Do you expect chlorophyll b to be more or less polar than chlorophyll a? why? |
Chlorophyll b is more polar than chlorophyll a because chlorophyll a has a methyl group in the same position that chlorophyll b has an aldehyde |
Do you expect xanthophyll to be more or less polar than B-carotene? |
Xanthophyll would be more polar than B-carotene because there is an alcohol on one of the phenol groups of xanthophyll |
Would you consider ethyl acetate to be a polar or non-polar solvent? |
I would consider ethyl acetate a polar solvent b/c the two oxygens pull the compound in different directions |
Why do we mark TLC plates with pencil and not with pen? |
The ink from pen is polar so it will run up the TLC plate along with the TLC solvent |
Why is it important not to dilute the initial sample before it has been loaded onto the chromatography column? |
If one dilutes the initial sample prior to it being loaded onto the chromatography column, it would become a wide band in the column. You wouldn’t be able to separate the compounds. |
How do you calculate Rf? |
(distance from origin to center of spot)/(distance from origin to solvent front) |
A more polar compound would be closer or farther away from the origin point? |
closer |
Which compound would you expect to elute first from the column: unreacted ferrocene, acetylferrocene, or diacetylferrocene? |
Unreacted ferrocene would elute first from the column because it is the least polar of the group |
What is a monomer? |
the repeating units of polymers |
What is a repeating unit? |
some molecule that is binded together repeatedly until a polymer is formed |
What is condensation polymerization? |
reaction where molecules join together to form polymers |
What is a cross-linked polymer? |
a polymer formed from the linkage of two polymers |
What are the layers formed when using interfacial polymerization from bottom to top? |
sebacoyl chloride -> hexamethylenediamine -> Nylon 10,6 |
Why cant we use vinyl alcohol in polymerization? |
Vinyl alcohol almost always exists as the tautomer |
What is the purpose of sodium carbonate in the Dyeing lab? |
Sodium carbonate deprotonates napthol resulting in an alkoxide ion |
Why do we add glacial acetic acid in Part 1B when we react with N, N-dimethylaniline, but we don’t use it with the other aromatic coupling reagents? |
Glacial acetic acid catalyzes the aniline, but not completely |
Which fabric was the most difficult to dye? |
Dacron (polyester) |
Which fabric was the next most difficult to dye? |
Orlon |
Which solvent ratio gave the best separation of the pigments? Why? |
50:50 ratio of hexane and ethyl acetate; It allowed there to be both a strong stationary phase and a strong moving phase |
Which pigment in the spinach lab was the least polar? |
Beta-carotene because it went the highest on the TLC plate |
Which pigment in the spinach lab was the most polar? |
chlorophyll B since it was the closest to the origin point |
How do you explain the difference in polarity of the two chlorophylls in your sample? |
Chlorophyll b is more polar than chlorophyll a because chlorophyll b has an aldehyde in the same position that chlorophyll a has a methyl group |
Why dont we simply oxidize p-toluidine with KMnO4 to make p-aminobenzoic acid? |
KMnO4 is a strong oxidizing agent and would oxidize the product past p-aminobenzoic acid |
In the benzocaine step, why dont we do the esterification step prior to the deprotection step? |
the nitro group would also undergo esterification therefore resulting in a mixture of the products |
What is a melting point? |
the temperature at which the solid phase is in equilibrium with the liquid phase |
What is acetophentidin? |
a synthetic compound that acts as an analgesic and an antipyretic |
What is an analgesic? |
Pain reliever |
What is an antipyretic? |
fever reducer |
What is the chemical name of acetophenetidin? |
4-ethoxyacetanilide |
What are the two ways to make acetophenetidin? |
Williamson ether synthesis of p-acetamidophenol and Amide synthesis with p-phenetidine |
How does recrystallization work? |
An impure sample is dissolved in a minimum amount of solvent at the boiling point. Any insoluble impurities are typically removed by hot gravity filtration. The hot, saturated solution is then allowed to cool slowly to room temperature |
During the cooling process after recrystallization, what occurs? |
Small, pure seed crystals of the desired compound are formed in the solution. These seed crystals serve as nucleation sites where more molecules of the desired compound deposit themselves in layers |
Why is the p-phenetidine sample reddish-brown? |
there is a small amount of impurities caused by air oxidation of the amino functional group in the compound |
Why do we use decolorizing carbon in the acetophenetidin lab? |
to remove the colored impurities from the p-phenetidine sample |
How do you calculate percent yield? |
(actual yield/theoretical yield) x 100 |
What is the best recrystallization solvent for acetophenetidin? |
water |
How do you calculate theoretical yield? |
moles of limiting reagent X molecular weight of product |
What is extraction? |
a technique that chemists use to remove selected components from a mixture, usually based on solubility differences or chemical reactivity |
Solid-liquid extractions are usually performed with… |
liquid CO2 |
What does immiscible mean? |
not soluble in each other |
Whats the difference between extracting and washing? |
In extractions, you are pulling the compound from one thing to another. When washing, you are simply trying to get rid of impurities. |
Draw an electrophilic aromatic substitution? |
Draw it bitch (pg. 63) |
Why do the functional groups that are already present on the aromatic ring influence the placement of new substituents? |
The intermediate formed in the EAS reaction is a charged species that is stabilized by resonance |
In the EAS lab, why do we use sodium iodide and household bleach? |
Sodium iodide is the source of iodine and bleach is the oxidizer |
What was the color change during the iodination of salicylamide? |
Reaction went from orange-yellow to pale green |
What is the mobile phase? |
when the mixture is placed in a gas or liquid phase |
What is the stationary phase? |
a solid support that contains the absorbent |
The components of the sample mixture pass through the stationary phase as areas of concentration called… |
bands |
What is the eluent? |
the solvent that is used for the mobile phase |
What is one way in which chain addition and condensation polymerization is different? |
a chain addition usually involves a vinyl-type monomer |
In the Benzocaine lab, what does a purple halo with brown in the middle during the halo test mean? |
There are still unreacted reagents present in the reaction mixture and you need to continue heating |
In the benzocaine lab, if the purple halo is no longer present, what has occurred? |
The oxidation of the methyl group is finished and the reaction is complete |
What color should the solution be after boiling and passing the halo test in the benzocaine lab? |
colorless or light pink |
What were the steps in the Benzocaine experiment? |
Protection, deprotection, esterification |
Orgo Lab Final Quiz
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