Organic chemistry 1105

Learning objectivescompounds carbon and other compounds... One element – one branch of chemistry Organic compounds based on carbon: 13 million and rising fast annually All 91 other el

Organic Chemistry

The unique chemistry

of carbon

Learning objectives

compounds

carbon and other compounds

One element – one branch of

chemistry

Organic compounds based on

carbon: 13 million and rising (fast)

annually

All 91 other elements combined:

only 300,000 compounds

Factoids about carbon

Fairly abundant in earth’s crust – but

not enough to explain domination

Highly significant to life

Key element in the human organism –

and all others

“God’s goof”:

The absence of stable mass 5

mass 5 is unstable

would have resulted in much heavier elements

Hoyle:

“Some supercalculating intellect must have designed the

properties of the carbon atom, otherwise the chance of my finding such an atom through the blind forces of nature would be utterly minuscule….The numbers one calculates from the facts seem to me so overwhelming as to put this conclusion almost beyond question”

Organic and inorganic carbon

Inorganic carbon: ionic compounds

where carbon is incorporated as

carbonate – CO3

2-Organic carbon: compounds of

carbon with itself, hydrogen and

Organic carbon forms a thin canopy

Unique (?) conditions on earth that

support life

Earth’s crust - inorganic

Earth’s surface - organic

Vitalism and organic chemistry

 Stable and easily synthesized

 Fragile and not easily synthesized

Belief in Vitalism posited that only living

create organic compounds



Seven ages of man - many ages of a

carbon atom

 Combustion: C + O2  CO2

 Neutralization by seawater: CO2 + Ca(OH)2  CaCO3 + H2O

 Reaction with acid rain: CaCO3 + H2SO4  CO2

 Photosynthesis: CO2  Organic compounds (OC)

 Vegetation decomposes: OC  fossil fuels (FF)

 Vegetation consumed by animal: OC  new compounds

(proteins, DNA etc.)

 Respiration: sugars  CO2 + energy

 Industrialization: FF  C, CO2 + energy

 Manufacturing: FF  Plastics, polymers, drugs etc.

 Waste disposal Fossil fuels, CO2

Two reasons why carbon is unique

Carbon can form four bonds – four

valence electrons

Carbon forms very strong bonds with

itself – chains, rings etc.

Classifying organic compounds

Hydrocarbons are the simplest

organic compounds

Contain only C and H

Simplest is CH4 (natural gas)

Intermediate C8H18 (petroleum)

Synthetic polymers contain

thousands of atoms

Summary of types

Representing molecules

Molecular formula

Structural formula

Condensed structural formula

Naming organic compounds

Meth - ane

Number of carbon atoms

Type of compound

Numbers game: count the carbon

atoms in the chain

Saturation bonding:

Multiple bonds and unsaturation

Saturated: no more bonds can be added

Unsaturated: more bonds can be formed

Alk ene s contain double bonds

Going bananas:

Ethylene and fruit ripening

Examples of alkynes

Number of isomers mushrooms as

chain length increases

Optical isomerism is a special

variation

Molecules exhibit handedness –

mirror images which are not imposable

super-Must have tetrahedral carbon with

four different groups attached

This carbon is chiral

Isomers and reaction yield

Each chiral carbon produces two

isomers

If there are n chiral carbon atoms

there are 2n isomers

Optical isomers are important in

nature

Amino acids are building blocks of

proteins

Amino acids are chiral

Proteins contain hundreds –

thousands of amino acids

Getting the correct isomer is a big

deal

Geometric isomers:

Isomerism and a healthy diet

What’s with all this trans fats anyway?

Ask a Chicago Alderman

Different geometry - same attachments

Cis isomers:

Aromatic: the stuff of dreams

Benzene ring contains 6 C atoms

Bonding is resonant – more stable

than expected

All aromatic compounds contain at

least one benzene ring

Benzene, C6H6, is one of the most

important industrial chemicals

Functional groups

Chemistry of organic compounds is

determined by functional groups

Functional group is an atom or group

of atoms that are different from C

properties on the substance

Heteroatoms affect physical and

Functionalized hydrocarbons

Chlorocarbons and the environment

Important uses – important problems

 Solvents CH2Cl2

Alcohols: hic

Functional group –OH

Polar molecules dissolve in H2O

Ethanol: good for your health/bad

for your health?

Smoke gets in my eyes: olefactory

pleasures of aldehydes

C=O is carbonyl group

Aldehyde contains RCHO

Formaldehyde is a preservative and a

product of burning wood

Acrolein is a product of barbequing

Ketone is R1R2CO

Acetone is a common solvent

Smell found in cinnamon

Raspberries

Carboxylic acids

Commonly found in citrus fruits and

any sour foods

Formic acid present in ant and bee Formic acid present in ant and bee

stings

Esters: sweet aromas and flavours

Ester group is R1COOR2

Sweet aroma in pineapples, jasmine

Synthetic versions are very common

Amines: the stench of death

Amines contain NR1R2R3

Rotting fish

Decaying flesh

Illicit drugs