OCHEM LAB FINAL :D
11. The purpose of spotting a mixture of all possible products on the TLC plate is to: a. identify which product was synthesized by comparing your product to the Rf values from the mixture b. demonstrate which products you should have had c. identify the dinitration product d. identify any impurities e. for comparison of the crude product
A
20. Which of the following is not a polyamide? a. Cotton b. Wool c. Silk d. Nylon e. Aramid
A
40. In order to determine whether the desired product type was produced in the Grignard Reaction, you obtained an IR spectrum. The main peak that should have been absent was at approximately: a. 1700-1720 cm-1 b. 2400-2580 cm-1 c. 3200-3600 cm-1 d. 3010-3100 cm-1 e. Fingerprint Region
A
44. What is the minimum equipment needed, in addition to a heat source, to set up a reflux reaction? I. Round Bottom Flask II. Distillation Head III. Condenser IV. Boiling Chips or Stir Bar V. Thermometer a. I, III, and IV b. I, II, and III c. I, III, IV, and V d. I, II, III, and IV e. all of the above
A
46. A possible cause for a Grignard reaction failing to initiate is the: a. use of magnesium with heavy oxide layer b. use of strictly anhydrous conditions c. presence of excess THF d. presence of excess magnesium e. use of an excess of alkyl halide
A
5. Upon heating, aspartame rearranges to form a cyclic compound known as _____. a. diketopiperazine b. cyclamate c. monellin d. saccharin e. Acesulfame-K
A
7. What is true of α-helix secondary structures? a. Involve hydrogen-bonding interaction between amino acid groups that are 4 residues apart on the same chain. b. Two chains are oriented in different directions. c. Rarely make up more than a small part of total protein structure. d. Are irregular in shape. e. Involve interactions between side chains of amino acid residues.
A
9. Which combination might give an ester that will not be volatile enough to have significant odor? a. benzyl alcohol and salicylic acid b. methyl alcohol and formic acid c. methyl alcohol and acetic acid d. acetic acid and 2-methyl-1-propanol e. formic acid and ethyl alcohol
A
Aspartame is used as a ______. People that have the metabolic disorder, PKU, should restrict their intake of aspartame because they lack the enzyme needed to metabolize ______. a. sweetener; phenylalanine b. souring agent; tyrosine c. sweetener; valine d. vapor rub; cysteine e. none of these
A
In an aqueous organic extraction, a. the less dense layer is on top b. the more dense layer is on top c. aqueous layer is always on top d. the phase with less sample dissolved is always on top e. the organic layer is always on top
A
The ceric nitrate test is used to detect the presence of ________ a. alcohols b. carboxylic acids c. amides d. aldehydes e. amino acids
A
To prepare 3-methyl-3-hexanol from a Grignard reaction, you need to use which starting materials? a. 1-bromoethane and 2-pentanone b. 2-bromobutane and propanal c. 2-bromopentane and acetaldehyde d. 1-bromoethane and 3-pentanone e. 2-bromopropane and 2-butanone
A
Under conditions of thermodynamic control, product distribution is governed by: a. the relative stabilities of the products b. the relative energies of the transition states leading to the products c. the rate at which each product is formed d. a and b e. b and c
A
What do you get when you combine acetic acid with ethanol and sulfuric acid and heat in a warm water bath for 15 minutes? a. ethyl acetate b. propionic acetate c. methyl acetate d. formic acetate e. ethyl acetoacetate
A
Which is the general category of compounds that are the common active ingredients in sun screens? a. conjugated aromatic compounds b. conjugated aliphatic compounds c. unconjugated aromatic compounds d. unconjugated aliphatic compounds e. fatty acids
A
Which of the following compounds would give a negative iodoform test? a. 2-methylbutanal b. acetaldehyde c. ethanol d. 2-undecanone e. isopropyl alcohol
A
Which of the following polymers is a polyamide comprising of repeating amino acid units? a. wool b. nylon c. dacron 54 d. cotton e. creslan
A
1. When camphor is reduced by sodium borohydride: a. borneol, the endo alcohol formed through the exo attack of hydride is the major product. b. isoborneol, the exo alcohol formed through the endo attack of hydride is the major product. c. borneol, the endo alcohol formed through the endo attack of hydride is the major product. d. borneol, the exo alcohol formed through the exo attack of hydride is the major product. e. equal amounts of borneol and isoborneol are obtained.
B
25. What is the name of ester prepared from propanoic acid and butyl alcohol? a. propyl butanoate b. butyl propanoate c. butyl propyl ester d. ethyl acetate e. none of these
B
44. Electrophilic substitution of methyl benzoate occurs meta to the substituent because: a. the ester group is electron donating and thus activates the ring in the meta position. b. the electron withdrawing ester group destabilizes the ortho and para positions more than the meta position. c. the most stable resonance structure leaves all the positive charge in the meta position. d. the electron withdrawing group activates the benzene ring to the otherwise inactive meta substitution. e. ortho substitution is preferred, but the steric crowding of the ester group causes meta substitution.
B
47.. The active site of Mandelate racemace involves the presence of a non-protein species in the active site to which you measured some bond distances. That species (called a prosthetic group) was: a. Atrolactate b. Mg2+ c. Na+ d. CO2 e. H2O
B
A student spills concentrated sulfuric acid on their hand, what should the student do? a. go find the TA and let them know what happened b. go to the sink and begin running water over the affected area, while your lab partner notifies your TA c. drive themselves to the hospital for the appropriate treatment d. do nothing, sulfuric acid is not harmful e. pour a solution of sodium hydroxide on the hand to neutralize the acid
B
Aspartame, a non-nutritive sweetener, can be written as: a. H-Asp-Glu-OCH3 b. H-Asp-Phe-OCH3 c. H-Val-Asp-OCH2CH3 d. H-Arg-Phe-OCH3 e. H-Thr-His-OCH3
B
In the reduction of camphor to isoborneol, sodium borohydride is used instead of lithium aluminum hydride because: a. lithium aluminum hydride is too mild b. lithium aluminum hydride would react with the solvent ethanol c. lithium aluminum hydride would reduce the camphor all the way to the alkane d. lithium aluminum hydride is a powerful oxidant e. lithium aluminum hydride would only reduce the camphor to the alcohol
B
In the reduction of ketones, an excess of sodium borohydride is usually used: a. to shift the equilibrium toward the alcohol b. because borohydride reacts slowly with the solvent c. to prevent ester formation d. because borohydride reacts vigorously with the solvent e. to prevent hydride rearrangements
B
Reaction of ethylmagnesium bromide with water will generate a. ethanol b. ethane c. butane d. ethyl magnesium hydroxide e. a peroxide
B
SPF refers to product effectiveness against the _____ rays of the sun. a. UVA b. UVB c. UVC d. UVA + UVB e. UVA +UVB + UVC
B
The UV region is a range of frequencies immediately greater than the ____________ region. a. X-ray b. visible c. gamma ray d. microwave e. radio
B
The molar extinction coefficient, e, is: a. The amount of electrons per mole of sample being emitted from the -system b. A measure of how strongly one mole of the sample absorbs light at that wavelength c. A constant quantity of moles emitting energy in the ultraviolet region d. A constant used to correct for different lengths of -systems in alkanes e. A constant specifying the number of moles possessing the energy for UVB absorption
B
To prepare 2-methyl-2-pentanol from a Grignard reaction, you need to use ____ and ____ as starting material. a. ethanol, 1-bromopropane b. acetone, 1-bromopropane c. acetone, 2-bromopropane d. butanone, 1-bromobutane e. acetone, 2-bromobutane
B
What is the role of the ether (THF) in the preparation of Grignard reagent? a. The ether makes the ketone more electrophilic. b. Electron pairs on oxygen increase the solubility of the magnesium of the Grignard reagent by forming a complex. c. The ether has no role and the Grignard reaction would work just as well in another solvent. d. The ether increase reaction enthalpy. e. It dissolves the magnesium, initiating the reaction.
B
What will happen if you don't cool the diazonium chloride salt before addition of phenol? a. It will still produce same diazonium compound b. It will be converted to a phenol c. It will be converted to an amine d. It will produce a different diazonium compound e. It will react with unreacted amine present in solution
B
Which of the following is false about a Grignard reagent? a. Reactions are carried out in ether. b. Grignard reagents function as electrophiles. c. Grignard reagents are protonated by alcohols. d. Grignard reagents have strongly basic properties. e. Grignard reagents react with some components of the atmosphere.
B
Which of these is necessary in order for a molecule to undergo an intramolecular aldol condensation reaction? a. A strong acid catalyst must be present. b. At least 2 carbonyl carbons c. π-bond conjugation d. Aromaticity e. The ability to form a carbocation intermediate
B
You are in lab, and you have already synthesized your indigo dye. You are heating your solution in a capped Erlenmeyer flask. You have added sodium dithionite and have gotten a clear yellow solution. However, as your solution heats, you notice that blue keeps creeping up the side of your flask, no matter how much sodium dithionite you add, but your solution is still clear yellow. Why is this? a. You added too much sodium dithionite b. There is a leak into your flask and the leucoindigo is being oxidized c. You haven't stirred the reaction enough to get it all off the sides d. The leucoindigo solution is losing water as it boils off the sides and leaves indigo e. You accidentally put in your azo dye compound
B
14. What happens when we irradiate a molecule with UV radiation? a. The bonds in the molecule start vibrating faster. b. The molecule breaks apart into smaller molecules. c. Electrons in the molecule get excited from to * orbitals. d. The molecules are polarized and aligned parallel to the UV beam e. The nuclear spin of the molecule is inverted.
C
37. The hydrolysis of esters can be done by both acid or base catalysis, however esterification of carboxylic acids can only be done by acid catalysis. Why is this? a. We cannot make a strong enough base to perform the reaction. b. Base will ruin the product produced. c. The carboxylic acid will be deprotonated by the base and will leave an unreactive carboxylate anion. d. The reaction can be catalyzed by base. e. none of these
C
A mixture of nitric acid and sulfuric acid was added to an equimolar mixture of C6H6, C6H5Z, C6H5Y. After warming and stirring for a few minutes the nitrated products were analyzed and found to consist of the products C6H4YNO2, C6H5NO2, and C6H4ZNO2 in the ratio of 750:30:1, respectively. This data allows one to conclude that: a. the nitro group is a meta director b. the Z group is an activator c. the Y group is an activator d. benzene is the least reactive e. the Z group is an ortho-para director
C
From the lab Molecular Modeling, we were able to determine that a. Ab initio methods provide information about electron distribution much faster than semi-empirical calculations b. The heat of formation of a product is the amount of energy by which a starting material differs from the final product c. The reactivity of an allylic carbocation center correlates to the degree of positive charge localized on the cationic carbon d. All of the above were determined by the Molecular Modeling lab e. Only a and c were determined by the Molecular Modeling lab
C
In an aldol condensation, the reactive intermediate generated by the reaction of a carbonyl compound with a strong base is an A , which acts as a B toward another carbonyl compound. a. A = enol : B = nucleophile b. A = enol : B = electrophile c. A = enolate : B = nucleophile d. A = enolate : B = electrophile e. A = aldol : B = electrophile
C
In the nitration of methyl benzoate, which of the following statements is correct? a. The major product is methyl o-nitrobenzoate. b. The major product is methyl p-nitrobenzoate. c. There is little or no dinitration. d. NO2 + is the nucleophile. e. The electron withdrawing carbonyl group stabilizes the carbonium ion resulting from addition of the nitronium ion.
C
The dimeric structure of diphosphomevalonate decarboxylase involves: a. Covalent amide linkages b. Van der Waals interactions of non-polar side chains c. Interactions of polar sidechains of amino acids d. Hydrogen bonding of amide carbonyls with nearby amide N-H bonds e. Covalent disulfide linkages
C
Using semi - empirical calculations with Spartan, which of the following were computed in the Molecular Modeling II lab? I. Transition state structure II. Heat of formation III. Distribution of Charge IV. Product Ratios a. II only b. I and II c. II and III d. I and IV e. All were computed
C
What is the observable feature in the Ceric Nitrate Test in the experiment of Peptides and Amino Acids? a. Bubbles of CO2 are formed when ceric ammonium nitrate (CAN) oxidizes alcohols. b. CAN reacts with MeOH and a bright yellow precipitate is formed. c. The aqueous ammonium complex of cerium produces a bright red solution. d. There is no observable change; CAN doesn't test for alcohols. e. CAN reacts with fresh aspartame and generates a red precipitate.
C
Which class of compounds is most resistant to hydrolysis (i.e. requires more time and harshest reaction conditions)? a. esters b. acid chlorides c. amides d. acid anhydrides e. aryl acid iodides
C
Which of the following carboxylic acid derivatives possesses the greatest reactivity toward nucleophilic acyl substitution? a. carboxylic acid anhydride b. ester c. alkyl acid chloride d. amide e. aromatic acid chloride
C
Which of the following is not true of Leucoindigo? a. It is the reduced form of indigo b. It is colorless c. It is an Azo Dye d. It is soluble e. It can be oxidized by air
C
Which of the following observations is the best evidence that an unknown compound is an aldehyde? a. formation of CHI3 WITH -OH/I2 b. presence of a C=O stretch in IR c. a silver mirror in Tollens' test d. formation of a yellow precipitate with 2,4-DNP e. a faint rose color with the Schiff reagent
C
Which of the following reagents would you use to prepare an intermediate for the synthesis of methyl benzoate? a. benzene and SOCl2 b. aniline and acetyl chloride c. benzoic acid and SOCl2 d. benzoic acid and methanol (CH3OH) e. benzoyl chloride and CH3CH2OH
C
Which test is used most often to detect the presence of amino acids? a. Ferric Chloride test b. Schiff's test c. Ninhydrin test d. Quinhydrone test e. Dragendorff's reagent
C
12. Which of the following chemicals will not react with Grignard Reagent? a. water b. carbon dioxide c. ethyl ester d. diethyl ether e. acetone
D
23. Which of the following statements is false about Grignard Reaction? a. The Grignard reagent may be viewed as a strong base. b. Grignard reagents are prepared by the reaction of alkyl or aryl halides with magnesium. c. Grignard reagents are often used in reactions with aldehydes or ketones. d. Alcohols are often used as solvents in the Grignard Reactions. e. Grignard reagents react with acids to give alkanes.
D
36. A positive result for the ninhydrin test to detect the presence of amino acids was marked by the appearance of a. blue color b. green color c. black color d. purple color e. brown color
D
40. Which of the following statements regarding the aldehydes and ketones experiment is false? a. Rosaniline hydrochloride is a triphenylmethane dye referred to as Schiff's Reagent. b. The hydrogen attached to an aldehyde's carbonyl carbon is very easily oxidized. c. The iodoform test gives positive results for compounds with a methyl group attached to the functional carbon in methyl ketones and methyl secondary alcohols. d. In the Tollens' test, aliphatic and aromatic aldehydes oxidize silver from silver(0) to silver(I). e. Tollens' test is negative with ketones.
D
49. Which of the following statements is true? a. The iodoform test is positive for both 2-butanone and benzaldehyde. b. The 2,4-DNP test is positive for both benzaldehyde and 2-propanol. c. The Schiff's test is positive for both cyclohexanone and acetaldehyde. d. The Tollens' test is positive for both hexanal and benzaldehyde. e. The Baeyer's test is positive for both benzene and cyclohexene.
D
A good classification test (reaction which provides easy detection of positive result) for a carboxylic acid is a. the Hinsberg test b. treatment with 2,4-dinitrophenylhydrazine solution c. sodium fusion d. the evolution of carbon dioxide upon addition of sodium bicarbonate e. reaction with thionyl chloride
D
All of the reactions below, except one, involve net oxidation or reduction of the organic reactant. Which reaction is neither an oxidation (increase in # of bonds from carbon to electronegative elements or decrease in # of C-H bonds) nor a reduction? a. nitration of benzene (benzene to nitrobenzene) b. camphor to borneol/isoborneol c. cyclohexanol to cyclohexanone d. ester synthesis (benzoic acid to methyl benzoate) e. Tollens' test (aldehyde + silver ammonia complex)
D
Choose the correct statement that compares the reactivity of acetanilide to ethylbenzoate toward electrophilic aromatic substitution. a. Acetanilide is less reactive toward electrophilic aromatic substitution owing to the electron-withdrawing group attached to the aromatic ring. b. Ethyl benzoate is more reactive toward electrophilic aromatic substitution owing to the electron-withdrawing group attached to the aromatic ring. c. The reactivities are approximately the same because both compounds have electron-withdrawing substituents. d. Acetanilide is more reactive toward electrophilic aromatic substitution owing to the electron-donating group attached to the aromatic ring. e. Ethyl benzoate is less reactive toward electrophilic aromatic substitution owing to the electron-donating group attached to the aromatic ring.
D
In the coupling reaction between the diazonium salt and the phenol compound in the Azo dye experiment the phenol acts as a(n): a. Arrhenius acid b. Brönsted-Lowry Base c. Electrophile d. Nucleophile e. The phenol does not take part in the reaction
D
What type of derivatives are prepared from ketones and aldehydes? a. benzamides and benzenesulfonamides b. methiodides and picrates c. 3,5-dinitrobenzoates and phenylurethanes d. semicarbazones and 2,4-dinitrophenylhydrazones e. 2,4,6-trinitrotoluenes and benzoates
D
Which compound can undergo an Aldol condensation with another molecule of itself? a. benzil b. benzaldehyde c. 1,1,1-trimethyl-acetaldehyde d. propanal e. TPCP
D
Which of the following statements is false for the aldol condensation? a. There is enolate formation. b. The base removes an acidic hydrogen from the -carbon. c. There is a nucleophilic attack at the carbonyl carbon. d. A carbonyl group is reduced to an alcohol. e. The product can easily dehydrate.
D
Which of the following statements is false for the reduction of camphor? a. A hydride is transferred from the borohydride ion to the carbonyl of camphor. b. Isoborneol is the major product. c. One mole of NaBH4 can reduce four moles of camphor. d. The borohydride ion can approach the camphor more easily from the exo side. e. If LiAlH4 is used instead of NaBH4, ethanol cannot be used as a solvent.
D
Which of the following statements is not correct? a. During the Fischer esterification, an alcohol adds to the carbonyl carbon of the carboxylic acid. b. Alkyl acid chlorides undergo an exothermic reaction with water. c. The product of the ammonolysis of benzoyl chloride is benzamide. d. Esters, acid chlorides, ethers and amides are all derivatives of carboxylic acids. e. none of these are correct
D
Which of the following will sodium borohydride not reduce? a. acetone b. benzaldehyde c. camphor d. methyl benzoate e. all are reduced
D
Which of these is true about thermodynamic and kinetic control? a. It always produces the most stable product b. Kinetic products always go through a higher energy transition structure c. The kinetic product is always the slowest to form d. The kinetic and thermodynamic product can be the same e. The thermodynamic product is higher in energy than the kinetic product
D
Why do we need to convert indigo to leucoindigo to dye a fiber? a. To learn how to do a reduction b. Leucoindigo is a better dye than indigo c. Indigo cannot be oxidized d. Indigo is not water-soluble e. Leucoindigo will be more expansive than indigo
D
16. Why do esters, which have higher molecular weights than carboxylic acids, have lower boiling points than the carboxylic acids they were made from? a. Carboxylic acids are solids and harder to liquefy than their esters. b. Carboxylic acids have much stronger intermolecular Van der Waals forces. c. Ester molecules have strong hydrogen bonding forces with other ester molecules which helps increase their volatility. d. Boiling points of all organic esters decrease with increasing molecular weight. e. Most carboxylic acids exist as dimers which are held together by two hydrogen bonds.
E
18. TLC is a technique easily used for a. the qualitative monitoring of reactions b. the quantitative monitoring of reactions c. purification of large amounts of an impure compound d. evaluation of the purity of any compound e. a and d
E
31. In general, ______________ are meta directors in electrophilic aromatic substitution. I. Strong electron-donating groups II. Strong electron-withdrawing groups III. Carbonyl groups IV. Esters a. I and IV b. III and IV c. II only d. II and III e. II, III, and IV
E
42. How could you have used infrared spectroscopy to determine if the sodium borohydride reduction of camphor had gone to completion? a. presence of a peak at 1746 cm-1 and absence of a peak at 3500 cm-1 b. presence of a peak at 1746 cm-1 and presence of a peak at 3500 cm-1 c. presence of a peak at 2900 cm-1 and absence of a peak at 3500 cm-1 d. absence of a peak at 1746 cm-1 and absence of a peak at 3500 cm-1 e. absence of a peak at 1746 cm-1 and presence of a peak at 3500 cm-1
E
Choose which statement is false regarding the nitration of methyl benzoate: a. Methyl benzoate is less reactive toward nitration than benzene. b. Methyl m-nitrobenzoate is less reactive toward nitration than benzene. c. The nitration of methyl benzoate occurs mainly at the meta position. d. The nitronium ion is the electrophile in nitration. e. Electron withdrawing groups activate the meta position.
E
In the peptides and amino acids lab, which of the following tests was used to detect the presence of an alcohol? a. Tollens' test b. Permanganate test c. Ceric nitrate test d. a and b are correct e. b and c are correct
E
In the reaction catalyzed by diphosphomevalonate decarboxylase what type of reactive intermediate is generated? a. An enolate b. A carbanion c. A carbon radical d. An alkoxide anion e. A carbocation
E
In the synthesis of an ester from a carboxylic acid, the reaction mixture contains a small amount of mineral acid. This acid: a. increases the yield of the ester b. decreases the yield of the ester c. prevents the formation of salt d. is required to react with the alcohol to form a carbocation e. acts as a catalyst
E
The first step in the Fischer esterification is: a. the loss of water b. the formation of tetrahedral intermediate c. the protonation of the hydroxyl oxygen of the alcohol d. the nucleophilic attack by a molecule of the alcohol e. the protonation of the carbonyl oxygen of the carboxylic acid
E
The imidazole functional group of histidine in an enzyme active site can act: a. as a base to remove a proton from a substrate b. as an acid to donate a proton to a substrate c. as a hydrogen-bonding site only d. as a nucleophile to form new C-N bonds e. both a and b
E
Which is an example of a cofactor in enzyme catalysis reactions? a. non-metal ions b. metal ions c. small organic molecules d. both a and c e. both c and d
E
Which of the chemical tests listed below could be used to distinguish between benzaldehyde and phenylacetone? a. ninhydrin b. Tollens' test c. 2,4-dinitrophenylhydrazine d. Iodoform test e. b and d
E
Which of the following is false? a. In thermodynamic control, the product ratio depends on the relative stability of the products. b. In kinetic control, the product ratio depends on the relative energies of the transition states. c. In some reactions, the less stable product is formed at a faster rate. d. For most reactions, the kinetic product and the thermodynamic product are the same. e. There is no way to control the outcome of a reaction in which the kinetic and thermodynamic products are different.
E
Which of the following statements about TPCP, the product in the aldol experiment, is true? a. TPCP is highly colored because the phenyl rings are coplanar with the cyclopentadienone ring. b. The phenyl rings of TPCP prefer to be oriented perpendicular to the cyclopentadienone ring, resulting in color because of the interactions of the pi systems of the phenyl rings. c. The isolated product would be optically active because the preferred structure is chiral (non-superimposable on its mirror image). d. The TPCP preferred structure is achiral. e. The phenyl rings of TPCP are twisted with respect to the plane of the cyclopentadienone ring, and each phenyl is twisted in the same direction as the others.
E
Which of the following substituents of an aromatic ring are electron-withdrawing? a. carbonyl b. nitro c. amino d. a and c e. a and b
E
Which statement best describes the first steps in the aldol condensation? a. -hydrogen abstraction followed by enolate formation b. nucleophilic attack by hydroxide on carbonyl carbon followed by hydride transfer c. aldehyde hydrogen abstraction followed by enolate formation d. aldehyde hydrogen abstraction followed by hydride transfer e. -hydrogen abstraction leading to enolate formation
E
Why is it that the combination of low molecular weight alcohols and acids or high molecular weights of alcohols and acids was not a good idea for the carboxylic acids and esters experiment? a. Low molecular weight esters decompose at high temperature. b. High molecular weight esters are not volatile enough to have a significant odor. c. Low molecular weight esters may evaporate too quickly. d. High molecular weight esters are not water soluble enough to have a significant odor. e. b and c are correct.
E
