Hydrocarbons Thornburg 2016

Hydrocarbons… Are composed of Hydrogen and Carbon Simplest form of Hydrocarbons are Alkanes Alkanes can exist in the form of a straight chain or a branched chain were originally thought to have only been created by living organisms

The 1st 10 Straight – Chain Alkanes Thornburg 2016 The 1st 10 Straight – Chain Alkanes

Thornburg 2016 Skeletal Formulas A common shorthand way to draw organic molecules is to use their skeletal formulas Only carbon atoms and functional groups are shown in a skeletal formula A skeletal formula uses lines to represent bonds between carbon atoms. Even though the hydrogen atoms are not drawn in the skeletal diagram, it is understood that the hydrogens are still there

Drawing Skeletal Formulas Thornburg 2016 Drawing Skeletal Formulas Draw the skeletal formula for these 2 molecules:

Thornburg 2016 Name these alkanes hexane heptane butane propane

Drawing Hydrocarbons Draw Lewis Dot Structures for the following: Ethane Pentane Thornburg 2016

Branched Chain Alkanes An alkyl group is a short side chain called a substituent that branches off from the parent chain of a hydrocarbon The alkyl group is named using the same prefixes as are used in naming the parent chain Example: 2 – methylpropane Thornburg 2016

Name these alkanes Thornburg 2016 3 - methylhexane 2,3 - dimethyl butane 2, 2 - dimethylpentane 3, 5 - dimethylheptane 4 – ethyl, 3,6 – dimethyloctane

IUPAC Rules Thornburg 2016 Find the longest carbon chain. This is the parent structure and will provide the root for the name of the molecule Number the carbon atoms. Start from the end that will give substituent chains and double bonds smaller numbers. Add numbers to show where double or triple bonds start within the parent chain. Add numbers to the substituent groups (ex: 3- methyl, 5 – ethyl) If a substituent shows up more than once, use prefixes to indicate this Put alkyl substituents in alphabetical order. Ignore prefixes Use proper punctuation. Commas separate numbers, dashes separate words. No spaces between names

Thornburg 2016 Functional Groups Functional Group: A functional group is anything that is added to a carbon chain (or carbon ring) that changes it chemically. This can be: Another carbon chain. A halogen gas atom. An alcohol group. A ketone. Etc. There are over 1000 functional groups. You will be expected to be familiar with 8 of these.

Common Functional Groups

Thornburg 2016 Alkenes Alkenes are hydrocarbon chains that have a double bond in their structure Examples: When naming alkenes, we identify the location of the double bond by using numbers

Practice with Alkenes Name these alkenes: Thornburg 2016 1 - pentene 2 – methyl – 1 – butene

Thornburg 2016 Alkynes Alkynes are hydrocabon chains that have a triple bond in their structure When naming alkynes, we identify the location of the triple bond by using numbers

Practice with Alkenes Name these alkynes: pentyne 4 – octyne