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

question

An extraction solvent should be ______ the solution solvent.

answer

immiscible with

question

Match the letter with the correct column component.

answer

A Elution solvent B Sand C Stationary phase (SiO2 or Al2O3) D Sand E Cotton (or glass wool) plug

question

The H-H bond is ______ when molecular hydrogen is adsorbed by a metal.

answer

weakened

question

After adding the sodium borohydride reagent, the balloon should stay inflated for at least ________.

answer

30 minutes

question

Which compound will strongly adsorb to the silver nitrate/silica gel stationary phase?

answer

octene

question

Acetone can react with sodium borohydride.

answer

true

question

What type of solvent extraction will be used in this experiment?

answer

liquid-liquid extraction

question

Which term can be used to describe the addition of hydrogen to make an alkene?

answer

saturation

question

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?

answer

less dense, top layer

question

What are the three steps (in order) of the mechanism for this experiment's polymerization?

answer

initiation, propagation, termination

question

What role does AIBN play in this polymerization?

answer

initiator

question

The viscosity of the reaction mixture will _____ as polymerization progresses.

answer

increase

question

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?

answer

on the main course content page of blackboard for this course

question

According to the experimental procedure, you should check the status of your reaction vial every _____.

answer

10 minutes

question

Methyl methacrylate is _____ and toxic. This polymerization must be performed _______.

answer

flammable, in the hood

question

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?

answer

no

question

You are preparing poly(methyl methacrylate), also called PMMA. What is the commercial name of this polymer?

answer

Plexiglas

question

When drawing reaction mechanisms, a ______ arrow is used to show the movement of a single electron.

answer

fishhook

question

How many points are deducted per business day for late lab reports?

answer

3 points

question

Which of the following structures is the final product of the first step in the following reaction?

answer

Structure B

question

Which acts as the active reagent in hydroboration?

answer

The monomer (BH3)

question

Why are alkylboranes not generally isolated out of solution?

answer

They are pyrophoric

question

Hydroboration (the addition of borane to an alkene) is a(n) _____ reaction.

answer

reduction

question

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"?

answer

sodium borohydride

question

Configuration is _____ in the oxidation step of the above reaction.

answer

retained

question

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.

answer

pericyclic

question

Organoboranes have become an attractive pathway for the preparation of which of the following?

answer

all of the above (alcohols, alkanes, amines, organohlides)

question

Why are highly concentrated solutions of hydrogen peroxide dangerous? (Select all that apply)

answer

caustic, can be explosive, can blister the skin

question

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?

answer

anti-Markovnikov addition

question

With what combination of electron-withdrawing and electron-donating groups can you speed up a Diels-Alder reaction?

answer

If the dienophile bears electron-withdrawing groups and the diene bears electron-donating groups.

question

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

answer

58% yield

question

Match the reactants in the below reaction with the correct term.

answer

Compound A = Diene Compound B = Dienophile

question

The Diels-Alder reaction is reversible.

answer

True

question

What does the "s" refer to in the term "s-cis confirmation" of the diene?

answer

The single bond connecting the two double bonds

question

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?

answer

hydroboration

question

This experiment's reaction combines a conjugated diene with an alkene (dienophile). What is the addition product of this reaction often called.

answer

adduct

question

When should you remove the rubber tubing from the filter flask?

answer

before turning the water off

question

What causes the bubbles to form in the polymerization of poly(methyl methacrylate), PMMA?

answer

evolution of nitrogen gas from AIBN

question

According to the lab manual, the first step in any filtration is:

answer

wet the filter paper with the solvent being used

question

What are some benefits of using a powder drying agent such as magnesium sulfate? (Select all that apply)

answer

increased rate of drying, high surface area

question

Which of the following chemicals is the missing reagent in the reaction below?

answer

acetyl chloride

question

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.)

answer

acetyl chloride and aluminum chloride

question

When setting up this experiment's reaction you should:

answer

use a capped vial and recap it between addition of each reagent

question

The cyclopentadienyl anion has chemistry similar to what well known aromatic ring compound?

answer

benzene

question

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."

answer

false

question

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?

answer

TAs will properly uncap all needles; students should not uncap or recap any needle

question

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

answer

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

question

What technique will you use to monitor the progress of the Friedel-Crafts acylation of ferrocene?

answer

TLC

question

Friedel-Crafts alkylations and acylations are catalyzed by _____.

answer

lewis acids

question

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)

answer

A = solvent. B = sand. C = alumina. D = Sand. E = glass wool/cotton plug. Instead of B = product alumina mixture and alumina.

question

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.

answer

ferrocene (2), acetylferrocene (3), diacetylferroecene (1)

question

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

question

Solvent that elutes from the column is collected in a series of _____.

answer

fractions

question

Why do you adjust the solvent system used to elute the products?

answer

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.

question

One of the major differences between column chromatography and TLC is that the mobile phase __________ in column chromatography and the mobile phase ________ in TLC.

answer

descends, ascends

question

When using multiple elution solvents, the ______________ solvent in which the material is readily soluble should be used to add the sample to the column.

answer

least polar

question

Match the types of phases in column chromatography: Stationary phase, mobile phase, alumina/silica, solvent

answer

Stationary phase = solid. mobile phase = liquid. alumina/silica = solid. solvent = liquid.

question

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?

answer

15 mg

question

A common phrase to remember when considering the solubility of a compound is _____.

answer

like dissolves like

question

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?

answer

1°, 2°, or 3° Amine with more than 8 carbons or an aromatic amine

question

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)

answer

extended conjugation in a molecule and the phenyl group

question

How can you test the solubility of a liquid sample?

answer

add a few drops of the liquid unknown to a 0.5 mL solvent in a shell vial or a test tube

question

What safety precautions should you take while testing the odor of an unknown compound? (Select all that apply)

answer

wear goggles. keep the sample several inches away from the nose. gently waft the vapor toward you

question

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?

answer

1°, 2°, or 3° aliphatic amine with 1-6 carbons

question

Which of the following changes blue litmus to red (acid to litmus)?

answer

phenols

question

Is it likely that an aliphatic compound with 14 carbons be soluble in water?

answer

no

question

Are "negative" results useful when attempting to classify an unknown organic compound?

answer

yes

question

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

answer

an aromatic aldehyde

question

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?

answer

1675-1840 cm-1

question

The lab manual states that there is one solvent in which all of the unknowns are soluble. What solvent is this?

answer

ethanol

question

Why is the 2,4-dinitrophenylhydrazine test a good test to run if you do not think the unknown is an amine?

answer

this is a rapid test and can be done early to eliminate several possibilities

question

What safety precautions should you take while performing the classifications tests for an unknown compound? (Select all that apply)

answer

wear gloves. always securely recap bottles after use. wear goggles

question

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

answer

a secondary alcohol

question

Which functional group can spontaneously form explosive peroxides and should be tested frequently and handled carefully?

answer

ethers

question

Bromine water is used to test for the presence of electron rich aromatic rings. What hazards are associated with the use of bromine?

answer

bromine is highly toxic and can cause severe burns

question

Of the functional groups that you are testing for in lab experiment 8 which are basic?

answer

amines

question

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

answer

a primary or secondary amine that contains an aromatic group

question

The IR spectrum shown below is of what compound?

answer

Propanol ****

question

Your derivative has an observed melting point range of 137-140. According to the table below, which compound is your unknown?

answer

propenoic acid

question

Why must and alcohol be anhydrous when synthesizing its derivative using an isocyanate?

answer

All of the above (Water can hydrolyze the isocyanate. Unwanted byproducts will be produced. Falsely high melting points may be obtained for the product)

question

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?

answer

3,5-Dinitrobenzoyl chloride

question

What gases evolve during the preparation of an acid chloride? Note - this reaction should be performed under the hood.

answer

hydrogen chloride, carbon dioxide, carbon monoxide

question

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?

answer

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%

question

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.

answer

spectral analysis

question

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?

answer

b. Propenoic acid - 141 °C; Propanoic acid - 141 °C

question

Which physical property of the prepared derivative is used to help identify your unknown?

answer

melting point

question

Match the types of phases in thin layer chromatography: Alumina/silica gel. Solvent

answer

Alumina/silica gel = Stationary phase. Solvent = mobile phase

question

In organic chemistry, what does the term "wet" mean?

answer

the material in question contains water

question

What should you do with a reaction vial in order to prevent loss of a product?

answer

place it in a small beaker to prevent tipping

question

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?

answer

carbon (from the Grignard reagent), carbon (from the carbonyl compound)

question

What properties of Grignard reagents give them their strong nucleophilic character? (Select all that apply)

answer

The carbanionic character at carbon and the highly polarized carbon - metal bond

question

During the isolation step of this experiment, the ether layer is on the bottom.

answer

false

question

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

question

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%

question

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

question

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

question

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?

answer

hardening

question

The type of esterification in the procedure for this specific experiment (Experiment 3106-12) is also known as _______________________.

answer

Fischer esterfication

question

Fats that contain a cis-alkene group are also called _______________________.

answer

unsaturated fats

question

What are high molecular weight (contains chains up to 36 carbons long), naturally occurring esters of fatty acids called?

answer

waxes

question

You should always smell new and unknown compounds.

answer

false

question

Your TA will dispense the sulfuric acid in the hood. What two specific things should you do if concentrated H2SO4 spilled onto your skin?

answer

wash the area for at least 15 min (in the safety shower if necessary) and notify your TA

question

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

question

Esterification is a nonreversible process.

answer

false

question

What is combinatorial chemistry?

answer

performing the same reaction with different reactants to get a library of products

question

How many -OH groups are present in glycerol?

answer

3

question

What natural product mentioned in the lab manual gains strength by a similar interaction as that exhibited in Nylon?

answer

silk fibers

question

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.

answer

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?

answer

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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