Module 4: Alcohols (Chapter 14) Flashcards
Polarity of alcohols
Polar due to having an O-H bond with a significant difference in electronegativity. Non-symmetrical molecule with a permanent dipole.
Solubility of alcohols
Soluble due to having hydrogen bonds in the form of an -OH group with the water molecules.
How does the influence of the -OH group change with increasing hydrocarbon chain length?
Influence decreases and the hydrocarbons become less soluble. Due to a larger proportion of the chain being non-polar the hydrocarbon is less soluble.
Volatility of alcohols
Low volatility due to hydrogen bonding providing strong intermolecular forces. Lots of energy is needed to overcome these forces, hence higher boiling points and low volatility.
How are alcohols classifed?
Primary, secondary and tertiary
Process of combustion in alcohols
Produces carbon dioxide and water
Exothermic releasing large amounts of energy as heat
Oxidation of primary alcohols with reagents and conditions
Aldehydes form with K2Cr2O7/H2SO4 and distillation (prevents further oxidation)
Carboxylic acid with excess K2Cr2O7/H2SO4 and reflux
Water a by-product of both
Purpose of reflux
Allows temperature to increase dramatically to a mixtures boiling point for a prolonged time. Mixture can evaporate before condensing back into the pear-shaped flask.
Oxidation of secondary alcohols
Fomation of ketones
K2Cr2O7/H2SO4 AND reflux
Water a by-product
Oxidation of tertiary alcohols
Not possible and solution remains orange
Colour change for primary and secondary alcohols
Orange to green
Dehydration of alcohols
Formation of alkenes and water
Concentrated H3PO4 OR H2SO4 with reflux
An elimination reaction
Substitution of alcohols
Haloalkane formation and water
NaX and H2SO4(aq)
Brady’s reagent
Identifies a carbonyl forming an orange precipitate to show ketones and aldehydes
Tollen’s reagent
Forms a silver mirror to identify an aldehyde
