Chapter 15 Flashcards
Nucleophile
Electron pair donator
Attracted to partially positive atoms
Forms covalent bonds
Examples of nucleophiles
OH -
H2O
NH3
Explain nucleophile substitution
Atoms or group of atoms with an electron pair is exchanged for another atom
The atom causing the substitution is a nucleophile that donates an electron pair
Nucleophile substitution
A haloalkane reacts with a nucleophile. The nucleophile replaces the halogen in a substitution reaction, forming a new product with a different functional group
Substitution reaction
Reaction where one atom is replaced by another to form a new product
what is Hydrolysis
The chemical reaction including H2O and OH (aq) that causes the breaking of bonds to form 2 products
Haloalkane (l) + NaOH (aq)
Alcohol + Na- halide
Haloalkane + H2O
Alcohol + H+ + X-
How does substitution reaction happen
Nucleophile approaches carbon on other side to reduce repulsion
The OH- donates it’s lone pair of electrons to the partially positive carbon
The lone pair induces heterolytic fission between C and leaving group
Forms new covalent bond with C
What affects the rate of hydrolysis
Pattern …
Depends on the strength of the C-H bond
As you go down group 7 it decreases
Measuring the rate of hydrolysis (practical)
Set up test tubes of chloro-bromo-iodobutane
Then add 1cm ethanol
Put in water bathe 60C
Add test tube of silver nitrate 0.1moldm-3
Test tubes reach constant
Add 1cm of AgNO3 to each tube
Record the time taken for precipitate to form
Haloalkane + silver nitrate
Alcohol + AgX
Why are chlorofluorocarbons inert
The high C-F C-Cl bond enthalpies make it hard to break
How does the ozone layer protect us
Acts as a filter by absorbing UV rays
The ozone layer naturally replenishes itself
O2 —> 2O*
O* + O2 —> O3
