October 21, 2011
Lab #6: Preparation of 2-chloro-2-methylbutane – an Sn 1 Reaction
The purpose of this experiment was to prepare an alkyl halide, 2-chloro-2-methylbutane by reacting 2-methyl -2-butanol (t-amyl alcohol) with hydrochloric acid. Alkyl halides are of wide interest because they are widespread and have diverse beneficial and detrimental impacts .The overall reaction is given below:
1 ml of 2-methyl-2-butanol was measured using 1 ml syringe and transferred into a 5 ml conical vial. 2.5 ml of highly concentrated Hydrochloric acid was then slowly added while the vial was constantly swirled. After mixing alcohol with HCl the vial was capped with a screw cap and gently shaken for about 10 seconds. The cap was then immediately loosened to ensure proper venting and release of excess pressure in the vial. The venting process was repeated a couple of times.
From conical vial contents were then transferred to a clean centrifuge tube. The mixture was allowed to separate into two layers. Newly formed aqueous layer was removed with a plastic pipette and stored in a 50 ml beaker.
1 ml of distilled water was then added to the organic layer in the centrifuge tube. Performing water wash promoted formation of organic layer on top of the aqueous layer. Another wash with 1 ml of saturated sodium bicarbonate solution was performed twice and aqueous layers were repeatedly removed.
Final organic layer was then transferred into a clean 10 ml Erlenmeyer flask and anhydrous sodium sulfate was added until some material remained free flowing like sand. The material was left to sit and dry for a short time. Dry organic material was then transferred to a pre- weighed clean conical vial. Product’s mass was then calculated based on acquired results.
Table of Physical Constants Compound | Structural Formula | Molecular Weight (g/mol) | Density (g/ml) | 2-methyl-2-butanol | (CH3)2C(OH)CH2CH3 | 88.15 | 0.815 | Hydrochloric Acid |