Organic Chemistry Lab 315 Fall, 2013

1. Organic Chemistry Lab 315 Fall, 2013

2. DUE DATES • Today • At beginning of lab – GC of Distillate Report • At end of lab -- copy of laboratory notebook pages for today's experiment • Next Week • Synthesis of t-BuCl Report • See my lab web site for instructions

3. Report Notes – Last Week • Instructions said to show on the graphs the data used to estimate the volumes of Et and Bu acetate. • In the summary, the assumptions would include explaining how you decided which data to use. • The summary should include the fact that you actually graphed vol. vs. T data. • Instructions said to explicitly compare the mole % calculated for each method. • That does not mean “about the same”, or “less than 10% difference”, etc.

4. 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.

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

8. In Lab Today • Two phases are the uppert-BuCl 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-BuCl layer with water (removes ___?) • Add sodium bicarbonate (aq.). The basic bicarbonate neutralizes the acid and forms CO2 gas. • Review drying organic solvents (See p. 696 in Pavia)

9. In Lab Today • Wash the t-BuCl with water again (removes __?) • The t-BuCl will be mostly pure with just a small amount of water present. • Review drying organic solvents (See p. 696 in Pavia) • Decantt-BuCl into clean dry vial.

10. Experiment Notes • Store t-BuCl product in a tightly capped vial, in a beaker -- it can easilyevaporate. • Dispose of aqueous solutions in the sink with plenty of water. • Pour distillation waste into waste jar in the hood.

11. Experiment Notes • During the next lab period, weigh the product, determine the refractive index, take an IR spectrum and calculate the percentage yield. • Time permitting, you can start this week. • Please do not leave the lab early without completing some of these procedures.

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. • A strong acid, HCl is used as a reagent, so be sure to follow the instructions for calculating the amount • Separation scheme (flow chart of procedure for separating a pure product from reaction by-products)