4.2.1 Alcohols Flashcards
What is the functional group of an alcohol?
Hydroxyl group
OH
What is the general formula of an alcohol?
Cn H2n+1 OH
How do you name alcohols?
one prefix, one suffix
Hydroxyl-
or
-ol
What kind of intermolecular forces do alcohols have?
Why?
Hydrogen bonding
Due to the difference in electronegativities in the OH bond
How do alcohols’ melting point and boiling point compare to other hydrocarbons’ of similar C chain lengths?
Why?
Higher boiling point that other hydrocarbons
Because they have hydrogen bonding (the strongest type of intermolecular force) , which is stronger than london forces
Are alcohols soluble in water?
Why does solubility depend on chain length?
Soluble when short chain
OH bonds to hydrogen to hydrogen bond in water
Insoluble when long chain
Non polarity of C-H bond takes presedence
What makes an alcohol primary?
C bonded to OH is only bonded to one other C atom
What makes an alcohol tertiary?
C bonded to OH is bonded to three other C atoms
Write an equation for the combustion of ethanol
C2H5OH (l) + 3O2 (g) –> 2CO2 (g) + 3H2O
What forms if you partially oxidise a primary alcohol
An aldehyde
What conditions are needed to partially oxidise a primary alcohol?
Dilute sulphuric acid , potassium dichromate (Vl), distill products as it’s produced, gentle heating
Write an equation for the partial oxidation of ethanol
CH3CH2OH (l) + oxidising agent –> CH3CHO (g) + H2O
What forms if you fully oxidise a primary alcohol?
A carboxylic acid
What conditions are needed to fully oxidise a primary alcohol?
Concentrated sulphuric acid, potassium dichromate (Vl) , heat under reflux
Write an equation for the full oxidation of ethanol
CH3CH2OH (l) + 2 oxidising agents –> CH3COOH (g) + H2O (l)
What forms if you oxidise a secondary alcohol?
A ketone
What conditions are needed for oxidation of a secondary alcohol?
Concentrated sulphuric acid, potassium dichromate (Vl), strong heating
Write an equation for the oxidation of propan-2-ol
CH3CH(OH)CH3 (l) + oxidising agent –> CH3COCH3 (g) + H2O (l)
Is it possible to oxidise tertiary alcohols?
No
What is a dehydration reaction?
A reaction where water is lost to form an organic compound
What are the products of dehydration reaction of alcohol?
Alkene and water
What are the conditions required for the dehydration of alcohol?
Conc sulfuric acid
or conc phosphoric acid
at 170 degrees
What are the products of the halide substitution reaction with alcohol
Haloalkane and water
In what form is the halide used in halide substitution reaction?
In the form of hydrogen halide
e.g. HBr
How is hydrogen halide made in situ?
Give examples
A salt is reacted with acid to form the hydrogen halide
e.g. sodium bromide reacts with sulfuric acid to form HBr
When iodine is reacted phosphoric acid is used as sulfuric acid oxidizes ions into iodine