Synthesis of t-Butyl Chloride from t-Butyl Alcohol - Chemistry of Alcohol - Lu Le Laboratory

tert-Butyl chloride is a colorless, liquid organic compound at room temperature. It is sparingly soluble in water, with a tendency to undergo spontaneous solvolysis when dissolved into it. The compound is flammable and volatile, and its main use is as a starting molecule to carry out nucleophilic substitution reactions, to produce different substances, ranging from alcohols to alkoxide salts. (Wikipedia)

Tertiary alcohols can be converted to alkyl chlorides very readily. In this experiment, you will convert t-butyl alcohol to t-butyl chloride by shaking the alcohol in a separatory funnel with concentrated HCl, then purifying the product by a simple distillation.

Reaction equation:

When you mix the reactants, you will observe that the mixture is initially a homogeneous solution because t-butyl alcohol is miscible with water. t-Butyl alcohol is more soluble than 1-butanol because its branched hydrocarbon chain is more compact and thus less hydrophobic than a four-carbon continuous chain. Immediately after the reactants are mixed, a second phase is formed. This second phase is the water-insoluble t-butyl chloride. The difference in the solubilities between the alcohol and the halide is attributed to the hydrogen bonding between t-butyl chloride and water.

t-Butyl chloride is extremely volatile. Because evaporation decreases the yield, any container of t-butyl chloride should be kept tightly stoppered between laboratory periods of or during drying. To minimize evaporation during the distillation, the receiving flask should be chilled in an ice bath.

Chemical

1.      Anhydrous Calcium chloride: ~0.8g

2.      5% NaHCO_3(aq): 2.5mL

3.      t-Butyl alcohol: 4.625g

4.      12M HCl_(aq): 17.5mL  

Procedure

1.      Pour 17.5mL HCl_(aq) in a 30 mL conical flask and cool it down to 5~8℃

2.      Weight 4.625g of t-butyl alcohol and pour it into a separatory funnel.

3.      Pour the cooled HCl_(aq) in the separatory.

4.      Mix the reacting mixture in the searatory funnel thoroughly for five minutes and let it stand for at least 20 minutes.

5.      Collect the upper layer.

6.      Use 2.5 mL water to wash the crude t-butyl chloride in the separatory funnel. Collect the upper layer.

7.      Use 2.5 mL 5% NaHCO_3(aq) to alkalize the t-butyl chloride. Collect the upper layer.

8.      Use 2.5 mL water to wash t-butyl chloride again. Collect the upper layer.

9.      Add sufficient anhydrous calcium chloride in the t-butyl chloride as a desiccant.

10.  Distillate the product. Collect 48~52℃ distillate.

11.  Figure out the yield and measure the ndex of refraction of t-butyl chloride.

Experimental Record

Weight of t-butyl chloride	4.315g
Theoretical weight of t-butyl chloride	5.775g
Yield	74.7%
nD21.8℃	1.3832
nD20.0℃	1.3840