4.2.2 Haloalkanes Flashcards
general formulae of haloalkane
CnH2n+1X
what does X stand for in general formulae
F, Cl, Br, I
naming haloalkane
longest carbon chain
arrange halogen in alphabetical order
use lowest combination of numbers
use di tri if multiple of the same halogen
How to make haloalkane
free radical substitution with UV light
alkene and hydrogen halide - electrophilic addition
from an alcohol - nucleophilic substitution
is the carbon or halogen more electronegative
the halogen
what’s wrong with making a haloalkane with UV light as free radical substitution
can make lots of products as radicals react
Nucleophile
species that donates a pair of electrons to make a new covalent bond
reaction of haloalkane with hydroxide ion reagents and products
NaOH or KOH
H.U.R and ethanol solvent
makes alcohol and NaBr
Haloalkane with water reagents and products
water H.U.R and ethanol solvent
makes alcohol and hydrogen halide (HBr)
Test for haloalkane method
heat with NaOH
add silver nitrate and acidified and dilute nitric acid
add ammonia
why do you add NaOH when testing for haloalkane
to break the C-X bond
why do you add silver nitrate and nitric acid when testing for haloalkane
releases X-ions to form precipitate
what happens to halides when add ammonia
Cl dissolves in dilute
Br dissolves in conc
I doesn’t dissolve
CFC’s
chlorofluorocarbon
properties of CFC’s
non toxic
volatile
non flammable
low reactivity
reactions to create ozone
O2 -> 2O UV light
O + O2⇌ O3
What do CFC’s do to the ozone
they destroy the ozone so more is destroyed than produced so more UV light reaches us, plants and animals causing cancer
CF2CL2 radicals
CF2Cl 2 → CF2Cl* + *Cl
*Cl + O3 → *ClO + O2
*ClO + O → *Cl + O2
reactivity of haloalkanes
C-F is the strongest carbon halogen bond and C-I is the weakest
therefore less energy is required to break the C-I bond so iodoalkanes will react fastest
