4.2 Alcohols, haloalkanes and analysis Flashcards
What is the definition of a primary alcohol
Where the functional group is attached to a carbon atom with o more than one alkyl group q
What is the definition of a secondary alcohol
Where the functional group is attached to a carbon with 2 alkyl groups
What is the definition of a tertiary alcohol
Where the functional group is attached to a carbon with 3 alkyl groups
How do the boiling points of alcohols and their corresponding alkanes differ
Hydrogen bonds between the alcohol molecules require more energy to overcome
Describe the volatility of alcohols
Alcohols aren’t as volatile as alkenes as they have higher boiling points and volatility decreases as boiling point increases
Describe the solubility of alcohols as you go down the homologous series
Alcohol group is polar so methanol, ethanol and propanol are soluble in water
A carbon chain increases the solubility decreases because the aliphatic chain cannot form hydrogen bonds at it makes up most of the molecule
What is the product when you oxidise a primary alcohol
1° alcohol (distillation) —> Aldehyde
1° alcohol (reflux) —> carboxylic acid
What is the product when you oxidise a secondary alcohol
2° alcohol (reflux) —> ketone
What is the product when you oxides a 3° alcohol
Nothing
Give examples of oxidising agents
acidified potassium dichromate - orange to dark green
Tollens reagent - silver mirror (aldehyde –> carboxylic acid)
Describe a dehydration reaction and its conditions
1° or 2° alcohols —> alkene + H2O
170°C and acid catalyst e.g. H2SO4
How do you make an ester
alcohol + carboxylic acid —> ester (-oate) + water
50°C and H2SO4 catalyst
How do you draw an ester from its name
Identify parent acid and alcohol
Draw displayed acid first then alcohol (opposite to name )
Take OH from acid and H from alcohol
O
II Draw new structure R-C-O
What are the two ways to make ethanol
Fermentation
Hydration
Describe how we make ethanol via fermentation
Conditions :
35°C 1atm Zymase catalyst (yeast)
glucose —> ethanol + carbon dioxide
Describe how we make ethanol via hydration
Conditions
300°C 70atm concentrated phosphoric acid catalyst
alkene + water (steam) —> ethanol
what type of process is fermentation
batch
what type of process is ethene reaction with steam
continuous
What is the reaction rate and purity of ethanol in fermentation
slow
impure
What is the reaction rate and purity of ethanol during the ethene reaction with steam
fast
pure
what is the definition of a primary haloalkane
the halogen is on the end of the alkyl chain
what is the definition of a nucleophile
an electron pair donor
what affects the reactivity of haloalkanes
the electronegativity of the halogen can make the molecule more polar
the higher the mean bond enthalpy the less likely the halide will react in a nucleophilic substitution reaction
what is the definition of nucleophilic substitution
a reaction where an atom or a group of atoms is exchanged for a nucleophile
what kind of fission does water undergo during hydrolysis of haloalkanes
heterolytic fission to produce the nucleophile OH-
how do we measure hydrolysis
add the haloalkane and ethanol AgNO3 and water to a test tube and heat in a water bath.
Start the timer and note down when a precipitate is formed
AgCl- white
AgBr- cream
AgI - yellow
how do we perform hydrolysis using aqueous alkali
e.g. NaOH and heat
it will dissociate into OH- and Na+
this is also a nucleophilic substitution reaction
what happens to the bonds in cfcs in the atmosphere
the C-Cl bond in C2F2Cl2 undergoes homolytic fission due to the UV radiation
C2F2Cl2 —> C2F2Cl• + Cl•
why is the ozone layer beneficial to us
it absorbs all of the UV - C radiation and most of the UV-B radiation protecting us from genetic damage and skin cancer
why are CFCs bas for the atmosphere
the chlorine radicals catalyse the breakdown of ozone to diatomic oxygen molecules and 1 CFC molecule can destroy 100,000 ozone molecules
What is the equation that shows the breakdown of ozone molecules
Cl•+ O3–> O2+ClO•
ClO•+O3–>Cl•+2O2
How can other radicals affect the ozone
nitrogen oxides (made from the high temperatures in exhaust engines and lighting) can also catalyse the breakdown of ozone to diatomic oxygen
Gove the equation that depicts the breakdown of ozone caused by other radicals
NO•+O3–> NO2•+O2
NO2•+O—> O2+NO•
give examples of drying agents
magnesium sulfate MgSO4
calcium chloride CaCl2
What is the test for alkenes
bromine water
orange to colourless
What is the test for a haloalkane
add silver nitrate, water and ethanol and a precipitate will form
how do you test for a carbonyl
ketones have no changes with all of the tests below but aldehydes do
acidified potassium dichromate orange to dark green
tollens reagent silver mirror
fehlings solution dark red precipitate
How do you test for a carboxylic acid
add universal indicator bc its slightly acidic
add a reactive metal and there will be effervescence
How do you test for and alcohol
Warm with a carboxylic acid and some H2SO4 and there will be a sweet smelling ester produced
give two examples of organic compounds with more that one functional group
aspirin — has a carboxylic acid and aromatic ring
niacin— has a carboxylic acid and pyridine group
