Organic Chemistry II Lab Final – 3106 – Flashcards

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question
A sample on a chromatographic column is subjected to which two opposing forces?
answer
its adsorption to the solid phase and its solubility in the elution solvent system
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An extraction solvent should be ______ the solution solvent.
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immiscible with
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Match the letter with the correct column component.
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A Elution solvent B Sand C Stationary phase (SiO2 or Al2O3) D Sand E Cotton (or glass wool) plug
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The H-H bond is ______ when molecular hydrogen is adsorbed by a metal.
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weakened
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After adding the sodium borohydride reagent, the balloon should stay inflated for at least ________.
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30 minutes
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Which compound will strongly adsorb to the silver nitrate/silica gel stationary phase?
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octene
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Acetone can react with sodium borohydride.
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true
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What type of solvent extraction will be used in this experiment?
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liquid-liquid extraction
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Which term can be used to describe the addition of hydrogen to make an alkene?
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saturation
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Refer to the SDS of pentane. Find pentane's density. Water's density is 1.0 g/mL. Is pentane more or less dense than water? Does this mean it will be the top layer or the bottom layer in an extraction with water?
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less dense, top layer
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What are the three steps (in order) of the mechanism for this experiment's polymerization?
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initiation, propagation, termination
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What role does AIBN play in this polymerization?
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initiator
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The viscosity of the reaction mixture will _____ as polymerization progresses.
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increase
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Where can you find a copy of the course syllabus that covers many things including policies concerning excused absences, grade determination and an outline for writing lab reports?
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on the main course content page of blackboard for this course
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According to the experimental procedure, you should check the status of your reaction vial every _____.
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10 minutes
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Methyl methacrylate is _____ and toxic. This polymerization must be performed _______.
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flammable, in the hood
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After thoroughly washing with water the polymer you produce today, you will be allowed to take it home. Should you ever take home chemicals from lab without permission?
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no
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You are preparing poly(methyl methacrylate), also called PMMA. What is the commercial name of this polymer?
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Plexiglas
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When drawing reaction mechanisms, a ______ arrow is used to show the movement of a single electron.
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fishhook
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How many points are deducted per business day for late lab reports?
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3 points
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Which of the following structures is the final product of the first step in the following reaction?
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Structure B
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Which acts as the active reagent in hydroboration?
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The monomer (BH3)
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Why are alkylboranes not generally isolated out of solution?
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They are pyrophoric
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Hydroboration (the addition of borane to an alkene) is a(n) _____ reaction.
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reduction
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Dr. Herbert Charles Brown developed an effective route for the synthesis of which chemical used in CHEM 3106 Experiment 1, "Catalytic Hydrogenation of an Alkene: Octane"?
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sodium borohydride
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Configuration is _____ in the oxidation step of the above reaction.
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retained
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The four centered transition state of the hydroboration step is shown below. This is a concerted addition reaction meaning all the bonds being made or broken at the same time. This mechanism is characteristic of a group of reactions called _____ reactions.
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pericyclic
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Organoboranes have become an attractive pathway for the preparation of which of the following?
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all of the above (alcohols, alkanes, amines, organohlides)
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Why are highly concentrated solutions of hydrogen peroxide dangerous? (Select all that apply)
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caustic, can be explosive, can blister the skin
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The net result of the reaction below involves addition of H and OH across a double bond. This hydroboration/oxidation allows the -OH group to add to the least substituted carbon. What is this type of addition called?
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anti-Markovnikov addition
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With what combination of electron-withdrawing and electron-donating groups can you speed up a Diels-Alder reaction?
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If the dienophile bears electron-withdrawing groups and the diene bears electron-donating groups.
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Calculate the percent yield of the reaction below using the given information. 0.10 g Cmpd A + 0.040 g Cmpd B -> 0.070 g Cmpd C MW Compound A = 200 m/mol MW Compound B = 100 g/mol MW Compound C = 300 g/mol
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58% yield
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Match the reactants in the below reaction with the correct term.
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Compound A = Diene Compound B = Dienophile
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The Diels-Alder reaction is reversible.
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True
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What does the "s" refer to in the term "s-cis confirmation" of the diene?
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The single bond connecting the two double bonds
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The Diels-Alder reaction is pericyclic meaning bonds are forming and breaking around the ring at the same time. What reaction have you performed this semester that is pericyclic?
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hydroboration
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This experiment's reaction combines a conjugated diene with an alkene (dienophile). What is the addition product of this reaction often called.
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adduct
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When should you remove the rubber tubing from the filter flask?
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before turning the water off
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What causes the bubbles to form in the polymerization of poly(methyl methacrylate), PMMA?
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evolution of nitrogen gas from AIBN
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According to the lab manual, the first step in any filtration is:
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wet the filter paper with the solvent being used
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What are some benefits of using a powder drying agent such as magnesium sulfate? (Select all that apply)
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increased rate of drying, high surface area
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Which of the following chemicals is the missing reagent in the reaction below?
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acetyl chloride
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What two reagents used in this experiment are moisture sensitive and irritants? (These chemicals should be dispensed in the hood and always recapped after use.)
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acetyl chloride and aluminum chloride
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When setting up this experiment's reaction you should:
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use a capped vial and recap it between addition of each reagent
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The cyclopentadienyl anion has chemistry similar to what well known aromatic ring compound?
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benzene
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You were supposed to calculate the percent yield of the product from the Diels-Alder experiment. Is the following statement true or false: "1 g or anthracene plus 1 g of maleic anhydride should produce 2 g of the Diels-Alder adduct."
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false
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This experiment requires the use of a needle and a syringe. Which of the following statements is true based on the needle/syringe policy in the CHEM 3105 and 3106 courses?
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TAs will properly uncap all needles; students should not uncap or recap any needle
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Match the "side effect" with the correct type of reaction. Polyalkylation, Ring deactivation, Ring activation, Rearrangement of the intermediate carbocation, Resonance stabilization of the acylium cation
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Polyalkylation = Friedel-Crafts Alkylation. Ring deactivation = F-C acylation. Ring activation = F-C alkylation. Rearrangement of the intermediate carbocation = F-C alkylation. Resonance stabilization of the acylium cation = F-C acylation
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What technique will you use to monitor the progress of the Friedel-Crafts acylation of ferrocene?
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TLC
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Friedel-Crafts alkylations and acylations are catalyzed by _____.
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lewis acids
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Match the letter with the correct column component as described in your prior reading section. You will use one option twice. (NOTE: the experimental procedure says another component should be added instead of B. Match that as well)
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A = solvent. B = sand. C = alumina. D = Sand. E = glass wool/cotton plug. Instead of B = product alumina mixture and alumina.
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Order the components of the crude product mixture in order of increasing polarity (least polar to most polar) as it pertains to column chromatography (not dipoles). Hint - this is the order of the products that will elute from the column.
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ferrocene (2), acetylferrocene (3), diacetylferroecene (1)
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The following scenario and calculations are meant to give you practice for the procedure & calculations you are required to do for this lab report. In this scenario, you started with 100 mg of ferrocene and then obtained 100 mg of crude product from Experiment 5's reaction. Experiment 6's procedure requires that you dissolve your crude product in 0.5 mL of CH2Cl2 and then mix it with 300 mg of alumina. According to the lab manual, if the crude product is greater than 75 mg, you're only supposed to add half of the alumina/product mixture. You isolate 11 mg of ferrocene, 25 mg of acetylferrocene, and 13 mg of diacetylferrocene from your column. Fill in the blanks for the missing values (remember significant figures) in the equations below. Use the information in the above paragraph and the formulas below to describe the following values: A =
answer
A = 0.011 g B = 0.075 g M = 0.025 g N = 0.013 g X = 0.22 mmol acetylferrocene Y = 0.096 mmol diacetylferroecene
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Solvent that elutes from the column is collected in a series of _____.
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fractions
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Why do you adjust the solvent system used to elute the products?
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Nonpolar solvents, like hexane, will increase the amount of time a nonpolar product, like ferrocene, spends in the mobile phase. To elute polar products, like diacetylferrocene, a more polar solvent system, like a methanol/dichloromethane mixture, needs to be used.
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One of the major differences between column chromatography and TLC is that the mobile phase __________ in column chromatography and the mobile phase ________ in TLC.
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descends, ascends
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When using multiple elution solvents, the ______________ solvent in which the material is readily soluble should be used to add the sample to the column.
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least polar
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Match the types of phases in column chromatography: Stationary phase, mobile phase, alumina/silica, solvent
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Stationary phase = solid. mobile phase = liquid. alumina/silica = solid. solvent = liquid.
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There is no sharp dividing between soluble and insoluble, however the manual suggests that to be considered soluble how many milligrams must dissolve in half a milliliter of solvent?
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15 mg
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A common phrase to remember when considering the solubility of a compound is _____.
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like dissolves like
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Use the flowchart from your lab manual (shown below and on page 225 of your lab manual) to answer the following question. What type of compound could your unknown be if it is insoluble in water, insoluble in 5% NaOH, and soluble in 5% HCl?
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1°, 2°, or 3° Amine with more than 8 carbons or an aromatic amine
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If you are careful you can use the color of your compound as an identification clue. Structures of the colored organic compounds stated in Experiment 7 (p 222) are shown below as well as the structure of salicylic acid for comparison as a colorless compound. Based on these structures, select which of the following is/are chromophore(s) that can cause organic compounds to be colored. (Select all that apply)
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extended conjugation in a molecule and the phenyl group
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How can you test the solubility of a liquid sample?
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add a few drops of the liquid unknown to a 0.5 mL solvent in a shell vial or a test tube
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What safety precautions should you take while testing the odor of an unknown compound? (Select all that apply)
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wear goggles. keep the sample several inches away from the nose. gently waft the vapor toward you
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Use the flowchart from your lab manual (shown below and on page 225 of your lab manual) to answer the following question. What type of compound could your unknown be if it is soluble in water, tests basic to litmus paper, and is soluble in ether?
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1°, 2°, or 3° aliphatic amine with 1-6 carbons
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Which of the following changes blue litmus to red (acid to litmus)?
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phenols
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Is it likely that an aliphatic compound with 14 carbons be soluble in water?
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no
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Are "negative" results useful when attempting to classify an unknown organic compound?
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yes
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What functional group(s) is/are likely to be present in your unknown if you observe the following classification test results: Formation of a red precipitate after performing the 2,4-DNP test Formation of a silver mirror after performing the Tollens Test Formation of a green precipitate after 80 seconds from the Chromic Acid Test
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an aromatic aldehyde
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You should obtain an IR spectrum of your unknown before you performed the classification tests. You will use the classification tests to confirm you interpretation of the IR spectrum. What is the IR frequency range for the carbonyl functional group as stated in the lab manual?
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1675-1840 cm-1
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The lab manual states that there is one solvent in which all of the unknowns are soluble. What solvent is this?
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ethanol
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Why is the 2,4-dinitrophenylhydrazine test a good test to run if you do not think the unknown is an amine?
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this is a rapid test and can be done early to eliminate several possibilities
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What safety precautions should you take while performing the classifications tests for an unknown compound? (Select all that apply)
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wear gloves. always securely recap bottles after use. wear goggles
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What functional group(s) is/are likely to be present in your unknown if you observe the following classification test results: No precipitate was formed after performing the 2,4-DNP test A red coloration from the Ceric Nitrate Test A blue-green coloration from the Jones Oxidation Formation of cloudiness after 5 minutes from the Lucas Test
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a secondary alcohol
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Which functional group can spontaneously form explosive peroxides and should be tested frequently and handled carefully?
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ethers
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Bromine water is used to test for the presence of electron rich aromatic rings. What hazards are associated with the use of bromine?
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bromine is highly toxic and can cause severe burns
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Of the functional groups that you are testing for in lab experiment 8 which are basic?
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amines
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What functional group(s) is/are likely to be present in your unknown if you observe the following classification test results: A blue-green coloration from the Copper Ion Test An insoluble precipitate forms after performing the Hinsberg test Decolorization of the bromine solution in the Bromine Water Test
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a primary or secondary amine that contains an aromatic group
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The IR spectrum shown below is of what compound?
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Propanol ****
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Your derivative has an observed melting point range of 137-140. According to the table below, which compound is your unknown?
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propenoic acid
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Why must and alcohol be anhydrous when synthesizing its derivative using an isocyanate?
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All of the above (Water can hydrolyze the isocyanate. Unwanted byproducts will be produced. Falsely high melting points may be obtained for the product)
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Which reagent used in one of the preparation of derivatives procedures tends to hydrolyze to form a carboxylic acid and must be checked for purity before use?
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3,5-Dinitrobenzoyl chloride
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What gases evolve during the preparation of an acid chloride? Note - this reaction should be performed under the hood.
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hydrogen chloride, carbon dioxide, carbon monoxide
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Your lab manual says, "Look at the blue notebook of possible unknowns and choose the derivative that gives the largest difference in melting points between your list of possibilities; make that derivative." According to the table below, which derivative should you prepare to determine if your unknown is either propenoic acid or propanoic acid?
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the p-toludide derivative of a carboxylic acid
question
Calculate the percent yield of the following reaction using the given information. Cmpd A --> Cmpd B In this scenario, you start with 30 g of Cmpd A and obtain 20 g of Cmpd B. MW Compound A = 300 g/mol MW Compound B = 250 g/mol [x1] % = percent yield NOTE: The answer should be input as an integer, no decimal places should be used for % yields. Do not include the percent sign, only input the whole number
answer
80%
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Even though modern chemists can readily identify unknowns by various _____________________, the old fashioned solubility tests, classification tests, and preparation of derivatives can serve as a useful learning tool for new students.
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spectral analysis
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You think your liquid unknown may be propenoic acid or propanoic acid. According to the table below, what are the boiling points of propenoic and propanoic acids?
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b. Propenoic acid - 141 °C; Propanoic acid - 141 °C
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Which physical property of the prepared derivative is used to help identify your unknown?
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melting point
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Match the types of phases in thin layer chromatography: Alumina/silica gel. Solvent
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Alumina/silica gel = Stationary phase. Solvent = mobile phase
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In organic chemistry, what does the term "wet" mean?
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the material in question contains water
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What should you do with a reaction vial in order to prevent loss of a product?
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place it in a small beaker to prevent tipping
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Grignard reactions are unique in organic synthesis because a new carbon-carbon single bond is formed; a ____________________ nucleophile attacks a ____________________ electrophile. Which compound contains the nucleophile and which contains the electrophile?
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carbon (from the Grignard reagent), carbon (from the carbonyl compound)
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What properties of Grignard reagents give them their strong nucleophilic character? (Select all that apply)
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The carbanionic character at carbon and the highly polarized carbon - metal bond
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During the isolation step of this experiment, the ether layer is on the bottom.
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false
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Calculate the amount (mL) needed of a 4.0 M phenylmagnesium chloride in THF solution to give 1.5 equivalents based on the amount of starting material used. Starting material needed: 0.58 mmol [x1] mL of 4.0 M phenylmagnesium chloride in THF (HINT: remember to convert to moles; think about what the units of molarity are; remember significant digits, 4.0 has two significant digits)
answer
o.22 mL
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Determine the percent yield for the following generic reaction using the information given below: Compound A --> Compound B if you start with 10.0 mL of Compound A and obtain 9.0 g of Compound B. Density of Compound A = 0.75 g/mL MW of Compound A = 150. g/mol MW Compound B = 300. g/mol [x1] % yield
answer
60%
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The Grignard reagent you will use in this experiment is commercially available. You will not need to prepare the reagent, but understanding how to prepare this kind of reagent is still important. Why is ether, a relatively nonpolar solvent, key in the synthesis of Grignard reagents?
answer
Ether will complex with the magnesium in the Grignard reagent to increase its solubility in the nonpolar solvent
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You are going to perform a "name reaction" in this experiment, the Grignard reaction, shown below. Which chemical in this Grignard reaction is the Grignard reagent?
answer
phenylmagnesium chloride
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Calculate the amount (mL) of Compound A needed to give 12 mmol. MW of Compound A: 32.04 g/mol Density of Compound A: 0.79 g/mL [x1] mL of Compound A equals 12 mmol (HINT: remember significant digits)
answer
0.49
question
According to the lab manual, hydrogenation of oils on a large scale is referred to as?
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hardening
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The type of esterification in the procedure for this specific experiment (Experiment 3106-12) is also known as _______________________.
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Fischer esterfication
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Fats that contain a cis-alkene group are also called _______________________.
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unsaturated fats
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What are high molecular weight (contains chains up to 36 carbons long), naturally occurring esters of fatty acids called?
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waxes
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You should always smell new and unknown compounds.
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false
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Your TA will dispense the sulfuric acid in the hood. What two specific things should you do if concentrated H2SO4 spilled onto your skin?
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wash the area for at least 15 min (in the safety shower if necessary) and notify your TA
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There is more than one route by which esters can be synthesized. Which route will be used in the procedure for this specific experiment (Experiment 3106-11)?
answer
esterification of a carboxylic acid with an alcohol in the presence of an acid catalyst
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Esterification is a nonreversible process.
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false
question
What is combinatorial chemistry?
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performing the same reaction with different reactants to get a library of products
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How many -OH groups are present in glycerol?
answer
3
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What natural product mentioned in the lab manual gains strength by a similar interaction as that exhibited in Nylon?
answer
silk fibers
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Acid halides react with atmospheric water to produce what compound?
answer
the corresponding carboxylic acid
question
What intermediary compound will be synthesized in this experiment before the formation of the product?
answer
the corresponding acid chloride of adipic acid
question
There are several methods described in the lab manual to trap gases that can be produced by organic reactions. The reactions performed in this experiment do produce three byproduct gases. These reactions will be performed in the hood to prevent gas from accumulating in the lab. What are the three byproduct gases that are produced in the acid chloride step of this reaction?
answer
carbon dioxide, carbon monoxide, and hydrochloric acid
question
During the industrial synthesis of Nylon-6,6, what compound is formed before the formation of the product?
answer
the corresponding amine salt of 1,6-hexandiamine
question
Lachrymators should only be used and/or produced in the hood because they can irritate your eyes and make them tear up.
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true
question
You will synthesize Nylon-6,6 in a beaker containing an organic phase (cyclohexane) and an aqueous phase (water). Where does the polymerization reaction occur?
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at the interface of the aqueous and organic layers
question
What functional group is present in Nylon-6,6?
answer
amide
question
What interaction makes the Nylon polymer so strong?
answer
hydrogen bonding between the C=O and N-H groups
question
What does the "6,6" refer to in the name Nylon-6,6?
answer
the number of carbons in each of the two comonomers
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