Task 1
Acidity of Carbonyl Compounds
a) Find Ka values for and order the following componds in order of acidity, most acidic first.
i) Ethanol ii) propanone (acetone) iii) ethyl ethanoate iv) ethylacetoacetate.
b) Draw the structures and identify the α carbons where appropriate.
c) Draw the enol form of the compounds in a) which can have an enol form, and use this and the Ka values to explain the difference in acidity.
Task 2
Enols and Enolate Ions
a) Draw the structures of 2 very stable enols, at least one of which should show Intra molecular hydrogen bonding.
b) Halogenation reactions of carbonyl compounds can take place in acid or base. Draw reaction mechanisms for the following reactions.
i) The reaction of propanone with bromine in the presence of a base. (include the intermediate enolate ion).
ii) The reaction of propanal with bromine in the presence of an acid. (Include the enol intermediate step).
Task 3
Aldol Condensations
a) Butanal can undergo an aldol addition reaction with itself in the presence of a base. Write a reaction mechanism to show this.
b) In the presence of acid and heat the hydroxyl aldehyde produced can dehydrate. Draw the structure of this product.
c) A crossed condensation reaction is much more useful as a synthetic route when one of the reactants does not have an α hydrogen. You carried out this type of reaction in class.
Write a laboratory report including, a theory section, for the aldol condensation you carried out. You may wish to include any photographs you have taken.
d) Critically evaluate the experiment you carried out.