1. Organic Chemistry

2. Organic Chemistry and Hydrocarbons “Organic” originally referred to any chemicals that came from organisms 1828 - German chemist Friedrich Wohler synthesized urea in a lab Today, organic chemistry is the chemistry of virtually all compounds containing the element carbon

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

4. Organic Chemistry and Hydrocarbons Over a million organic compounds, with a dazzling array of properties Why so many? Carbon’s unique bonding ability! Can form 4 covalent bonds Form double or triple bonds Bonds with other carbon atoms.

5. Alkanes Only have single bonds between them (saturated) Formula C n H 2n+2 Naming hydrocarbons Prefixes used # Carbon atoms 12345678910 PrefixMeth-Eth-Prop-But-Pent-Hex-Hept-Oct-Non-Dec-

6. Naming alkanes End in –ane Prefix used corresponds to number of carbons in chain. Ex.

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

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

9. 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 -)

10. Rules for naming branched alkanes p753 in textbook 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

11. Ex. 1 Name the following alkane: CH 3 CH 2 CH CH 3 CH 3 1. Choose parent chain and name it butane 1234 43 21 2. 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

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

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

14. 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 1 356 2 4

15. Ex.2 CH 3 CH CH 2 CH 2 CH 3 CH 2 CH 3 Name of organic compound 3-methylhexane 1 356 2 4

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

17. 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

18. 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

19. Writing structural formulas: Identify the substituent groups and their position: CH 3 C C C CH 3 123 1. Write the complete structural formula for 2,2-dimethylpropane There are two (di) methyl groups (CH 3 -) in carbon #2

20. 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

21. Cycloalkanes A hydrocarbon ring (has 3 C or more) is called a cyclic hydrocarbon Cycloalkanes: cyclic hydrocarbon with single bonds only Ex. Cyclohexane: used in paint and varnish removers Representing cycloalkanes Structural formula Line structure

22. Naming cycloalkanes: Ring structure is considered parent chain. Count # C in the ring, name ring; use prefix cyclo- Numbering is started in the carbon that is bonded to the substituent group: If there is only 1 substituent group, no numbering is necessary If there are 2 or more substituent groups, C are numbered in way that gives lowest possible set of numbers for substituents. Ex. Name the following cycloalkanes

23. Ex. 2 Write the structure for: Ex. 3 1,2-dimethylcyclopropane Ex. 4 1-ethyl-2-methylcyclobutane

24. Properties of alkanes Alkanes are nonpolar Good solvents for other nonpolar substances Not miscible in water Have low reactivity CW: p757 #10-11, p758 #13,14,16