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
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