Flashcards in Haloalkanes Deck (20):
How do the boiling points of haloalkanes compare to alkanes and alcohols? And why is this?
Higher than alkanes, lower than alcohols. This is because Cl gives more electrons than the H it replaces, however adding an O in alcohols allows them to hydrogen bond, joining together more strongly.
How are haloalkanes prepared from alkanes?
What are the three stages of radical substitution?
What is the condition for radical substitution?
How are haloalkanes prepared from alkenes?
Which way of making haloalkanes has a higheratom economy?
Electrophilic addition is more economic than radical substitution, as no other molecules are produced
What is hydrolysis?
A chemical reaction involving water or OH- (Hydride) ions in solution that causes the breaking of a bond in a molecule.
What is the general formula for a reaction between:
a) A haloalkane and water
b) A haloalkane and OH- ions
a) Haloalkane (halogen X) + H20 ---> Alcohol + HX
b) Haloalkane (halogen X) + (Group one metal)OH ----> Alcohol + (Group one metal) X
What are the reagents and conditions for the preparation of an alcohol by hydrolysis of a haloalkane?
Reagent : Aqueous OH- (Normally NaOH)
Conditions: Heat under reflux
What is reflux?
Continuous evaporation + condensation of a reaction mixture to prevent the loss of volatile materials
Why do organic reactions normally require heating under reflux?
Because a lot of organic molecules have a low boiling point
What is a nucleophile?
Something that donates e- pairs
What does a curly arrow show, where do they start and what do they point to?
The movement of e- pairs, starting at the e- pair and pointing to the destination of the e- pair.
What type of fission is shown in hydrolysis?
How is a hydrolysis reaction shown?
A curly arrow from the lone pair on the oxygen of the nucleophile to the C (with a delta positive charge) bonded to the halogen. ---> Alcohol + Halogen with a lone pair and a - charge.
What is the order of reactivity of haloalkanes from fastest to slowest?
Iodoalkanes > Bromoalkanes > Chloroalkanes
Why is the iodoalkane hydrolysis reaction much faster than the chloroalkane reaction?
Iodine has a much larger atomic radius and more shielding e- so there is less force of attraction in a bond. Therefore this bond is much easier to break.
Why is ethanol used in the rate of hydrolysis of haloalkanes experiment?
Ehanol dissolves the haloalkane into the solution.
Why is the rate of hydrolysis of haloalkanes experiment done in a water bath?
To increase the rate of the reaction.