Transcript DUE DATES - George Mason University

Organic Chemistry Lab 315
Fall, 2013
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
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.
In Lab Today
•Synthesis of tert-butyl chloride
– The mechanism of the reaction is SN1
CH3
CH3 C OH
CH3
CH3
H Cl
CH3 C O
CH3
H
Cl
H
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.
In Lab Today
•Synthesis of tert-butyl chloride
– The mechanism of the reaction is SN1
CH3
CH3
CH3 C OH
H Cl
CH3 C O
CH3
CH3
CH3
CH3 C
CH3
H
CH3
OH2
CH3 C
CH3
H2O
Cl
H
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.
In Lab Today
•Synthesis of tert-butyl chloride
– The mechanism of the reaction is SN1
CH3
CH3
CH3 C OH
H Cl
CH3 C O
CH3
CH3
CH3
CH3 C
CH3
OH2
CH3 C
CH3
CH3
H2O
CH3
Cl
H
Step 2 is the dissociation of the
oxonium ion to form the tert-butyl
carbocation and the leaving
group, H2O.
CH3
CH3
CH3 C
H
Step 1 is an acid/base reaction
between HCl (acid) and alcohol
(base) to form the oxonium ion.
Cl
CH3 C
Cl
CH3
Step 3 is the reaction (Lewis
acid/base) between the
carbocation and the nucleophile,
Cl-, resulting in overall
substitution.
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.
In Lab Today
• Two phases are the upper t-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.
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)
• Decant t-BuCl into clean dry vial.
Experiment Notes
• Store t-BuCl product in a tightly capped
vial, in a beaker -- it can easily evaporate.
• Dispose of aqueous solutions in the sink
with plenty of water.
• Pour distillation waste into waste jar in the
hood.
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.
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)