Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Organic Chemistry I > CHP 10 - 11 > Flashcards

CHP 10 - 11 Flashcards

1
Q

What are the 3 steps in radical chain rxn mechanisms?

A
  1. Initiate
  2. Propagation (rxn)
  3. Terminate (radicals go away)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What happens in the initiation step of a radical chain mechanism?

A

homolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What happens in the propagation step of a radical chain mechanism?

A

Product always ends up in propagation step

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What happens in the termination step of a radical chain mechanism?

A

The radicals (terminate) go away

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is Heterolysis?

A

The movement of 2 full electrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is homolysis?

A

The movement of 1 electron at a time. Energy introduced into the system to create a radical. AKA homolytic bond cleavage when the bond breaks, each atom will add 1 electron.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Name this overall reaction

A

Reaction of Radical: Halogenation of Alkanes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Why is there selectivity (differenced in reactivity) between Br and Cl?

A

Reaction Kinetics.
The rxn of Cl2 has exothermic intermediates
The rxn of Br2 has endothermic intermediates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How to predict the major product of the following reaction

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is N-bromosuccinimide (NBS) and N-chlorosuccinimideused (NBS) for?

A

NBS and NCS are specifically used for brominating and chloronating allylic/benzylic positions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What radical initiators can be used with NBS?

A

peroxides ROOR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Name this overall reaction

A

Halogenation at the allylic/benzylic position

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Name this overall transformation

A

Addition of radicals to Alkenes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Properties of Addition of radicals to Alkenes

A
  1. Anti-Markov addition of H-Br
    1. Radicals do not rearrange ( remember carbocations do rearrange)
    2. Reaction does not work w/ HI or HCl
      Stereochemistry (50/50 mixture)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the initiation step of the radical chain reaction mechanism for Addition of radicals to Alkenes?

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the propagation step of the radical chain reaction mechanism for Addition of radicals to Alkenes?

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the termination step of the radical chain reaction mechanism for Addition of radicals to Alkenes?

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the following examples?

A

Examples of stereochemistry in Addition of Radicals to Alkene mechanisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Solve this Addition of Radicals to Alkenes synthesis

A

What’s changed? New C-C bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are the two organometallic compounds to know for this class?

A

organolithium (R-Li) and Grignard organomagnesium (RMgBr)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the reactivity of R-Li and RmgBr?

A

Carboanion Reactivity:
1. Very strong base
2. Strong nucleophile

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Name this organometallic mechanism

A

R-Li
Conjugate acid is a stronger acid because pka is greater that 8 points so the rxn is R->P irreversible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Name this organometallic mechanism

A

RMgBr Grinard

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What type of solvents should be used for R-Li and RMgBr reactions?

A

Anhydrous or “dry” solvents such as Et2O to avoid H2O ruining the reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
How does RMgBr react with epoxides?
RMgBr acts as a strong nucleophile (base)
26
What are the two main coupling reactions that we are learning?
Gilman- Organocuprates (CuLi) and Suzuki-Miyaura Reaction (B(OH)2 and Pd(0))
27
Name this coupling mechanism
Organocuprates Gilman Reagent + alkyl halide=stitched compound
28
Name this coupling mechanism
Organocuprates Gilman Reagent + alkyl halide=stitched compound
29
Name this coupling mechanism
Suzuki-Miyaura Reaction (B(OH)2 and Pd(0))
30
What type of reaction with B(OH)2 and Pd(0) always make?
coupling reaction
31
What does this overall transformation represent?
General scheme for substitution nucleophilic 2nd order biomolecular (SN2) reactions. The overall reaction is in 2nd order and rate=k[Nu][R-L.G]
32
What does this overall transformation represent?
General scheme for substitution nucleophilic 2nd order biomolecular (SN2) reactions. The overall reaction is in 2nd order and rate=k[Nu][R-L.G]
33
Name this mechanism
SN2 mechanism
34
In SN2 reactions, how does attacking the backside of a leaving group change the stereochemistry?
We get an inversion of stereochemistry a the carbon
35
What does the rate of SN2 reactions depend on?
The class of L.G, sterics of beta carbon (carbon right next to the carbon with the alkyl halide), and L.G. ability to leave (weaker the better) methyl>> 1 > 2 >> 3 (tertiary cannot happen)
36
What is the rate of leaving trend for L.G. in a SN2 rxn?
37
Define Nucleophiles
Nucleophiles (electron rich substance that want to share electrons with a nucleus) are electron pair donors (Lewis base) and react with a nucleus (carbon nucleus)
38
Define Electrophile
Electrophile (electron deficient willing to accept electrons) is an electron pair acceptor (Lewis acid)
39
Define Leaving groups (L.G)
Leaving groups (L.G): typically stable ions or neutral species when they leave. Conjugate bases of strong acids (pKa<5)
40
Strong nucleophiles go SN2. Compounds with negative charges are more nucleophilic than neutral species because
they want to share electrons to relieve the negative charge.
41
pKa of alcohols
16
42
pKa of phenols
10
43
pKa of carboxylic acids
5
44
Polar Aprotic solvents used in SN2 reactions where strongest base = strongest Nu
DMSO DMF DMA HMPA acetone THF If the solvent is polar aprotic then it is SN2 because we can dissolve the SM, stabilizes the charge better, and stabilizes the TS.
45
Polar Protic solvents used in SN1, E2, and E1 reactions where the strongest base = weakest Nu
H2O EtOH, MeOH NH3 AcOH
46
How are nucleophiles affected by sterics?
More sterics = bad nucleophile Less sterics = good nucleophile
47
Predict the product and state whether this is SN1, SN2, E1, or E2
SN2
48
Predict the product and state whether this is SN1, SN2, E1, or E2
SN2
49
Predict the product and state whether this is SN1, SN2, E1, or E2
SN2
50
Predict the product and state whether this is SN1, SN2, E1, or E2
SN2
51
How many steps are in SN1?
2
52
Name the reaction of this general scheme
SN1
53
Show the mechanism for this SN1 reaction
54
What is the rate trend of the L.G. class in SN1 reactions?
55
What is the pKa L.G. trend for SN1?
56
Predict the product of this SN1 reaction
57
Predict the product of this SN1 reaction
58
Predict the product of this SN1 reaction
59
Predict the product of this SN1 reaction
60
Predict the product of this SN2 reaction
61
Predict the product of this SN1 reaction
62
Predict the product of this SN2 reaction
63
Predict the product of this SN1 reaction
64
What is Zaitsev's rule and when is it used?
The major product is the more substituted/stable product. Used in E2 reactions
65
What are the exceptions to Zaitsev's Rule?
All follow Hoffman's which is anti=Zaitsev Conjugated Alkenes Big Bulky Bases Fluorine L.G.
66
Predict the product of the following E2 reaction
67
Predict the product of the following E2 reaction
68
Predict the product of the following E2 reaction
69
Predict the product of the following E2 reaction
70
Predict the product of the following E2 reaction
71
Predict the product of the following E2 reaction
72
Predict the product of the following E2 reaction
73
What are the rates of leaving groups I, Br, Cl, F in E2 reactions?
74
Strong charged bases such as NaOH, KOH, NaOCH3 and KOEt can do both SN2 and E2 rxns. How do we determine which way the rxn will go?
pKa values and the class of L.G. When pKa > 11 then E2 because basic When pKa < 11 then SN2 because nucleophilic
75
Write the mechanism for the following E1 rxn
76
Does heat favor E1 or SN1? Do warm conditions favor E1 or SN1?
Heat favors E1 and warm conditions favor SN1
77
How many steps are there in E1 rxns?
2
78
What reaction is described below? Properties: 1. Rate depends on formation of carbocation. 3 > 2 >(1 does not form) 2. The alkene formed is on the most substituted and thermodynamically stable carbon 3. Mechanism has rearrangments 4. Rate of L.G. = I > Br > Cl > (F does not form) and H2O (dehydration)
E1
79
Write the mechanism for the following E1 reaction
80
Write the mechanism for the following E1 reaction
81
Predict the product of the following rxn
82
Predict the product of the following rxn
83
Predict the product of the following rxn
84
Predict the product of the following rxn
85
Complete this radical halogenation mechanism
86
Complete this Gilman reaction
87
Why would concentrated HBr be an inappropriate catalyst for the dehydration of alcohols?
The conjugate base Br is a good nucleophile and it would attack the carbocation to form an alkyl bromide.
88
What would be the first step in the dehydration of cyclohexanol in sulfuric acid?
protonation of the alcohol
89
What time of reaction is a one step process with inversion of configuration?
SN2

Organic Chemistry I (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions