Organic Chemistry Why Carbon?

Conformations of butane Atoms can rotate around a single carbon-carbon bond – Different arrangements that can occur because of this are called conformations

Structural Isomers of Butane Compounds with the same formula but different arrangements of atoms.

Structural Isomers of Pentane

Structural Isomers of hexane(5)

Structural Isomers of Heptane (9)

Cycloalkanes C 3 H 6 C 4 H 8 C 6 H 12

Many important biological molecules such as sugars, steroids, cholesterol, and sex hormones contain these ring systems

Conformations of Cyclohexane

Monosubstituted cyclohexanes chlorocyclohexane (chair conformation) Cl

Disubstituted cycloalkanes 1,2 - dichlorocyclohexane

Chiral Molecules

Plane Polarized Light

Optical activity is a unique property of chiral molecules + -

In the 1960s, many pregnant women who had taken thalidomide gave birth to deformed babies. Ensuing investigations showed only one optical isomer of the drug to prevented morning sickness but the other optical isomer caused birth defects Sold over the counter in a number of pain remedies such as Advil and Nuprin, ibuprofin contains therapeutic activity only in the (+) isomer. Our bodies can only metabolize (+) glucose and not (-) glucose. (+) leucine tastes sweet while (-) leucine bitter. Our bodies can utilize only (-) amino acids.

Alkanes are typically not very reactive due to strong C-C single bonds. They are nonpolar The most typical reaction is combustion, where an alkane reacts with oxygen to produce carbon dioxide, water, and energy. Chemical Properties of Alkanes

Uses of Alkanes Small number of carbons (1 – 4 carbons) – gases – Heating fuels – propane, butane 5 – 8 carbons – Liquids – Fuels – gasoline, kerosene, diesel, jet fuel 18 + carbons – Waxy solids – Waxes (paraffins), Vaseline

Alkenes

Properties of Alkenes/Alkynes Nonpolar Very reactive

Addition Reactions  Pi bonds are weaker than sigma bonds and are easily broken.  In the addition reaction, reactants are added to the carbon atoms in the double (or triple bond).

Addition Reactions H 2 C=CH 2 + A—B  H 2 C H 2 C – CH 2 A B

Hydrogenation  In hydrogenation, hydrogen atoms add to the carbon atoms of a double bond or triple bond.  A catalyst such as Pt or Ni is used to speed up the reaction.

Hydrogenation of Oils  When hydrogen adds to the double bonds in vegetable oils, the products are solids at room temperature.

Halogenation In halogenation, halogen atoms add to the carbon atoms of a double bond or triple bond.

Testing for Double and Triple Bonds When bromine (Br 2 ) is added to an alkane, the red color of bromine persists. When bromine (Br 2 ) is added to an alkene or alkyne, the red color of bromine disappears immediately.

Hydrohalogenation In hydrohalogenation, the atoms of a hydrogen halide add to the carbon atoms of a double bond or triple bond.

Unsymmetrical alkenes Markovnikov’s Rule When an unsymmetrical alkene undergoes hydrohalogenation, the H in HX adds to the carbon in the double bond that has the greater number of H. “He who hath, gets”

Hydration Adds Water In hydration, H and OH from water add to the carbon atoms of a double bond or triple bond to form alcohols (OH). Also follows Markovnikov’s rule The reaction is catalyzed by acid H +.

Mechanism of Addition Reactions It is a two-step mechanism: – The first step is the slow, rate-determining step. – The second step is fast.

Polymerization Polymers are large molecules formed by bonding smaller molecules such as alkenes (monomers) together to form very long chains

Ethylene H H H H │ │ │ │ C=C + C=C → │ │ │ │ H H H H

Chloroethene (vinyl chloride) H H H H | | | | C=C + C=C → | | | | H Cl H Cl

Polyvinyl chloride

tetrafluoroethene F F F F | | | | C=C + C=C | | | | F F F F

Polytetrafluoroethene

Aromatics

Benzene Derivatives

Functional Groups Groups of atoms that give organic compounds special properties

Alcohols

Carboxylic Acids (organic acids)

Fatty Acids Organic acids that contain 3 or more carbon atoms

Trans Fats Starting January 1, 2006, all foods sold in the the United States will have to list the amount of trans fat they contain right below the amount of saturated fat on their Nutrition Facts label. Note that on this label there is no % Daily Value amount listed in the column for Trans Fat--it's that way because there is none recommended for human consumption

fat Tr trans fatfat cis fat s satutated fat cis fat saturated fat

Omega-3 fatty acids Heart Healthy Fat

Esters

Aldehydes

Ketones

Ethers

Amines

Amphetamines

Glycine

Aspirin

Organic Synthesis Synthesis of acetylsalicylic acid (aspirin)

Identification of Organic Molecules Melting/Boiling Point Infrared Spectroscopy (IR) Mass Spectroscopy (MS) Nuclear Magnetic Resonance Spectroscopy (NMR)

IR Spectrophotometer

IoIo I %T = I/I o x 100 IR

CH 3 OH

O-H

CH 3 OH O-H

CH 3 OH O-H C-H

CH 3 OH O-H C-H

CH 3 OH O-H C-H

CH 3 OH O-H C-H

CH 3 OH O-H C-H C-O

O-H

C-H O-H

C-H O-H C=O

C-H O-H C=O C-H

O-H C=O C-H C-C

C-H O-H C=O C-H C-C C-O

C-H

C=O

C-H C=O C-H

C=O

C-H C=OC-H

C=OC-HC-O

Mass Spectrometer

Ethyl acetate

88g/mol

Ethyl acetate 88g/mol ?

Ethyl acetate 88g/mol CH 3 +

Ethyl acetate 88g/mol CH 3 + ? ?

Ethyl acetate 88g/mol CH 3 + ? C2H5+C2H5+

Ethyl acetate 88g/mol CH 3 + ? C2H5+C2H5+ ?

Ethyl acetate 88g/mol CH 3 + ? C2H5+C2H5+ CH 3 CO +

NMR-Nuclear Magnetic Resonance

Ethyl acetate

MRI-Magnetic Resonance Imaging (NMR)