Coffee Chemistry


(published in Ruminator Review, Spring, 2002)


It’s 1967.  I’m eleven years old, and my mother and I are golfing.  We’ve been going golfing nearly once a week all summer.  We always go in the early morning, and we’re often the first ones on the course.  When we reach the greens, we have to hit our putts extra hard, because the dew spins off the ball, slowing it down as it travels toward the hole.  When we reach the fourth tee, on a cliff overlooking the river that runs down the left side of the fourth fairway, we sit down on the bench, like always, and take our break. 

Mom reaches in her golf bag and brings out two thermos bottles and a foil wrapper that she undoes to reveal my breakfast.  This morning she’s brought donuts—my favorite.  She opens my thermos bottle and pours me a cup of cold milk.  And then, once I’m enjoying my breakfast, she twists the cap off her thermos.  Steam rises as she pours herself a cup of hot, black liquid.  She leans back, listening to the birds, looking at the sunlight slanting through the trees, and she gives a gentle sigh as she raises the steaming cup to her lips. 

Somehow I know that this is a special moment for the two of us—a moment of contentment and togetherness.  It’s the day I first sense that there is something magical about coffee.

Coffee.  Coffee.  Coffee.  Just saying the word invokes a rich brew of images for me.

It's 1976.  I'm sitting in the basement of a student flat in Oxford, England, making instant coffee with four American and Swiss classmates on a semester-abroad program.  It's our own little version of Ye Olde English Coffeehouse, and we're feeling bohemian, intellectual, and just a bit lonely for home. 

It's 1981.  My wife and I are celebrating our second anniversary at Maison Robert, one of the finest French restaurants in Boston.  We're reminiscing about our soon-to-end days of graduate school and wondering what the future will hold for us.  The waiter is pouring me a cup of the richest, blackest coffee I've ever seen.  When we move to Washington, D.C., will it be one dinner after another like this? 

It's 1984.  My brother and I are camping in the Boundary Waters Canoe Area of northern Minnesota.  I can see my breath even though it's August.  A small pan of water is boiling on our portable gas burner, and I have a dull headache from caffeine withdrawal.  I'm sprinkling precious crystals of instant coffee from a 35-mm film canister into my metal cup.

It’s 1989.  I’ve just poured a cup of weak, warm black liquid—I hesitate to call it coffee—into a white Styrofoam cup.  I’m sitting down to join other members of a men’s support group that meets weekly in a church basement.  On the surface, my life is going well, with a high-status job in downtown Washington and two young sons in the suburbs.  Inside, though, I’m feeling more and more confused and empty. Tonight, as I hear these other men talk about the disappointments and frustrations in their lives, I realize I’m not alone.

It's 1995.  I'm sipping an iced coffee while sitting on a picnic bench at Wayzata Beach on Lake Minnetonka.  My four sons are splashing in the water.  I’m keeping a close eye on two-year-old Ben even though he is wearing a bright orange Coast Guard-approved life preserver.  It’s a warm summer evening, and purple martins skim low over the surface of the water, gobbling up insects.

It's 2004.  I'm sitting at Caribou Coffee in Wayzata, Minnesota, with my large skim latté, my laptop computer, and my cellular phone.  As I look around the room, I see friends, acquaintances, and strangers.  I hear bits and pieces of five different conversations—"remodeling,"  "engaged," "dot-com," "divorce," "cabin."  My kids are all in school this morning, and I'm procrastinating on a writing assignment. 

Coffee.  One simple liquid associated with so many images, so many memories, so much meaning.  It seems to have a mystical power to transport me and others to a place of contentment and community.  How can this be, I wonder?

As soon as I articulate this question, my chemist-self takes over, and I start speculating about this "simple liquid."   I turn on my laptop computer and use the wireless modem to connect to the Internet.  A bit of quick research on a Web site in Jamaica reveals that the elixir known as coffee contains more than six hundred naturally occurring chemicals.  One of those chemicals, of course, is the one that gives coffee its kick—caffeine.

Some more quick Web research—and I am moving quickly now as the large skim latté enters my bloodstream—informs me that caffeine works in the body in several different ways, most importantly by blocking the action of an enzyme called phosphodiesterase.  One of the jobs of phosphodiesterase is to break down and eliminate the messenger chemicals that stimulate the production of adrenaline. 

I close my eyes to imagine what this really means for my body, and I get an image of hundreds of Ping-Pong balls bouncing around in my central nervous system.  Each Ping-Pong ball carries the message to produce more adrenaline and release more energy. It's just a normal day in my body, as the different parts send messages to each other, calling for the amount of adrenaline and energy they require to accomplish their tasks.  Scurrying around, sucking up Ping-Pong balls like little vacuum cleaners, are the phosphodiesterase enzymes.  The vacuum cleaners keep my energy-regulation system relatively uncluttered. 

However, the caffeine molecules from my large skim latté are just the right size and shape to plug up the phosphodiesterase vacuum cleaners.  After I drink my coffee, the molecular vacuum cleaners grind to a halt, the Ping-Pong balls just keep bouncing around in my system, and my body churns out more and more adrenaline, releasing more and more energy.  No wonder conversations, relationships, writing, and life itself seem more intense here in this coffeehouse. 

I already knew that caffeine was a drug and stimulant, so this biochemical explanation makes good sense to me.  But I'm unsatisfied.  It doesn't capture the full experience.  I'm still convinced there is something magical about coffee and caffeine.  So I keep researching, probing deeper and deeper.

Maybe the chemical structure of caffeine itself will reveal the answer to me.  I surf to a Web site of molecular structures and stare at the caffeine molecule. As the molecular structure rotates slowly on my laptop's screen, I experience one of those Eureka moments that scientists live for.  There is something going on here!  And it's in the bonds, the chemical bonds.

The molecular structure of caffeine features a core of nine atoms—five carbon atoms and four nitrogen atoms.  These atoms are linked together in alternating fashion to make up a five-membered ring and a six-membered ring.  The two rings share one common side, so the structure resembles a lopsided  figure eight, with one ring just a bit smaller than the other ring.  

This core structure, called a purine ring, looks like a simple drawing of a snowman made out of just two snowballs.  Jutting off this core is an assortment of carbon, oxygen, and hydrogen atoms.  They protrude out into space like abstract limbs and appendages on a headless snowman created by Picasso. 

I remember, from playing with molecular models thirty years ago in my college chemistry class, that the purine ring structure serves as one of the most basic building blocks in organic chemistry.  Just by substituting various atoms branching off the unchanging purine ring core, I could build many important molecules.  In fact, I recall that two of the four bases that make up the genetic code used by DNA are built on the purine ring structure.  (Adenine and guanine, the “A” and the “G” of the A-T-C-G genetic code, are known as the “purine bases.”)

The nine atoms found in the purine ring structure form a tight community, held together by two distinctly different kinds of chemical bonds.  As I gaze at the caffeine molecule still lazily twirling on my laptop screen, I suddenly grasp that it's these two different types of bonds that give caffeine its mystical qualities.

The first type of bond is the one between two neighboring atoms.  Each one of the carbon and nitrogen atoms shares two or three direct bonds with adjacent atoms.  This kind of direct bond between two atoms is known to chemists as a single bond.  In a single bond, each of the two atoms contributes a single electron to the relationship.  The electrons form a matched pair, sort of like two friends shaking hands, and you’ve got a strong chemical bond.

Looking around Caribou Coffee this morning, I can see three people that I have bonded with in this manner. Carolyn is my writer friend. She’s working on her first novel.  It’s now in a second draft, and we share inspirational moments, rejection letters, and our daily struggles with writer’s block.  Each rejection letter strengthens our bond just a bit more.  We fantasize that we’ll include each other’s names in the acknowledgments sections of our first books.

Meredith was the first-grade teacher for three of my four children.  It was easy to buy Christmas presents for her—we’d just give her a card with a gift certificate for coffee.  She’s one of the most effervescent people I know, and I smile inwardly whenever I see her walk into the coffee shop.  We always trade stories about our children and chat about what’s happening at the elementary school.  At times, we’ve even talked here about more personal topics, such as my recent divorce and her plans for a career change.  At those moments, the bond is a very strong one.

Steve has walked here again with his dog Buddy, a beautiful black retriever.  Buddy waits patiently outside, his leash attached to a street sign.  Steve is going through a divorce, and we swap stories about our scary reentry into the world of dating. 

The rest of the people here today are strangers, although I have seen some of them in here before.  Carolyn and Meredith are more extroverted than I am, and they know many of the others who come in and out.  Even if I don’t know the others, I feel like we’re part of the same community, simply by virtue of sharing a common friend.

As I visualize all the single bonds that exist between those of us here in the coffeehouse (or at other community meeting places such as the elementary school, the church, the local beach, the soccer field, the grocery store, or the video store), I begin to understand what it means to be a community.  But to be a real community, you need a second type of bond, and this is the essential lesson the caffeine molecule has taught me today.

 In a caffeine molecule, the second type of bond is not just between two atoms. It is a special bond that includes all nine atoms in the purine ring.  In the world of chemistry, this is called a delocalized bond, and each atom contributes one electron to this community bond.  Instead of being localized between two atoms, like the electron pair in a single bond, the nine electrons in this delocalized bond form a big electron cloud that embraces the entire purine ring.  

How can nine electrons be smeared out over this whole structure?  In some sense the electrons are nowhere—and everywhere—at once.  It’s impossible to explain in terms of Newtonian mechanics.   With quantum mechanics, molecular orbital theory, and complicated mathematical equations, however, we can describe the situation.  We can even make predictions about the molecular properties of caffeine.  These equations predict that a molecular structure with delocalized bonds is stabler and more resistant to outside forces.  Chemists have learned that they can tinker easily with the appendages, the parts of the molecule on the fringes.  But it’s very difficult to change the core.

Similarly, there is a cloud of shared values here in my community that embraces me and everyone else in Caribou Coffee this morning.   A demographer or a social scientist would be able to describe our community in terms of beliefs, ethnic origins, lifestyles, educational background, economic considerations, traffic patterns, and many other factors.  In fact, a multifactorial equation from a sociology journal might very well predict that Wayzata, Minnesota, is a stable community, and that this coffeehouse forms one of several nuclei for the whole community.

With all these equations and theories, however, have we really captured the essence of the caffeine molecule, the essence of community?  Do we really understand it?   I don’t believe so.  It’s not something that can be understood with our heads but rather must be felt in our bodies or hearts.

Some days, sitting here at Caribou with a caffeine buzz, I feel like one of the delocalized electrons.  I have a connection to several people in the place.  We know each other, and they know each other.  They introduce me to new people, I enter into conversation, and my sense of community grows and extends to embrace everyone.  I feel expansive and ennobled.  I’m part of something bigger and more important than just myself.

Other days, I feel like an atom on the fringe of the caffeine molecule.  I’m tied to the whole community, but the bonds are weaker.  There are no delocalized electrons whirring around out here, and I feel content to just sit in the coffee shop.  I don’t need to talk to anyone, but I like the energy around me, the sense of people talking, exchanging ideas, or taking solitary time to plan their day, their week, their life. 

And still other days, I feel like a completely separate and superfluous molecule, and it’s painful to sit here.  Those are the days I yearn for community, for acceptance, for understanding, but I simply don’t feel any such bonds.  I know there’s something missing in my life.

An ache buried deep within me, within the marrow of my bones, within the nuclei of every cell in my body calls out for me to connect with other people.  Perhaps it’s the delocalized electrons in the purine bases of my DNA—of everyone’s DNA—that compels each of us to reach out to others.  Perhaps our purpose as humans is simply to build strong and meaningful bonds with others.  Perhaps those bonds allow some part of us to participate, just like those delocalized electrons in caffeine and DNA, in a larger and inexplicable entity and purpose.

Wait a minute.  Chemists aren’t allowed to ramble outside the realm of rational language and models, are they?

Are they?  While chemists certainly won’t speak about it in public, they will sometimes admit to more mystical and imaginative leaps of understanding.  They might even admit to a secret sense of pride that they can trace the roots of their science back to the alchemists of the Renaissance, the Middle Ages, and ancient Egypt.  And if you want to see a chemist’s eyes sparkle, just ask him or her to tell you the story of the German chemist, August Kekulé, who, in 1865, had the initial insight that carbon atoms can link together in a ring structure.

Kekulé's insight came, not from equations, theories, deductions, or meticulous observations, but rather from a dream.  In his dream, a snake curled around on itself and bit its own tail, thus forming a circle.  The image of a snake holding its tail in its mouth, called the Ouroboros, just happens to be one of the most important alchemical symbols.  In alchemy, it’s often accompanied with the phrase, “All is one.”

When Kekulé awoke from his dream, he quickly wrote down his ideas on the molecular structure of benzene, the simplest of all the organic ring compounds.  With this elegant solution to a problem that had perplexed chemists for years, Kekulé opened up a whole new frontier of organic chemistry.  And his dream also pointed the way, more than a century later, to my insight about caffeine, delocalized bonds, and community.

I feel a bond with Kekulé.  I suspect that he might have been drinking some coffee before he went to sleep that night. 

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