Haloalkanes Flashcards
(21 cards)
What is the general formula for a haloalkane ?
C n H 2n+1 X (where X is any halogen)
What is the functional group of a haloalkane ?
a halogen atom
What are the uses of haloalkanes ?
- PVC plastic
- teflon coatings on non-stick pans
What type of mechanism is the formation of a haloalkane ?
free radical substitution
What is a nucleophile ?
an electron pair donor
What does a curly arrow show ?
the movement of an electron pair
What is the reagent of substitution of a haloalkane with -CN ions ?
KCN (or NaCN) in ethanol
What is heterolytic fission ?
one species takes both electrons in the covalent bond
What is hydrolysis ?
the breaking of a water molecule
What are the two methods of hydrolysis of a haloalkanes ?
- with hydroxide ions
- with water
What are the reagents for hydrolysis of a haloalkane with hydroxide ions ?
hot aqueous NaOH or KOH
What is the condition needed for hydrolysis of a haloalkane with hydroxide ions ?
reflux
What is produced from the hydrolysis of a haloalkane with hydroxide ions ?
an alcohol and a halide ion
What are the reagents needed for hydrolysis of a haloalkane with water ?
- water (in the presence of silver nitrate)
- ethanol (as a solvent)
What is the process of measuring the rate of hydrolysis of haloalkanes ?
- add ethanol to test tubes
- add the haloalkanes to the test tubes
- place the solutions in a waterbacth
- add silver nitrate to each test tube
- time it, to see how long each precipitate takes to form
What needs to be added to measure the rate of hydrolysis and why ?
silver nitrate, to form coloured precipitates with halide ions
What forms when silver nitrate reacts with iodide ions ?
a yellow precipitate
What forms when silver nitrate reacts with bromide ions ?
a cream precipitate
What forms when silver nitrate reacts with chloride ions ?
a white precipitate
What is the ionic equation for the reaction of silver ions and chloride ions ?
Ag+ (aq) + Cl- (aq) => AgCl (s)
Which is the most reactive haloalkane out of chloroethane, bromoethane and iodoethane and why ?
- iodoethane
- the C-I bond has the lowest bond enthalpy, so it is weaker than the C-Br bond and the C-Cl bond, so it breaks more easily.
