Chapter3UnsaturatedHydrocarbons：3章不饱和烃.doc

UNSATURATED HYDROCARBONSWhy are alkanes referred to as saturated hydrocarbons? All carbon-carbon bonds are _ bonds, and the molecule contains the _ number of hydrogen atoms bonded to the carbon chain.What are some examples of unsaturated hydrocarbons? Unsaturated hydrocarbons contain _ and _ bonds. Physical Properties of Unsaturated Hydrocarbons Newman projections of alkanes showed that single-bonded molecules can rotate around the sigma bonds holding the atoms together. Is this possible in alkenes and alkynes? Predict the relative boiling points of alkenes in relation to alkanes. Are the boiling points of alkenes considerably different from that of alkanes? What about alkynes? How is the solubility of unsaturated hydrocarbons affected by their multiple bonds?General Reactivity Are unsaturated hydrocarbons more reactive than saturated hydrocarbons?ALKENESWhat type of bonding occurs in ethene to form 3 equal-energy bonds? Carbon has 4 valence electrons.C _ _ _1s 2s 2p _ s orbital and _ p orbitals hybridize to form _ equal-energy sigma bonds.CSo for ethene, C2H4The double bond therefore contains _ sigma bond and _ pi bond.Sigma bonds from sp2 orbital overlap Pi bonds from p orbital overlap- sp2 hybridization allows for _ _ geometry, and a bond angle of _. Discuss Sources and Uses of Unsaturated Hydrocarbons handout.Alkene Nomenclature All rules of alkane nomenclature apply to the naming of alkenes. The only difference is that the location of the double bond must be indicated using a number. Number to get the lowest number possible for the location of the double bond. Always use the number of the first carbon of the double bond. This number is placed between the prefix and the ene ending. Examples:Name:Name: Draw: propeneDraw: but2ene There is an additional aspect that we must consider. How would you name these two different alkenes? Look at the Cahn-Ingold-Prelog EZ System of Nomenclature handout. Examples:Dienes If a molecule has two double bonds, assi