Organic Chemistry

“ The most important hypothesis in all of biology…is that everything that animals do, atoms do. In other words, there is nothing that living things do that cannot be understood from the point of view that they are made of atoms acting according to the laws of physics.” Richard Feynman ( )

Organic Chemistry and Hydrocarbons “Organic” originally referred to any chemicals that came from organisms German chemist Friedrich Wohler synthesized urea in a lab Today, organic chemistry is the chemistry of virtually all compounds containing the element carbon

Allotropes of carbon Carbon exists naturally in three forms: Graphite Diamonds Fullerenes

Organic Chemistry and Hydrocarbons Over a million organic compounds, with a dazzling array of properties Why so many? Carbon’s unique bonding ability!

Organic Compounds  Contain carbon  Have covalent bonds  Have low melting points  Have low boiling points  Burn in air (oxygen)  Are soluble in nonpolar solvents  Form large molecules

Alkanes Contain C and H only Contain single bonds C-C Have 4 bonds to every carbon (C) atom Are nonpolar Straight chain alkanes: Contain any number of carbons atoms, one after the other, in a chain. Each carbon atoms is bonded to 1 or 2 other carbon atoms.

Complete Structural Formulas Show the bonds between each of the atoms H H  H  C  HH C H  H H CH 4, methane

More Alkanes H HCondensed Structural Formulas H C C HCH 3 CH 3 H HEthane H H H H C C C HCH 3 CH 2 CH 3 H H H Propane

IUPAC Names Name# carbons Structural Formula Methane1CH 4 Ethane2CH 3 CH 3 Propane3CH 3 CH 2 CH 3 Butane4CH 3 CH 2 CH 2 CH 3 Pentane5CH 3 CH 2 CH 2 CH 2 CH 3

IUPAC NAMES Name # carbons Structural Formula Hexane 6 CH 3 CH 2 CH 2 CH 2 CH 2 CH 3 Heptane 7 CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 3 Octane 8 CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 3 Nonane 9 CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 3 Decane 10 CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 3

Learning Check Alk1 A. What is the condensed formula for H H H H H C C C C H H H H H B. What is its molecular formula? C. What is its name?

Solution Alk1 A.CH 3 CH 2 CH 2 CH 3 B. C 4 H 10 C.butane

Reactions of Alkanes Combustion alkane + O 2 CO 2 + H 2 O + heat

Combustion In the Cell Metabolic oxidation is combustion C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O + heat glucose

Learning Check Alk2 Complete the combustion reaction for C 3 H 8 + O 2 + Balance your equation

Solution Alk2 Step 1 C 3 H 8 + O 2 CO 2 + H 2 O Step 2 C 3 H 8 + O 2 3 CO H 2 O Step 3 C 3 H O 2 3 CO H 2 O

Learning Check Alk3 Complete and balance the reaction for the complete combustion of C 7 H 16

Solution Alk3 Step 1 C 7 H 16 + O 2 CO 2 + H 2 O Step 2 C 7 H 16 + O 2 7 CO H 2 O Step 3 C 7 H O 2 7 CO H 2 O

Occur when a carbon atoms bonds with three or four carbon atoms. Branched chain alkanes:

Substituents: take place of a hydrogen atom on a parent hydrocarbon. Branched chain alkanes: c c c c c c c c c c c c c Parent alkane (propane) Parent alkane (hexane) substituent

Hydrocarbon substituents Are called alkyl group Name ending with –yl Methyl group (CH 3 -) Ethyl group (CH 3 CH 2 -) Propyl group (CH 3 CH 2 CH 2 -)

Rules for naming branched alkanes 1. Find the longest chain of carbons in the molecule or parent chain. (not necessarily a straight line) 2. Number the carbons in parent chain. Start at the end that will give the groups attached to the chain the smallest numbers. 3. Identify with numbers the positions of the substituents on the chain. 4. Use prefixes to indicate the appearance of the same group more than once: di- (twice), tri- (three times) 5. List the names of the substituents groups in alphabetical order. 6. Commas separate numbers, hyphens separate numbers and words. Name is written without spaces

Ex. 1 Name the following alkane: CH 3 CH 2 CH CH 3 CH 3 1. Choose parent chain and name it butane Number parent chain in a way that substituents have smallest numbers. 3. Identify position of substituent group and name it. 2- methyl (located in carbon 2) 4. Not applicable 5. List substituent groups in alphabetical order. 2-methyl 6. Separate letters and numbers with hyphen

Ex.2 CH 3 CH CH 2 CH 2 CH 3 CH 2 CH 3

Parent alkane Does not have to be a straight line, only longest chain. Name of parent alkane: hexane

Ex.2 CH 3 CH CH 2 CH 2 CH 3 CH 2 CH 3 Number Parent alkane Number in way that substituent group has smallest number. Name and position of substituent group: 3-methyl

Ex.2 CH 3 CH CH 2 CH 2 CH 3 CH 2 CH 3 Name of organic compound 3-methylhexane

Cw p 226 #1

Writing structural formulas: 1. Write the complete structural formula for 2,2-dimethylpropane

Writing structural formulas: 1. Write the complete structural formula for 2,2-dimethylpropane Write only the carbons first. Start with the parent alkane. 2,2-dimethylpropane C C C

Writing structural formulas: 1. Write the complete structural formula for 2,2-dimethylpropane Number the parent alkane from left to right. C C C 123

Writing structural formulas: Identify the substituent groups and their position: CH 3 C C C CH Write the complete structural formula for 2,2-dimethylpropane There are two (di) methyl groups (CH 3 -) in carbon #2

Writing structural formulas: Add the necessary hydrogen bonds so that each carbon has a maximum of 4 bonds. H CH 3 H H C C C H H H CH 3 1. Write the complete structural formula for 2,2-dimethylpropane

Classwork p226 #2,3

Isomers Are compounds that have the same molecular formula but different structural formulas. Have different physical properties, like boiling point and melting point and different chemical reactivities. Ex. C 4 H 10 CH 3 CH 2 CH 2 CH 3 butane CH 3 CH CH 3 CH 3 2-methylpropane

Classwork Draw and name the isomers for the organic compounds with the following molecular formulas: a)C 5 H 12 (3 different structures) b) C 6 H 14 (5 different structures)