohols. The reaction in this case is the Appel reaction.

The reaction of tertiary alkyl halides may undergo a hydrolysis reaction -under proper conditions- to form an alcohol and a hydrogen halide.

I hope it helps!