CHEM 344 Summer 2024 Midterm Exam (100 pts)
Name:
TA Name:
Exam Length = 120 min
DO NOT REMOVE ANY PAGES FROM THIS EXAM PACKET.
Directions for drawing molecules, reactions, and electron-pushing mechanisms:
Draw all lone pairs, bonds, arrows, formal charges, and stereochemistry explicitly in all molecular
structures.
Take care when drawing molecules and labeling them with NMR assignments that you do not change the
chemical formula. Examples for 2-methyl-2-butanol are shown below.
acceptable acceptable acceptable unacceptable unacceptable
Directions for all calculations:
Explicitly show all work on all calculations and include all important labels.
, 1) Treatment of tert-amyl alcohols (2-methyl-2-butanol and 3-methyl-2-butanol) with HCl leads to the
formation of one or more alkyl chlorides. (46 pts)
Experimental procedure for synthesis using 2-methyl-2-butanol
To a sample of 2-methyl-2-butanol (51 mmol) in a 60 mL separatory funnel is added conc. hydrochloric
acid (HCl, ~15 mL). After shaking and venting of the separatory funnel for five minutes, the organic layer
is isolated and washed with sat. aq. sodium bicarbonate (NaHCO3) solution. The organic layer is then
isolated and stirred over solid, anhydrous magnesium sulfate (MgSO4). After gravity filtration, the organic
layer is purified by fractional distillation and the resulting distillate is analyzed by NMR (CDCl3) and GC-
MS (CH2Cl2).
Experimental procedure for synthesis using 3-methyl-2-butanol
To a sample of 3-methyl-2-butanol (51 mmol) in a 25 mL round bottom flask is added conc. hydrochloric
acid (HCl, ~15 mL). The reaction mixture is heated and the product distilled into a receiving flask. Without
further purification, the resulting distillate is analyzed by NMR (CDCl3) and GC-MS (CH2Cl2).
a) In the workup of the reaction of 2-methyl-2-butanol with hydrochloric acid, the organic layer is washed
with sat. aq. sodium bicarbonate (NaHCO3) solution. Provide a balanced chemical equation that
demonstrates the reason for washing with sodium bicarbonate solution. Additionally, identify the locations
of the desired product, water, and any residual 2-methyl-2-butanol after the wash on the diagram below.
Assume that the organic phase has a density < 1 g/mL and is immiscible in water. (6 pts)
Name:
TA Name:
Exam Length = 120 min
DO NOT REMOVE ANY PAGES FROM THIS EXAM PACKET.
Directions for drawing molecules, reactions, and electron-pushing mechanisms:
Draw all lone pairs, bonds, arrows, formal charges, and stereochemistry explicitly in all molecular
structures.
Take care when drawing molecules and labeling them with NMR assignments that you do not change the
chemical formula. Examples for 2-methyl-2-butanol are shown below.
acceptable acceptable acceptable unacceptable unacceptable
Directions for all calculations:
Explicitly show all work on all calculations and include all important labels.
, 1) Treatment of tert-amyl alcohols (2-methyl-2-butanol and 3-methyl-2-butanol) with HCl leads to the
formation of one or more alkyl chlorides. (46 pts)
Experimental procedure for synthesis using 2-methyl-2-butanol
To a sample of 2-methyl-2-butanol (51 mmol) in a 60 mL separatory funnel is added conc. hydrochloric
acid (HCl, ~15 mL). After shaking and venting of the separatory funnel for five minutes, the organic layer
is isolated and washed with sat. aq. sodium bicarbonate (NaHCO3) solution. The organic layer is then
isolated and stirred over solid, anhydrous magnesium sulfate (MgSO4). After gravity filtration, the organic
layer is purified by fractional distillation and the resulting distillate is analyzed by NMR (CDCl3) and GC-
MS (CH2Cl2).
Experimental procedure for synthesis using 3-methyl-2-butanol
To a sample of 3-methyl-2-butanol (51 mmol) in a 25 mL round bottom flask is added conc. hydrochloric
acid (HCl, ~15 mL). The reaction mixture is heated and the product distilled into a receiving flask. Without
further purification, the resulting distillate is analyzed by NMR (CDCl3) and GC-MS (CH2Cl2).
a) In the workup of the reaction of 2-methyl-2-butanol with hydrochloric acid, the organic layer is washed
with sat. aq. sodium bicarbonate (NaHCO3) solution. Provide a balanced chemical equation that
demonstrates the reason for washing with sodium bicarbonate solution. Additionally, identify the locations
of the desired product, water, and any residual 2-methyl-2-butanol after the wash on the diagram below.
Assume that the organic phase has a density < 1 g/mL and is immiscible in water. (6 pts)
