Chapter 14-Alcohols Flashcards
Why are alcohols less volatile than alkanes
In the liquid state, alcohol has hydrogen bonds holding molecules together. Alkanes have London forces only. Hydrogen bonds are stronger than London forces so they require more energy to be broken. As a result, alcohols are less volatile
What intermolecular forces do alcohols have?
They have hydrogen bonds
Because polar OH bond because O is extremely electronegative
Therefore molecule is polar
Why are alcohols soluble in water?
Hydrogen bonds form between the alcohol and the water molecule
What is the trend in solubility as the chain length increases?
As the hydrocarbon chain increases in size, the influence of the OH group decreases, as does the solubility
Primary alcohols
The OH group is attached to a carbon atom that is attached to 2 hydrogen atoms and 1 alkyl group
Secondary Alcohols
The OH group is attached to a carbon atom attached to 1 hydrogen atom and 2 alkyl groups
Tertiary alcohol
The OH group is attached to a carbon atom which is attached to 0 hydrogen atoms and 3 alkyl groups
What are the products when alcohols combust?
Carbon dioxide and water
How are aldehydes prepared
Catalyst: K2Cr2O7/H2SO4
Distilled
Oxidation of a primary alcohol (step 1)
How are carboxylic acids prepared
Catalyst: K2Cr2O7/H2SO4
Heated under reflux
Oxidation of a primary alcohol (step 2)
Preparing a ketone
Catalyst: K2Cr2O7/H2SO4
Heat under reflux
Oxidation of a secondary alcohol
Is it possible to oxidise a tertiary alcohol
No
Dehydration of alcohols
Heated under reflux
Concentrated phosphoric acid catalyst or concentrated sulfuric acid
Alcohol ———>alkene + water
Substitution reactions of alcohols
Hydrogen halide formed in situ
Sodium halide + sulfuric acid ———> sodium hydrogen sulfate + hydrogen halide
Alcohol + hydrogen halide ———> haloalkane+ water
Overall reaction
Alcohol + sodium halide + sulfuric acid ——> haloalkane + sodium hydrogen sulfate + water
