Feed Your Head (MIT)

Solution to Feed Your Head

Author: Zak Fallows

This puzzle begins with 15 one-sentence clues, and the answer to each clue is a psychoactive drug:

This VMAT inhibitor is structurally related to reserpine.	bietaserpine
This is the most popular stimulant in the world, found in coffee.	caffeine
Dirk Diggler has trouble "performing" because of this drug.	cocaine
This sedative was the most prescribed drug in the US from 1969 to 1982.	diazepam
This antihistamine puts the "PM" in Tylenol PM.	diphenhydramine
This opioid painkiller is available as a lollipop.	fentanyl
This SSRI antidepressant has a very long half-life of 4 to 6 days.	fluoxetine
This is Mark Renton's favorite drug.	heroin
This drug was first synthesized and (accidentally) ingested by Albert Hofmann.	LSD
This club drug damages serotonergic nerve terminals while causing a feeling of social connectedness.	MDMA
The Nazi Method and Shake-and-Bake are two ways to synthesize this stimulant.	methamphetamine
Toxins associated with this drug cause 440,000 deaths per year in America.	nicotine
This 5-HT₃ antagonist gained FDA approval in 1991.	ondansetron
This barbiturate sedative was introduced in 1912.	phenobarbital
If ether and Freon 115 had a baby, it might look something like this popular and sweet-smelling anesthetic gas.	sevoflurane

After the list of clues, there are 11 chemical structures organized into 4 boxed sets. Each structure is a drug from the list above plus an extra functional group. Remove the extra functional groups and combine them to fill in the blank space at the end of the boxed set. For example, the first boxed set consists of nicotine, cocaine, and diazepam. The extra functional groups from those 3 drugs combine to form MDMA, which is also found in the list above. The extra functional groups are highlighted in red below.

Each drug is labeled with an equation. The first drug (nicotine) is labeled with "H × 4 = Hf". This equation describes the full structure shown to the solver: The H represents the number of hydrogen atoms (18), you multiply by 4 to get 72, and the element with atomic number 72 is hafnium (Hf). The Hf is highlighted red because the solver needs to change it. Hf is correct for the full structure (nicotine plus an extra functional group), but it is not correct for nicotine alone. Nicotine has only 14 hydrogens, 14 times 4 is 56, and the element with atomic number 56 is barium (Ba). Doing this for all 15 drugs gives the following sequence of elements:
Ba Se Pa Ir Li K Eu Ra C I Li N O Si Ne.

That sequence of 15 elements can be read as the phrase "base pair like uracil-inosine". Uracil-inosine is a wobble base pair, and so the final answer is WOBBLE.