1. MUDDLE YOUR WAY THROUGH ORGANIC MECHANISMS KNOCKHARDY PUBLISHING A VERY BRIEF INTRODUCTION 2008 SPECIFICATIONS

2. INTRODUCTION This Powerpoint show is one of several produced to help students understand selected topics at AS and A2 level Chemistry. It is based on the requirements of the AQA and OCR specifications but is suitable for other examination boards. Individual students may use the material at home for revision purposes or it may be used for classroom teaching if an interactive white board is available. Accompanying notes on this, and a full range of AS and A2 topics, are available from the KNOCKHARDY SCIENCE WEBSITE at... www.knockhardy.org.uk/sci.htm Navigation is achieved by... either clicking any grey arrows at the foot of each page orusing the left and right arrow keys on the keyboard KNOCKHARDY PUBLISHING MUDDLE YOUR WAY THROUGH MECHANISMS

3. MEET THE ATTACKERS Press the space bar

4. MEET THE ATTACKERS I AM A NUCLEOPHILE I HAVE A LONE PAIR WHICH I CAN USE TO FORM A NEW BOND. I ATTACK ELECTRON DEFICIENT AREAS (those with a + or  )

5. MEET THE ATTACKERS Press the space bar

6. MEET THE ATTACKERS I AM AN ELECTROPHILE I HAVE A + CHARGE or a  CHARGE. I ATTACK ELECTRON RICH AREAS SUCH AS C=C DOUBLE BONDS.

7. MEET THE ATTACKERS Press the space bar

8. MEET THE ATTACKERS AND I AM A FREE RADICAL I HAVE AN UNPAIRED ELECTRON WHICH I WANT TO PAIR UP. I AM VERY REACTIVE AND DON’T MIND WHERE I ATTACK… WATCH OUT!

9. THE BONDING IN A MOLECULE INFLUENCES WHAT WILL ATTACK IT WHO IS ATTACKED?

10. THE BONDING IN A MOLECULE INFLUENCES WHAT WILL ATTACK IT SINGLE A typical covalent bond with one shared pair – nothing to tempt an attacking species WHO IS ATTACKED?

11. THE BONDING IN A MOLECULE INFLUENCES WHAT WILL ATTACK IT SINGLE MULTIPLE A typical covalent bond with one shared pair – nothing to tempt an attacking species Bond has twice as many electrons – species which like electrons will be attracted WHO IS ATTACKED?

12. THE BONDING IN A MOLECULE INFLUENCES WHAT WILL ATTACK IT SINGLE MULTIPLE NON-POLAR A typical covalent bond with one shared pair – nothing to tempt an attacking species Bond has twice as many electrons – species which like electrons will be attracted Similar atoms have an equal attraction for the shared pair of the covalent bond WHO IS ATTACKED?

13. THE BONDING IN A MOLECULE INFLUENCES WHAT WILL ATTACK IT SINGLE MULTIPLE NON-POLAR POLAR A typical covalent bond with one shared pair – nothing to tempt an attacking species Bond has twice as many electrons – species which like electrons will be attracted Similar atoms have an equal attraction for the shared pair of the covalent bond Atoms have different electronegativities and the shared pair will be attracted more to one end – species known as nucleophiles will be attracted to the slightly positive end WHO IS ATTACKED? 

14. THE BONDING IN A MOLECULE INFLUENCES WHAT WILL ATTACK IT SINGLE MULTIPLE NON-POLAR POLAR A typical covalent bond with one shared pair – nothing to tempt an attacking species Bond has twice as many electrons – species which like electrons will be attracted Similar atoms have an equal attraction for the shared pair of the covalent bond Atoms have different electronegativities and the shared pair will be attracted more to one end – species known as nucleophiles will be attracted to the slightly positive end WHO IS ATTACKED? 

15. ALKANES ARE RELATIVELY UNREACTIVE ORGANIC COMPOUNDS ALKANES CONTAIN TWO BOND TYPES C-H and C-C WHAT ATTACKS ALKANES? Both bonds are single – no electron rich areas Bonds are non-polar - no electron deficient areas Free radicals are very reactive and do attack FREE RADICAL SUBSTITUTION

16. ALKENES ARE MUCH MORE REACTIVE THAN ALKANES ALKENES CONTAIN A C=C BOND There will be twice as many electrons between the carbon atoms as there are in a single bond WHAT ATTACKS ALKENES? C=C bond is double – an electron rich area Bonds are non-polar - no electron deficient areas ELECTROPHILIC ADDITION

17. HALOGENOALKANES ARE MUCH MORE REACTIVE THAN ALKANES HALOGENOALKANES CONTAIN A POLAR BOND The halogen is more electronegative than the carbon attracts the shared electron pair. WHAT ATTACKS HALOGENOALKENES? Bond is single – not an electron rich area Bond is polar – the greater electronegativity of the halogen creates a dipole making the carbon atom electron deficient.  NUCLEOPHILIC SUBSTITUTION

18. © 2008 JONATHAN HOPTON & KNOCKHARDY PUBLISHING THE END MUDDLE YOUR WAY THROUGH ORGANIC MECHANISMS NOW INVESTIGATE THE MECHANISMS IN DETAIL