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Lesson #1: Intro to organic chemistry Organic chemistry – deals with the chemistry of carbon compounds - There are millions of carbon compounds Organic molecules are the basis for life Carbon bonds 4 times Carbon can bond with itself and make long chains, rings, spheres, and cylinders Carbon can make single, double and triple bonds https://www.youtube.com/watch?v=WFacA6OwCjA Vocabulary: Hydrocarbon: - compounds containing only hydrogen and carbon Carbon backbone: - the longest carbon chain in a compound Saturated hydrocarbon: - hydrocarbon with only single bonds (i.e., the molecule contains a maximum number of hydrogen atoms) Ethene (unsaturated) Note that the number of hydrogen decreases when a double bond is present. Alkanes: - the name given to all saturated hydrocarbons The molecular formula for any alkane is CnH2n +2 where n is the number of atoms. Naming system for alkanes: 1. Names end in “-ane” 2. A prefix system is used to describe the number of carbons in the longest chain 3. Branches use the same prefix system but end in “-yl” Prefix system: 1C Meth- 2C Eth- 3C Prop- 4C But- 5C Pent- 6C Hex- 7C Hept- 8C Oct- 9C Non- 10C Dec- Exercises: Name the following alkanes Molecular Formula: C10H22 Structural diagram: Below C C -C–C–C–C–C–C–C– C Note: the hydrogens have been removed to simplify the diagram. Step 1. Identify the longest continuous carbon chain. C C -C–C–C–C–C–C–C– 8C would be named octane. C Step 2. Choose the smallest possible numbering system on the carbon backbone to locate the branches. In this case 3&6 are the lowest numbers regardless of whether we count left to right or right to left. Step 3. Name the branches in alphabetical order ending in “-yl” and include the carbon number where they are located. 3,6 – dimethyloctane. Note that the prefix “di” is used to indicate the presence of two “methyl” branches. Name: C5H12 -C–C–C–C C The longest chain is 5C. Therefore this is pentane. Name: C5H12 C -C–C–C– C The longest chain is 3C, therefore the carbon backbone is called propane. There are two methyl branches on the #2 carbon, therefore 2,2 – dimethyl 2,2 – dimethylpropane. (While this question and the previous one have the same molecular formula, the structural diagram is different. These structural differences when the formulas are the same are called structural isomers). Name: C C C -C–C–C–C–C–C–C– C C C C C The carbon backbone is 8C, therefore this is a type of octane. The smallest numbering system is from right to left. 4-ethyl-3,5-dimethly-5-propyloctane (note that the prefixes used for indicating the number of branches is not used to determine the alpha order for naming) Draw the following molecules: 3-ethyl-2methylpentane Step #1: Draw the carbon backbone C–C–C–C–C or H3C CH3 Step #2: Number the carbons from left to right and attach the branches. C C–C–C–C–C C C CH3 H3C or CH3 H3C Question: Does it matter whether the branches point up or down? Answer: No. Single bonds “spin” so the orientation of the branches is not fixed. Draw: 4-ethyl-2,4-dimethylheptane H3C Step #1: Draw heptane Step #2: Add branches CH3 H3C CH3 CH3 CH3 Assignment: Hebden pg. 221 #8 and 9 CH3