(1.2) Hydrocarbons - An Introduction

Organic Compounds Organic compounds are molecular compounds of carbon. A hydrocarbon is an organic compound that contains only C and H atoms. Ex. butane (C4H10) or benzene (C6H6)

Organic or Inorganic Sugar vs. Salt C12H22O11 Sugar vs. Salt Which is inorganic and which is organic? Organic compounds are carbon based, therefore sugar is organic, and salt is inorganic. NaCl

Why Study Organic Chemistry? When you study organic chemistry you are studying the substances that make up your body and much of the world around you. We can use the knowledge of organic compounds and synthesize them from inorganic compounds.

Classifying Hydrocarbons We classify hydrocarbons based upon their covalent bonds between carbon atoms and functional groups. Hydrocarbons Aliphatics Alkanes Alkenes Alkynes Aromatics Derivatives ex. Alcohols, esters, amino acids

Classification of Aliphatic Hydrocarbons Recall: Carbon can share 4 electrons There are 3 types of aliphatic hydrocarbons: 1. Alkanes: all carbon atoms are bonded to one another by single bonds C-C have maximum possible # of H atoms referred to as saturated hydrocarbons

Classification of Aliphatic Hydrocarbons 2. Alkenes: at least 1 double bond between carbon atoms is present C=C have less than maximum possible # of H atoms referred to as unsaturated hydrocarbons 3. Alkynes: at least 1 triple bond between carbon atoms is present C  C also referred to as unsaturated

Properties of Alkanes Consider the properties of the following alkanes: CH4 (natural gas) - methane C3H8 (propane burner) - propane C4H10 (fuel in a cigarette lighter) - butane C8H18 (gasoline) - octane C25H52 (paraffin wax) Note the variety!

The “Backbone” These carbon – carbon bonds are referred to as the backbone of organic compounds. That is because they are the main structure from which the functional groups branch. The backbone can be a straight chain, branched chain, or cyclic.

Representing Hydrocarbons Molecular formula e.x. pentane C5H12 Expanded molecular formula e.x. CH3CH2CH2CH2CH3 Condensed Molecular formula e.x. CH3(CH2)3CH3

Drawing Hydrocarbons – 4 Methods Consider 3 hydrocarbons - - methane, butane, pentane There are four methods used to draw these molecules 3-Dimensional sketch show shape around C atoms show all the atoms use lines, dashes and wedges to represent the 3-D structure of the bonds between atoms.

Drawing Hydrocarbons – 4 Methods Consider 3 hydrocarbons - methane, butane, pentane 2) Complete Structural Diagram show all the atoms use lines to represent bonds between atoms

Drawing Hydrocarbons – 4 Methods Consider 3 hydrocarbons - methane, butane, pentane 3) Condensed Structural Diagram show only C-C bonds C-H bonds are assumed to be present but not shown

Drawing Hydrocarbons – 4 Methods Consider 3 hydrocarbons - methane, butane, pentane 4) Line Structural Diagram show only C-C bonds the ends of the lines, and points where they meet, represent C atoms

Naming Hydrocarbons Need to memorize the “root”. # C atoms Root 1 Meth 2 Eth 3 Prop 4 But 5 Pent 6 Hex 7 Hept 8 Oct 9 Non 10 Dec Need to memorize the “root”. We name hydrocarbons based upon how many carbon atoms are present.