Transcript Reaction Mechanisms Powerpoint presentation

Presented by
Leticia Bonita Prince
Newcastle University 4th Year MChem Student
Aims of Today
• Increase your understanding of reaction
mechanisms and the bromination of alkenes
• Increase your spatial skills and awareness
using software designed by the CCDC
What are Spatial Skills?
• The ability to mentally manipulate 2-dimensional and 3dimensional figures.
• Important in chemistry, biology, medicine, mathematics,
physics and everyday life.
Curly Arrows
• In a chemical reaction NEW BONDS ARE MADE and BONDS ARE
BROKEN. A reaction mechanism illustrates how this happens.
• Curly Arrows are used to highlight the MOVEMENT OF
ELECTRONS.
H+ + Cl-
A FULL ARROW REPRESENTS
2 ELECTRONS
Heterolytic
Fission
2Cl
.
A HALF ARROW REPRESENTS
1 ELECTRON
Homolytic
Fission
Direction of Movement
NUCLEOPHILE
ELECTROPHILE
Nucleophiles
• Electron Pair DONORS
• Lewis Bases
-CN, -OH,
Cl
Electrophiles
• Electron Pair ACCEPTOR
• Lewis Acids
+
+
H , CH3 ,
+
NO2
Electrophilic Addition to
Ethene (Bromination)
• Ethene has a π bond which has high electron
density – NUCLEOPHILE
• Bromine molecule will have a δ+ from Van der
Waals’ - ELECTROPHILE
Mechanism
The REAL Mechanism
Proof Bromonium Ions Exist
The WebCSD
• Type in
http://webcsd.ccdc.cam.ac.uk/teaching_database_demo.php
• Answer the questions by typing the refcodes into the “find
entry” box
THANK YOU!
ENJOY THE REST OF YOUR
DAY!