Applying IB chemistry to a diet pill
Sunday 23 September 2018
One of the reasons why life expectancy is starting to fall in certain parts of the world is the increase in obesity.
The number of overweight and obese people worldwide has increased from 857 million in 1980 to 2.1 billion in 2013. Of these, 671 million are obese. (Source: Medical News Today)
Recent studies by a team led by Dr Erin Bohula published in the New England Journal of Medicine have identified a drug which can reduce weight in humans. The study, which involved 12,000 people who were either obese or overweight, showed that those who took the drug lorcaserin twice a day lost an average of 4 kg (approximately 9 lbs) in 40 months compared to those who took a placebo. This is not a huge weight loss and dieticians still stress the necessity for a healthy diet coupled with regular exercise. The importance of the study though is that, unlike other appetite suppressers, lorcaserin, appears to have no serious long-term adverse effects on the heart. It is thought to work by suppressing appetite by activating a type of seratonin receptor known as 5-HT2C in the hypothalamus.
Lorcaserin has an interesting structure and could be used in your teaching to check whether students can apply what they have learned during the course (Topics 10, 11, 18, 20 and Option D) to a real life example.
1. Deduce the molecular formular of lorcaserin.
2. Calculate the index of hydrogen deficiency (IHD) of lorcaserin.
3. Predict whether or not lorcaserin will readily undergo an electrophilic addition reaction with bromine.
4. Deduce whether lorcaserin is a weak acid, a weak base or a neutral substance.
5. Suggest why lorcaserin is normally administered as a salt, such as lorcaserin hydrochloride.
6. Explain whether structure B represents an enantiomer of lorcaserin as shown in structure A.