Final

Question 1

Experiment 15: Basis of separation in thin-layer chromatography

Answer 1

Certain compounds will travel further due to the differences in their structure and functional groups, which causes different compounds to be either more or less partial to the developing solvent.

Question 2

Experiment 15: How to calculate Rf

Answer 2

Compound/Solvent

Question 3

Experiment 15: What compound travels further?

Answer 3

The less polar one. Not always obvious.

Question 4

Experiment 9: Lycopene absorbs in 400-500 nm region. Why? What color is it? How can you explain this?

Answer 4

It’s long conjugated system
Red

Red light is reflected, other wavelengths absorbed.

Question 5

Experiment 9: You mix acetone, water, and petroleum ether in separator funnel. How many layers? What is in each layer?

Answer 5

Two Layers.

Petrolumn ether/water on top (less polar)

Acetone on the bottom

Question 6

Experiment 9: in a silica-gel column, what is first, what is last, and why?

Answer 6

1. Beta-Carotene (less CDB)
2. Lycopene (More CDB)
3. Zeaxanthin (Hydroxyl groups)

Zeaxanthin is last because it contains polar hydroxyl groups that are strongly attracted to alumina.

Lycopene has 13 double bonds and is more attracted to the alumina than beta carotene, which only has 11-12.

Question 7

Experiment 26: What is addition polymerization?

Answer 7

Adding monomers together (polymerizing them) without any additional by products.

Question 8

Experiment 26: what is condensation polymerization?

Answer 8

Another type of polymerization involving the loss of small molecules, such as HCl or H2O.

Question 9

Experiment 26: Chain-growth polymerization.

Answer 9

The one actually done in experiment 26.

Involves an initiator (benzoyl peroxide) being exposed to heat/light which begins the polymerization by adding each monomer onto the next (like a chain)

Question 10

Experiment 26: Step-growth polymerization

Answer 10

Involves each monomer being added to the next by a different initiator (they don’t all add at once)

Question 11

Experiment 26: What is the initiation step of polymerization of styrene?

Answer 11

The initiating step is when benzoyl peroxide is exposed to heat/light which causes it to break down, heading to the next step, the propagation of radicals.

Question 12

Experiment 29: Define reduction.

Answer 12

Gaining of hydrogen or loss of oxygen.

Question 13

Experiment 29: Does NaBH4 reduction involve electrophilic or nucleophilic addition to carbonyl carbon? What is actually being added.

Answer 13

Nucleophilic

2 hydrogen atoms

Question 14

Experiment 29:

We use sodium borohydride instead of LiAlH4 because LiAl H4 reacts violently with water and other hydroxylic solvents to release _____. It is best to use _____% excess sodium borohydride. The reaction is _____ ____ in respect to sodium borohydride (as well as the carbonyl), using excess increases reaction rate.

Answer 14

LiAlH4

Hydrogen

50-100%

First Order

Question 15

Experiment 29: Sodium borohydride solutions are usually carried out in ____ ____ ____ solutions or an ______.
The reagent is NOT stable at ____ pH.
_____ temperatures may decompose sodium borohydride, and adding ____ _____ to alkaline ____ _____ solutions may cause side reactions of base-sensitive substrates.

Answer 15

Dilute aqueous NaOH

Alcohol

Low pH

High Temperatures

Carbonyl Compounds

Alkaline Sodium Borohydrides Solution

Question 16

Experiment 29: _____ are considerably more reactive substrates than _____ and that aliphatic carbonyls compounds are more reactive that aromatic ones.
The excess sodium borohydride is decomposed by adding ___ to the reaction mixture slowly while stirring.

Answer 16

Aldehydes

Ketones

Adding HCl

Question 17

Experiment 40: The insect repellant “6-12” or 2-ethyl-1,3hexanediol (IUPAC name) is manufactured by ____ condensation reaction of butanol followed by reduction reaction using ____ and ____.

Answer 17

Adol

H2 and Ni

Question 18

Experiment 40: 6-12 contains two _____ groups will be transformed to a _____ compound through an ______ reaction using the environmentally friendly oxidizing agent _____.

Answer 18

Alcohol

C=O (ketone)

Oxidation

NaClO

Question 19

Experiment 40: Acetic acid is added to reaction mixture to convert NaOCl to _____ which is probably actual oxidant. Iodide-starch test paper turns _____ if excess NaOCl. If the test is ____ at any time, you will need more NaOCl. The reaction is _______ so it’s important to stir reactant vigorously to keep the layers well mixed. When reaction is complete, unreacted NaOCl can be converted to ____ by adding _____.

Answer 19

HOCl

Blue-black

Negative

NaOCl

Heterogenous

NaCl, NaHSO3

Question 20

Experiment 37: Typical Friedel-Crafts acylation reaction uses a ____ ___ ___ as the acylation agent and anhydrous ___ ____ as the catalyst. When the acyl group is acetyl, _____ moles of ____ is often used as acylating agent because some of the acylating agents forms complexes with the ___ ___ produced during the reaction, making it an ineffective catalyst.

Answer 20

Carboxylic acid chloride

Aluminum Chloride

2-3, AlCl3

Acetic Acid

Question 21

Experiment 37: This reaction is highly _____ so it will be carried out by adding acetic anhydride _____ to other reactants, and then heating under reflux to complete the reaction. Pouring the product into ice water will ____ the aluminum chloride complex of the product and transfer inorganic salts to the aqueous phase. Your product is both a ___ and ____.

Answer 21

Exothermic

Slowly

Decompose

Ether and a Ketone

Question 22

Experiment 15: Operations. Thin Layer Chromatography

Answer 22

Put the TLC plate in the developing chamber (beaker), with a developing solvent. Put a paper wick around, and mark the starting line at the bottom, and measure how far up it travels.

Question 23

Experiment 9: Operation Column Packing

Answer 23

Separator funnel with elunt - chromatography column - beaker (collector). Inside column should be bottom to top: glass wool, sand, absorbent, sand, eluent level.

Question 24

Experiment 26: IR for styrene polymer

Answer 24

Benzene H’s around 3000-3200.
-CH/CH2 around 1600.

C-C around 1130

Question 25

IR C=O

Answer 25

Aroun 1600-1700

Question 26

IR -O-

Answer 26

around 1200-1300

Question 27

IR C=C

Answer 27

1500-1600

Question 28

IR 2x -OH signals

Answer 28

Around 3500, then again from 3200-3000

Question 29

IR -OCH3

Answer 29

1275-1200, 1775-1720

Question 30

H NMR Aldehydes, and alcohols

Answer 30

Aldehydes are 9.6-10ppm.

Alcohols are 3.4-3.5ppm, exception is vanillin which has alcohol at 7ppm and product at 4.5ppm.

Question 31

Aromatic Benzene H’s vs. C=C H’s. HNMR

Answer 31

Aromatic 7.5-8ppm

C=C H’s are 6.5-6.6ppm.

Question 32

H NMR:

Ethers (-OCH3)

Answer 32

3.5-4.0ppm

Question 33

H NMR: Ketones and Esters (R-C=O, OR’)

Answer 33

around 2.5ppm

Question 34

H NMR: Carboxylic Acids

Answer 34

11ppm