organic chemistry i chem 2211 - university of south...

Organic Chemistry II

CHEM 2211

Dr. Xiaodong Michael Shi TR, 6:30 pm--7:45 pm

Topic I. Structure and Bonding

NO

NHOH OH

OH

O

F

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•  Carbon §  Group #: 4A §  Atomic #: 6 §  Element symbol: C §  Elemental name: carbon §  Atomic weight: 12.011 §  Electron distribution: 1s2 2s22p2

•  Carbon: the most important element to life! §  Blood: various minute by minute §  Bone: 0.8% §  Tissue: 67% §  Total amount in body: 16 kg


Only carbon forms strong single bond to itself that are stable

enough to resist chemical attack under ambient conditions


q  Bonding: the joining of two atoms in stable arrangement.

Lewis Structures

Bond Length

Bond Angle

Geometry

Formal Charge

And ……


q  Formal Charge Knowing the following key #:

Valence electrons:

Electron ownership:


q  Formal Charge Knowing the following key #:

Valence electrons:

Electron ownership:

Electron ownership: Unshared electrons + ½ of shared electrons

Formal charge = # of valence electron – electron “owns”


q  Formal Charge

CH3

O

CH3

OH

CH2

O


q  Formal Charge

NO2


q  Octet rule

H3C Me

O

SO

ε= 21

ε= 47


q  Resonance: Re-allocation of electrons

n  Single resonance structure does not represent the structure of a molecules, only the hybrid/combination does.

n  Resonance structures are not in equilibrium. They are the different formats of a same molecule.

n  Resonance structure are not isomers.

NO2


q  Bond length

H-H 0.74 H-F 0.92 C-F 1.33 C-H 1.09 H-Cl 1.27 C-Cl 1.77 Page 25


•  Bond strength and bond length (C-C)

Bond length (Å) strength (kcal/mol) CH3-CH3 1.53 88 CH2=CH2 1.34 152 CHΞCH 1.21 200

•  Bond Angle

–  Linear 180o

–  Trigonal planar 120o

–  Tetrahedral 109.5o


•  Bond Angle



•  Hybridization: SP3, SP2, SP

•  s factor


•  Bond strength and bond length (C-H)

Bond length (Å) strength (kcal/mol) CH3-H 1.11 98 CH2=CH-H 1.10 104 CHΞC-H 1.09 125

Topic II. Curved arrow electron pushing

•  Curved arrow notation for electron moving


•  How to draw curved arrow notation:

Where to start: pair of electrons Where to go: how or something can move


•  How to draw curved arrow notation: Where to start and where to go!



C C

C CH2

H

+

Topic III. Acid and Base Chemistry

•  Acid/Base reaction

HA H+ + A-Keq



HA1 HA2 + A1-Keq

+ A2-


•  Acid/Base reaction O

OHH3C+ Na OMe

O

O NaH3C+ HOMe

Keq

Q: What is the Keq? What is ΔG?


•  Acid strength and pKa Resonance effect and inductive effect

O

OHH3C

OHH3C OH


•  Acid strength and pKa O

H3C

O

CH3 H3C

O

CH3

O

H3C

O

CH3

O

H3C

O

OCH3

O

H3CO

O

OCH3


•  Acid strength and pKa Hybridization effect

H H H

Topic IV. Stereochemistry

•  Isomers Isomers: different compounds with the same molecular formula

Constitutional isomers Stereoisomers

Diastereomers

Enantiomers


•  Isomers CH3CH=CHCH3


•  Chiral and Achiral Chiral: a molecule that is not superimposable on its mirror


•  Chiral and Achiral

H

H FCl

H

HFCl

H

H FCl

H

H FCl


•  Chiral and Achiral

Br

H FCl

Br

HFCl

H

Br FCl

Br

H FCl


•  Stereogenic Center Br

H FCl

H

H FCl

F

Cl

H

H

Br

H FCl

F

Cl

Br

H

Topic V. Others

•  Newnam Projection

eclipsed staggered

Topic V. Others

•  Chair conformation:

Topic V. Others

•  Four key types of reactions: SN1

SN2

E1

E2

Topic V. Others

•  Oxidation state:

H CH

HH

[O]

[H]H CH

HO

[O]

[H]H O

H

H [O]

[H]O

H

HO [O]

[H]C OO

H HH HH H

[O]

[H]

[O]

[H]

organic chemistry i chem 2211 - university of south...

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