3. An Example - Don’t Copy this!

4. What is a mechanism? If you took an old wind up watch and wanted to find out how it worked you might open it up and examine the MECHANISM. The mechanism is all the parts that together make the whole watch work We couldn’t really claim to know about watches if we didn’t know a bit about the mechanism.

5. What is a mechanism? A reaction mechanism shows not just the reactants and products but all the little stages along the way that make it work. It usually shows the movement of pairs of electrons using curly arrows.

6. If you haven’t really grasped what these are all about, mechanisms can seem like a nightmare!

7. Questions to Answer As you Go Through the Mechanism Rules and Hints 1.Where can curly arrows start? 2.How can we tell which atoms will be charged? 3.How can we predict the sign of the charge? 4.If we move 2e - from a double bond what will it become?

8. :

10. : : :

15. Mechanism problems – draw next structure

17. Mechanism problems – add the arrows

21. Mechanism problems – draw next structure Clue – pick either carbon

22. Mechanism problems – draw next structure Clue – pick either carbon

23. Mechanism problems – add the arrows

29. Half arrows may help understanding of radicals

31. Naming Mechanisms Only certain words are allowed in your answers: substitution, addition, elimination sometimes paired up with nucleophillic, electrophillic or free radical. For example nucleophillic substitution

32. Some Terms Substitution –Swapping one group for another A-B + C → A-C + B

33. Some Terms Addition –Joining two (or more) groups together to give a single product A + B → A-B

34. Some Terms Elimination (literally: the process of removing something) –The reverse of an addition reaction, usually the smaller molecule is said to have been eliminated. A-B → A + B

35. http://www.knockhardy.org.uk/mechs.htm http://www.chemguide.co.uk/mechmenu.html

36. More Terms These go before the term addition or substitution. Nucleophilic, Electrophilic, Free Radical This describes the attacking species

37. Terms we will use a Lot Nucleophile / Nucleophillic Electrophile / Electrophillic What do they mean? Lets wait a moment to find out…

38. Things ending in …phile (NIS) Suffixes with the common part -phil- (- phile, -philia, -philic) are used to specify some kind of attraction or affinity to something, in particular the love or obsession with something. They are antonymic to suffixes -phob-. antonymic-phob- Can you think of any ending in phile?

39. Things ending in …phile (NIS) Some you may just be able to guess at; Gerontophilia:Gerontophilia –sexual attraction towards the elderly Acousticophilia:Acousticophilia –sexual arousal from certain sounds Celebriphilia:Celebriphilia –pathological desire to have sex with a celebrity.

40. The Definitions (species attracted to regions of ……charge, literally ………..lover) (species attracted to regions of ……..charge, literally ……....lover)

42. Fission = splitting, division