Here is a list of questions that I have come across and some recommended answers to each.
- You have three compounds mixed together: compound A (amino acid), compound B (amine) and compound C (carboxylic acid). How would you separate them?
- How might you make paracetamol (known in the USA as acetaminophen)?
In a job interview you should stop right there. But I hear the more curious chemist ask: How is N acylation carried out without any O acylation? Acylations are highly pH dependent. An acid medium would prevent reaction at the OH but it would also protonate the NH2 to give NH3+ and prevent acylation at the N. The acylation step is therefore done in a water/sodium acetate solution. This keeps the hydroxyl from becoming deprotonated, but does not protonate the NH2. At this pH the acetic anhydride reacts so slowly with the water as to be negligible compared with the rate of reaction with the amino group. A slight molar excess of acetic anhydride is used and the reaction is shaken and occurs at room temperature. Excess acetic anhydride is quenched slowly by water on workup and the reaction is seen to occur in high yield (>90%).
- Name and describe a carbon-carbon bond forming reaction.
- Are you familiar with the Diels-Alder reaction? What is the catalyst?
- Is it possible to form a C-C bond to an aryl carbon?
Not a chemistry question, but I was once asked:
- When we call your referees, what bad things might they say about you?
Another non-chemistry question I was asked recently:
- When do you see yourself in five year?