1. Organic Chemistry Lab 315
Fall, 2016

2. DUE DATES Today Next Week
At beginning of lab – GC of Distillate Report
At end of lab -- copy of laboratory notebook pages for today's experiment
Please finish the last Spec. II problem
Next Week
Synthesis of tert-Pentyl Cl Report
See my lab web site for instructions on writing Synthesis reports.

3. Report Notes – Last Week
Simple and Fractional Distillation Report
Read the instructions
Follow the instructions
Never adjust data from Notebook in a Report (unless specifying why at the first opportunity)
Never tear out an original Notebook page
Do not submit a page of calculations and then repeat the calculations in your written summary.

4. Notes
The next slides show the mechanism for the formation of a tertiary alkyl chloride from a tertiary alcohol. The specific example used is tert-butyl. You can easily re-write it using tert-pentyl.
When you look up the reaction starting materials, products and by-products you will likely need to use the systematic IUPAC names.
tert-Pentyl is also known by its common name, tert-amyl.

5. Synthesis of tert-butyl chloride
In Lab Today
Synthesis of tert-butyl chloride
The mechanism of the reaction is SN1
Step 1 is an acid/base reaction between HCl (acid) and alcohol (base) to form the oxonium ion.
Step 2 is the dissociation of the oxonium ion to form the tert-butyl carbocation and the leaving group, H2O.
Step 3 is the reaction (Lewis acid/base) between the carbocation and the nucleophile, Cl-, resulting in overall substitution.

6. Synthesis of tert-butyl chloride
In Lab Today
Synthesis of tert-butyl chloride
The mechanism of the reaction is SN1
Step 1 is an acid/base reaction between HCl (acid) and alcohol (base) to form the oxonium ion.
Step 2 is the dissociation of the oxonium ion to form the tert-butyl carbocation and the leaving group, H2O.
Step 3 is the reaction (Lewis acid/base) between the carbocation and the nucleophile, Cl-, resulting in overall substitution.

7. Synthesis of tert-butyl chloride
In Lab Today
Synthesis of tert-butyl chloride
The mechanism of the reaction is SN1
Step 1 is a Bronsted-Lowry acid/base reaction between HCl (acid) and alcohol (base) to form the oxonium ion.
Step 2 is the dissociation of the oxonium ion to form the tert-butyl carbocation and the leaving group, H2O.
Step 3 is the reaction (Lewis acid/base) between the carbocation and the nucleophile, Cl¯, resulting in overall substitution of Cl for OH.

8. In Lab Today Reaction takes place within a separatory funnel
tert-pentyl alcohol and HCl are mixed to form one phase initially, and they then begin to react.
As the products tert-pentyl chloride and water form, the reaction mixture separates into two phases.

9. In Lab Today
Two phases are the upper t- PentCl phase (with some water and aq. acid) and the lower aqueous phase with dissolved acid.
Separate the phases (keeping upper phase in funnel).
Wash the t-PentCl layer with water (removes ___?)
Add aq. sodium bicarbonate. The basic bicarbonate neutralizes the acid and forms CO2 gas.
Review drying organic solvents (See p. 696 in Pavia)

10. In Lab Today Wash the t-PentCl with water again (removes __?)
The t-PentCl will be mostly pure with just a small amount of water present.
Review drying organic solvents (See p. 696 in Pavia)
Decant t-PentCl into clean dry pre-weighed vial (± .001g).
Do not distill.

11. Experiment Notes
Determine the refractive index, take an IR spectrum and calculate the percentage yield.
Store t-PentCl product in a tightly capped vial in the storage drawer.
Dispose of aqueous solutions in the sink with plenty of water.

12. Synthesis Report
See the instructions on the web site for writing a Synthesis report.
Pay particular attention to the table on the Report Form, which is actually a calculation of theoretical yield.
Since the carbocation is not isolated or measured, it is not included in the table.
A strong acid, HCl is used as a reagent, so be sure to follow the instructions for calculating the amount of HCl used.
Separation scheme -- flow chart of procedure for separating a pure product from reaction by- products. (Even though you do not do a final distillation, include it on the Separation Scheme.)

13. Lab Clean-up
Ii, Alexandra N.
Marcus, Erin M.