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Organic Chemistry > Chapter 9: Substitution Reactions > Flashcards

Chapter 9: Substitution Reactions Flashcards

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1
Q

What is this type of substitution reaction?

A

SN2

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2
Q

What is this type of substitution reaction?

A

SN1

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3
Q

The rate of a SN2 reaction is dependent on what?

A

the concentrations of nucleophiles and electrophiles

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4
Q

The rate of a SN1 reaction is dependent on what?

A

the loss of a leaving group

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5
Q
A

Primary Substrate

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6
Q
A

Secondary Substrate

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7
Q
A

Benzylic Group (Bn)

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8
Q
A

Allylic Group

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9
Q
A

Tertiary Substrate

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10
Q

What carbocations are most stable and why?

A

tertiary
the 3 alkyl groups stabilize the charge

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11
Q

What substrates do SN2 reactions favor?

A

primary and secondary substrates
nucleophiles can’t attack tertiary substrates because of steric hinderance

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12
Q

What substrates do SN1 reactions favor?

A

tertiary substrates
no steric hinderance because the nucleophilic attack doesn’t happen in the first step of the reaction. SN1 reactions also depend on the stability of the carbocation formed from loss of LG and tertiary substrates are more stabilized

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13
Q

Why do these molecules favor SN1 reactions?

A

the carbocation formed from the loss of LG can be stabilized through resonance

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14
Q

What type of reaction is dependent on the nucleophile and why?

A

SN2 reactions
the nucleophilic attack happens in the first step of the reaction

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15
Q

What makes a strong nucleophile?

A

a negative charge and polarizability (related to size of atom and number of valence electrons)

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16
Q
A

Strong nucleophiles
favor SN2

17
Q
A

Weak nucleophiles
favor SN1

18
Q

What reaction is more sensitive to the LG and why?

A

SN1
the loss of a LG is the rate determining step in SN1 reactions

19
Q

What makes a good leaving group?

A

good LG are conjugate bases of strong acids (hint: strong acids have weak conjugate bases)

20
Q

What makes a strong acid?

A

ARIO
Atom
Resonance
Induction
Orbitals

21
Q
A

Good LG

22
Q
A

Bad LG

23
Q
A

tosylate (TsO)

24
Q
A

mesylate (MsO)

25
Q
A

triflate (TfO)

26
Q

What is a polar aprotic solution?

A

no H+ on electronegative atoms

27
Q

What type of reaction do polar aprotic solutions favor?

A

SN2

28
Q
A

Dimethylsulfoxide (DMSO)

29
Q
A

Acetone

30
Q
A

Dimethylformamide (DMF)

31
Q

Why do polar aprotic solutions favor SN2 reactions?

A

A nucleophile dissolved in a polar aprotic solution won’t have a solvent shell around the negative charges to prevent a nucleophilic attack (SN2 dependent more on the NA)

Organic Chemistry (8 decks)

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