1. Reaction mechanism Mgr. Renata Köhlerová, PhD.
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Reaction mechanism
Mgr. Renata Köhlerová, PhD.

2. Choose the correct contention(s) about nucleophilic agents:
Task 1
Choose the correct contention(s) about nucleophilic agents:
They have affinity for reactants with positive charge.
They belong to positively charged ions.
Example of them is molecule of water.
They originate by homolytic bond cleavage.
Answer
Explanation
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3. Napište všechny izomery sloučeny C6H12.
Answer 1
Napište všechny izomery sloučeny C6H12.
Choose the correct contention(s) about nucleophilic agents:
A. They have affinity for reactants with positive charge.
B. They belong to positively charged ions.
C. Example of them is molecule of water.
D. They originate by homolytic bond cleavage.
bla bla
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Explanation
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4. Agents Explanation 1 Answer
The mechanism of the reaction is determined by particles called agents in organic chemistry and biochemistry. Agents frequently arise by cleavage of the molecule into two parts. If a non-polar covalent bond is cleavaged symmetricaly, they are produced two particles with an unpaired electron - radicals. It is a homolytic cleavage.
A polar covalent bond is cleavaged asymmetricaly. The atom with the higher electronegativity obtains both bonding electrons and the atom the lower electronegativity will have place in valence orbital. It is a heterolytic cleavage. Such they arise carbocations and carbanions.
Nucleophilic agents arise by heterolytic cleavage. They have non-bonding electron pairs or contain p electrons.They often are anions.
For example molecular: H2O, NH3 and ionic: OH-, NH2-, Cl-, I-, CN-
Electrophilic agents arise by heterolytic cleavage, too. They have incomplete valence octet and have full or partial positive charge.
For example molecular: HCl, H2SO4, AlCl3 and ionic: H3O+, NH4+, N02+, Br+, CH3+
Answer
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5. What is the mechanism halogenation of ethene of benzene of ethane
Task 2
What is the mechanism halogenation
of ethene
of benzene
of ethane
of buta-1,3-diene?
Answer
Explanation
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6. What is the mechanism halogenation of ethene of benzene of ethane
Answer 2
What is the mechanism halogenation
of ethene
of benzene
of ethane
of buta-1,3-diene?
CH3-C-H O
CH2=CH OH
electrophilic adition
electrophilic substitution
radical substitution
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Explanation
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7. Chemical reaction Explanation 2 Answer
Chemical transformations are not random events, but they have the exact causes case inner structure of the reactants. It is characterized for chemical reactions, that some bonds are destroyed and others are arised. The journey from reactants to products usually comes through many intermediates, which - if they exists only a very short period of time – we called activated complexes.
The reaction mechanism is a detailed description of all the particular changes at the molecular level during the reaction. It is important for understanding chemical processes.
We use the terms substrate and agent instead of reactants in biochemistry.
We use chemical equations to write the chemical reactions in iorganic chemistry and reaction schemes in organic chemistry. Schemes show only qualitative, not quantitative changes.
The reaction can be split according to many aspects. The most common division is substitution, addition, elimination and rearrangement of organic chemistry.
continue
Answer
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8. Chemical reaction - continue
Explanation 2
Chemical reaction - continue
Substitution
Atom or group of atoms in the carbon chain are exchanged with another atom / group. The most exchanged atom is hydrogen.
It is typical for saturated hydrocarbons and arenes.
Adition
The saturated bond is created from unsaturated (C=C , C=O) bond. unsaturated hydrocarbons, oxoderivatives
Elimination
The small particule is cleavaged from molecule (H2, H2O, NH3, HX, X2 …) and double bond is created.
Rearrangement
intramolecular substitution (fe. keto – enol)
continue
Answer
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9. Chemical reaction – continue: Substitution
Explanation 2
Chemical reaction – continue: Substitution
Type of reaction
Example of substrates
Reaction
radical
alkanes
halogenation
burning (oxidation)
electrophilic
arenes
nitration
sulfonation
nucleophilic
halogen derivatives
hydroxy compounds
Answer
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continue
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10. Chemical reaction – continue: Adition
Explanation 2
Chemical reaction – continue: Adition
Type of reaction
Example of substrates
Reaction
radical
arenes
hydrogenation
electrophilic
alkenes alkynes
halogenation
nucleophilic
oxo compounds
creating of hemiacetals
Answer
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11. Substitutional reactions are typical for A) benzene B) oktane
Názvosloví
Task 3
Substitutional reactions are typical for
A) benzene
B) oktane
C) cyklohexene
D) ethyne
Answer
Explanation
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12. Substitutional reactions are typical for A) benzene B) oktane
Answer 3
Substitutional reactions are typical for
A) benzene
B) oktane
C) cyklohexene
D) ethyne
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Explanation
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13. Substitution Explanation 3 Type of reaction Example of substrates
Atom or group of atoms in the carbon chain are exchanged with another atom / group. The most exchanged atom is hydrogen.
It is typical for saturated hydrocarbons and arenes.
Type of reaction
Example of substrates
Reaction
radical
alkanes
halogenation
burning (oxidation)
electrophilic
arenes
nitration
sulfonation
nucleophilic
halogen derivatives
hydroxy compounds
Answer
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14. The typical mechanism of chloration of butane is electrophilic adition
Názvosloví
Task 4
The typical mechanism of chloration of butane is
electrophilic adition
radical substitution
C) nucleophilic substitution
D) radicaladition
Answer
Explanation
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15. The typical mechanism of chloration of butane is electrophilic adition
Answer 4
The typical mechanism of chloration of butane is
electrophilic adition
radical substitution
C) nucleophilic substitution
D) radicaladition
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Explanation
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16. Cl* + CH4  HCl + H3C* Radical substitution – chloration of methane
Explanation 4
Radical substitution – chloration of methane
Iniciation (origin of radicals)
Cl2  2 Cl*
Propagation
Cl* + CH4  HCl + H3C*
H3C* + Cl2  CH3Cl + Cl*
Termination
2 Cl*  Cl2
Cl* + H3C*  CH3Cl
H3C* + H3C*  CH3CH3
Answer
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17. A) ES requires attacking agent wiht a positive charge.
Názvosloví
Task 5
Choose the correct contention(s) about electrophilic substitution (ES):
A) ES requires attacking agent wiht a positive charge.
B) ES requires attacking agent wiht a negative charge.
C) We need Br+ + for the bromination of benzene.
We need Br- for the bromination of benzene.
Answer
Explanation
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18. A) ES requires attacking agent wiht a positive charge.
Answer 5
Choose the correct contention(s) about electrophilic substitution (ES):
A) ES requires attacking agent wiht a positive charge.
B) ES requires attacking agent wiht a negative charge.
C) We need Br+ for the bromination of benzene.
We need Br- for the bromination of benzene.
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Explanation
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19. Electrophilic substitution
Explanation 5
Electrophilic substitution
It is very common reaction of arenes. At first electrophilic particle reacts with -electron of aromatic system and creates  complex. At second it is rearranged on  complex, there is an electrophilic particle bonded to a certain atom and the compound temporarily loses its aromatic character. Then the proton is separated and aromatic character is restored. It is a typical mechanism for nitration, sulfonation and chlorination.
H2O + +NO2
H-O-NO2 + H-O-SO2-O-H -> H-O-NO2+ -O-SO2-O-H H
nitronion
cation
nitration mixure
Answer
NO2
+ H-O-SO2-O-H H
+ +NO > H
+NO2 ----> H
NO >
-O-SO2-O-H
Back
π complex
σ complex
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20. A) The first reaction is nucleophilic addition.
Názvosloví
Task 6
Reaction of two molecules of ethanal in the presence of a suitable catalyst is an example of two-step reaction:
A) The first reaction is nucleophilic addition.
B) The attacking particule has a positive charge.
C) The second reaction is dehydration.
D) The product is 2-butenal.
Answer
Explanation
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21. A) The first reaction is nucleophilic addition.
Answer 6
Reaction of two molecules of ethanal in the presence of a suitable catalyst is an example of two-step reaction:
A) The first reaction is nucleophilic addition.
B) The attacking particule has a positive charge.
C) The second reaction is dehydration.
D) The product is 2-butenal.
Next
Explanation
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22. Condensation Explanation 6
It is a very common type of reaction in organic chemistry. Basically there are two subsequent reactions - addition and elimination. We talk about aldol condensation in the case of aldehydes.
Answer
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23. The condensation reaction is: addition with the consequent elimination
Názvosloví
Task 7
The condensation reaction is:
addition with the consequent elimination
formation of polyvinyl chloride
reaction of two molecules of ethanol to give diethyl ether
reaction of two molecules of acetaldehyde
Answer
Explanation
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24. The condensation reaction is: addition with the consequent elimination
Answer 7
The condensation reaction is:
addition with the consequent elimination
formation of polyvinyl chloride
reaction of two molecules of ethanol to give diethyl ether
reaction of two molecules of acetaldehyde
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Explanation
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25. Condensation Explanation 7
It is a very common type of reaction in organic chemistry. Basically there are two subsequent reactions - addition and elimination. We talk about aldol condensation in the case of aldehydes.
Answer
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26. Markovnikovo rule is applied in the reaction molecule of HCl with
Názvosloví
Task 8
Markovnikovo rule is applied in the reaction molecule of HCl with
A) 2-butene
B) 1-butene
C) cyklohexene
D) ethene
E) propenoic acid
Write formulas and name products of these reactions.
Answer
Explanation
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27. Markovnikovo rule is applied in the reaction molecule of HCl with
Answer 8
Markovnikovo rule is applied in the reaction molecule of HCl with
A) 2-butene
B) 1-butene
C) cyklohexene
D) ethene
E) propenoic acid
Write formulas and name products of these reactions.
2-chlorobutane
chloorcyklohexane
chloroethane
2-chloropropanoic acid
Next Cl
Explanation
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CH3-CH2Cl
CH3-CH-COOH Cl
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28. Hydrogen bonds to the carbon, which has more hydrogens.
Explanation 8
Markovnikov´s rule
The most electronegative part of the attached molecule is bonded to the carbon which carries fewer hydrogens. or
Hydrogen bonds to the carbon, which has more hydrogens.
Answer
CH2=CH-CH3 + HCl -->
CH3-CH-CH3 Cl
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29. A) leads to a loss of hydrogen. B) belongs to the oxidative reactions.
Názvosloví
Task 9
Dehydratation
A) leads to a loss of hydrogen.
B) belongs to the oxidative reactions.
C) usually leads to the formation of a double bond.
D) belongs to the reductive reactions.
Answer
Explanation
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30. A) leads to a loss of hydrogen. B) belongs to the oxidative reactions.
Answer 9
Dehydratation
A) leads to a loss of hydrogen.
B) belongs to the oxidative reactions.
C) usually leads to the formation of a double bond.
D) belongs to the reductive reactions.
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Explanation
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31. Reactions in v biochemistry
Explanation 9
Reactions in v biochemistry
Additions and eliminations are common reactions in living organisms. They are basically opposite processes. A low molecular weight compound binds to the multiple bond in addition, thus contrary a double bond is formed and a small part is separated in elimination. If that compound is hydrogen, we can talk about hydrogenation (reduction) in the case of addition and dehydrogenation (oxidation) for elimination.
continue
+2H
-2H
CH3CHO CH3CH2OH
Answer
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32. Reactions in v biochemistry
Explanation 9
Reactions in v biochemistry
Hydratation Dehydratation
Carboxylation Decarboxylation
Amination Deamination
+H2O
-H2O
CH2=CH-COOH CH3CHCOOH OH
+CO2
-CO2
CH3 -CO~CoA
HOOC-CH2-CO~CoA
Answer
NH2
CH=CH-COOH CH2-CH-COOH N H
Back
+NH3
-NH3
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33. Creating of 2-butanone from secondary butanol is A) reduction
Názvosloví
Task 10
Creating of 2-butanone from secondary butanol is
A) reduction
B) hydrogenation
C) oxidation
D) dehydration
E) dehydrogenation
Answer
Explanation
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34. Creating of 2-butanone from secondary butanol is A) reduction
Answer 10
Creating of 2-butanone from secondary butanol is
A) reduction
B) hydrogenation
C) oxidation
D) dehydration
E) dehydrogenation
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Explanation
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35. Hydrogenation Dehydrogenation
Explanation 10
Reactions in v biochemistry
Additions and eliminations are common reactions in living organisms. They are basically opposite processes. A low molecular weight compound binds to the multiple bond in addition, thus contrary a double bond is formed and a small part is separated in elimination. If that compound is hydrogen, we can talk about hydrogenation (reduction) in the case of addition and dehydrogenation (oxidation) for elimination.
continue
+2H
-2H
CH3CHO CH3CH2OH
Answer
Hydrogenation Dehydrogenation
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36. Reactions in v biochemistry
Explanation 10
Reactions in v biochemistry
Hydratation Dehydratation
Carboxylation Decarboxylation
Amination Deamination
+H2O
-H2O
CH2=CH-COOH CH3CHCOOH OH
+CO2
-CO2
CH3 -CO~CoA
HOOC-CH2-CO~CoA
Answer
NH2
CH=CH-COOH CH2-CH-COOH N H
Back
+NH3
-NH3
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37. A) positive inductive effect of chlorine.
Názvosloví
Task 11
The fact that trichloroacetic acid is a stronger acid than acetic acid can be explained by
A) positive inductive effect of chlorine.
B) positive mesomeric effect of chlorine.
C) negative inductive effect of chlorine.
D) negative mesomeric effect of chlorine.
Answer
Explanation
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38. A) positive inductive effect of chlorine.
Answer 11
The fact that trichloroacetic acid is a stronger acid than acetic acid can be explained by
A) positive inductive effect of chlorine.
B) positive mesomeric effect of chlorine.
C) negative inductive effect of chlorine.
D) negative mesomeric effect of chlorine.
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Explanation
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39. -X -NO2 -CO -CN -COOR -COOH -COR -SO3H
Explanation 11
Effects
Inductive and mesomeric effect
A shift of electric charge is a result of its compensation in some derivatives of hydrocarbon. If  electrons move to one atom, we talk about induction effect (I effect). If  electrons move, it is a mesomeric effect (M-effect).
If is direction of moving of electric charge to a heteroatom,
we talk about the negative (-) effect.
If is direction of moving of electric charge to a hydrocarbon, we talk about the positive (+) effect.
Answer
I-effect
M-effect +
Mg Li -R
-X -NH2 -
-X -NO2 -CO -CN -COOR -COOH -COR -SO3H
-NO2 -CO -CN COOR -COOH
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40. Názvosloví
Task 12
Do we find any organic compound (aliphatic or aromatic) which is bonded one of the halide elements in the organism?
Answer
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41. Only one type –thyroid hormones with iodine
Answer 12
Do we find any organic compound (aliphatic or aromatic) which is bonded one of the halide elements in the organism?
Only one type –thyroid hormones with iodine
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42. Assign to that type of reaction one of the following answers:
Názvosloví
Task 13
Assign to that type of reaction one of the following answers:
hydration
electrophilic substitution
decarboxylation
condensation
during β-oxidation of fatty acids
in the formation of citric acid; in the pentose cycle
iodination of tyrosine to form thyroid hormone
in the formation of biogenic amines from amino acids
Answer
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43. Assign to that type of reaction one of the following answers:
hydration
electrophilic substitution
decarboxylation
condensation
1A, 2D, 3B, 4C
during β-oxidation of fatty acids
in the formation of citric acid; in the pentose cycle
iodination of tyrosine to form thyroid hormone
in the formation of biogenic amines from amino acids
Next
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44. Homolytic cleavage of bond leads to the formation of radicals.
Názvosloví
Task 14
Homolytic cleavage of bond
leads to the formation of radicals.
can be induced by UV radiation.
leads to the formation of highly reactive residue.
proceeds in with alkenes in the presence of benzoyl peroxide
Answer
Explanation
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45. Homolytic cleavage of bond leads to the formation of radicals.
Answer 14
Homolytic cleavage of bond
leads to the formation of radicals.
can be induced by UV radiation.
leads to the formation of highly reactive residue.
proceeds in with alkenes in the presence of benzoyl peroxide
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Explanation
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46. Homolytic cleavege Explation 14
A symmetrical cleavage of non-polar covalent bond and production of two particles with an unpaired electron - radicals.are typical manifestation of homolytic ceavage.
Homolytic agents usually attack the non-polar covalent bonds.
Answer
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47. Which reaction we can marked as reduction?
Názvosloví
Task 15
Which reaction we can marked as reduction?
fat hardening (hydrogenation)
creating of fumarate from succinate
creating of enolpyruvate from pyruvate
creating of haemiglobin from haemoglobin
Answer
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48. Which reaction we can marked as reduction?
Answer 15
Which reaction we can marked as reduction?
fat hardening (hydrogenation)
creating of fumarate from succinate
creating of enolpyruvate from pyruvate
creating of haemiglobin from haemoglobin
Hydrogenation is binding of hydrogen to unsaturated compounds - an example of reduction.
It is dehydrogenation - example oxidation reaction.
This is not a redox reaction, but the rearrangement (tautomerism).
It is the loss of electron from Fe2+ and its oxidation to Fe3+.
Next
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49. Are you sure you can quit?No
Yes