27. Triphenylmethyl and an Introduction to Carbonyl Chemistry

Freshman Organic Chemistry II (CHEM 125B)

Painstaking studies of his "hexaphenylethane" and its reactivity convinced Gomberg that he had prepared the first trivalent carbon compound, triphenylmethyl radical, the discovery of which marked the emergence of fundamental organic chemistry in America. Isotopic labeling could decide whether protonated cyclopropane plays a role in Friedel-Crafts alkylation. C-13 NMR spectra of aldehydes and ketones show how characteristic chemical shifts are established empirically. The carbonyl group is thermodynamically stable but kinetically reactive. Its acid- and base-catalyzed reactions often involve loss of an [gr]α-proton to form an enol or enolate intermediate. Carboxylic acids display four fundamentally different reaction patterns. Acid-catalyzed hydrolysis of acetals illustrates a multistep reaction mechanism involving the carbonyl group.

00:00 - Chapter 1. Triphenylmethyl: Chemistry Comes to America
15:39 - Chapter 2. Protonated Cyclopropane in Friedel-Crafts Alkylation?
22:05 - Chapter 3. Carbonyl Compounds: Energy and Spectroscopy
26:06 - Chapter 4. Carbonyl Compounds: Reactivity Patterns

Complete course materials are available at the Open Yale Courses website: http://oyc.yale.edu

This course was recorded in Spring 2011.