C13- halogenoalkanes Flashcards
what us a halogenoalkane
a saturated hydrocarbon containing one or more halogen
name two uses of halogenoalkanes
solvents and pharmaceuticals
what happens to the polarity of the C - X bond down group 7
it decreases
what dies the letter X represent
a halogen atom
what intermolecular forces are between halogenoalkane molecules?
van der waals forces
permenant dipole-dipole interactions
whats permenant dipole dipole interactions
Polar molecules display attractions between the oppositely charged ends of the molecules.
what solvents are halogenoalkanes soluble in?
organic solvents
are halogenoalkanes soluble in water
no
what mechanism is used to make halogenoalkanes
free-radical substitution
what is a substitution reaction
where one functional group is replaced by another
what are the stages of free-radical substitution?
initiation
propagation
termination
what is a free radical
a species with an unpaired electron
what is a homolytic fission
the breaking of a covalent bond to form two radicals
what is a CFC
chlorofluoroalkanes
what has caused the destruction of the ozone layer
chlorine radicals
what is used instead of CFCs to protext the ozone layer?
HFCs (hydrofluorocarbon)
what is a nucleophile
an electron pair donor
nake three nucleophiles
hydroxide
cyanide
ammonia
what us represented by a curly arrow?
the movement of an electron pair
where can a curly arrow begin?
at a lone pair or the centre of a bond
what is a leaving group?
the group that is lost in nucleophilic substitution
what conditions are required for nucleophilic substitution of hydroxide?
dissolve halogenoalkanes in ethanol, aqeuous NaOH and reflux
what is hydrolysis
the breaking of chemical bonds with water/hydroxide ions
rate of nucleophilic substitution of halogenoalkanes
stronger the C-X bond the slower the rate
what happens tk the strength of the C-X bond down geoup 7?
it decreases
what is a hydrogen ion
a proton
what conditions are required for nucleophilic substitution of cyanide
dissolve halogenoalkane in ethanol, aqueous KCN and reflux
what conditions are required for nucleophilic substitution of ammonia
dissolve halogenoalkane in ethanol, concentrated ammonia in excess and reflux
what is the 2nd ammonia used for
acts as a base to remove a hydrogen ion
what is a:
1) primary amine
2) secondary amine
3) tertiary amine
1) RNH2
H | H - N - X | R
2) R2NH
H as amine goes from prim/sec | /tert, thats how much R is R - N - X attached to the N, which | affects amount of H in bond. R
3) R3N
R | R - N - X | R
what is an elimination reaction
a reaction where a small group is removed
what is the solvent in an ethanoic solution
ethanol
how does hydroxide behave in an erhanoic solution
as a base
what is a base
a proton acceptor
what mechanism is most likely for a tertiary halogenoalkne
elimination
what mechanism is more likely for a primary halogenoalkane
nucleophilic substitution
nucleophilic reaction
a class of reactions in which an electron rich nucleophile attacks a positively charged electrophile to replace a leaving group
