A Morning in Organic Chemistry II Lab

It’s a Tuesday morning on the second floor of the Noyce Science Center. Students in Steve Sieck’s Organic Chemistry II Lab section filter into a computer lab across the hall from the organic laboratory. For the past two months, they’ve been applying the technical skills they gained in previous chemistry courses to identify a series of unknown compounds received at the start of the semester. Today is the last day for students to determine the structure of their third and final unknown compound:

7:58 a.m. A sleepy quiet fills the room. The early hour doesn’t promote a particularly raucous mood.

8:00 “All right let’s get started,” says Steve Sieck, associate professor of chemistry, breaking the silence. Chatter erupts.

8:02 A handful of students grab lab goggles and notebooks and head across the hall to the laboratory, while others gather around laptops and printed analyses of their compounds.

8:05 In the lab, Duncan Steele-Maley ’24 warms a flask of ethanol in which he plans to dissolve his fluffy, yellow compound (reminiscent of astronaut ice cream). “I’ve discovered that my compound is insoluble in nearly everything,” he laments, “except for this.”

8:06 In another fume hood, a student liquefies her compound in a tiny glass tube of dimethyl sulfoxide. She heads down the hallway with this chemical pixie-stick, toward the nuclear magnetic resonance (NMR) spectrometry room.

NMR will allow her to collect detailed information about the electronic structure of a molecule. Analyzing the spectral output has been key as students have pieced together what atoms and structures are present in their unknown compounds.

8:10 “So we just burn it?” Based on their NMR spectra, two students think their compounds might contain halogens. If so, their unknowns should produce distinctly colored flames when burnt.

8:11 No one can find the chlorobenzene, and they need the chlorine-containing control to compare with the flames produced by their unknowns.

8:15 Still no chlorobenzene to be found, and the crew decides to use chloroform instead. “It should do the job – it still contains chlorine.”

8:16 The knob that controls the gas supply to the Bunsen burner is stuck, and backup (the professor) is called in. Sieck, too, cannot open the valve.

8:17 Never mind, he got it. Bunsen burner: on!

8:23 Steeley-Maley mixes his (finally) dissolved unknown with iodine and sodium hydroxide. The mixture turns cloudy and yellow, which tells him his compound contains a structure known as a ketone. He jots this down.

8:30 Jenna Keller ’24 has noticed some unusual peaks on the NMR spectra she gathered, and she plans to check her compound’s purity using a technique called thin layer chromatography.

8:38 Megan Szalay ’25 enters the lab. She’s signed up to defend her compound declaration at 8:40. “Wait, am I supposed to meet Professor Sieck in his office?”

8:40 She is, in fact, supposed to meet him in his office. Off she goes to her final unknown compound declaration. Godspeed, Megan.

8:52 A student prepares a titration that she hopes will allow her to calculate her compound’s molecular weight. Free-pouring sodium hydroxide into a narrow glass burette is not easy and is, she learns, best done over a sink.

8:57 Szalay returns from her unknown defense, triumphant. She’s correctly determined her compound’s structure!

9:08 Across the hall in the computer lab, a few students are digitally refining their NMR spectra. Someone creates a hydrogen correlation spectroscopy plot — an analysis called COSY. This name is, in my opinion, adorable.

9:16 Two chemists have finished their unknown compound analyses and are tweaking the protocol for the synthesis project that they’ll begin next week. They plan to synthesize curcumin — a yellow pigment found in turmeric.

9:18 Keller reviews her lab notebook before her unknown compound defense in 12 minutes. “By the third unknown declaration — you’re a professional,” she laughs. “Well…sort of …”

9:22 In the laboratory, the notoriously tedious titration setup continues. “I’m measuring this like my life depends on it,” the student says as she peers through a 10 mL graduated cylinder.

9:33 Garret Bean ’24 enters the lab for one final chemical test — the ketone test that Steeley-Malley did earlier.

9:39 Minutes later and Bean has produced the cloudiest, yellowest reaction I’ve seen all day. Does his compound contain a ketone? I think yes.

9:40 Red indents span all our foreheads, the lingering mark of lab goggles.

9:43 Keller returns from her defense. She, too, got her compound spot on. This lab section is on a roll.

9:47 In the computer lab, two classmates sketch, erase, and re-sketch structures on the board. They’ve joined forces as one of them races against the clock to solve his unknown’s structure.

10:03 A student decides to confirm her compound by testing its melting point. She heads to the lab and rapidly heats the powder while watching through a microscope for signs of melt. “I’m going fast because I’m impatient,” she explains. I admire her frankness.

10:11 A student from a different section of O-Chem II has dropped by the classroom to offer insight to a friend. Now, two pairs of collaborators work at the blackboard.

10:28 A squeal pierces the chatter, and I scan the room to see a student doing a fairly energetic victory dance. “Ugh, I am SO happy right now.” Structure? Solved. 

10:30 Only a handful of students remain in the computer lab. The laboratory is empty. No more chemical tests: It’s analysis crunch time. Twenty minutes until students must declare the structure of their unknowns.

10:35 “I’m not super confident about my structure,” a student confides to Sieck. “But” he asks, smiling wryly, “do you like Subway? I have a gift card.”

10:36 “Are you BRIBING me???” Sieck counters. Academic honesty reigns another day.

10:42 The last structure is turned in and the unknowns unit is officially over. Congratulations, organic chemists.