Organic Chemistry Unit 4: Chapter 9

9.1 Hydrocarbons Organic Compound – a covalent compound containing carbon. CH4, CH3CH2OH Inorganic Compound – a compound that does not contain carbon. NaCl, FeCl3 Hydrocarbon – compounds containing both carbon and hydrogen. C3H8, C4H10

Natural Versus Synthetic Many organic compounds exist naturally – sugars, starches, carbohydrates, fats, proteins, enzymes, DNA, wool, cotton, silk, etc. Chemists can also synthesize (make) many organic compounds. As many as 250 000 new organic compounds are made each year – cough medicines, painkillers, anti-depressants, perfumes, food flavorings, plastic, materials made of rubber or plastic, fabrics such as nylon, rayon, polyester, etc.   Most hydrocarbons come from the Earth. Coal, Petroleum, and Natural gas are the main sources of fuel for humans.

9.2 Representing Hydrocarbons Organic chemistry is based on one element – CARBON. Reasons : C has four bonding locations C can form single, double or triple bonds These properties allow carbon to form a variety of structures, including chains and rings.

Representing Structures and Bonding Complete Structural Diagram Condensed Structural Diagram shows all atoms in the molecule shows bonds between carbons – not the hydrogens

Line Structural Diagram Expanded Molecular Formula shows no carbon or hydrogen atoms. each point represents a carbon shows grouping of atoms without drawing lines for bonds. brackets are used to indicate the location of branched chains CH3CH(CH3)CH2CH2CH3

1 2 3 4 5 6 7 8 9 10 Basic Roots for Organic Compounds Meth Eth Prop But 4 Pent 5 Hex 6 Hept 7 Oct 8 Non 9 Dec 10

9.3 Classifying Hydrocarbons Alkanes hydrocarbons containing single covalent bonds use suffix “ane” known as aliphatic hydrocarbons – form chains and non-aromatic rings formula CnH2n+2 C3H8, C4H10 , C6H14 Straight Chain Alkanes – Unbranched Alkanes   Naming: use the number of carbons to get the root add the suffix “ane”

Branched Hydrocarbons Branched hydrocarbons have alkyl groups that come off of the main chain. Prefixes are used to show how many alkyl groups there are; di, tri, tetra, penta, etc.

IUPAC Rules for Alkane Nomenclature 1. Find and name the longest continuous carbon chain. 2. Identify and name groups attached to this chain. 3. Number the chain consecutively, starting at the end nearest a substituent group. 4. Designate the location of each substituent group by an appropriate number and name. 5. Assemble the name, listing groups in alphabetical order. The prefixes di, tri, tetra etc., used to designate several groups of the same kind, are not considered when alphabetizing. Always put a dash between all numbers and letters. Always put commas between numbers.

Isomers organic compounds that have the same chemical formula but different structural arrangements. Structural Isomers of C6H14 CH3-CH2-CH2-CH2-CH3 CH3-CH2-CH-CH2-CH3