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Esercizi di ricapitolazione
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1
Classify each reaction below as a(n)
a. addition
b. elimination
c. substitution
d. rearrangement
1.1
1.2
2
Classify the structure below as a nucleophile or electrophile and briefly
explain your choice
3
The alkane formed by hydrogenation of (S)-4-methyl-1-hexene is optically
active while the one formed by hydrogenation of (S)-3-methyl-1-pentene is
not. Explain.
4
Answer the question(s) below consider the following reaction
4.1 Write the complete stepwise mechanism for this reaction. Be sure to show all intermediate
structures and all electron flow using arrows.
4.2 The observed stereochemistry of addition of chlorine to cyclohexene is explained by the
intermediacy of a:
a- cyclonium ion
b- carbocation
c- chloronium ion
4.3 Since the two chlorine atoms add to opposite faces of the cyclohexene double bond, we
say that the reaction occurs with
a- syn stereochemistry
b- cis stereochemistry
c- anti stereochemistry
d- retention of stereochemistry
4.4 Draw the most stable chair conformation of trans-1,2-dichlorocyclohexane
5 Draw the product(s) of the reaction of (R)-3-chlorobutene with HBr. Indicate stereochemistry
6 Consider partial hydrogenation of the following substance
6.1
Which of the following describes this reaction?
a.
b.
c.
d.
6.2
The product would contain trans double bond(s).
The product would be saturated.
The product would lower blood cholesterol.
All of the above would occur.
Is the starting compound chiral?
6.3
6.4
The presence of a _____ double bond causes a decrease in the
melting point. Explain.
Triglycerides that are solids at room temperature are called
______, while those that are liquids at room temperature are
called _______.
17.1 Which of the following compounds does not have an alpha hydrogen?
A) I
B) II
C) III
D) IV
E) all of the above
17.2 The Hell-Volhard-Zelinsky reaction involves:
A) the α-bromination of carboxylic acids.
B) the α-bromination of ketones.
C) the bromination of alcohols.
D) the oxidation of aldehydes to acids.
E) none of the above
17.3 Which of the following reagents will quantitatively convert an enolizable
ketone to its enolate salt?
A) lithium hydroxide
B) lithium diisopropylamide
C) methyllithium
D) diethylamine
E) pyridine
17.4 Which of the following aldehydes does not undergo an aldol addition when
mixed with base?
A) I
B) II
C) III
D) IV
E) V
17.5 Which of the following statements describes the first step in the mechanism of
the aldol condensation?
A) An alpha hydrogen is abstracted by the base to form an enolate anion.
B) A nucleophilic base attacks the carbonyl carbon atom.
C) The carbonyl oxygen is protonated by the base ion.
D) The alpha hydrogen is abstracted by an acid to the enolate anion.
E) The carbonyl oxygen of one aldehyde attacks the carbonyl carbon of another.
17.6 What product results when malonic ester is treated with the following
sequence of reagents:
1) NaOCH2CH3;
2) PhCH2Br;
3) H3O+, Δ?
17.7.1 Which of the following molecules cannot generate an enolate?
17.7.2 Which of the previous molecules can generate two types of enolates?
17.8 Draw the most stable enol of the following ketone
17.9 Fill in the empty boxes
18.1 Name the following compound
18.2 What is the structure of styrene?
18.3 Why does benzene undergo electrophilic substitution rather than
electrophilic addition?
18.4 Provide the major resonance structures of the intermediate sigma
complex in the reaction of benzene with the generic electrophile E+.
18.5 Which of the following is one of the resonance contributors of
the intermediate produced in a Friedel-Crafts alkylation of benzene?
18.6 Which of the following is the electrophile that attacks the aromatic ring
during nitration?
A) NO2
B) HNO3
C) HNO3D) NO2+
E) NO218.7 What is the major product of the following Friedel-Crafts alkylation?
18.8 What is the structure of 3-phenylpentane? Is the compound chiral?
18.9 In electrophilic aromatic substitution reactions, a chlorine substituent is:
A) a deactivator and a m-director
B) a deactivator and an o,p-director
C) an activator and a m-director
D) an activator and an o,p-director
E) none of the above
18.10 What is the major product of the following reaction?
18.11 What factors affect the ortho/para ratio in electrophilic aromatic substitution
reactions?
18.12 Which is the best method for carrying out the following reaction?
18.13 Which is the best method for preparing m-chloroaniline from benzene?
18.14 Provide a series of synthetic steps by which 2-bromo-4-nitrobenzoic acid
can be prepared from toluene
18.15 Which of the following is the most acidic?
18.16 Does cycloheptatriene have a higher or lower pKa than cyclopentadiene? Explain
18.17 Propose a synthesis of meta-bromobenzaldehyde
19.1 What is the systematic name for the following compound?
A) aziridine
B) oxetane
C) oxirane
D) azetidine
E) thiirane
19.2 Which of the following is the structure for azetidine?
19.3 What is the systematic name of the following compound?
19.4 Draw the structure of piperidine
19.5 Provide the name for the compound shown:
19.6 Draw the structures of piperidine and morpholine and explain their relative
basicities.
19.7 Which is the stronger base in the pair below? Explain your choice
19.8 Give the major product for the following reactions:
19.8.1
19.8.2
19.9 Draw the structure of indole
19.10 Which is the stronger base in the pair below? Explain your choice.
19.11 Do you expect pyridine to undergo electrophilic substitution reactions?
Give an example.
19.12 Do you expect pyridine to undergo nucleophilic substitution reactions? If
yes, on what position would the substitution occur? Give an example
19.13 Draw the structures of the keto forms of both 2-hydroxypyridine and
4-hydroxypyridine.
19.14 Which nucleic acids contain the pyrimidine ring structure?
19.15 Draw the structure of purine.
19.16 Name the following compound
A) adenine
B) guanine
C) cytosine
D) uracil
E) thymine
19.17 Fill in the empty
9.9
Predict the product of treating each compound with HNO3/H2SO4.
9.23 The following alkylation reactions do not yield the compounds shown as
the major product. Predict the major product for each reaction and provide a
mechanism for their formation.
(b)
9.25 How many monosubstitution products are possible when
1,4-dimethylbenzene (p-xylene) is treated with Cl2/AlCl3?
When m-xylene is treated with Cl2/AlCl3?
9.36
Account for the fact that phenol (pKa 9.95) is a stronger acid than
cyclohexanol (pKa 18).
9.38
From each pair, select the stronger base:
C6H5O- and OHa
C6H5O- and HCO3b
C6H5O- and CH3COOc
9.50
Which compound is a better nucleophile?
10.1 Identify and define all chiral centers in coniine, nicotine, and
cocaine.
10.13 Draw examples of 1°, 2°, and 3° amines that contain at least four sp3hybridized carbon atoms. Using the same criterion, provide examples of 1°,
2°, and 3° alcohols. How does the classification system differ between the
two functional groups?
10.15 Epinephrine (Adrenaline) is a hormone secreted by the adrenal medulla.
Among epinephrine's actions, it is a bronchodilator.
Draw the structure of Adrenaline:
4-[(1R)-(-)-1-hydroxy-2-(methylamino)ethyl]benzene-1,2-diol
10.23 Account for the fact that substitution of a nitro group makes an aromatic
amine a weaker base, but makes a phenol a stronger acid. For example, 4-nitroaniline is a weaker base than aniline, but 4-nitrophenol is a stronger acid than
phenol.
10.31 Procaine was one of the first local anesthetics for infiltration and regional
anesthesia. Its hydrochloride salt is marketed as Novocaine.
Which nitrogen atom of procaine is the stronger base? Draw the formula of
the salt formed by treating procaine with one mole of HCl.
10.32 Provide IUPAC names for the following compounds
a
b
12.5
Show how these three compounds can be synthesized from the same
Grignard reagent:
12.13 Complete these reactions:
12.17 Name these compounds:
a
b
c
d
12.19 Write an equation for the acid-base reaction between phenylmagnesium
iodide and a carboxylic acid. Use curved arrows to show the flow of electrons in
this reaction. In addition, show that this reaction is an example of a stronger acid
and stronger base reacting to form a weaker acid and weaker base.
12.23 5-Hydroxyhexanal forms a six-membered cyclic hemiacetal
that predominates at equilibrium in aqueous solution.
(a)
Draw a structural formula for this cyclic hemiacetal.
(b)
How many stereoisomers are possible for 5-hydroxyhexanal?
(c)
How many stereoisomers are possible for this cyclic hemiacetal? Define.
(d)
For each stereoisomer draw the chair conformation.
12.36 Draw a structural
formula for the product
formed by treating butanal
with each of the following
sets of reagents:
12.41 Many tumors of the breast are estrogen dependent. A widely used antiestrogen
drug is tamoxifen:
(a)
How many stereoisomers are possible for tamoxifen?
(b)
Specify the configuration of the stereoisomer shown here.
(c)
Show how tamoxifen can be synthesized from
the given ketone using a Grignard reaction, followed
by dehydration.
12.46 Test your cumulative knowledge of the reactions learned thus far by
completing the following chemical transformations. Note: Some will require
more than one step.
13.2 Match each compound with its appropriate pKa value:
pKa 0.22 3.85, 5.03
13.3 Draw the product of the reaction of salicylic acid with (a) one equivalent
of NaOH, (b) two equivalents of NaOH, and (c) two equivalents of NaHCO3.
13.10 Draw a structural formula for each carboxylic acid:
4-Aminopentanoic acid
(E)-3,7-Dimethyl-2,6-octadienoic acid
(Z)-3-Hexenedioic acid
13.11 Zinc 10-undecenoate, the zinc salt of 10-undecenoic acid, is used to treat
certain fungal infections, particularly tinea pedis (athlete’s foot).
Draw a structural formula of this zinc salt
13.12 The normal pH range for blood plasma is 7.35–7.45.
Under these conditions, would you expect the carboxyl group of lactic acid
(pKa 3.85) to exist primarily as a carboxyl group or as a carboxylate anion?
13.13 The pH of human gastric juice is normally in the range from
1.0 to 3.0.
What form of lactic acid (pKa 4.07), lactic acid itself or its anion,
would you expect to be present in the stomach?
13.14 Give the expected organic products formed when phenylacetic acid,
PhCH2COOH, is treated with each of the following reagents:
13.15 Show how to convert (R)-2-phenylpropanoic acid to (R)-2-Phenyl-1propanamine
14.1 Draw a structural formula for each compound:
Dimethyl carbonate
Diethyl oxalate
Ethyl (Z)-2-pentenoate
Ethyl benzoate
14.2 Write the IUPAC name for:
14.41 Procaine (whose hydrochloride is marketed as Novocaine) was one of the
first local anesthetics for infiltration and regional anesthesia.
There are two nitrogen atoms in procaine. Which of the two is the stronger base?
14.42 Following are structural formulas for two
local anesthetics: Lidocaine was introduced in
1948 and is now the most widely used local
anesthetic for infiltration and regional
anesthesia. Its hydrochloride is marketed under
the name Xylocaine.
Mepivacaine (its hydrochloride is marketed as
Carbocaine) is faster and somewhat longer in
duration than lidocaine.
(a) Propose a synthesis of lidocaine from 2,6dimethylaniline, chloroacetyl chloride
(ClCH2COCl), and diethylamine.
(b) What amine and acid chloride can be
reacted to give mepivacaine?
14.51 At low temperatures, the amide exhibits cis-trans (E-Z) isomerism, while at higher temperatures it does
not. Explain how this is possible.
19.18 Which heterocyclic ring is present in cytosine DNA base?
19.19 Which of the following amino acids contain a heterocyclic ring?
A) tryptophan
B) proline
C) histidine
D) alanine
E) tryptophan, proline and histidine
19.20 Fill in the empty
20.1 All chiral D-sugars rotate plane-polarized light
A) clockwise.
B) counterclockwise.
C) +20.0°.
D) in a direction that cannot be predicted but must be determined experimentally
20.2 What is the relationship between the following compounds?
15.4 Draw the product of the crossed aldol reaction between
benzaldehyde and 3-pentanone
15.6 Show the product of Claisen condensation of ethyl 3-methylbutanoate
in the presence of sodium ethoxide.
15.8 Depict the crossed Claisen condensation between ethyl benzoate
and ethyl phenylacetate
15.29 When a 1:1 mixture of ethyl propanoate and ethyl butanoate is treated with
sodium ethoxide, four Claisen condensation products are possible.
Draw a structural formula for each product.
15.30 Draw a structural formula for the β-ketoester formed in the crossed Claisen
condensation of ethyl propanoate with each ester:
12.35 In dilute aqueous acid, (R)-glyceraldehyde is converted into an
equilibrium mixture of (R,S)-glyceraldehyde and dihydroxyacetone.
Explain and propose a mechanism for this isomerization.
20.3 At which carbon are the following sugars epimers of each other?
20.4 Assign the proper configurational
descriptor to each asymmetric center in Dglucose (Fischer)
20.5 Draw the open-chain form of D-idose
20.6 Draw the Fischer projection for the openchain form of D-fructose
20.7 Provide the structure of the product which results when D-ribose is treated
with bromine water
20.8 What nucleophilic carbon species is used in the Kiliani-Fischer synthesis?
20.9 In solution, glucose exists as:
A) the open-chain form only.
B) the cyclic hemiacetal form only.
C) the cyclic acetal form only.
D) an equilibrium mixture of the open-chain form and cyclic acetal forms.
E) an equilibrium mixture of the open-chain form and cyclic hemiacetal forms.
20.10
When a monosaccharide reacts to give the cyclic form from its open-chain
form, how many distinct forms are possible?
20.11
Anomers of D-glucose differ in their stereochemistry at which carbon atom?
20.12
20.13
When pure α-D-glucopyranose is dissolved in water, the optical rotation
of the resulting solution changes over a period of time. What is the name
of this phenomenon and why does it occur?
Draw the Haworth structure of α-D-ribofuranose.
20.14
Draw the most stable chair conformer of α-D-glucopyranose
20.15
Give the name for the following structure:
20.16
Why is β-D-glucopyranose more stable in nature than α-D-glucopyranose?
20.17
Which of the following statements best describes the meaning of a
glycoside?
A) It is the mirror image of a sugar.
B) It is the hemiacetal of a sugar.
C) It is the acetal of a sugar.
D) It is the enantiomer of a sugar.
E) It is the enol-keto form of a sugar.
20.18
Which of the following would give a positive Tollen's test?
A) α-D-glucopyranose
B) methyl β-D-glucopyranoside
C) sucrose
D) methyl α-D-ribofuranoside
E) none of the above
20.19
Which of the following is true about sucrose?
A) It hydrolyzes to fructose and glucose.
B) It is a reducing sugar.
C) It is a monosaccharide.
D) It undergoes mutarotation in water.
20.20
What is the main structural difference between amylose and cellulose?
20.21
20.22
Draw the most stable chair conformer of D-glucose.
Which of the following is a disaccharide?
A) galactose
B) fructose
C) erythrose
D) lactose
E) all of the above
21.1
Which of the following amino acids has an aromatic R group?
A) serine, B) cysteine, C) asparagine, D) tyrosine, E) leucine
21.2
Which of the following amino acids has a sulfur in the R group?
A) serine, B) cysteine, C) asparagine, D) tyrosine, E) leucine
21.3
The α-carbon of all the α-amino acids is a chirality center except for:
A) glycine, B) threonine, C) proline, D) aspartic acid, E) arginine
21.4
Explain what essential amino acids are and list all of them.
21.5
Draw the form of L-tryptophan which is present at its pI
21.6
Name the following compound:
21.7
What is the pI of glycine? The structure and pKa values are shown
below.
21.8
Define what is meant by isoelectric point (pI) and give an
example for an amino acid that have no ionizable side chain.
What is the pI value? If the amino acid has an ionizable side
chain, what is the pI value?
21.9
21.10
Calculate the isoelectric point for the following compound:
When a disulfide linkage is formed, the starting compound
originating this new linkage has been:
A) hydrolyzed; B) dehydrated; C) electrolyzed; D) oxidized; E) reduced.
21.11
Provide the structure of Ala-Ser-Gly
21.12
In conventional peptide synthesis, the nitrogen of a given amino
acid must be deactivated or blocked while the carboxyl group is
activated. Which of the following reagents is used to protect the
amino group of an amino acid?
A) di-tert-butyl dicarbonate
B) dicyclohexylcarbodiimide
C) ninhydrin
D) trifluoroacetic acid
E) phenylisothiocyanate
21.13
21.14
Name the tetrapeptide:
Which of the following protein structures does denaturation destroy?
A) primary and secondary structures
B) secondary and tertiary structures
C) tertiary and quaternary structures
D) secondary, tertiary, and quaternary structures
21.15
What are enzymes?
A) saccharides that catalyze chemical reactions
B) nucleic acids that catalyze chemical reactions
C) unsaturated fats that catalyze chemical reactions
D) DNA molecules that catalyze chemical reactions
E) proteins that catalyze chemical reactions
21.16
α-Helix of proteins is stabilized by:
A) disulfide bridges.
B) hydrogen bonds.
C) electrostatic interactions.
D) hydrophobic interactions.
E) none of the above.
23.1
How does NAD+ serve as a catalyst in oxidation reactions?
A) It accepts a hydride ion at the 4-position of its pyridinium ring.
B) It accepts a hydride ion at the amide carbonyl group at the 3-position.
C) It accepts a proton at the 4-position of its pyridinium ring.
D) It accepts a proton at the amide carbonyl group at the 3-position
23.2
Identify all true statement(s). You may choose more than one answer.
A) NADH is oxidized to NAD+.
B) NADPH is oxidized to NADP+.
C) NADH is reduced to NAD+.
D) NADPH is reduced to NADP+.
E) NAD+ is oxidized to NADH.
23.3
The common name of vitamin B1 is?
23.4
How does CoASH used in biological systems to activate carboxylic
acids?
23.5
Which of the following is not a lipid-soluble vitamin?
A) vitamin A
B) vitamin D
C) vitamin E
D) vitamin C
E) vitamin K
23.6
Which of the following vitamins are radical inhibitors or antioxidants?
A) niacin
B) vitamins B1 and B12
C) vitamins B2 and B6
D) vitamins A and D
E) vitamins C and E
23.7
Which of the following vitamins can be synthesized by all mammals
except humans and guinea pigs?
A) vitamin B12
B) riboflavin (B2)
C) vitamin C
D) thiamine (B1)
E) pyridoxine (B6)
23.8
What are holoenzymes and apoenzymes?
23.9
Which type of vitamins, water-soluble or lipid-soluble, can cause overdose?
23.10
Which molecule does the following structures represent?
A
B
25.1
Which of the following statements is not true about fatty acids?
A) Fatty acids are carboxylic acids with long hydrocarbon side chains.
B) The double bonds in unsaturated fatty acids are always conjugated.
C) Most naturally occurring fatty acids contain even numbers of carbons and are unbranched.
D) Fatty acids can be saturated or unsaturated.
E) Physical properties of fatty acids depend on the length of the hydrocarbon chain and the
degree of unsaturation.
25.2
Myristic acid has the formula CH3(CH2)12CO2H. Provide the structure
of the triglyceride trimyristin
25.3
Why do most naturally occurring fatty acids contain an even number
of carbon atoms?
25.4
Which of the following statements is true about terpenes?
A) They are a class of lipids that can be isolated from plants.
B) They contain carbon atoms in multiples of five.
C) Tetraterpenes have 40 carbon atoms.
D) all of the above
25.5
What is the IUPAC name for isoprene?
25.6
One five-carbon compound used for the biosynthesis of terpenes
is called isopentenyl pyrophosphate (IPP). Draw its structure.
This compound is in equilibrium with
dimethylallylpyrophosphate (DMAPP): show the structure.
25.6a
The structures of steroids are based on a tetracyclic ring
system, involving three six-membered rings and one _____membered ring.
The chemical name of this tetracyclic compound is
________________________________________________
25.6b
The ring fusions are all _______ in most steroids, giving
steroids their rigid geometry.
25.6c
A terpene with 10 carbon atoms is called a ___________________,
while a terpene with 20 carbonatoms is called a _______________.
25.7
In nature, biosynthesis of cholesterol starts from:
A) phosphoglyceride.
B) amino acids.
C) squalene.
D) prostaglandin.
E) steroid
25.8
Most hormones are:
A) phosphoglycerides.
B) terpenes.
C) squalenes.
D) prostaglandins.
E) steroids.
25.9
What is the most abundant steroid in our body?
A) cholesterol
B) aldosterone
C) hydrocortisone
D) estradiol
E) prostaglandin
25.10
What is the precursor of bile acids?
A) phosphoglyceride
B) acetyl CoA
C) squalene
D) prostaglandin
E) cholesterol
26.1
What is a nucleoside?
26.2
What is a nucleotide?
26.3
26.4
What are the four common ribonucleosides?
What is the major structural difference between a ribonucleoside and a
ribonucleotide?
26.5
Besides a possible difference in base structure, what is the major
structural difference between ribo- and deoxyribonucleosides?
26.6
Name the two pyrimidine bases which serve as components in
deoxyribonucleotides
26.7
Show that you understand how
the structural components of
DNA are bonded together by
drawing a linear segment that
contains 3 base residues
26.8
Name the two purine bases which serve as components in
ribonucleosides
26.9
Identify the nucleoside
shown:
26.10
Draw the structure of AMP
26.11
26.12
Identify the structure
Identify the structure
26.13
Identify the sugar and
the base in the structure
below
26.14
Identify the sugar and
the base in the structure
below
26.15
Draw the structure of cytidine 5'-phosphate.
26.16
A commonly known nucleotide is adenosine 3', 5'-phosphate
(cAMP). What is the structure of cAMP?
28.1
Show with arrows the electron movement for the following
Diels-Alder (pericyclic) reaction: