Chemistry of Caffeine

Hopewell Valley Student Podcasting Network

Chemistry Connections

Episode #3

Welcome to Chemistry Connections, our names are Neve and Alana and I am your host for episode #3 called Chemistry of Caffeine Today we will be discussing The chemical structure and function of the caffeine molecule.

Segment 1: Introduction to Caffeine

Introduce the episode topic

Include definitions, vocabulary, interesting background information and context

Alana: Hey everyone, I’m Alana…and I’m Neve… and welcome to this week's episode of Chemistry Connections, where today, we will be discussing the chemistry of everyone's favorite chemical: caffeine!!!!!!!! Caffeine is a chemical compound which is commonly found in beverages and serves as a central nervous system stimulant, and it is the most widely used CNS stimulant in the world.

Neve: Whether it be in your morning coffee, or your pre-workout energy drink, people these days can’t get enough of this energizing substance.

Alana: In one year, Americans will consume over 971 tons of pure caffeine (Cooper Aerobics). That's a LOT!

Neve: Since we consume so much of it, it's probably important to understand it better.

Segment 2: The Chemistry Behind Caffeine

Alana: Caffeine at its foundation, is just a combination of Carbon, Hydrogen, Nitrogen, and Oxygen, with a chemical structure of C8H10N4O2.

Neve: The molecule has 25 sigma bonds and 4 pi bonds. Sigma bonds are bonds that are directly in line with the nuclei of the bonding atoms. Pi bonds occur when there are multiple bonding spots, located either above or below the nuclei of the bonding atoms.

Alana: Each single bond is made up of one sigma bond, and each double bond is made up of one sigma and one pi bond. Because of this, there are 25 sigma bonds and 4 pi bonds that make up a caffeine molecule. Neve: All the bonds in a caffeine molecule are stable, covalent bonds, as the bonding allows each atom to completely fill its valence shell.

Alana: These bonds are slightly polar, making the caffeine molecule a polar molecule. The molecule is polar because there are EN differences between the oxygen/nitrogen and carbon atoms, allowing the oxygen/nitrogen atoms to slightly pull the electrons towards them in the bond.

Neve: Because the caffeine molecule is polar and there are dipole moments formed between atoms, there are dipole-dipole IMFs that exist between the atoms in the molecule. Additionally, the caffeine molecule has London Dispersion Forces. LDFs exist between all particles, regardless of polarity.

Alana: The covalent bonds in a caffeine molecule are very strong, and the strength of these bonds lend themselves to a high melting point at around 230 degrees.

Neve: The stronger the bond, the stronger the IMFs between the molecules, meaning more energy is needed to break these bonds. In this case, the energy comes in the form of heat, meaning caffeine has a high melting point.

Alana: The covalent bonds in the caffeine molecule also allow for hydrogen bonding to occur between caffeine and water molecules. The strongest H-bond forms at the top C=O group, but additional bonds can form between water and the bottom C=O group, as well as between the nitrogen atoms and water molecules.

Segment 3: Caffeine: Is it an acid or a base?

Neve: It's also important to understand that even though people may think that caffeine is super acidic, caffeine is only a weak acid, meaning it can protonate a strong base.

Alana: This means that caffeine wants to give hydrogen atoms to basic substances.

Neve: One reason that caffeine is acidic has to do with the structure’s outer nitrogen atoms. Nitrogen atoms have a lone pair of electrons in their outer shell, which are readily available to give protons aka hydrogen atoms.

Alana: Because of this, caffeine can react with other substances which are bases to form salts.

Neve: It's not typical in nature for this formation of salts to happen, as the only times that caffeine typically forms into salts are in lab settings.

Alana: Caffeine Hydrochloride, Caffeine Sodium Benzoate, and Caffeine Sulfate are a few types of caffeine salts.

Neve: In your morning cup of coffee, however, your caffeine is likely in the form of a “free Alkaloid”. This means that the caffeine molecules are not bonded to any other types of molecules.

Alana: This is because caffeine is a very very weak acid.

Neve: The molecule is such a weak acid that it's practically neutral. In fact, it has a pH of 6.55, which is very close to a 7, which is neutral on the pH scale.

Alana: The addition of sugar or cream to your coffee can have impacts on the pH, though the effects are very minimal as the pHs of milk and sugar are very close to being neutral.

Neve: The acid may be weak, but I like my coffee strong!!!

Segment 4: Personal Connections

What interested you in this topic? Why is it important? Anything else you’d like to share.

Neve: We were particularly interested in the topic of caffeine, since we are such fanatics ourselves.

Alana: We’ve gotten very good at making it and ordering it. What’s your go-to coffee Neve?

Neve: If I’m making it at home, it’s usually a cold brew with some alond milk and sugar or that carmel flavor syrup. But, if I’m ordering it, it depends on Dunkin or Starbucks. My Dunkin order is ___ and my Starbucks order is __.

Alana: Ooooh those are good choices. If I’m making it myself, it’s def gotta be either a lavender latte or a caramel latte. If it’s Dunkin though, its gotta be an iced coffee with oatmilk and caramel. And then from Starbs I get either a latte with something or the shaken espressos.

TALK ABOUT COFFEE FOR A BIT

Alana: Oftentimes I find myself over-consuming caffeine, so it's important to understand the chemical properties and effects that it has on the body.

Neve: Caffeine is a fascinating molecule that has so many attributes. There are many different chemicals that caffeine causes the human body and brain to produce.

Alana:Norepinephrine, a neurotransmitter and hormone, plays an important role in your body's “fight-or-flight” response.

Neve: Dopamine, acts on areas of the brain to give you feelings of pleasure, satisfaction and motivation

Alana: And serotonin, a chemical that carries messages between nerve cells in the brain and throughout your body.

Neve: These are just a few of the many effects caffeine has on the human brain.These qualities also contribute to the addictive trait of many of our favorite caffeinated beverages. WE HAVE 30 SECONDS KEEP GOING

Thank you for listening to this episode of Chemistry Connections. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.