The aldol reaction is a means of forming carbon-carbon bonds in organic chemistry. Discovered independently by the Russian chemist Alexander Borodin in 1869 and by the French chemist Charles- Adolphe Wurtz in 1872, the reaction comvines two carbonyl compounds to form a new B-hydroxy carbonyl compound. These products are known as aldols, from the aldehyde + alcohol, a structural motif seen in many of the products. Aldol structural units are found in many important molecules, whether naturally occuring or synthetic. For example, the aldol reaction has been used in the large-scale production of the commodity chemical penaerythritol and the synthesis of the heart disease drug Lipitor. The aldol reaction unites two relatively simple molecules into a more complex one. Increased complexity arises because up to two new stereogenic centers are formed. Modern methodology is capable of not only allowing aldol reactions to proceed in high yield but also controlling both the relative and absolute configuration of these stereocenters. This ability to selectively synthesize a particular stereoisomer is significant because different stereoisomers can have very different chemical and biological properties. For example, stereogenic aldol units are espcially common in polyketides, a class of molecules found in biological organisms. In nature, polyketides are synthesized by enzymes that effect iterative Claisen condensations. The 1,3-dicarbonyl products of these reactions can then be variously derivatized to produce a wide variety of interesting structures. Often, such derivitization involves the reduction of one of the carbonyl groups, producing the aldol subunit. Some of these structures have potent biological properties: the immunosuprresant FK506, the anti-tumor agent discodermolide, or the antifungal agent amphotericin B, for example. Although the synthesis of many such compounds was once considered nearly impossible, aldol methodology has allowed their efficient synthesis in many cases. A typical modern aldol addition reaction, might involve the nucleophilic addition of a ketone enolate to an aldehyde. Once formed, the aldol product can sometimes lose a molecule of water to form an a, B-unsaturated carbonyl compound.
During the halogenation reactions of 1-butanol, 2-butanol, and 2-methyl-2-propanol, there is a formation of water from the OH atom of the alcohol, and the H atom from the HCl solution. The OH bond of the alcohol is then substituted with the Cl atom. Therefore all of the degrees of alcohol undergo halogenation reactions, and form alkyl halides as products. This is because the functional group of alkyl halides is a carbon-halogen bond. A common halogen is chlorine, as used in this experiment.
A reaction of the Grignard reagent and carbon dioxide results in an acid, and reaction of a nitrile and a Grignard reagent produce a carbonyl via an imine intermediate. These are show below, respectively.
The synthesis of the alkyl halide n-Butyl Bromide from alcohol is the foundation for the experiment. During the isolation of the n-butyl bromide, the crude product is washed with sulfuric acid, water, and sodium bicarbonate to remove any remaining acid or n-butyl alcohol. The primary alkyl halide halide n-butyl bromide is prepared by allowing n-butyl alcohol to react with sodium bromide and sulfuric acid. The sodium bromide reacts with sulfuric acid to produce hydrobromic acid . Excess sulfuric acid acts to shift the equilibrium and speed up the reaction by producing a higher concentration of hydrobromic acid. The
A chemical reaction is when substances (reactants) change into other substances (products). The five general types of chemical reactions are synthesis (also known as direct combination), decomposition, single replacement (also known as single displacement), double replacement (also known as double displacement), and combustion. In this lab, the five general types of chemical reactions were conducted and observations were taken before, during, and after the reaction. Then the reactants and observations were used to determine the products to form a balanced chemical equation. The purpose of this lab was to learn and answer the question: How can observations be used to determine the identity of substances produced in a chemical reaction?
The Diels-Alder reaction was discovered and named after the Nobel Prize winning scientists Kurt Alder and Otto Diels in 1928. Such a reaction occurs when a diene with two adjacent double bonds is mixed with a dienophile consisting of a double bond in order to create a cyclohexene. The diene must be in the s-cis conformation in order for the electron transfer to engage correctly. If the diene in question is in s-trans conformation then the access to the molecules is limited, thus, no reaction can occur. The dienophile we used was maleic anhydride. Maleic anhydride possesses high electron withdrawing characteristics which caused a very quick reaction. The reaction will
In the Cannizaro reaction an aldehyde is simultaneously reduced into its primary alcohol form and also oxidized into it 's carboxylic acid form. The purpose of this experiment is to isolate, purify and identify compounds 1 and 2 which contain 4-chlorobenzaldehyde, methanol, and aqueous potassium hydroxide. Compounds 1 and 2 are purified by crystallization. . The purified product will be characterized by IR spectroscopy and melting point.
Abstract: Using hypochlorous acid to convert secondary alcohol called cyclododecanol to the corresponding ketone which is cyclododecanone by oxidation.
Purpose: The purpose of this experiment is to observe a variety of chemical reactions and to identify patterns in the conversion of reactants into products.
The goals in this lab were to have a reaction occur with 4-methylcyclohexanol and an acid catalyst to form our product of 4-methylcyclohexene via an E1 reaction. This reaction is accomplished by removing the –OH group on 4-methylcyclohexanol via dehydration and to have a double bond form via a loss of a hydrogen on a β-Carbon.
1. Purpose: to clarify the mechanism for the cycloaddition reaction between benzonitrile oxide and an alkene, and to test the regiochemistry of the reaction between benzonitrile oxide and styrene.
The Grignard reaction is an important synthetic process by which a new carbon to carbon bond is formed. Magnesium metal is first reacted with an organic halide forming the Grignard reagent. The Grignard reaction is the addition of an organomagnesium halide (Grignard reagent) to a ketone or aldehyde, to form a tertiary or secondary alcohol, respectively. For example, the reaction with formaldehyde leads to a primary alcohol. Grignard Reagents are also used in the following important reactions: The addition of an excess of a Grignard reagent to an ester or lactone gives a tertiary alcohol in which two alkyl groups are the same, and the addition of a
Within the field of Organic chemistry the Diels-Alder reaction is a method to create six membered rings by reacting a s-cis-diene with an alkene. The reaction occurs using the pi electrons present from the diene (4 pi electrons) and the alkene (2 pi electrons) to create a six membered ring in a concerted (one step) mechanism. This reaction is stereospecific, creating the endo product when the diene is part of a ring and the alkene has a cis configuration. When the diene is not part of a ring the product maintains the stereochemistry of the reactants. The particular reaction done in the lab reacted butadiene sulfone and maleic anhydride to create 4-cyclohexene-cis-1,2-dicarboxcylic acid. Since the reactant Butadiene sulfone is a gas at room temperature it was first reacted with heat to create 1,3-butadiene (a solid cis diene), which was then reacted with maleic anhydride to give the product. The resulting product was identified using IR as the reactants have no sp3-hybridized carbons and the product has four sp3 carbons. The product was also assessed for purity using melting point.
In this preparative lab, an aldol (trans-p-anisalacetophenone) was produced from the reaction between p-anisaldehyde and acetophenone with the presence sodium hydroxide. The reaction also showed the importance of an enolate and the role it played in the mechanism. Sodium hydroxide acts as a catalyst in this experiment and is chosen because of its basic conditions and pH. The acetophenone carries an alpha hydrogen that has a pKa between 18 and 20. This alpha hydrogen is acidic because of its location near the carbonyl on acetophenone. When the sodium hydroxide is added, it deprotonates the hydrogen and creates an enolate ion. This deprotonation creates a nucleophilic carbon that can attack an electrophilic carbon (like a parent
Enzymes are central to every biochemical process. Due to their high specificity they are capable of catalyzing hundreds of reactions that signifies their vast practical importance.
In this experiment, benzopinacol was to be synthesized through photochemical reaction and its acid-catalyzed rearrangement product benzopinacolone.