Transcript Slide 1

CHEM 213
Organic Laboratory
CHEM 213 – Organic Lab
Important Information:
Lab Section
001 T (2:30 – 5:00 PM)
002 W (1:25 – 3:55 PM)
003 R (9:30 AM – 12:00 PM)
004 R (2:30 – 5:00 PM)
Instructor
Dr. Martin Kociolek
Mrs. Tracy Halmi
Dr. Michael Justik
Office
37 Hammermill
35 Hammermill
32 Hammermill
Email
[email protected]
[email protected]
[email protected]
Phone
898-6411
898-6045
898-6412
Web Page
chemistry.bd.psu.edu/kociolek/
chemistry.bd.psu.edu/halmi/
chemistry.bd.psu.edu/justik/
Office Hrs
T 9:30 –11:00 AM
W 1:30 – 3:00 PM
M 1:25 – 3:15 PM
W 9:30 – 10:45 AM
F 1:25 – 2:15 PM & by appt
M 8:00 –11:00 AM
Recitation: All students will attend mandatory lab recitation on Mondays 3:35 PM.
Recitation will NOT meet every week, see attached schedule for recitation dates.
Laboratory Schedule
Recitation Readings
EXPERIMENT
ASSIGNMENT
DUE DATES
8/27*
Techniques
1, 2, & 3
Check-in
Safety Quiz
9/3
Techniques
6, 9, & 10
Experiment #1:
Purification of Solid Organic Compounds
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9/10*
Techniques
11, 13, 16, & 18
Experiment #2:
Purification of Liquids by Distillation
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9/17
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Experiment #2: continued
Exp #1 Short Report
9/24*
Technique 8 & 11.7
Experiment #3: Steam Distillation
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10/1
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Experiment #3: continued
Exp #2 Short Report
& Notebook
10/8*
Handout
Experiment #4: Acid/Base Extraction
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10/15
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Experiment #4: continued
Exp #3 Short Report
10/22*
Technique 15
Experiment #5:
Thin-Layer Chromatography
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10/29
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Experiment #5: continued
Exp #4 Full Report
11/5*
Technique 17
Experiment #6: Benzoylation of Ferrocene
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11/12
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Experiment #6 continued
Exp #5 Full Report
11/19
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Thanksgiving Week – No Lab
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11/26*
Handout
Experiment #7: Synthetic Puzzle
Exp #6 Full Report
12/3*
Final exam
Experiment #7: continued
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12/10
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No Lab
Exp #7 Full Report
& Notebook
Week of
* NOTE: Lab recitation will only meet on these Mondays.
Required Materials:
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Text:
Techniques in Organic Chemistry, 2nd edition
Jerry R. Mohrig et al, W. H. Freeman and Company, 2006
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Handouts:
Downloaded from instructor’s web site prior to recitation
for each new experiment
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Notebook:
A bound notebook is required
 unacceptable - spiral or three-ring bound notebooks
 most convenient - composition notebook
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Goggles:
Any goggles or safety glasses with side-shields
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Software:
ChemDraw @ https://downloads.its.psu.edu/
Assignments:
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Notebook (35 pts)
PreLab
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Quizzes (50 pts)
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Lab Reports (275 pts):
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First 3 experiments a short report (25 pts each), emphasizing a particular section
Final 4 experiments require a full report (50 pts each)
Late reports will be penalized at two points per day up until they are one week late when
they will not longer be accepted.
Final Exam (75 pts):
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recitation includes a short (10 pt) quiz on the readings
six quizzes - no make-up quizzes – but one quiz may be dropped
A comprehensive final exam will be given during the recitation. (see schedule)
General Lab Courtesy:
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Failure to collaborate, cooperate and abide by the safety rules will result in an automatic
deduction of points from that lab, at the discretion of the instructor. Students who do not
checkout their desk equipment will be charged a $25 checkout fee.
Grades:
Notebook
35 pts
Quizzes (5 x 10 pts)
50 pts
Lab Reports (3 x 25 pts, 4 x 50 pts)
275 pts
Final Exam
75 pts
Total
435 pts
The minimum grade you will receive :
A (100-93%), A- (92-90 %), B+ (89-87%), B (86-83%), B- (82-80%),
C+(79-75%), C (74-70), D (69-60%), F (<60%).
Notes:
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Academic Integrity: It is expected that each student will do his/her own
work on all assignments including quizzes and laboratory reports.
This includes but is not limited to …
 stealing, purchasing or copying quizzes and/or laboratory reports from present
or previous students.
 even the possession of other student’s notebook, laboratory reports, or
quizzes constitutes a violation of the academic integrity polity at Penn State.
For more information see the Academic Integrity & Academic Dishonesty (Senate
Policy 49-20) at http://www.psu.edu/ufs/policies/ or Behrend’s Academic Integrity
policy at http://www.pserie.psu.edu/faculty/academics/integrity.htm.

Students with disabilities: If you have a disability-related need for
modifications or reasonable accommodations in this course, contact the
Disability Specialist in the Office of Student Affairs, Room 115 Reed Union
Building, 898-6111.
WELCOME to CHEM 213
Purification of Organic Solids
Identification using Melting Point Determination
Experiment 1
Experimental Objectives
• become familiar with common heating & cooling methods (Technique 6)
• purify organic unknown using recrystallization (Technique 9)
• identify unknown by melting point & solubility data (Technique 10)
Recrystallization
 crystalline material (solute) is dissolved in a hot solvent
then returns to solid when cooled
 important to understand “dissolving”
solvent
solid
 choice & amount of solvent is critical
http://server1.fandm.edu/departments/chemistry/Van%20Arman%20Virtual%20Lab/Recrystallization/Recrystallization3.html
Solubility
solvent temperature - solubility increases with temperature
solvent volume - amount of solute vs. volume of solvent
solvent properties - solute/solvent interactions “like dissolves like”
- polar H2O dissolves most (polar) inorganic compounds
- nonpolar organic solvents dissolve most (nonpolar) organics
http://bioweb.wku.edu/courses/Biol220CAR/2ChemBond/waterFig.html
Recrystallization Solvents
Polarity Index
0.0
2.3
2.9
3.4
4.3
4.3
5.2
5.4
6.6
9.0
Common Name of Solvent
Structure
hexane
toluene
diethyl ether (ether)
methylene chloride
ethyl acetate
chloroform
ethanol
acetone
methanol
water
CH3(CH2)4CH3
C6H5CH3
(CH3CH2)2O
CH2Cl2
CH3CO2CH2CH3
CHCl3
CH3CH2OH
(CH3)2C=O
CH3OH
H2O
www.chem.umd.edu/organiclabs/Chem232/01Recrystallization/Lab01.ppt
(least polar)
(most polar)
7 Steps to
Recrystallization
1.
2.
3.
4.
5.
6.
7.
find “best” solvent
dissolve bulk sample in solvent
decolorize (if necessary)
remove insoluble impurities (if necessary)
cool solute/solvent mixture
collect crystals
dry & analyze crystals
Step 1
1. find “best” solvent
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small (test tube) size using a sand bath
dissolves went hot – not when cold
limited to six initial solvent choices
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water
ethanol
ethyl acetate
methylene chloride (dichloromethane)
toluene
hexane
Steps 2 - 4
2. dissolve bulk sample in solvent
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3.
decolorize (if necessary)
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4.
minimum amount of solvent to dissolved solute with heat
this will be unique to solute & solvent choice
use boiling chips or sticks
charcoal adheres to colored impurities
remove insoluble impurities (if necessary)
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hot gravity filtration
Hot Filtration
Hot Plate
Step 5
5. cool solute/solvent mixture
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cool slowly to eliminate soluble impurities from
crystallizing
If crystals do not form try…
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scratching with glass stir rod
add a seed crystal
evaporate some excess solvent
http://wulfenite.fandm.edu/labtech/crystals.htm
Step 6
6. collect crystals
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vacuum filtration using Buchner Funnel
to vacuum
Step 7
7. dry
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leave on vacuum filter
leave crystals in funnel open in desk
heat under a heat lamp – take care
Review Steps 2 – 6: video
http://server1.fandm.edu/departments/chemistry/Van%20Arman%20Virtual%20Lab/Recrystallization/recrystallization1.mov
Percent Recovery
 evaluates recrystallization quantitatively
 do not forget to record weight of unknown
 not the same as a percent yield
amount of solid recovered
%=
X 100
amount of initial solid
Melting Points
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temperature where solid & liquid phases in equilibrium
characteristic physical property of solid
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the identity of an organic solid
the purity of an organic solid
most organic solids melt 25 - 250 oC
A. Sublimation
B. Melting
C. Evaporation
Melting Points
Organic molecules within the solid are held together
by intermolecular forces
Hydrogen bonding
Dipole-dipole interactions
Van Der Waals forces (temporary dipole)
2 – 10 kcal/mol
0.5 - 2 kcal/mol
0.5 kcal/mol
compare to a intramolecular covalent bond ~100 kcal/mol
Melting Points
Consider the effects of intermolecular forces on the
melting point of three organic compounds of similar mass:
O
O
H
O
benzoic acid
O
ethyl benzoate
ethyl benzene
Hydrogen Bonding
Benzoic acid
melting point 122-3 oC
O
O
O
H
H
O
O
O
O
H
H
O
O
H
O
Dipole-Dipole
Ethyl benzoate,
melting point -23 oC

C
O
O
O


C

O
Dipole-dipole interactions are weaker. Ethyl benzoate is
heavier than benzoic acid, yet its melting point is below room
temperature, almost 150o below benzoic acid.
Van Der Waals
Ethyl benzene,
melting Point -95 oC
Temporary dipoles are the weakest form of intermolecular force.
Solids held together by these forces have low melting points.
Melting Point Determination
The energy (heat) required to break these intermolecular interactions is
the same for any two molecules within the solid
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pure organic compounds have a distinct melting point that can be
used for identification
•
melting point should also occur over a very narrow range of
temperatures
•
impurity in the solid disrupts intermolecular forces – takes less
energy to melt solid – therefore lowering and broadening melting
point range
Pure Solid
The Van Der Waals
forces that hold the
solid together are regular
are the same from
molecule to molecule
Pure naphthalene
melts at 82-83oC
Impure Solid
cyclohexane contaminated
naphthalene, mp 62-69oC
Melting Point Determination
Problem:
Suppose you are cleaning the chemical stockroom and you
encounter a reagent bottle whose label has decomposed. You
suspect that the compound could be either benzoic acid (mp 122123 oC) or succinimide (mp 123-5 oC). You take a melting point,
and sure enough the unknown melts at 123 oC.
How would you use what you have learned to determine the true
identity of the contents of the bottle?
Mixed Melting Point
Solution:
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obtain known samples of benzoic acid & succinimide
mix each of the known samples with a portion of the unknown
determine the melting point for each mixed sample
MP Pure A
MP Pure B
Temp (◦C)
100% A
100% B
Mole % Composition
Thomas-Hoover
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silicone oil bath
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five samples simultaneously
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oil slow to respond to temperature
changes – so a slower, better melting
point can be obtained
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silicone oil has a temp limit 200 °C
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good choice for organics that melt
between 20-200 °C
Mel-Temp
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uses a heated aluminum block
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three samples simultaneously
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aluminum is quick to respond to
temperature changes – higher temps
can be achieved more quickly
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advantage in determining high
melting points
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good choice for organics that melt
over 200 °C
MP Sample Size
Use the minimum amount of sample & slowest heating rate to obtain
the sharpest, most accurate melting point.
Sample size: samples placed in a mp
capillary tube. Use the minimum amount
seen through the magnifier (1-2 mm)
Heating Rate: quickly go to
20 °C below the expected MP,
then slow to 1-2 °C per minute
to observe the correct MP
Melting Point Video
Introduction
Brief Paragraph (2-5 sentences)
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interesting background information
goals/objective
reaction (if applicable)
proper reference
Do not include:
 explanation
 procedure
Conclusion
Brief Paragraph (2-3 sentences)
 statement summarizing discussion
 must include conclusion
Typed, 12 point black font, double spaced
 grammar, spelling, etc.
Notebook
Chapter 3 in Mohrig
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table of contents (leave room)
numbered pages (no pages torn out)
Prelab
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title, date
purpose including balanced reaction (if applicable)
chemical data table
do not write out the procedure (outline if helpful)
Observations
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in class notes recorded in ink
calculations
Questions?
Comments?