Orgo Lab Final
c
A 1H NMR spectrum of an organic molecule showed two signals: a triplet and a quartet. Which of themolecules shown would exhibit this splitting pattern?
a
A reaction has yielded a phenol (pKa 10) dissolved in an aqueous solution at pH 12, but you want to isolate the phenol as a powder. Which option below might successfully isolate the phenol as a powder? (a) Adjust the solution to pH 7 with HCl, then extract into ether and evaporate the ether with a rotovap (b) Extract the phenol into ether, then evaporate the ether with a rotovap (c) Precipitate the phenol by adding brine (d) Extract the phenol into ethanol, then evaporate the ethanol with a rotovap (e) Adjust the pH to 14 with NaOH, then extract with ether and evaporate the ether with a rotovap
d
A student carried out an organic synthesis and obtained 2.63 grams of crude product. The student decidedto recrystallize 1.50 grams of the product, and they recovered 1.28 grams of pure material. What is thepercent recovery for the recrystallization? a) 49% b) 57% c) 74% d) 85% e) 90%
0.27, Compound A, more polar
A student conducted an organic reaction where 1 mole of Compound A was reacted with 1 mole of Compound B. The TLC plate below was spotted with Compound A, Compound B, and a sample from the reaction mixture (Rxn mix) and shows the results after eluting with 50/50 ethyl acetate/hexane. Given these results, use the dropdowns below to answer the following questions: a) What is the Rf value for Compound B? b) Which compound, A or B, was the limiting reagent in this reaction? c) Consider the lane that shows the reaction mixture. Are the starting materials more or less polar than the reaction product?
b
A student reacted 1.43 grams of salicylamide (137.14 g/mol) and 1.72 grams of sodium iodide (149.89g/mol) to produce iodosalicylamide (263.03 g/mol). Calculate the theoretical yield for this transformation. a) 2.51 g b) 2.74 g c) 3.02 g d) 3.15 g e) 3.30 g
c
A student was asked to prepare 8 mL of a 6:4 eluent solution of solvent A: solvent B for their TLC developing chamber. What volumes of solvent A and solvent B are needed to prepare the requested eluent mixture? a) 4.4 mL of solvent A and 3.6 mL of solvent B b) 4.4 mL of solvent A and 2.9 mL of solvent B c) 4.8 mL of solvent A and 3.2 mL of solvent B d) 5.4 mL of solvent A and 2.6 mL of solvent B
b
A student was carrying out a reaction in the organic lab. At a point during the reaction, the reactionmixture (R) was spotted on a TLC plate along with a reference of the starting material (S) which is thelimiting reagent. The plate was then eluted with 60:40 hexane/ethyl acetate. What can you concludeabout the reaction from the TLC results shown here? a) The reaction is complete, and there are two products formed b) The reaction is not yet completed since there is unreacted starting material present c) The product of the reaction is more polar than the starting material d) Both (b) and (c) are correct e) None of these statements are correct
b
A student was setting up a block copolymer reaction, and while he was transferring the reactants to thevial, he dropped a small amount of the initiator on the benchtop. How will this impact the molecularweight of the polymer that is formed? a) lower MW than expected b) higher MW than expected c) no impact on molecular weight
c
A student's notebook entry is given below for the synthesis of Nylon 10,6 that was done during thepolymers lab. Consider the underlined statements, and indicate how many of these statements areincorrect."The Nylon-10,6 is a polyester polymer which was synthesized from sebacoyl chloride andhexamethylene diamine as shown above. This is an example of a condensation polymerizationwhere water was obtained as the byproduct. The product (Nylon-10,6) was readily soluble inorganic solvents such as toluene and acetone." a) 1 b) 2 c) 3 d) 4 e) no incorrect statements
a
The purpose of using a trap during vacuum filtration is to catch any overflowing filtrate before it can enterthe house vacuum system. a) True b) False
a
Two groups of students (Group A and Group B) analyzed the pigments present in a spinach extract by thin layer chromatography (TLC). For the extract preparation, both groups ground a mixture of spinach, sand, and magnesium sulfate using a mortar and pestle. The mixture was transferred to a test tube and anhydrous acetone was added. The mobile phase of the TLC was 30:70 hexane/ethyl acetate for both groups. Group A observed a good separation of the pigments, while Group B recorded larger Rf values and some spots were overlapping. Which mistake Group B could have done? (a) Not adding enough magnesium sulfate to remove the water from the spinach (b) Not adding enough acetone for the pigments extraction (c) Not using enough spinach to extract the pigments (d) Not adding the filter paper to the TLC developing chamber
b
Two students synthesized aspirin (lit. m.p. = 135°C) and measured melting points of their samples: StudentA recorded 131-135°C and Student B recorded 133-134°C. Which statement is correct about these samples? a) Sample A is more pure than sample B. b) Sample A is less pure than sample B. c) Both samples are equally pure. d) Purity cannot be determined using melting point.
addition or chain-growth, condensation or step-growth, and cross-linked
What are 3 general classes of polymers
1) a chain addition usually involves a vinyl type monomer 2) a chain addition creates polymers that have a simple hydrocarbon backbone and any functional group is pendant to the polymer chain 3) the empirical formula of a chain addition polymer is identical to that of a monomer
What are the 3 ways that chain addition differs from vinyl-type moment
very brittle and stiff
What are the characteristics of poly(L-lactide)
end groups are ch3 and repeating units are ch2
What are the end groups and repeating units of octane?
ethanol and biodiesel
What are the two most common biofuels for transportation
Pechmann condensation and Knoevenagel condensation
What are the two reactions to make coumarin derivatives?
williamson ether and amide (we only did amide in class)
What are the two synthetic methods used to form acetophenetidin
orange
What color is the acetylferrocene when it elutes
red
What color is the diacetylferrocene when it elutes
yellow
What color is the ferrocine when it elutes?
pale yellow
What color is the reaction in EAS after you add the bleach and let it sit for 10-15 minutes
polystyrene
What did we make in the lab with our chain addition polymerization?
nylon-6,10
What did we make in the lab with our condensation polymerization?
ferrocine, cospot, and product
What do the F, C, and P stand for on the TLC plates in the acetylation of ferrocine
increase the amount of nonpolar solvent
What do you do with the solvent if something flowing too fast in the mobile phase when using a TLC plate for chromatography
increase the amount of polar solvent
What do you do with the solvent if something is too stuck to the baseline in using a TLC plate for chromatography
OH is an activating, ortho/para directing substituent. The amide group is a deactivating meta directing substituent. These two groups reinforce eachother, so there is no electron donating group dominating the positioning.
What do your results tell you about the directing effects of the substituents on salicylamide. Interpret both IR and 1HNMR data (EAS lab)
functional groups
What does IR spec tell?
grams compound per mL organic solvent/grams compound per mL water
What does Kd equal
structure and bonding of the molecule
What does NMR spec tell?
The device heats up faster
What does a higher ramp rate mean
less polar compound
What does an Rf close to 1 indicate
it is more efficient to do multiple extractions using smaller volumes of organic solvents
What does the Kd usually tell about the number of extractions?
3-acetyl-7-(diethylamino)-2H-1-benzopyran-2-one
What does the Knoevenagel reaction produce?
the number of repeat units of the copolymer
What does the amount of initiator affect
spinach, chlorophyll b, B-carotene
What does the s, b, and c stand for on the TLC plate made with the best solvent?
not just removing water, it means that the solution contains no dissolved water
What does the term "drying" mean in organic chemistry
lowers and broadens it
What effect does the presence of a soluble impurity have on the melting point?
no effect
What effect does the presence of an insoluble impurity have on the melting point?
it will begin to solidify into an opaque solid
What happens if you let the polymer cool for more than 2 minutes in the copolymers lab?
may be slow to anneal
What happens in samples with large amounts of L-lactide incorporation and a high yield
it changed to a variety of colors
What happens to the strip when it was treated with the test identification stain?
influence speed at which compounds will elute through stationary phase
What happens when we change the ratio of solvents in the eluent mixture?
soap, and several portions of DI water and brine for breaking up foam
What is a common byproduct of formation of biodiesel and how can it be removed?
vegetable oils and a simple transesterification catalyzed by hydroxide ion
What is biodiesel made from and how is it made
techniques for separating, analyzing, and identifying compounds
What is chromatography
acid base indicator
What is congo red also used for
it must be level so the column elutes properly
What is important about the sand when packing the column?
the initiator in our reaction was a diol, so the number of repeating units will be divided between the two reactive sites, giving n/2 repeating units on either side of the initiator
What is important in terms of determining the repeating units per chain in the copolymers lab that we did in class
neutralization and HCl
What is needed to be done in extraction after the desired compound has been extracted into the aqueous phase and what is used to do this process?
it has polar sulfonate groups that interact well with other polar sites in fibers
What is significant about the azo dyes that you made
they have alcohol functional groups on the end of the polymer chain, meaning they can act as initiators for the polymerization of a second monomer
What is significant about the first polymers synthesized in the copolymers lab?
the stationary phase is packed into a glass tube or column that is equipped with a stopcock
What is the difference between column chromatography and TLC?
the length of the side chain which can change the properties of the corresponding copolymer
What is the difference between decalactone and dodecalactone
extraction removes the desired compound from its current solution and washing means removing impurities from a solution while leaving behind the desired compound
What is the difference between extracting and washing
their stability to temperature changes and resistance to corrosion and degredation make them great for commercial purposes, but can have harmful effects to our health and environment
What is the double edged sword of polymers
mol monomer/mol initiator
What is the formula to find the number of repeating units per chain?
polar head and nonpolar tail, a micellin
What is the generic structure of soap
to look at different ratios of poly(L-lactide) incorporation in either dodecalactone or decalactone and see how it influences properties such as flexibility, clarity, tackiness, or other properties
What is the point of the copolymers lab
e
What is the purpose of dilute HCl in the synthesis of Acetophenetidin? (a) To activate the decolorizing carbon (b) To protonate the acetic anhydride making it a better nucleophile (c) To protonate the p-phenetidin to make it a better nucleophile (d) To neutralize excess sodium acetate used in the reaction (e) To protonate p-phenetidin to increase its solubility in the solution
b
What is the purpose of sodium thiosulfate in the iodination of salicylamide? (a) Acidifies the reaction mixture (b) Removes any residual iodine from solution (c) None of these (d) Removes any residual salicylamide from solution (e) Precipitates the product
it supports the packing material and prevents it from clogging the stopcock during elution
What is the purpose of the cotton in the column?
it acts as a buffer to drive the reaction forward
What is the purpose of the sodium acetate solution in the amide synthesis of acetophenitidin?
it removes a proton from HSO3- and makes sulfonic acid soluble and electron rich, so it is highly activated
What is the purpose of the sodium carbonate in Part 1A of the dyes lab?
we can generate a variety of dyes using the same synthetic pathway
What is the purpose of using a combinatorial approach for dye synthesis?
b
What is the role of potassium hydroxide in the synthesis of biodiesel? (a) Potassium hydroxide is the nucleophile that reacts with the triglyceride to form biodiesel. (b) Potassium hydroxide reacts with methanol to form potassium methoxide. (c) Potassium hydroxide deprotonates the oil. (d) Potassium hydroxide is a Lewis acid that activates the ester for faster transesterification.
remove any residual iodine from solution
What is the role of the sodium thiosulfate in the EAS reaction
d
What is the splitting pattern for the underlined protons in the molecule shown? (a) triplet (b) singlet (c) doublet (d) quartet
the greater the L-lactide, the more crystalline properties and the less flexible
What is the trend between increasing %L-lactide incorporation in the synthesis of copolymers?
two monomers react to form a larger unit while a small molecule is eliminated
What occurs in the condensation polymerization
chlorophyll B
What pigment in the spinach lab was the most polar (moves the least)
amorphous is PDDL because of its saturation and crystalline is L-lactide because of its ability to bond
What polymer is amorphous block and what is crystalline block in the copolymers lab?
4-methylumbelliferone
What product is the Pechmann (green synthesis) making?
Pechmann
What reaction is green synthesis doing
b
What should you do if some of your product still remains in the reaction flask when you are trying to collectit via vacuum filtration? a) Dissolve the product, and pour the solution into the Büchner funnel b) Use some of the reaction solvent to transfer the product into the Büchner funnel c) Dissolve the product, and pour the solution into the liquid waste d) Wait for the product to be mostly dry, and then scrape it into the solid waste e) Dispose of the flask in the solid waste and obtain a replacement from the stockroom
CO2 (dry ice in our case)
What solvent is usually used to perform solid-liquid extractions?
50-50 between hexane and ethyl acetate because there was a strong stationary phase and a strong moving phase simultaneously
What solvent ratio gave the best separation of pigments and why?
d
What type of chemical interaction(s) will cause a dye to adhere to a piece of fabric? a) van der Waals attractions b) hydrogen bonding c) covalent bonding d) all of the above
a
What type of organic reaction is the aryl diazonium coupling shown below? a) Electrophilic aromatic substitution b) Nucleophilic aromatic substitution c) E2 elimination d) SN1 substitution e) SN2 substitution
cross-linked
What type of polymer is slime
4-methyl was a green color and 3-acetyl was blue
What was the color of the fluorescence of 4-methyl vs the 3-acetyl
D-limonene
What was the orange oil that we extracted called?
a
What was the role of Dowex 50WX4 beads in the coumarin synthesis? a) acid b) base c) drying agent d) nucleophile e) filter agent
No purification has occurred
What would happen if you chose a re-crystallization solvent that is insoluble to impurities too at cold temperatures
e
When aqueous 2 M HCl is added to an organic phase inside a separatory funnel, a new layer forms at thebottom of the funnel as the organic phase rises to the top. Which of the following can be concluded basedon this observation? a) Most of the major product is present in the aqueous layer b) Most of the major product is present in the organic layer c) The solvent in the organic phase has a density greater than 1 g/mL d) The concentration of the aqueous phase is less than the concentration of the organic phase e) The solvent in the organic phase has a density less than 1 g/mL
F
When choosing a recrystallization solvent, you want to use a solvent in which both the product and impurities are highly soluble at all temperatures. True or False
d
When conducting an extraction, the bottom layer in the separatory funnel is always the ____ . (a) aqueous phase (b) less dense solution that is being used (c) organic phase (d) more dense solution that is being used
b
When do you record the first temperature within the melting point range of a sample? a) When the sample starts to compress b) When you see the first drop of liquid in the capillary c) When the entire sample in the capillary is a liquid d) When you press start on the instrument
c
When performing a polymerization, why is it important to know the exact amount of initiator used? a) The initiator is highly reactive and can dimerize if used in excess. b) When too much initiator is used, the molecular weight of the polymer will be higher than expected. c) The amount of initiator determines the number repeat units in the polymer. d) The initiator requires a catalyst to react.
the minimum amount possible, you may not need to use the entire amount
When you dissolve the solid pieces of polymer, how much ethyl acetate should you use
ortho/para position
Where do electron donating groups direct substituents
meta position
Where do electron withdrawing groups direct substituents
d
Which molecule is most likely represented by the IR spectrum shown here (attached)? (a) hexane (b) hexanoic acid (c) 2-hexene (d) 3-hexanol
d
Which of the following is not a valid resonance structure for 4-(diethylamino)salicylaldehyde (shown at the right):
a
Which of the following wavelengths of light is the highest in energy? (a) 250 nanometers (b) 3 centimeters (c) 400 micrometers (d) 450 nanometers
b
Which of the molecules listed below is most likely to give this IR spectrum (attached)? (a) hexane (b) 1-hexene (c) 2,3-dimethyl-2-butene
b
Which of the sequences below represents a block copolymer? (Assume "A" and "B" as two different repeating units.) (a) none of these is a block copolymer (b) ·····AAAAAAABBBBBBBBB····· (c) ·····ABABABABABABABAB····· (d) ·····AABABBBABABBABAA·····
b
Which of these esters would give the proton NMR spectrum shown? (a) ethyl acetate (b) methyl propionate (c) propyl formate
amide synthesis
Which procedure, Williamson ether or amide synthesis is more green?
it exists largely in the keto form which is not accessible to react in this polymerization, thus vinyl alcohol is too unstable to use
Why can't we use vinyl alcohol in the polymerization of PVA?
the acid halide is more reactive
Why did we use diacid chloride in this experiment rather than dicarboxylic acid that is typically used industrially?
because the inorganic solids that do chromatography have many sites for hydrogen bonding
Why do more polar compounds absorb more readily into the stationary phase than nonpolar compounds
Aniline derivatives are highly activated unless they become protonated. it will catalyze without fully protonating the aniline, some of the glacial acetic acid won't react with aniline to initiate reacting with the diazonium salt
Why do we add glacial acetic acid in part 1B when we react with N,N-dimethylaniline, but we dont use it with the other aromatic coupling reagents?
it removes the colored impurities from the sample caused by air oxidation of amino functional group
Why do we use the activated carbon as the first step in synthesis of acetophenetidin?
prevent methanol from evaporating
Why do you cork the flask after pouring methanol into KOH
prevent steam pockets
Why do you stir the vegetable oil periodically when heating
the stem could develop crystals on it which could affect your yield as well as create a blockage
Why do you use the stemless funnel for hot gravity filtration?
e
Why does the boiling point of a solvent drastically drop in a rotovap? (a) the density of the solvent is being reduced (b) the cold water in the condenser lowers the boiling point of the solvent (c) the reaction mixture is being heated in the water bath (d) there is a greater surface area due to rotating the flask (e) the pressure in the system is being lowered
they may lack the types of functional groups necessary to interact with the polar dyes
Why don't some fibers work well to dye
the oil from your fingertips can contaminate the plates
Why is it important to handle the TLC plates by the edges
if you boil all of the methoxide out of the solution, there will just be water remaining which will make exclusively soap and no biodiesel
Why is it important to monitor the temperature of the oil prior to adding the potassium methoxide solution and not exceed the target range?
the entire sample must enter the column in as compact of a band as possible and very subtle differences must be recognized between different samples and concentrated solutions can best distinguish this.
Why is it not important to dilute the initial sample before it has been loaded into the chromatography column
b
Without doing a calculation, which of the bonds below would you expect to have the higher stretching frequency? (a) C-O (b) C=O
a
You are asked to recrystallize succinic acid with one of three solvents (hexane, ethanol and acetone). The solubility data for each is shown in the table below. Which one is the best solvent to obtain the highest yield for the recrystallization? (a) Acetone (b) Hexane (c) Ethanol
4.31
You are asked to synthesize 8.83 grams of coumarin via Pechmann reaction. Assuming that your reaction will proceed with 100%, what volume (mL) of resorcinol is required? Report your answer to two decimal places.
0.72
You conducted a TLC experiment and found that your compound traveled 6.75 cm and the eluting solvent traveled 9.33 cm. What is the Rf value for your compound? Report your answer to two decimal places (i.e., 0.01).
d
You need to use your separatory funnel for an extraction, but you notice that there is some residual water in it from when it was washed during the previous lab period. What should you do? (a) Use a paper towel to dry the inside of the funnel prior to using it again (b) Borrow a lab mate's funnel and wait for yours to dry (c) Take the funnel to the stockroom and ask to exchange it (d) Go ahead and use the funnel - you will be adding aqueous solutions anyway
2.04
You were asked to dissolve 9.61 g of compound A in 60 ml of water. After single extraction with 60 ml ether, you recovered 6.45 g of compound A from the ether layer. Calculate the Kd value for the compound A in ether/water system. Report your answer to 2 decimal places (i.e., 0.01). Recall that
using acetic anhydride
how do we generate our acylium ion electrophile in the acetylation of ferrocine
vacuum filtration and then wash the solid with 2mL saturated sodium chloride to rinse the dark liquid from the product
how do you collect the product in the dyes lab?
black
if all light is absorbed, what color does the object appear
under UV light
if compounds on the TLC plate are not colored, how are they visualized
it must be dry
in the acetytation of ferrocine, what is an important fact about the glassware?
the white is the reduced form because it has two OH groups compared to the blue that has two carbonyl groups and oxidation
looking at the structures of blue indigo and white indigo, how can you tell that the white indigo is in the reduced form? what chemical process happens as the fabric dries
an amide linkage was formed between an acid halide and an amine with an elimination of HCl
what actually happened in the condensation polymerization that we did in class
a compound that is highly conjugated and usually has a characteristic group such as an azo (-N=N-), nitro, or carbonyl
what are chromophores?
chlorophyll a and b, B-carotene, xanthophylls
what are the phytonutrients that are highly colored compounds and can be separated using chromatography
to rinse the diazonium salt residue
what do you use a few drops of water for in the dyes lab
they are all chromophores
what is one thing that all dyes have in common
the bonds between borate ion and alcohol functional groups of PVA are wear and the cross links can form and break easily under the weight of the gel or with handling
what is significant about the bonds in a cross-linked polymer?
neutral
what is the pH that you are aiming for after adding NaOH in the acetylation of ferrocine before you vaccum filter
eluent
what is the solvent for the mobile phase called
carotene
what pigment in the spinach lab was the least polar (moves the furthest)
when solvent front is 1cm from edge of TLC plate and then mark top of solvent in pencil
when do you remove the plate from the developing chamber
at the interface between the two layers in the beaker
where does the nylon form in the condensation polymerization
1 cm from the bottom in pencil
where should the TLC plate be marked for the origin
unreacted ferrocinine because it is the most nonpolar
which compound do you expect to first elute from the column: unreacted ferrocine, acetylferrocine, or diacetylferrocine?
the ink pigments are soluble in organic solvents and will be chromatographed along with the desired material.
why do we mark TLC plates with pencil and not pen
small
Are Rf values of polar compounds large or small
101
Assume that you are conducting a chain-addition polymerization using 4.09 grams of monomer (MW= 68.7g/mol) and 112 mg of initiator (MW= 190.5 g/mol). What is the expected number of repeat units (n) per chain? Report your answer to the nearest whole number (i.e., an answer of 112.3 should be reported as 112).
73.62
Assume that you carried out a recrystallization of ibuprofen using ethanol. If you started with 5.42 grams of crude ibuprofen and isolated 3.99 grams of pure ibuprofen, what is your percent recovery? Report your answer to the nearest 0.01%.
b
Assume that you dissolved a mixture of benzoic acid and phenol in diethyl ether, and then extracted withaqueous NaHCO3. Which equation represents the species present after this extraction?
c
Consider a sample comprised of two components A and B. When the sample was spotted on a TLC plateand eluted using 50:50 of hexane/ethyl acetate, the results were as shown below. If you made a new TLCplate of the same sample and eluted with 70:30 of hexane/ethyl acetate, what change in Rf values wouldyou expect to see? a) The Rf values of both A and B will remain the same b) The Rf value of both A and B will increase c) The Rf value of both A and B will decrease d) The Rf value of A will decrease, while the Rf value of B will increase e) The Rf value of A will increase, while the Rf value of B will decrease
b
Consider the formation of the coumarin derivative shown below. If you wanted to make 4.75 grams ofproduct, how many grams of 4-(diethylamino)salicylaldehyde should be used? a) 2.38 g b) 3.54 g c) 6.37 g d) 7.05 g e) none of these
a synthetic process called polymerization where the repeating units (monomers) are chemically linked together
How are polymers formed?
least polar eluting first
How are the compounds separated as they travel through the column?
d
How could 1H NMR distinguish between 1-Butanal and 2-Butanone? a) 4 signals are expected for 1-Butanal and 3 signals are expected for 2-Butanone b) 1-Butanal is expected to have one signal that has an integration value of 1, but 2-Butanone will not. c) 1-Butanal is expected to have a sextet but 2-Butanone will not d) All of the above e) Aldehydes and ketones cannot be distinguished by 1H NMR
they move at different rates depending on their interaction with the stationary phase.
How do the bands move in chromatography?
draw their repeating units in parentheses or brackets and have a subscript of n, indicating the number of repeating units
How do you draw polymer structures effectively?
first step the aromatic ring acts as a nucleophile and attacks an electrophile, then the aromatic ring is regenerated through the loss of a proton
How does EAS occur
the active species continues to add individual monomer units to the end until all of the monomer is used up. the end result is that long polymer chains are generated quite rapidly
How does chain addition polymerization work?
using solid base catalysis
How does the Knoevenagel synthesis work
as CO2 sublimes, pressure builds up and causes CO2 to liquify and it then percolates through the orange rind and extracts. then the liquid CO2 becomes gas and escapes as the tube heats up
How does the use of CO2 dry ice as a solvent extract the orange oil?
aqueous and the dye penetrates into the fiber and fixes to the fabric through a variety of intermolecular forces such as van der waals, hydrogen bonding, and covalent bonding
How is dye usually applied to fabric and how does it work
the color can be abraded from the fabric surface
How is indigo dye unique?
even though we use the same kinds of reactions (like additions and esterifications), these reactions happen hundreds or thousands of times to create a polymer
How is polymer chemistry different from regular chemistry?
as a colloid and becomes fixed through H bonding
How is the congo red dye applied and sticks to fabric
two because it is a diol
How many chains will one initiator molecule make in the block copolymers lab?
0.1
How many decimal points do you record your temperature going to?
3
How many distinct peaks would you expect to see in the 1H NMR of the following compound?
10^5
How many more times is ferrocine reactive than benzene in EAS?
a
How many proton NMR signals will be observed for the molecule shown below? (a) 3 (b) 4 (c) 2 (d) 5
very little, so molecular weights are looked at in terms of repeating units mainly
How much does the initiator contribute to the overall polymer characteristics in terms of mass
must dissolve compound and impurities when hot, and as it cools, compound becomes insoluble but impurities remain soluble
How should you chose your re-crystallization solvent
1-2mm
How tall must the sample be in the capillary tube for melting point?
mass of recovered recrystallized product/mass of crude product used in re-crystallization
How to calculate percent recovery
actual over theoretical
How to calculate percent yield?
add the molar mass of initiator to (repeating units + molar mass of the monomer (decalactone))
How to calculate the theoretical molecular weight (Mn) of polylactone homopolymer (initial)
add the Mn of copolymer (initial) to (the number of repeating units times the molar mass of L-lactide)
How to calculate the theoretical molecular weight of triblock copolymers (second rxn)
divide the (number of repeating units times the molar mass of L-lactide) by the total Mn of the triblock copolymer
How to calculate the theoretical weight percent of PLA?
fragrant compound with a sweet odor
How to characterize coumarin
divide all percentages gathered by the molar mass and then divide all by the smallest number of mols found
How to find empirical formula
decanting or gravity filtration and evaporation
How to remove the drying agent and organic solvent from the extraction lab?
wash with brine, then contact it with an anhydrous inorganic salt which will absorb the water dissolved in the solvent
How to remove the water absorbed by immiscible solvents in extraction?
d
How would you collect the product contained in the aqueous layer after the extraction? a) Dry with anhydrous magnesium sulfate, decant, and evaporate under reduced pressure. b) Neutralize with dilute acid, then evaporate under reduced pressure. c) Neutralize with sodium hydroxide, then collect product using vacuum filtration. d) Neutralize with dilute acid, then collect product using vacuum filtration.
c
If 100 g of oleic acid triglyceride (885.4 g/mol) is converted to oleic acid methyl ester (296.5 g/mol) using excess methanol and KOH according to the equation below. How many grams of glycerin (92.1 g/mol) byproduct are formed? a) 104 g b) 35 g c) 10.4 g d) 31 g
spend more time in stationary phase and travel more slowly
If a component has a greater affinity for the stationary phase, what happens?
white
If all light is reflected, what color does the object appear
back extraction using a fresh portion of organic solvent
If precipitation does not occur after neutralization, what is needed to be done
less polar
If something travels further on the TLC plate, does it mean its more or less polar
more polar
If something travels less on the TLC plate, does it mean its more or less polar
fine with just one extraction
If the Kd is large (10 or more) what does this mean in terms of number of extractions?
a
If the Rf value of chlorophyll-a is smaller than b-carotene, this means: (a) Chlorophyll-a is more polar than b-carotene (b) none of these are correct statements (c) Chlorophyll-a is less polar than b-carotene (d) Rf value cannot determine the more polar sample
pure hexane (least polar)
If the TLC analysis showed that unreacted ferrocine was present in the sample, what solvent do you use to elute first?
no, they would be even less distinguishable
If the chain were longer on octane, would the protons on C3 be very distinguishible from C792
b
If the reaction was conducted using 3.25 grams of 4-chlorobenzaldehyde, what is the theoretical yield of 4-chlorobenzoic acid (in grams)? a) 1.46 grams b) 1.81 grams c) 2.92 grams d) 3.62 grams
b
If you measure the melting point of a sample, allowed the capillary to cool, and then measure the melting point of the sample a second time, will the second melting point reading be identical to the first? a) Yes - the melting point of a compound is a fixed value and would not be impacted by heating and cooling. b) No - the crystal structure of the sample may change during the heating and cooling, and this will impact the melting point range. c) It is not possible to take a second melting point on the sample because it will remain in liquid form after the first melting point measurement.
4
If you took a 1HNMR of octane, how many signals would you expect to see?
F
Impurities disrupt the crystalline lattice of a sample so more energy is required to convert the solid phase into a liquid phase. True or False
31.9
In an EAS iodination reaction, 1.06 grams of phenol (MW: 94.11 g/mol) was reacted with 2.99 grams of sodium iodide (MW: 149.89 g/mol) . If 0.79 grams of product (MW: 220.01 g/mol) was collected, what was the percent yield (%) of the reaction? Report your answer to one decimal place (i.e., 23.1% should be entered as 23.1).
the solvents must be immiscible and the compounds must have different affinities for the two solvents.
In liquid-liquid extractions, what is the criteria for the two solvents and the compounds that need to be extracted
sodium iodide and household bleach (sodium hypochlorite NaOCl)
In the EAS lab, what is the source of iodine and what is the oxidizer
the alcohol because it does the attacking
In the Pechman, what is the important functional group
dissolve 20mg product in 2-3 mL of 95% ethanol 3 tubes each with different pH being edited by adding 2 mL of 10% HCl to one and 2 mL of a 10%Na 2CO3 to another
In the Pechmann (green) how do you observe fluorescence
dissolve the solid
In the Pechmann (green) what is the small volume of hot ethanol for?
a
Letícia and her group are trying to determine the distribution coefficient as part of their extraction lab.They dissolved 1.50 grams of benzoic acid in 75 mL of water and used 75 mL of diethyl ether to extract it.After the extraction was completed, Letícia noted they'd been able to extract 1.35 grams. What is theirdistribution coefficient? Recall that Kd = (concentration in organic phase)/(concentration in aqueousphase). a) 9 b) 0.1 c) 0.9 d) 1.1
diesel is heavier, oilier, higher boiling point, higher energy density (more efficient in burning fuels) hobe
Main differences between diesel and gasoline (4)
Pechmann is catalyzed then undergoes EAS. Knovenagel begins by attacking the middle then the alcohol completes the ring
Major differences between the Knoevenagel and Pechmann
both begin with an aromatic alcohol and both use ethyl acetoacetate
Major similarities between the Knoevenagel and Pechmann
Buchner funnel, filter flask, pinch clamp, hose connector to vaccum
Match the items in the filtration apparatus below with their name/function. Item A Item B Item C Item D
broad, 3200-3650
O-H stretch peak
pure ethyl acetate
Once the acetylferrocene has eluted from the column, what should you switch to elute the diacetylferrocene?
b
Plate X represents the TLC of a compound that was separated using a 70:30 hexane/ethyl acetate mixture.Which plate corresponds to the results that would be observed on a longer plate, using the same solventmixture? a) Plate A b) Plate B c) Plate C d) no way to predict
e
Poly (vinyl alcohol) is the starting material we use for "slime" synthesis. However, poly(vinyl alcohol) is not made from vinyl alcohol, but instead from vinyl acetate. What type of chemical reaction is performed to convert poly(vinyl acetate) into poly(vinyl alcohol), shown below? (a) Depolymerization (b) Reduction (c) Transesterification (d) Combustion (e) Hydrolysis
distance from origin to center of spot/ distance from origin to solvent front
Rf formula
b
Safety glasses are no longer required in the lab once a student finishes an experiment and locks their drawer. a) True b) False
b
See image
b
The chemical transformation involving the conversion of vegetable oil into biodiesel can be called: a) Saponification b) Transesterification c) Hydrolysis d) Gasification e) None of the above
diethyl ether, water
Assume that an extraction has been carried out using water and diethyl ether, similar to the Kd experiment in the lab, as illustrated with the separatory funnel drawn below. The solvent in the top layer will be _____ and the solvent in the bottom layer will be _____ .
2200-2250
C-N nitrile stretch
30.14
Consider the dehydration reaction shown below. If you started this reaction with 38.28 mL of cyclohexanol (MW 100.16 g/mol, density 0.96 g/mL), what is the theoretical yield of cyclohexene in grams (MW 82.14 g/mol, density 0.81 g/mL)? Report your answer to two decimal places.
singlet, sextet, doublet, singlet
Consider the molecule shown below, and use the dropdown menus to indicate the expected splitting patterns for the indicated protons.
4
Dopamine,C8H11NO2, has ____________ degrees of unsaturation.
absorb water
Even though organic solvents frequently used for extraction are immiscible with water, what usually still happens?
1/2 (2C+2+N-H-X)
Formula for IHD
final mass of solute (still dissolved) / initial mass solute = ( Vwater / Vwater + Vorg x Kd) to the power of the number of extractions
Formula used to calculate Kd
exploits differences in pKa values for various organic compounds
How does selective extraction work?
if the oxygen in water attacks the carbonyl rather than the anhydrous methanol
How does soap form in the synthesis of biodiesel
The Pechmann condensation produces coumarins via the acid-catalyzed reaction of a phenol with a β-keto ester
How does the Pechmann condensation work?
sharp 3100-3550
N-H stretch peak
ethanol, electrophilic aromatic substitution, dehydration
The synthesis of one of the coumarin derivatives proceeds through the following mechanism. The first step is transesterification, with the small molecule of ____ being lost. This is followed by a ring-closing step via ____. The final step in this mechanism is the loss of water, also known as a ____.
False
True or False: Light with a higher frequency will have a longer wavelength. True or False
gasoline burns quicker than biodiesel and yes because diesel must be under pressure to burn so it burns slower
What are the observations from the burn tests of gasoline and biodiesel and does this align with the information from the video?
the temperature at which the solid phase is in equilibrium with the liquid phase
what is the melting point defined as
it protonates the p-phenitidin, raising its polarity and increasing its solubility
why is HCl used instead of just plain deionized water in the acid base reaction when p-phenitidine is dissolved in HCl?
false
Addition polymerizations have a small molecule byproduct. True or False
b
After completing the reaction and isolating both products, you went out for a lunch break but you were sohungry that you forgot to label the products before you left the lab. How can you tell them apart using IRspectroscopy? a) The alcohol product will show a signal at about 3500 cm-1 but the carboxylic acid will not. b) The carboxylic acid will have a signal at about 1730 cm-1 but the alcohol will not. c) It isn't possible to distinguish these molecules using IR alone.
a more polar solvent such as a 70:30 mixture of hexane and ethyl acetate
After the ferrocine was eluted, what do you use to elute the acetylferrocene?
a
After the reaction is complete, the product mixture is dissolved in ether and extracted with two portions ofsodium bicarbonate solution. Which compound remains in the ether layer after this extraction? a) (4-chlorophenyl)methanol b) 4-chlorobenzoic acid
5 minutes undisturbed
After vaccum filtrating, how long should you let the cake sit?
a
All compounds that act as dyes contain a chromophore. a) True b) False
a
An advantage of synthesizing block copolymers is the ability to tune the properties of the material by varying the length of each block. Of the following block copolymers, which composition would have the highest degree of crystallinity? (a) 75% PLA, 25% poly(-decalactone) (b) 25% PLA, 75% poly(-decalactone) (c) 45% PLA, 55% poly(-decalactone) (d) 50% PLA, 50% poly(-decalactone) (e) 10% PLA, 90% poly(-decalactone)
1700
C=O stretch peak
d
Changing the moles of which of the following will affect the number of repeat units in a chain additionpolymer? a) Initiator b) Monomer c) catalyst d) both (a) and (b) e) all of these
b
Daniel was trying to make a polyester. He knew that he needed to utilize condensation polymerization, so he added ethyl alcohol and butanoic acid together in the presence of sulfuric acid. However, when the reaction ceased, he was left with a clear, non-viscous liquid that had a fruity odor. It appeared as if no polymerization had occurred. What did Daniel do wrong? (a) He ran the polymerization under acidic conditions. He needed to run the reaction in basic conditions in order for the polymerization to occur. (b) He needed to use difunctional molecules like ethane-1,2-diol and propane-1,3-dicarboxylic acid in order to form the polymer he desired. (c) You cannot form a polyester via condensation polymerization. He should have utilized addition polymerization. (d) He didn't do anything wrong. The fruity odor is indicative of the polymerization working.
they can be heated to soften or melt and remold into other shapes
Define thermoplastics
cross-linked polymers that when heated continue to harden and additional heating will only result in decomposition
Define thermoset plastics
a
Ethanol is formed during the cyclization reaction shown here: a) True b) False
sample mixture is in a liquid or gas phase in the mobile phase and is then carried by mobile phase through stationary phase which is a solid support that contains an absorbent. The components of the sample mixture pass through the stationary phase as bands or areas of concentration
Explain the process of chromatography
either decalactone or dodecalactone
In the copolymers lab, what do we use as the monomer for the first reaction?
L-lactide
In the copolymers lab, what do we use as the monomer for the second reaction?
the aldehyde because it is attacked
In the knoevenagel reaction what is the important functional group?
ring-opening transesterifications under acidic catalytic conditions with an alcohol initiator
In the synthesis of renewable triblock polymers, what type of reactions fo the lactones undergo and what initiates them
chlorophyll b is more polar because it has more cho groups
Is chlorophyll b or a more polar
polar solvent
Is ethyl acetate a polar or nonpolar solvent
it is not possible because some of it will still be dissolved in the solvent that was utilized from when it was extracted
Is it ever possible to extract 100% of a compound from a solution?
no
Is the exact amount of catalyst very crucial in the copolymers lab
b
______ is often formed as an undesired by-product during the reaction that produces biodiesel. a) Glyceraldehyde b) Soap c) Ethylene glycol d) None of these
2850-3000
alkane C-H stretch
regions of a polymer where chains are randomly assigned in space and have weak intermolecular interactions
define amorphous
drug to relieve pain
define analgesic
drug to reduce fever
define antipyretic
the temp that a monomer of specific concentration will not polymerize
define ceiling temperature
any form of step-growth polymerization where monomers react with each other to form larger structural units, while releasing byproducts such as water and methanol
define condensation polymerization
polymers that are formed when long polymer chains are cross-linked together to create a 3D network, the links themselves are covalent or ionic bonds
define cross-linked polymers
ordered regions of a polymer where strong intermolecular interactions exist. Examples of interactions are van der waals or hydrogen bonding
define crystalline
a molecule that can be bonded to other identical molecules to form a polymer.
define monomer
a part of a polymer whose repetition would produce the complete polymer chain by linking them together successively along the chain, like beads on a necklace
define repeating unit
it changed to blue
did you notice any significant changes when the congo red fabric was treated with acid?
they are more polar because of the oxygen group that B-carotene does not have
do you expect xanthophylls to be more or less polar than B-carotene?
