Organic Chemistry II

Source: Vy M. Dong and Daniel Kim, Department of Chemistry, University of California, Irvine, CA Organic synthesis is about transforming a readily available reagent into a more valuable product. Having clean glassware is crucial for the efficiency of this process. Dirty glassware can potentially affect the reaction and make isolation of the final product more challenging. Thus, a synthetic chemist must keep the glassware spotless. The methods described here will detail different glass cleaning...

Source: Vy M. Dong and Daniel Kim, Department of Chemistry, University of California, Irvine, CA Nucleophilic substitution reactions are among the most fundamental topics covered in organic chemistry. A nucleophilic substitution reaction is one where a nucleophile (electron-rich Lewis base) replaces a leaving group from a carbon atom. SN1 (S = Substitution, N = Nucleophilic, 1 = first-order kinetics) SN2 (S = Substitution, N = Nucleophilic, 2 = second-order kinetics) This video will help to...

Source: Vy M. Dong and Daniel Kim, Department of Chemistry, University of California, Irvine, CA Controlling the reactivity and selectivity during the synthesis of a molecule is very important criteria for chemists. This has led to the development of many reagents that allow chemists to pick and choose reagents suitable for a given task. Quite often, a balance between reactivity and selectivity needs to be achieved. This experiment will use IR spectroscopy to monitor the reaction and to...

Source: Vy M. Dong and Faben Cruz, Department of Chemistry, University of California, Irvine, CA This experiment will demonstrate how to properly carry out a Grignard reaction. The formation of an organometallic reagent will be demonstrated by synthesizing a Grignard reagent with magnesium and an alkyl halide. To demonstrate a common use of a Grignard reagent, a nucleophilic attack onto a carbonyl will be performed to generate a secondary alcohol by forming a new C-C bond.

Source: Vy M. Dong and Diane Le, Department of Chemistry, University of California, Irvine, CA This experiment will demonstrate a simple technique to titrate and obtain an accurate concentration of the organolithium reagent, n-butyllithium (n-BuLi). Organolithium reagents are extremely air- and moisture-sensitive and proper care must be taken to maintain the quality of the reagent so that it may be used successfully in a reaction. The n-BuLi titration experiments should be performed regularly...

Source: Vy M. Dong and Jan Riedel, Department of Chemistry, University of California, Irvine, CA A Dean-Stark trap is a special piece of glassware, which allows the collection of water during a reaction through an azeotropic distillation. The desire to collect water from a reaction can have various reasons. It can drive the equilibria in reactions, where water is formed as a byproduct. According to Le Chatelier's principle, a change in temperature, pressure, concentration, or volume will cause...

Source: Vy M. Dong and Zhiwei Chen, Department of Chemistry, University of California, Irvine, CA This experiment will demonstrate an example of an ozonolysis reaction to synthesize vanillin from isoeugenol (Figure 1). Ozonolysis of alkenes, an oxidation reaction between ozone and an alkene, is a common method to prepare aldehydes, ketones, and carboxylic acids. This experiment also demonstrates the use of an ozone generator and a low temperature (−78 °C) reaction. Figure 1. Diagram showing...

Source: Vy M. Dong and Faben Cruz, Department of Chemistry, University of California, Irvine, CA This experiment will demonstrate the concept of organocatalysis by illustrating the proper setup of a reaction that utilizes enamine catalysis. Organocatalysis is a form of catalysis that uses substoichiometric amounts of small organic molecules to accelerate reactions. This type of catalysis is complementary to other forms of catalysis such as transition metal or biocatalysis. Transition metal...

Source: Vy M. Dong and Faben Cruz, Department of Chemistry, University of California, Irvine, CA This experiment will demonstrate the concept of a palladium-catalyzed cross coupling. The set-up of a typical Pd-catalyzed cross coupling reaction will be illustrated. Pd-catalyzed cross coupling reactions have had a profound effect on how synthetic chemists create molecules. These reactions have enabled chemists to construct bonds in new and more efficient ways. Such reactions have found widespread...

Source: Vy M. Dong and Diane Le, Department of Chemistry, University of California, Irvine, CA Merrifield's solid-phase synthesis is a Nobel Prize winning invention where a reactant molecule is bound on a solid support and undergoes successive chemical reactions to form a desired compound. When the molecules are bound to a solid support, excess reagents and byproducts can be removed by washing away the impurities, while the target compound remains bound to the resin. Specifically, we will...

Source: Vy M. Dong and Zhiwei Chen, Department of Chemistry, University of California, Irvine, CA This experiment will demonstrate the hydrogenation of chalcone as an example of an alkene hydrogenation reaction (Figure 1). In this experiment, palladium on carbon (Pd/C) will be used as a heterogeneous catalyst for the process. A balloon will be used to supply the hydrogen atmosphere. Figure 1: Diagram showing the hydrogenation of chalcone to 3-phenylpropiophenone.

Source: Vy M. Dong and Jan Riedel, Department of Chemistry, University of California, Irvine, CA Polymers are made from macromolecules, which are composed of repeating units (the so called monomeric units). In our modern world, polymers play an important role. One of the first important polymers was nylon, which is a polyamide. It found widespread application in tooth brushes and stockings.

Source: Vy M. Dong and Jan Riedel, Department of Chemistry, University of California, Irvine, CA One of the most important properties of a crystalline solid is its melting point. It can be used to determine the purity of a known compound and gives important information about the stability of the formed crystals.

Source: Vy M. Dong and Zhiwei Chen, Department of Chemistry, University of California, Irvine, CA This experiment will demonstrate the use of infrared (IR) spectroscopy (also known as vibrational spectroscopy) to elucidate the identity of an unknown compound by identifying the functional group(s) present. IR spectra will be obtained on an IR spectrometer using the attenuated total reflection (ATR) sampling technique with a neat sample of the unknown.

Source: Vy M. Dong and Diane Le, Department of Chemistry, University of California, Irvine, CA This experiment will demonstrate the use of a polarimeter, which is an instrument used to determine the optical rotation of a sample. Optical rotation is the degree to which a sample will rotate polarized light. Optically active samples will rotate the plane of light clockwise (dextrorotatory), designated as d or (+), or counterclockwise (levorotatory), designated as l or (−).