Functional Groups 1: Alkyl Halides Flashcards
Why are alkyl halides useful in industry?
They are very versatile
Due to polarity of C-X group
Makes them a useful starting material for a variety of reactions
What is PVC and what is it used for?
Polyvinyl chloride
Used to make waterproof jackets and pipes (remains rigid in contact with hot water)
What are CFCs and what are they used for?
Chlorofluorocarbon
Used for refrigeration
Decomposes ozone in the atmosphere so damages the ozone layer
Hydrocarbons are now used instead as they are more environmentally friendly
What are the three methods of synthesising alkyl halides?
1) From alkenes (using hydrogen halides or halogens)
2) From alcohols (using thionyl chloride)
3) From alcohols (using phosphorous tribromide)
Why are alkyl halides polarised?
Because there is a difference in electronegativity between the carbon atom and the halogen atom, so the halogen withdraws electrons in the C-X bond, creating δ+ and δ- regions
Give the order, from highest to lowest, of the effectiveness of halogens as leaving groups.
Best leaving group
Iodine
Bromine
Chlorine
Fluorine
Worst leaving group
What is the best leaving group out of the halogens and why?
Iodine
Because the C-I bond is the weakest
As iodine is the least electronegative of the halogens
So is easiest to break, and it is easiest for iodine to leave
What is a nucleophile?
Negatively charged (or neutral) species with a pair of electrons in a high energy filled orbital that they can donate to electrophiles
Give four examples of uncharged nucleophiles.
Ammonia
Water
Dimethylsulfide
Trimethylphosphine
Give four examples of negatively charged nucleophiles.
Hydroxide
Bromide
Cyanide
Methane thiolate
What are electrophiles?
Neutral or positively charged species with an empty atomic orbital or a low energy anti-bonding orbital
Give three examples of uncharged electrophiles.
Carbonyls
Aluminium trichloride
Boron trifluoride
Give three examples of positively charged electrophiles.
H+
NO2+
H3O+
