Chapter 15-Haloalkanes Flashcards
(20 cards)
what is the general formula of haloalkanes
CnH2n+1X
what are the 4 halo groups
fluoro
chloro
bromo
iodo
why does haloalkanes have polar bonds
because halogen atoms are more elctronegative that carbon
the c-x bond polarity decreases down the group
what is a nucleophile
it is a partially pr fully negatively charged atom or group of atoms with a lone pair of electron that can donate an electron deficient carbon atom to form a covalent bond
what influences the reactivity of the haloalkanes
the strength of the c-x bonds
what happens in nucleophilic substitions of haloalkanes
a nucleophile replaces the halogen in the haloalkane which is lost as a halide ion
what happens when theirs hydrolysis with aqueous hydroxide ions
hydroxide ions are nucleophiles with a lone pair of electrons on the oxygen atom atom which can be donated to form a covalent bond.
can you draw out the nucleophilic substition mechanism
look in book page 92
what hapens with hydrolysis of water with haloalkanes
haloalkanes can also be hydrolysed by water in the presence of silver nitrate to form a alcohol
what acts as the nucleophile in the nucleophilic substitution of a haloalkane with water
water
how can the rates of hydrolysis of different carbon-halogen bonds be tested and what is shown
measuring the time it take for the silver halide precipitate to form
shows that iodoalkanes react faster then bromoalkanes which react faster then chloroalkanes
why does iodoalkanes react fastest
has the highest lowest bond enthalpy
what are the uses of organohalogen compounds
CFCs are used as proppelant in aerosols, as refridgerants and in air conditioners
why are CFCs used
because they have low reactivity, high volatility and their non toxic
what are the benefits of the ozone layer
helps filter out harmful ultraviolet radiation that can cause cancer and destroy crops
how does uv break down the ozone layer
it provides energy to form radicals
what happens when CFCs escape into the atmosphere
they slowly diffuse into the upper atmosphere. then in the presence of uv the c-cl bonds in the CFC molecules by homolytic fission to form radicals
where does the breakdown of ozone take place
by the 2 propagation steps catalysed by chlorine radicals
what are the 3 equation in the steps of breakdown by chlorine radicals
1st= Cl.+O3= ClO. + O2
2nd= ClO.+O= Cl.+O2
overall= O3+O=2O2
what are the 3 equation in the steps of breakdown by nitrogen oxide radicals
1st= .NO+O3=.NO2+O2
2nd= .NO2+O=.NO+O2
overall= O3+O=2O2
