Biological Chemistry FIRST YEAR ORGANIC CHEMISTRY Lecture One Introduction, Nomenclature, Bonding Convenor : Dr. Fawaz Aldabbagh

What is Organic Chemistry? It is defined as the study of hydrocarbons (compounds of hydrogen and carbon) and their derivatives 7 million Organic Compounds 1.5 million Inorganic Compounds Animal and plant matter, Foods, Pharmaceuticals, Cosmetics, Fertilizers, Plastics, Petrochemicals, Clothing

Carbon Why is it the element of life on earth? Has Four Bonding Electrons Unique Strong Covalent Bonds Strong Single, Double and Triple Bonds Average Bond Energies (KJ mol -1 ) C-C607 Si-Si230C-H416Si-H323 C-N754Si-N470C-O336Si-O368 O-Si-O = Sand and Rocks

Simplest Organic molecule Covalent Bonding – Atoms Share Electrons

Ionic Bonding – transfer of one or more electrons from one atom to another to create ions Ionic Compound = LiF Ionic Compound = MgCl e + 2 e

lowest energy state Hybridization Excited state 4 sp 3

Methane is Tetrahedral Sp 3 hybridized carbon 4 equivalent C-H bonds (  bonds) All purely single bonds are called  bonds

Alkanes Rotation of groups joined by single bonds does not usually require lots of energy C n H 2n+2

IUPAC-Nomenclature The ending of all names of alkanes is ane – remove H = alkyl 3D – models show that because of the tetrahedral carbon atoms the chains are zig-zagged and not at all straight

Constitutional Isomers Has the same molecular formula as butane, C 4 H 10 Has the same molecular formula as pentane, C 5 H 12 Have different Physical Properties, Mpt, Bpt, densities, indexes of refraction etc

Naming Compounds 2-methylhexane 2-propylheptane 4-ethyl-3-methylhexane 2,3,5-trimethylhexane 2,2,4,4-tetramethylpentane 4-tert-butyloctane or 4-(1,1-dimethylethyl)octane

C1-C4 Alkanes Methane - origins of life. Atmosphere of Jupiter, Saturn, Uranus and Neptune. Marsh Gas, Cow’s stomach. Coal Mines and Natural Gas. Unprocessed Natural Gas contains 50-90% methane, 1- 10% ethane and up to 8% propane and butane. Methane and Ethane are handled as compressed Gases Propane and Butane are stored in low pressure cylinders In liquified forms (Bottled Gas). All are Colourless, odourless gases, non-toxic – Danger in inhaling lies in potential suffocation due to a lack of Oxygen or Explosions when mixed with air.