1. Alkenes

3. What are isomers?

4. What does it mean when it talks about ‘straight chain isomers’?

5. Alkenes General Formula: C n H 2n Name ends in – ene 2 double bonds = - diene

6. Make models of and draw Ethene and ethane Propene What do you notice about the shape of the C=C? Compare and explain bond rotation in ethene and ethane. Explain why the double bond is so attractive to positively charged groups.

7. Make a model of butene You should be able to make more than one model – they are isomers

8. How do we name them to distinguish between the 2 straight chain isomers?

9. From butene on you will need to include numbers to show the position of the double bond

10. Draw Pent-1-ene Pent-2-ene Pent-3-ene. Does pent-3-ene exist? How many straight chain isomers of ‘hexene’ can you draw (and name)

13. Today we are learning How to simply predict the products of reacting alkenes with small molecules. How to write equations for these reactions.

14. Reactions of Alkenes Alkenes generally react by adding things across the double bond The thing being added breaks into two parts these go on opposite ends of the double bond. The double bond becomes a single bond. Things we need to know can add: H 2 O, H 2, HX e.g.HBr,X 2 e.g.Br 2 Draw and name the product of propene + each of H 2, Br 2

15. Hydrogenation This is adding what to an alkene?! A Ni catalyst is needed A temp of 180 o C The starting material is often a polyunsaturated oil (many what?) – a vegetable oil The product has less double bonds and is therefore more saturated and higher melting point – a solid fat. Why is the melting point higher? This product is sold as Margarine.

16. Reactions with unsymmetrical molecules Write out the equation for Ethene + HBr

17. Make a model of propene and add HCl to it.

18. You should find that there are 2 possible products – name each one.

19. Predict the 2 possible products in the following reaction, draw out the mechanism with comments to explain this. methylpropene + HBr

20. Using Mechanisms predict the two products in the reaction of 2-methylbut-2-ene with HCl. Explain your reasoning and name the mechanism. Name both the products.

21. Do the same with but-2-ene and HCl

22. This time there is only one product because the double bond is in the middle of the chain so it doesn’t matter which way the HCl adds.

23. Do the same with but-2-ene and HCl This time there is only one product because the double bond is in the middle of the chain so it doesn’t matter which way the HCl adds. You will only be asked to write equations for symmetrical alkenes with HX or H 2 O

24. Addition of steam to alkenes – also called hydration. Reagent: Steam Conditions: high temperature (300 o C), high pressure (70 atm), phosphoric acid catalyst. Product: alcohol

25. Ethene + steam ethanol Write the symbol equation for this reaction

26. Ethene + steam ethanol Write the symbol equation for this reaction This reaction is economically important as an industial way of making ethanol

27. Ethene + steam ethanol Write the symbol equation for this reaction This reaction is economically important as an industial way of making ethanol Draw the product of the reaction between but-2-ene and steam – can you name the product too?

29. describe the addition polymerisation of alkenes; deduce the repeat unit of an addition polymer obtained from a given monomer; identify the monomer that would produce a given section of an addition polymer;

30. Addition Polymers animation http://www.knockhardy.org.uk/polymer.htm To draw the repeat unit: Draw the alkene Rub out one of the two alkene bonds Put an extra horizontal bond at each end Put it in brackets with these new bonds going through Reverse this if finding the monomer

31. Draw the monomer and repeating unit for - Polypropene –Polychloroethene (PVC) –Polypropene

32. Complete the table Name of alkene StructureRepeat unit of polymer Name of polymer

33. PTFE Poly(tetrafluoroethene) Very useful for non stick applications Burning it produces toxic gases

34. Distinguishing between alkanes and alkenes Use bromine water An alkene will decolourise bromine water, an alkane doesn’t

35. Read pp199-205 which covers alkenes