(PMT) Halogenoalkanes Flashcards
Are halogenoalkanes
soluble in water?
Insoluble as C-H bonds are non-polar, not
compensated for enough by C-X bond polarity
Do halogenoalkanes have a
polar bond? why?
Yes polar, as halogen has a higher electronegativity than C ( halogen is δ-, carbon is
δ+)
Which intermolecular forces
do they have? why?
Permanent dipole-dipole and van der Waals
forces of attraction
C-X bond polarity creates permanent dipoles
When would they have
higher boiling points?
Increase Carbon chain length
Halogen further down group 7
How would the mass of a
haloalkane compare with
the mass of an alkane of the
same chain length?
Greater as mass of halogen > mass of H
What is the most important
factor in determining their
reactivity?
Carbon-halogen bond enthalpy
What would bond polarity
suggest the order of
reactivity would be?
C-F would be most reactive as most polar bond
What would bond enthalpies
suggest the order of
reactivity would be?
C-I would be most reactive as lowest bond
enthalpy
What is a nucleophile?
A negatively charged ion/δ− atom with a lone pair
of electrons which can be donated to an electron
deficient atom
Give 3 examples of
nucleophiles
:OH-
:CN-
:NH3
What is nucleophilic
substitution?
A reaction where a nucleophile donates a lone
pair of electrons to δ+ C atom, δ− atom leaves
molecule (replaced by nucleophiles)
What are CFCs?
Chlorine-fluoro-carbons - haloalkanes containing
C, F and Cl only (no H)
What is the problem with
CFCs?
Although unreactive under normal conditions,
they catalyse the breakdown of ozone in the
atmosphere via free radical substitution
What are CFCs being
replaced with?
HCFCs (hydrogen, chlorine, fluorine, carbon)
HFCs (hydrogen, fluorine, carbon)
What are the conditions/
reactants needed for the
elimination reaction of
haloalkanes?
NaOH or KOH dissolved in ethanol (no water
present)
Heated
