Alcohols Flashcards
what do alcohols contain ?
contain hydrocarbon chains with a hydroxyl functional group
how do we make alcohols ?
chloroethane + H20
ethanol + HCI
how do we make alcohols ?
propene + H20
propan - 1- ol ( H3PO4)
how do we make alcohols ?
ethene + acidified
KMNO4 -> diol
physical properties of alcohols - boiling point
they have higher boiling point than their analogous alkanes and longer chain alcohols have higher boiling points
physical properties of alcohols - intermolecular forces
they have stronger intermolecular forces
- london forces, PD - PD interactions and hydrogen bonds
physical properties of alcohols - solubility
more similar intermolecular forces with the solvent means greater solubility
what did both water and alcohol form ?
hydrogen bonds making alcohols soluble in water
complete combustion of butanol
C4H9OH (l) + 6O2 (g) -> 4CO2 (g) + 5H2O (l)
incomplete combustion of propanol
C3H7OH + 2.5O2 -> 2CO (g) + C + 4H2O (l)
making halogenoalkanes - chloro (alcohol)
- reaction
C2H5OH + PCI5 -> C2H5CI
making halogenoalkanes - chloro (alcohol)
- what reaction does it make ?
- how can it be made ?
- substitution reaction
- teritary chloroalkanes can be made by reacting conc HCI with a tertiary alcohol
what appearance would be made when phosphorius (III) chloride reacts with hydrochloric acid ?
steamy fuse
making halogenoalkanes - bromo (alcohol)
- reaction
C2H5OH + HBr -> C2H5Br H2O
making halogenoalkanes - bromo (alcohol)
- what has been made in the flask ?
- what is required ?
- HBr is made in the flask creating a 50:50 mixture of sulphuric acid and KBr
- heating is required
making halogenoalkanes - iodo (alcohol)
- reaction
3C2H5OH + PI3 -> 3C25HI H3PO3
making halogenoalkanes - iodo (alcohol)
- what has been made in the flask ?
- PI3 is made in the flask by mixing red phosphorus with iodine
making alkenes
- an acid catalysed dehydration reaction (elimination)
dehydration reaction - define
a reaction where water is lost from a larger molecule
primary alcohols
- what is the first reaction of an alcohol ?
- the oxidation of an alcohol to an aldehyde
CH3CH2CH2OH + [O] -> CH3CH2CHO + H2O
what is required to get a pure sample of aldehyde - the oxidation of an alcohol
dilute sulphuric acid and distillation
what smell is produced from an aldehyde ?
sweet smell
primary alcohols
- what does the aldehyde undergo further oxidation into ?
- carboxylic acid
CH3CH2CHO + [O] -> CH3CH2COOH
what is required to get carboxylic acid - the oxidation of an alcohol
dilute sulphuric acid and reflux
what smell is produced from a carboxylic acid ?
acidic smell
what is required in an oxidation reaction ?
an oxidising agent
what is the chemical used in the oxidation of alcohols ?
potassium dichromate (VI)
how does the name K2Cr2O7 come from ?
the chromium present has lost six electrons - oxidation state of 6+
what colour does potassium dichromate make ?
orange
as these reaction, what is the chromium ions reduced from and to ?
Cr (VI) to Cr (III)
how can you tell when the oxidation reaction has occurred in alcohols ?
orange solution will turn into a green solution
secondary alcohols can only undergo a single reaction into what ?
a ketone
CH3CH(OH)CH3 + [O] -> CH3COCH3 + H2O
what conditions are required in secondary alcohols ?
heat and reflux
can tertiary alcohols undergo oxidation ?
no
what is the test for tertiary alcohols ?
add acidified potassium dichromate (VI) and heat
what does Benedict’s /Fehling’s solutions contain ?
blue Cu (II) ions - capable of oxidising
when the reaction occurs in the testing for aldehydes or ketones what forms ?
orange - brown precipitate of Cu (I) oxide is formed
what functional group will be a blue -> orange colour change be seen ?
positive result only occurs with aldehydes
besides the benedict’s / Fehling’s solution what is another test ?
tollens reagent - silver mirror
what is the tollens reagent a mixture of ?
silver nitrate and ammonia
- Ag+ ions are reduced by an aldehyde to form silver metal
