4.2 Flashcards
primary alcohol
one carbon is attached to the carbon bonded to the OH
secondary alcohol
2 carbons are attached to the carbon bonded to the OH
tertiary alcohol
3 carbons are attached to the carbon bonded to the OH
what’s the oxidising agent for alcohols and what happens to it
acidified potassium chromate, its reduced and the alcohol is oxidised
what are primary alcohols oxidised to if the oxidation is carried out under distillation
primary alcohols to aldehydes
what are primary alcohols oxidised to if the oxidation is reflux
primary alcohols to carboxylic acids
definition of reflux
heating chemicals strongly) while cooling the vapour into a liquid using a condenser
what are secondary alcohols oxidised to
to form ketones
are tertiary alcohols oxidised in these conditions
no
what does tollens reagent, fehlings solution and *k2Cr2O2/H2SO4 oxidise a aldehyde to
aldehyde to carboxylic acid
what does [O] mean
oxidising agent
what happens when a primary alcohol is oxidised twice
in equation its 2[O] and the primary alcohol is oxidised into a carboxylic acid.
with oxidation of alcohols what do you use to oxidise them
acidified potassium dichromate
in order to vigorously oxidise something, what do u do
use reflux
to get an aldehyde from a primary alcohol, what do u do
distil
what do u do for:
- primary alcohol to aldehyde
- primary alcohol to carboxylic acid
- distil
- reflux
what are haloalkanes
alkanes with halogen atoms
talk about the bond in haloalkanes and what does this mean
- the bond is polar
- the delta + carbon is deficient thus can get attacked by a nucleophile
whats a nucleophile and what are some examples
an electron pair donor- it could be a negative ion or atom with a lone pair of electrons
OH-, CN- and NH3. water is a weak nucleophile
halogenoalkanes can be hydrolysed to make alcohols, what type of reaction is this
nucleophilic substitution
halogenoalkanes can be hydrolysed to make alcohols, what compounds are needed for this reaction to take place
a warm aqueous alkali, e.g sodium hydroxide or potassium hydroxide
which halogenoalkanes are hydrolysed the slowest
fluoroalkanes hydrolyse the slowest as they have the strongest bonds
describe the test used to highlight the rate of reaction with haloalkanes- 2-iodopropane, bromoalkene, chloroalkane
- mix haloalkane with water (a nucleophile so nucleophilic sub takes place) to form an alcohol
- put in silver nitrate so the silver will react with the halide.
- heat in waterbath
- yellow precipitate form quickly with 2-iodopropane so iodoalkanes are most reactive
- bromoalkenes react slower and chloroalkanes react the slowest- both form a white precipitate
what are CFCs
chlorofluorocarbons
- contain only fluorine, chlorine and carbon
- they’re very stable, volatile, non flammable and non toxic
- scientists discovered they’re destroying the ozone layer
how is ozone formed naturally
when an oxygen molecule is broken down into two free radicals by uv radiation, the free radicals attack other oxygen molecules forming ozone
O2—UV–>O+O—->O2+O–>O3
why are holes in the ozone layer forming
because CFCs in the upper atmosphere absorb UV radiation and split to form chlorine free radicals- they destroy ozone molecules and regenerate to destroy more ozone
draw the mechanism of CFCs destroying ozone.
also draw the overall mechanism
E.G CF2CL2----uv---> •CF2CL+•CL main mechanism: Cl•+O3--->O2+CLO• CLO•+O-->O2+CL• (the O radical comes from the breakdown of oxygen buy UV) -overall reaction- O3+O-->2O2 (Cl• is the catalyst)
what can also break down ozone apart from CFCs
Nitrogen oxides
draw the mechanism for nitrogen oxides breaking down the ozone.
also draw the overall mechanism
O3+•NO—->O2+•NO2
•NO2+O—>•NO+O2
(the O radical comes from the breakdown of oxygen buy UV)
O3+O–>2O2
