p. 445 chapter 12: organohalides 12.5 – 12.15 : substitution and elimination reactions 12.4 : the...

p. 445

Chapter 12: Organohalides

12.5 – 12.15 : Substitution and Elimination Reactions12.4 : The Grignard Reagent12.1-12.3 : Preparation of Alkyl Halides

Fig. 12-2, p. 455

The Walden Inversion Cycle (1896)

(+)-Maleic Acid[]D = +2.3

(-)-Maleic Acid[]D = -2.3

(+)-chlorosuccinic acid

(-)-chlorosuccinic acid

Fig. 12-5, p. 459

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Characteristics of the SN2 reaction

1.Rate equation

Characteristics of the SN2 reaction

1.Rate equation

2.Molecular factors effecting SN2 reaction rate

Fig. 12-6, p. 460

The Effect of Reactant and Transition Structure Energies on Reaction Rate

p. 461

Effect of ELECTROPHILIC CARBON on SN2 rate

Fig. 12-7, p. 461

Effect of ELECTROPHILIC CARBON on SN2 rate

The sterics around the electrophilic carbon alters the SN2 rate by changing…

0%

0% A. The ground state energy of the starting materials.

B. The energy of the transition state.

Effect of ELECTROPHILIC CARBONon SN2 rate

p. 463

Effect of LEAVING GROUP on SN2 rate

The leaving group alters the SN2 rate by changing…

0%

0% A. The ground state energy of the starting materials.

B. The energy of the transition state.

Effect of LEAVING GROUP on SN2 rate

Table 12-2, p. 462

Effect of NUCLEOPHILE on SN2 rate

The nucleophile alters the SN2 rate by changing…

52%

48% A. The ground state energy of the starting materials.

B. The energy of the transition state.

Effect of NUCLEOPHILE on SN2 rate

p. 465

Effect of Solvent on SN2 rate

Poorly solvated anion(increased nucleophilicity)

O

CNH

CH3

CH3

+

-

OC

N

H

CH3

H3C

O

CN H

H3C

CH3

O CN

H

H3C

CH3

++

+-

-

-X-

Well solvated anion(reduced nucleophilicity)

The solvent alters the SN2 rate by changing…

20%

80% A. The ground state energy of the starting materials.

B. The energy of the transition state.

O

CNH

CH3

CH3

+

-

OC

N

H

CH3

H3C

O

CN H

H3C

CH3

O CN

H

H3C

CH3

++

+-

-

-X-

Solvent effects on SN2 rate

Fig. 12-8, p. 466

Characteristics of the SN1 reaction

1.Rate equation

Characteristics of the SN1 reaction

1.Rate equation

2.Molecular factors effecting SN1 reaction rate

p. 467

Effect of electrophilic carbon on SN1 rate

Fig. 12-11, p. 469

Stereochemical effects of the SN1 mechanism

Fig. 12-12, p. 470

Stereochemical effects of the SN1 mechanism

p. 472

Effect of electrophilic carbon on SN1 rate:

Carbocation Stability

Fig. 12-13, p. 471

Effect of electrophilic carbon on SN1 rate:

Resonance in Carbocations

p. 472

Bond Disassociation Energies and Carbocation Stability

<

p. 472

Effect of LEAVING GROUP on SN2 rate

Effect of LEAVING GROUP on SN1 rate

Fig. 12-15, p. 474

Effect of Solvent on SN1 rate

p. 474

Effect of Solvent on SN1 rate

SN2 vs. SN1

What is the mechanism for the reaction below?

50%

50% A. SN1

B. SN2

Cl NaI

DMF

I

What is the mechanism for the reaction below?

50%

50% A. SN1

B. SN2

CH3

OHCH3

ClHClH2O

What is the mechanism for the reaction below?

50%

50% A. SN1

B. SN2

OHHBr

BrCH3CO2H

What is the mechanism for the reaction below?

50%

50% A. SN1

B. SN2

BrCH3ONa

OCH3CH3OH

Elimination Reactions

1.Intro: Eliminations vs. Substitutions

The E2 Mechanism

1.Rate

2.Molecular factors effecting the E2 mechanism

Stereochemistry

Zaitzev’s Rule

Barton’s Experiments

Fig. 12-19, p. 482

Stereochemistry of the E2 mechanism

Elimination Reactions : The E1 Mechanism

1.Rate

2.E1 and SN1

3.Molecular factors effecting the E2 mechanism

Stereochemistry

Zaitzev’s Rule

Summing it all up : SN1, SN2, E1 and E2

1. Primary Alkyl Halides

2. Secondary Alkyl Halide

3. Tertiary Alkyl Halides

Table 12-1, p. 446

Properties of Alkyl Halides

p. 447

Properties of Alkyl Halides

p. 453

The Grignard Reagent

p. 227

Synthesis of alkyl halides : review1. Addition of HX to an alkene (section 7.6)

a. Obeys Markovnikov’s Rule (section 7.7)

p. 239

Synthesis of alkyl halides : review1. Addition of HX to an alkene (section 7.6)

a. Obeys Markovnikov’s Rule (section 7.7)b. Carbocations that can rearrange, will rearrange (section 7.10)

p. 255

Synthesis of alkyl halides : review2. Addition of X2 to an alkene (section 8.2)

Anti addition

p. 255

Synthesis of alkyl halides : review3. Radical Halogenation (section 6.3)

CH3

CC

CH3

HH

H H

+Cl2

CH3

CC

H2C

HH

H HClCH3

CC

CH3

HH

H Clheator

light

Statistical

Synthesis of alkyl halides : New

1. From alkynes

Allylic bromination with N-Bromo

Succinimide

2. From Alcohols

a. Using strong acid

b. Via Tosylates

c. Using SOCl2 and PBr3

N

O

O

Br

Fig. 12-1, p. 449

The Allyl Radical

End