SCIENCE EDUCATION > Chemistry

Organic Chemistry II

This collection covers the theory and reactions necessary to carry out syntheses on a more advanced level. In addition, a few videos introduce methods commonly used to analyze the reaction products such as infrared spectroscopy and polarimetry.

  • Organic Chemistry II

    07:29
    Cleaning Glassware

    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 techniques that are regularly used to remove organics, metals, grease, and salts.

  • Organic Chemistry II

    14:20
    Nucleophilic Substitution

    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 visualize the subtle differences between an SN1 and SN2 reaction and what factors help to speed up each type of nucleophilic substitution reaction. The first section will focus on reactions that will help to better understand and learn about nucleophilic substitution reactions. The second section will focus on a real-world example of a substitution reaction.

  • Organic Chemistry II

    10:18
    Reducing Agents

    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 understand the reactivity of carbonyl compounds as well as the reactivity of hydride-reducing reagents.

  • Organic Chemistry II

    07:19
    Grignard Reaction

    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.

  • Organic Chemistry II

    06:57
    n-Butyllithium Titration

    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 to obtain accurate concentrations prior to use in a chemical reaction. Subsequently, we will demonstrate the addition of the titrated n-BuLi to benzaldehyde.

  • Organic Chemistry II

    05:56
    Dean-Stark Trap

    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 a readjustment of a reversible reaction to establish a new equilibrium. An acetal formation is a reversible reaction, where water is formed as a byproduct. In such cases, achieving good yields is possible by driving the equilibrium towards the product side via the removal of water. The Dean-Stark trap also allows the determination of water content or can be used to remove water from a solvent mixture through an azeotropic distillation.

  • Organic Chemistry II

    06:51
    Ozonolysis of Alkenes

    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 the ozonolysis of isoeugenol to vanillin.

  • Organic Chemistry II

    06:30
    Organocatalysis

    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 catalysis involves transition metals as catalysts and biocatalysis uses enzymes as catalysts. Some advantages of organocatalysis include the low toxicity and cost of the organocatalysts in comparison to many metal catalysts. In addition, most organocatalysts are not sensitive to air and moisture, unlike metal catalysts. In contrast to enzymes found in living organisms, the small molecules that act as organocatalysts are typically easy to access. Furthermore, organocatalysis offers complementary and new reactivity not observed with other forms of catalysis.

  • Organic Chemistry II

    06:18
    Palladium-Catalyzed Cross Coupling

    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 applications in the fine chemical and pharmaceutical industries. Pd-catalyzed cross coupling reactions add another tool to the chemist's toolbox for constructing carbon-carbon bonds, which are central to organic chemistry. The combination of the importance of making carbon-carbon bonds and the impact of Pd-catalyzed cross coupling have resulted in these reactions being the subject of the 2010 Nobel Prize in Chemistry. Ei-ichi Negishi, one of the recipients of the 2010 Nobel Prize in chemistry, explained in his Nobel lecture that one of his motivations for developing this chemistry was to develop "widely applicable straightforward Lego-like methods for hooking up two different organic groups".

  • Organic Chemistry II

    09:41
    Solid Phase Synthesis

    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 showcase an example of solid-phase peptide synthesis (SPPS) to demonstrate this concept.

  • Organic Chemistry II

    06:05
    Hydrogenation

    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.

  • Organic Chemistry II

    06:44
    Polymerization

    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.

  • Organic Chemistry II

    05:11
    Melting Point

    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.

  • Organic Chemistry II

    08:10
    Infrared Spectroscopy

    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.

  • Organic Chemistry II

    07:11
    Polarimeter

    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 (−).

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