Alcohols Flashcards
What is the functional group of an alcohol?
-OH
What is the general formula of an alcohol?
CnH2n+1 OH
What type of intermolecular forces do alcohols have?
Hydrogen bonding due to the electronegativity difference in the OH bond
How do alcohols melting and boiling point differ to other hydrocarbons of similar chain lengths?
Alcohols have higher bp because of its strong hydrogen bonding but as chain length increases, the contribution of the -OH decreases
Are alcohols soluble in water?
Alcohols can form hydrogen bonds with water molecules
How do you classify alcohols as primary, secondary and tertiary?
One alkyl group = primary
Two alkyl groups = secondary
Three alkyl groups = tertiary
What forms if you partially oxidise a primary alcohol?
Aldehyde (-COH)
What conditions are needed to partially oxidise a primary alcohol?
Dilute H2SO4 and K2Cr2O7, distil product as its produced with gentle heating
What forms if you fully oxidise a primary alcohol?
A carboxylic acid
What conditions are needed to fully oxidise a primary alcohol?
Concentrated H2S04 and K2Cr207, heated strongly under reflux
What forms if you oxidise a secondary alcohol?
A ketone
What conditions are needed for the oxidation of a secondary alcohol?
Concentrated H2SO4 and K2CR207, strongly heated under reflux
Is it possible to oxidise a tertiary alcohol?
No
What other by-product is formed whenever an alcohol is oxidised?
H2O
What is the colour change of K2Cr207?
The orange dichromate ions (CR207 2-) is reduced to green chromium ions (Cr3+)
What is a dehydration reaction?
A reaction where water is lost to form an organic compound
What are the products of a dehydration reaction of alcohol?
Alkene and water
What conditions are required for the dehydration of alcohol?
Concentrated acid (H2SO4 or H3PO4) and 170 degrees
What happens in a substitution reaction?
The -OH is substituted by a halide, so the alcohol is transformed into a haloalkane. The reaction requires H2SO4 and a sodium halide (NaBr)
Do alcohols have a lower or higher volatility than alkanes and why?
Lower because the strong hydrogen bonds needs to be broken to change state
