What molecular formula does 2-ethyl-3-methylbutanoic acid have?
How many chiral carbon atoms are there in a molecule of 2-ethyl-3-methylbutanoic acid? If none, write 'none'.
A sample of 2-ethyl-3-methylbutanoic acid can be made by oxidising 2-ethyl-3-methylbutan-1-ol, (CH$_3$)$_2$CHCH(C$_2$H$_5$)CH$_2$OH. State the reagent(s) needed for this oxidation and describe the colour change that would be seen.
This reaction is done by heating the reactants together. What could be the main organic impurity in the acid sample? Explain your answer.
State whether a distillation apparatus or a reflux apparatus should be used. Explain your answer.
A structural isomer of 2-ethyl-3-methylbutan-1-ol is 2-ethyl-3-methylbutan-2-ol, $(\text{CH}_3)_2\text{CHC}(\text{OH})(\text{C}_2\text{H}_5)\text{CH}_3$. What colour change would be seen if this were heated with the reagents you have given in (b)(i)? Explain your answer as clearly as you can.
An isomer of 2-ethyl-3-methylbutanoic acid which is an ethyl ester is a very strong smelling compound which is found in some wines. This ethyl ester has a branched hydrocarbon chain and is chiral. Draw the displayed formula of this ethyl ester. Identify the chiral carbon atom with an asterisk (*).