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Many areas rely on organic chemistry, including:

Biology Petroleum Polymers Genetic Engineering Agriculture Pharmacology Consumer Products

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H C

H

H

H

H C

H

C

H

H

H

H

H C

H

C

H

C

H

H

H

H

H H C

H

C

H

C

H

H

H

H

C H

H

H

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Organic molecules can have very complex structures.

A number of formats are used to represent organic compounds.

Each has its own advantages but the goal is the same, to accurately describe the structure of a compound.

Lets look at some different representations.

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Similar to structural formula. Each line represents a bond. Carbons are assumed to be present at the end

of each line segment. Hydrogen is not shown when bound to carbon.

N OH H

H 2 C C H 2

C H 2

CH 2

H 2 C

H 2 C

H 2 C C H 2

C H 2

H 2 C

H 2 C

H 2 C

H 2 C C H 2

C H 2

N

H 2 C

H 2 C

H 2 C C H 2

C H 2

H 2 C

H 2 C

H 2 C

OH H H 2 C

CH 3

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Three dimensional representations

Both are models of propane. 22 - 10

Another key feature of carbon is its ability to form double and triple bonds.

This can be between two carbons alkenes (C=C) and alkynes (C C)

It can also be between carbon and another element.

C=O C=N- C N

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C=C H

CH3

H3C

H C=C

CH3

H H

H3C

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Light causes a change from cis- to trans-. This is how we see.

Several enzymes are required to convert trans-retinal Back to the cis-form.

cis-retinal

trans-retinal

O

light several steps

O

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cis-

trans-

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If you dont believe it, give it a try!

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CHO

HO H

C

CH OH2

CH OH2

H

CHO

HO

CHO

H

C

CH OH2

OH

CH OH2

H

CHO

OH

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Chiral center

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Is the red carbon a stereocenter?

H!

HO!

H!H3C-!

H!

CH2CH3!H3C-!

H! Cl!

Br!

I!

F!

H!H!H!

H!Cl! Cl!

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Light is passed through a polarized filter. A solution of an optical isomer will rotate the light one direction.

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Simplest members of the hydrocarbon family.

contain only hydrogen and carbon only have single bonds

All members have the general formula of

CnH2n+2

Twice as many hydrogen as carbon + 2!

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These go up as the number

of carbons increases.!

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Name bp, oC mp, oC Density at 20 oC

Methane -161.7 -182.6 0.000 667 Ethane - 88.6 -182.8 0.001 25 Propane - 42.2 -187.1 0.001 83 Butane -0.5 -135.0 0.002 42 Pentane 36.1 -129.7 0.626 Hexane 68.7 - 94.0 0.659 Heptane 98.4 - 90.5 0.684 Octane 125.6 - 56.8 0.703 Nonane 150.7 -53.7 0.718 Decane 174.0 -29.7 0.730

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heat or light

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Prefix Carbons Meth- 1 Eth- 2 Prop- 3 But- 4 Pent- 5 Hex- 6 Hept- 7 Oct- 8 Non- 9 Dec- 10

I see much memorization in

your future!!

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Lets practice some names

We will be leaving out the hydrogens.

This makes the carbon chain easier to see.

Its also easier to draw!!

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C - C - C - C - C - C!

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C - C - C - C - C!C!

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3,5-dimethyl heptane

2,3,3,7,8-pentamethyldecane

3-ethyl-5-methylheptane

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Name the following.

(CH3)2CHCH2CH2CH(CH3)2

This is a condensed structural formula.

First convert it to a carbon skeleton, leaving out the hydrogens.

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(CH3)2CHCH2CH2CH(CH3)2

C C | | C - C - C - C - C - C

Now name it!

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1. Longest chain is 6 - hexane

2. Two methyl groups - dimethyl

3. Use 2,5-dimethylhexane

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C - C - C - C - O - H

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1. Follow the same system as with alkanes.

2. Give the name and carbon number for the halide just like a side branch.

C - C - F C - C - C C-C-C-C-C | |

Cl C-Br

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The mechanism takes place in a single step. This is supported by the observed rate law.

Rate = k [HO-][CH3Br]

SN2 reactions also take place with inversion of configuration.

CH3 ClCH3

OH

+ HO- + Cl-

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H O-

+ Br-

Br

H

C

HH

HO

H

C

H H

H

H H

BrHO!+ !-

!- !+

To account for the inversion, the nucleophile must approach from the back of the carbon

The nucleophile acts as a Lewis base and the substrate as a Lewis acid.

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Predicting whether an SN2 reaction will occur is possible.

The SN2 reaction

Nuc:- + RX RNuc + X-

is similar to a Bronsted-Lowry acid base reaction

B:- + HX HB + X-

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C C

H

H

H

H

C C

Cl

H

H

H

-CH2-CH2- ( )

-CH2-CH - ( ) | Cl

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Formula Name Monomer Polymer

Polypropylene CH3CH=CH2 CH-CH2

Polystyrene -CH=CH2 CH-CH2

Polychloroprene H2C=CHC=CH2 CH2CH=CCH2 | Cl

( ) |

CH3

( )

|

Cl

( )

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Rad + CH2 CHCl Rad CH2 CHCl

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Rad-CH2-CHCl + CH2 CHCl

Rad-CH2-CHCl -CH2-CHCl

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Rad-CH2-CHCl -CH2-CHCl + Rad-CH2-CHCl -CH2-CHCl

Rad-CH2-CHCl -CH2-CHCl CHCl-CH2-CHCl-CH2-Rad

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ClC(CH2)4CCl || O

|| O

H2N(CH2)6NH2

Adipoyl chloride hexamethylenediamine

ClC(CH2)4C || O

|| O

-NH(CH2)6NH2 + HCl

+

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Product still has two reactive groups.

Polymer length is a function of time.

ClC(CH2)4C || O

|| O

-NH(CH2)6NH2

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HO

O

HO

O

HO

O

HO

O

HO

HO

O

HO

O

HO

O

HO

O

HO

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crosslink

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