The Friedel-Crafts reaction creates new alkyl- or acyl-aromatic bonds, with or without cation rearrangement. Designing reaction sequences, especially those involving diazonium intermediates, so as to access a wide variety of substituted benzenes provides a good introduction to the challenges of synthetic organic chemistry. Aromatic rings with strong electron withdrawal can undergo nucleophilic aromatic substitution, which plays an important role in biochemistry.

Proton decoupling simplifies C-13 NMR spectra. Dilute double labeling with C-13 confirmed the complex rearrangement scheme in steroid biosynthesis. Two-dimensional NMR yields correlations between NMR signals that underlie structural determination of proteins and identification of the mechanism of a rapid carbocation rearrangement. Substitution of an electrophile for a proton on an aromatic ring proceeds by a two-step association-dissociation mechanism involving a cyclohexadienyl cation intermediate.

Because spin-spin splitting depends on electron spin precisely at a nucleus, splitting by a C-13 depends on its orbital’s hybridization. "Higher-order effects" that give complex multiplets for nuclei with similar chemical shifts can be understood in terms of the mixing of wave functions of similar energy. Averaging of chemical shifts or spin-spin splitting may be used to measure the rate of rapid changes in molecular structure, such as changes in conformation or hydrogen bonding. Since the spectroscopic time scale depends on frequency differences, averaging is easier in NMR than in IR.

Through-space interaction between magnets of fixed strength and orientation averages to zero during random molecular tumbling, suggesting that the local field about a proton should be sensitive only to electrons that orbit about itself. The chemical shift can be sensitive to electrons orbiting elsewhere if the amount of orbiting varies with molecular orientation. This "diamagnetic anisotropy" is commonly used to rationalize the unusual chemical shifts of protons in acetylene and in aromatic and antiaromatic compounds.

Magnetic resonance imaging (MRI) requires gradients in the applied magnetic field, while chemical nuclear magnetic resonance (NMR) requires a highly uniform field. When protons in different parts of the body can be driven to broadcast different frequencies, tomography allows reconstructing a three-dimensional image showing water location. Dependence of the signal intensity on relaxation allows BOLD functional MRI that shows brain activity.

Infrared spectroscopy provides information for analyzing molecular structure and for understanding bonding and dynamics. Although the normal modes of alkanes involve complex coordinated vibration of many atoms, the unusual strengths of multiple bonds give alkenes and alkynes distinctive stretching frequencies.  The intensity of characteristic out-of-plane C-H bending peaks allows assignment of alkene configuration.

Time-dependent quantum mechanics shows how mixing orbitals of different energy causes electrons to vibrate. Mixing 1s with 2p causes a vibration that can absorb or generate light, while mixing 1s with 2s causes "breathing" that does not interact with light. Many natural organic chromophores involve mixing an unshared electron pair with a vacant pi orbital, whose conjugation determines color. Infrared spectra reveal atomic vibration frequencies, which are related by Hooke’s law to bond strengths and "reduced" masses.

Cyclic conjugation that arises when p-orbitals touch one another can be as important for transition states as aromaticity is for stable molecules. It is the controlling factor in "pericyclic" reactions. Regiochemistry, stereochemistry, and kinetics show that two new sigma bonds are being formed simultaneously, if not symmetrically, in the 6-electron Diels-Alder cycloaddition. Although thermal dimerization of thymine residues in DNA is forbidden, photochemistry allows the 4-electron cycloaddition.

Professor Wai Chee Dimock introduces the class to Hemingway’s novel To Have and Have Not, which originally appeared as a series of short stories in Cosmopolitan and Esquire magazines. She focuses on Hemingway’s designation of taxanomic groups (“types”) by race, class, and sexuality, arguing that Hemingway’s switch of narrative perspectives throughout the course of the novel casts every character, even protagonist Harry Morgan, as a classifiable kind of human being.

Professor Wai Chee Dimock closes her reading of The Sound and the Fury by reading section four--the section related by an omniscient narrator--through Luster and Dilsey, the two black characters whose personal and racial histories are woven into the history of the Compson family. Luster and Dilsey’s centrality to the final section of the novel, particularly their interactions with the Reverent Shegog on Easter Sunday, transform The Sound and the Fury into a story of redemption; they reconstitute a sense of community whose loss is mourned in Jason’s section.