ANALGESICS -AND THE SYNTHESIS OF ASPIRIN

This is part of my ongoing experimentation on how to deliver chemistry topics to students in a more engaging and contextually relevant way.

What are Analgesics?

The students were curious about painkillers, so we decided to take a deeper dive into this world.

There are two main types of analgesics on the market: non-opioid analgesics and opioid analgesics.

Non-opioid analgesics are the most common type of pain reliever. They work by blocking the production of prostaglandins, which are chemicals that cause inflammation and pain. Non-opioid analgesics include:

• Acetaminophen (Tylenol)
• Ibuprofen (Advil, Motrin)
• Naproxen (Aleve)
• Diclofenac (Voltaren)
• Ketoprofen (Orudis)
• Piroxicam (Feldene)

Opioid analgesics are stronger pain relievers than non-opioid analgesics. They work by binding to opioid receptors in the brain and spinal cord, which blocks the transmission of pain signals. Opioid analgesics can be addictive, so they are only used for severe pain. Some examples of opioid analgesics include:

• Codeine
• MorphinE
• Hydrocodone (Vicodin)
• Oxycodone (OxyContin)
• Fentanyl

In addition to these two main types of analgesics, there are also a number of other medications that can be used to relieve pain. These include:

• Anticonvulsants, such as gabapentin (Neurontin) and pregabalin (Lyrica)
• Muscle relaxants, such as cyclobenzaprine (Flexeril) and baclofen (Lioresal)
• Topical analgesics, such as capsaicin (Zostrix) and lidocaine (Lidoderm)
• Neuromodulation devices, such as spinal cord stimulators and transcutaneous electrical nerve stimulation (TENS) units

In the lab we decided that we would take a stab at sythesising Aspirin

Aspirin Synthesis

They are a few different ways of synthesizing Aspirin in the lab we choose:

SALICYCLIC ACID + ETHANOIC ACID = METHYL SALICYCATE + WATER

Synthesis of Aspirin

Aspirin is used to introduce the students to functional groups and organic synthesis. In this experiment, students compare the properties of salicylic acid and acetylsalicylic acid through pH and iron chloride testing. They extract salicylic acid from willow bark and use it to produce acetylsalicylic acid (the active ingredient in Aspirin), and in the second synthesis the students add acetic acid to salicylic acid too produce acetylsalicylic acid (the active ingredient in (Aspirin). The students tested for the presence of Aspirin using Ferric Chloride.

FeCl3 Test for Aspirin

Reactants and lab equipment used in this synthesis

Synthesis methods outlined and Microwells

Synthesis in progreSynthesis in progress

Synthesis in progress

In this synthesis we jumped straight into producing the Aspin later we went back and figured out the chemical reactions and looked at the functionality of the molecules.

To keep the students engaged, there are two things at play here. It seems to be better to jump straight into an an experrient semi blind and later figure out the chemistry. The other things that holds engagement is the familiarity of the product, its part of their day-to-day. Introducing chemicals that know gives the chemistry a cointext for them. I find that both of these simple solutions work.