Part E (1 hour); Part F (1 hour)

316 Pages·2012·1.4 MB·English

Experiment 1

SOLUBILITY

TIME ESTIMATE: Parts A-D (3 hours); Part E (1 hour); Part F (1 hour)

CHEMICALS AND SUPPLIES PER 10 STUDENTS:

Part A

Benzophenone (Grind up the flakes into a powder) 0.5 g

Malonic acid 0.5 g

Biphenyl 0.5 g

Methyl alcohol 40 mL

Hexane 40 mL

Part B

Methyl alcohol 13 mL

1-Butanol 13 mL

1-Octanol 13 mL

Hexane 40 mL

Part C

Ethyl alcohol 13 mL

Diethyl ether 13 mL

Methylene chloride 25 mL

Hexane 13 mL

Part D

Benzoic acid 1.2 g
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Ethyl 4-aminobenzoate 1.2 g

1M NaOH 25 mL

1M HCl 25 mL

6M NaOH 6 mL

6M HCl 6 mL

Litmus paper

Part E

1. Acetone 25 mL

Hexane 13 mL

2. We give each pair of students two mixtures. Each mixture
contains 2 mL of each liquid and about 0.1 g of the dissolved
solid. There are many possible combinations of substances to
use. The mixtures we have used contain one of the following
combinations of solid and liquids (the solid is listed first):
fluorene, methylene chloride, water; triphenylmethanol, diethyl
ether, water; salicylic acid, methylene chloride, 1M NaOH;
ethyl 4-aminobenzoate, diethyl ether, 1M HCl; naphthalene,
hexane, water; benzoic acid, diethyl ether, 1M NaOH;
p-aminoacetophenone, methylene chloride, 1M HCl. The
mixtures containing ethyl 4-aminobenzoate and
p- aminoacetophenone should be made up fresh on the same day
as the lab, otherwise the solutions become colored.

3. Tetraphenylcyclopentadienone 0.3 g

Methyl alcohol 13mL

Part F

Self-Assembled Monolayer Demonstration Kit
Available from Asemblon, Inc., 15340 N.E. 92nd St., Suite B,
Redmond, WA 98052; phone [phone]; asemblon.com.
Instructions for filling the Asemblon pen with the thiol are provided
with the kit.

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If done as a demonstration, one kit is sufficient. Otherwise one kit
for every 4 students works well.

Butane to fill the torch for erasing the gold slide

Methyl alcohol 10 mL

Acetone 10 mL

CAS Registry numbers:
Benzophenone 119-61-9
Malonic acid 141-82-2
Biphenyl 92-52-4
Hexanes 73513-42-5
Methyl alcohol 67-56-1
1-Butanol 71-36-3
1-Octanol 111-87-5
Ethyl alcohol (ethanol), 95% 64-17-5
Diethyl ether 60-29-7
Methylene chloride 75-09-2
Benzoic acid 65-85-0
Ethyl 4-aminobenzoate 94-09-7
Acetone 67-64-1
Fluorene 86-73-7
Triphenylmethanol 76-84-6
Salicylic acid 69-72-7
Naphthalene 91-20-3
p-Aminoacetophenone 99-92-3
Tetraphenylcyclopentadienone 479-33-4

SPECIAL NOTES

In Part A, it is very important that students follow the instructions
carefully for stirring the mixtures. The bigger spatula shown in Figure 12.10 on
page 697 of the Textbook is very effective in achieving consistent stirring from
one mixture to another.

We have found that some students have difficulty performing Critical
Thinking Application #2 (p. 9 of the Text) on the same day that they complete
the rest of this experiment. Many students need time to assimilate the material
in this experiment before they can complete this exercise successfully. One
approach is to assign Critical Thinking Applications from several technique
experiments (for example, Experiments 1 - 3) on a laboratory period following
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the completion of the individual technique experiments. This provides an
effective way of reviewing some of the basic techniques.

Part A (expected results)

Compound Water Methyl alcohol Hexane

Benzophenone Insoluble Soluble in about Soluble in about
25 sec 60 sec

Malonic acid Soluble in about Soluble in about Insoluble
10 sec 10 sec

Biphenyl Insoluble Partially soluble Soluble in about
40 sec

Part B (expected results)

Compound Water Hexane

1-Octanol Insoluble Soluble

1-Butanol Partially soluble Soluble

Methanol Soluble Insoluble

Part F

In Part F, a butane torch is used to erase the gold slide. It is best that
this be done by the instructor. When erasing the slide, keep the torch moving
and do not hold it in one spot on the slide. Heating one spot for too long can
cause the slide to shatter.

ANSWERS TO QUESTIONS

1. a) yes 2. a) miscible
b) no b) miscible
c) yes c) miscible
d) no d) immiscible
e) no e) miscible
f) yes f) miscible
g) no
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3. Ibuprofen is a carboxylic acid which is converted to a water-soluble salt
in 1.0M NaOH.

4. Thymol has a phenolic OH group which is acidic. In 1.0M NaOH,
thymol is converted into a water-soluble salt.

5. Cannibinol is only slightly soluble in methyl alcohol because the large
hydrocarbon component of cannibinol negates the fact that they belong
to the same family.

6. When you write on the slide, a monolayer of thiols is deposited on the
slide. The OH groups will be located at the top surface of the coated
area. Since hydroxyl groups are hydrophilic, water is attracted to the
part of the slide that was written on. The rest of the surface is coated
with hydrocarbons from the air and is hydrophobic, so the water rolls off
and does not stick.

7. Water adheres to the gold surface immediately after flame cleaning
because the gold surface is a high-energy surface that attracts water
molecules. Within several minutes, the surface becomes coated with
hydrocarbons from the air, making the surface hydrophobic.

8. A methyl group on the end of the thiol molecule would make the surface
nonpolar or hydrophobic.

9. Heating the slide with a butane torch burns off the thiols.

10. When you write on a glass surface with a crayon or wax pencil, you are
transferring a thick layer of material rather than a monolayer. You can
even see this difference since you can see the film made by the wax, but
you cannot see the monolayer after it forms on the gold slide.

11. This is caused by the very high surface tension of water that allows
water molecules to span the gap of the hole in these letters.

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Experiment 2

CRYSTALLIZATION

TIME ESTIMATE: Parts A and B (3 hours), Parts C (about 1hour)

CHEMICALS AND SUPPLIES PER 10 STUDENTS:

Part A

Impure sulfanilamide (5% fluorenone the impurity) 10 g
Grind thoroughly to make homogeneous.

95% Ethyl alcohol 250 mL

Filter paper for (cid:31)üchner funnel

Melting point capillary tubes

Waste container for non-halogenated organic wastes.

Part B

The appropriate solvent for crystallizing the impure fluorene is methyl
alcohol. Fluorene is too soluble in toluene and insoluble in water at all
temperatures.

Impure fluorene (5% fluorenone as the impurity) 10 g
Grind thoroughly to make homogeneous.

Methyl alcohol 300 mL

Toluene 25 mL

Waste container for non-halogenated organic wastes.

Part C

Acetylsalicylic acid 5 g
Benzoic acid 5 g
Benzoin 5 g
Dibenzoyl ethylene 5 g
Succinimide 5 g
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o-Toluic acid 5 g

Prepare unknowns consisting of pure samples of the above 6
compounds; about 0.2 g for each unknown sample.

Part D (Answers)

1. Phenanthrene
95% ethyl alcohol - best solvent
water - not soluble
toluene - too soluble

2. Cholesterol
ether - too soluble
95% ethyl alcohol - best solvent
water - not soluble

3. Acetaminophen
95% ethyl alcohol - too soluble
water - best solvent
toluene - not very soluble

4. Urea
Water - too soluble
95% ethyl alcohol - best solvent
Hexane - not very soluble

CAS Registry numbers:
Sulfanilamide 63-74-1
Acetanilide 103-84-4
95% Ethyl alcohol (Ethanol) 64-17-5
Fluorene 86-73-7
Fluorenone 486-25-9
Methyl alcohol (methanol) 67-56-1
Toluene 108-88-3
Acetylsalicylic acid 50-78-2
Benzoic acid 65-85-0
Benzoin 119-53-9
Dibenzoyl ethylene 4070-75-1
Succinimide 123-56-8
o-toluic acid 118-90-1

SPECIAL NOTES

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In the Pre-lab Calculations for Part A, students calculate the amount of
sulfanilamide which will remain in the mother liquor. If they perform the
Optional Exercise in Part A, they determine the weight of solid in the mother
liquor. However, the actual weight of solid in the mother liquor is usually much
greater than the amount calculated in the Pre-lab Calculations. This is because
the calculation does not take into account the impurity, which ends up in the
mother liquor. Also, the calculation assumes that a minimum amount of solvent
is used to dissolve the impure sulfanilamide at 78 oC. It is likely that most
students use more than the minimum amount.

ANSWERS TO QUESTIONS

1. Too much solvent was added. Since 10 mL of 95% ethyl alcohol will
dissolve 0.14 g of sulfanilamide at 0 oC, none of the 0.1 g of
sulfanilamide will crystallize when the solution is cooled. To make the
crystallization work, the excess solvent must be evaporated.

2. The boiling point of the solvent is higher than the melting point of
fluorenol. While performing this crystallization, it is possible that the
fluorenol would melt rather than dissolve, thus forming an oil which
could be difficult to crystallize.

3. Biphenyl is highly soluble in both hot and cold benzene. The solubility
curve would like C in Figure 11.1 on page 663 of the Textbook.

Experiment 3

EXTRACTION

TIME ESTIMATE: Parts A-D (3-4 hours); Part E (30 minutes)

CHEMICALS AND SUPPLIES PER 10 STUDENTS:

Part A

Caffeine 2.2 g

Methylene chloride 200 mL

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Anhydrous sodium sulfate (granular) 38 g

Evaporation station in a hood (optional)

Waste containers for aqueous and non-halogenated organic wastes (note:
there will be some methylene chloride in the aqueous waste)

Part B

(These quantities are based on the assumption that each student does this part
with only one of the compounds.)

Benzoic acid 0.4 g

Succinic acid 0.4 g

Sodium benzoate 0.4 g

Methylene chloride 25 mL

Anhydrous sodium sulfate (granular) 5 g

Evaporation station in a hood (see “Equipping the Organic Chemistry
Laboratory” earlier in this manual).

Waste containers for aqueous and non-halogenated organic wastes (note:
there will be some methylene chloride in the aqueous waste)

Optional Exercise in Part B

Caffeine 1.0 g

Methylene chloride 30 mL

Anhydrous sodium sulfate (granular) 5 g

Part C

We give a set of all three mixtures to each pair of students. Each
mixture contains about 2 mL of each liquid. The three mixtures are: (1) water
and n-butyl chloride; (2) water and n-butyl bromide; and (3) n-butyl bromide
and saturated aqueous sodium bromide. It is best if the aqueous sodium
bromide is not quite saturated. Otherwise, it may salt out when mixed with
n-butyl bromide. Do not dilute it too much, however, since it should be more
dense that n-butyl bromide. Each mixture should be prepared in a stoppered
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test tube or centrifuge tube.

Waste container for halogenated organic wastes.

Part D

Each student receives an unknown which contains 0.24 g of a neutral
compound and 0.12 g of benzoic acid, the acid impurity. The neutral compound
should be one of the following: fluorenone, fluorene,
1,2,4,5-tetrachlorobenzene, or triphenylmethanol.

1.0M NaOH 120 mL

6.0M HCl 12 mL

Saturated aqueous NaCl 60 mL

Diethyl ether 120 mL

Anhydrous sodium sulfate (granular) 10 g

Litmus paper

Evaporation station in a hood (see “Equipping the Organic Chemistry
Laboratory” earlier in this manual).

Waste containers for aqueous, non-halogenated and halogenated

Optional Exercise in Part D

Each student receives an unknown which contains 0.24 g of a neutral
compound and 0.12 g of ethyl 4-aminobenzoate, the base impurity. The neutral
compound should be one of the following: fluorenone, fluorene,
1,2,4,5-tetrachlorobenzene, or triphenylmethanol.

1.0M HCl 120 mL

6.0M NaOH 12 mL

Saturated aqueous NaCl 60 mL

Diethyl ether 120 mL

Anhydrous sodium sulfate (granular) 10 g

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