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UNIT 1: Organic Chemistry Chapter 1: Structure and Physical Properties of Organic Compounds Chapter 2: Reactions of Organic Compounds 2

Chapter 2: Reactions of Organic Compounds UNIT 1 Chapter 2: Reactions of Organic Compounds Chapter 2: Reactions of Organic Compounds Chemical reactions of organic compounds have provided an abundance of products we rely on. However, the properties that make them so useful can also cause environmental problems. The Plastika sailboat was built from plastic bottles to raise awareness of plastic pollution in ocean ecosystems. TO PREVIOUS SLIDE

2.1 Types of Organic Reactions UNIT 1 Chapter 2: Reactions of Organic Compounds Section 2.1 2.1 Types of Organic Reactions Organic reactions can convert simple organic molecules into large, complex ones. TAXOL is an anti-cancer drug that chemists can synthesize. Important types of organic reactions: The material in this section is an overview of important organic reactions. For each type of reaction, students should be able to identify the type of reaction, given a chemical equation predict the products of a reaction, given the reactants identify the reactants, given the product(s) oxidation reduction combustion addition elimination substitution condensation esterification hydrolysis TO PREVIOUS SLIDE

Addition Reactions UNIT 1 Chapter 2: Reactions of Organic Compounds Section 2.1 Addition Reactions Reactions between an alkene or alkyne and a small molecule (HOH, H2, HX, X2) Atoms of a small molecule are added to carbons of a double or triple bond Reactions of alkynes can produce alkenes or alkanes Constitutional isomers may form The general formula for an addition reaction is shown in this slide. An alkene or alkyne reacts with a small molecule, typically H2O, H2, HX, or X2 (where X = F, Br, Cl, or I). For alkynes: bonds with three new atoms can form, leaving a single bond between the two carbon atoms if the amount of the small molecule is limited, an alkene is formed For asymmetric alkenes: more than one product might form (isomers are produced) if the two atoms or groups of atoms being added are different (e.g. HX, HOH), they can be placed on either of the two carbons involved in the double bond The following slide shows an example: pent-2-ene reacting with HCl(g) Carbon atoms of the multiple bond have more atoms bonded to them in the product. TO PREVIOUS SLIDE

Answer on the next slide UNIT 1 Chapter 2: Reactions of Organic Compounds Section 2.1 Learning Check Show how constitutional isomers can form from the following reaction. Answer on the next slide TO PREVIOUS SLIDE

UNIT 1 Chapter 2: Reactions of Organic Compounds Section 2.1 Learning Check The chlorine atoms can be added to either carbon 2 or 3 in this addition reaction. For this reaction, both 3-chloropentane and 2-chloropentane are produced. TO PREVIOUS SLIDE

Addition Reactions (cont’d) UNIT 1 Chapter 2: Reactions of Organic Compounds Section 2.1 Addition Reactions (cont’d) One constitutional isomer will predominate. To predict the major product: Markovnikov’s rule: The hydrogen atom of the small molecule will attach to the carbon atom of the double bond that is bonded to the most hydrogens. For reactions involving asymmetric alkenes and small molecules, there is one isomer that will be more abundant. Use Markovnikov’s rule to predict the more abundant isomer that will form: the hydrogen atom of the small molecule will attach to the carbon of the double bond that is already bonded to the most hydrogen atoms. The 2-chloropropane isomer will be the major product. TO PREVIOUS SLIDE

Elimination Reactions UNIT 1 Chapter 2: Reactions of Organic Compounds Section 2.1 Elimination Reactions Two atoms bonded to carbon atoms of an organic molecule are removed and a double bond forms The double bond forms between the carbon atoms that have had the atoms removed Elimination reaction can be thought of as the reverse of an addition reaction The general formula for an elimination reaction is shown in this slide. In this reaction, the organic reactant loses two atoms bonded to carbons and a double bond is formed between the two carbons that have lost those atoms. Alcohols undergo elimination reactions in the presence of a strong acid catalyst, such as sulfuric acid (H2SO4). An alkene and water are the products. Haloalkanes undergo elimination reactions when they are heated in the presence of a strong base, such as sodium ethoxide (NaOCH2CH3). An example is on the following slide. Carbons of the organic product are bonded to fewer atoms than carbons of the reactant. TO PREVIOUS SLIDE

Answer on the next slide UNIT 1 Chapter 2: Reactions of Organic Compounds Section 2.1 Learning Check Draw the product of the following elimination reaction. Answer on the next slide TO PREVIOUS SLIDE

Learning Check UNIT 1 The product formed is: Chapter 2: Reactions of Organic Compounds Section 2.1 Learning Check The product formed is: For this reaction, both 3-chloropentane and 2-chloropentane are produced. TO PREVIOUS SLIDE

Elimination Reactions (cont’d) UNIT 1 Chapter 2: Reactions of Organic Compounds Section 2.1 Elimination Reactions (cont’d) What if an asymmetric molecule undergoes elimination? When asymmetric molecules undergo elimination, there is also a general rule that is used to predict the major product. In the example shown, the hydrogen atom is most likely to be removed from the third carbon. Therefore, but-2-ene is the major product (i.e., it is produced in higher abundance). Note that both the cis and trans isomers are formed. Only the trans form is shown. The minor product is formed by the removal of the hydrogen from the first carbon. General rule: The hydrogen atom is more likely to be removed from the carbon atom with the most C-C bonds. TO PREVIOUS SLIDE

Substitution Reactions UNIT 1 Chapter 2: Reactions of Organic Compounds Section 2.1 Substitution Reactions Reaction in which a hydrogen or functional group has been replaced by another functional group Two compounds react to form two different compounds The same number of atoms are bonded to the carbon atoms of the reactants and products The general formula for a substitution reaction is shown in this slide. In this reaction, a hydrogen or functional group (e.g., –OH, -X) is replaced by a different functional group. Alcohols can react with an acid that contains a halogen (e.g. HCl). The –OH group of the alcohol is replaced by the halogen, producing a haloalkane. Haloalkanes can react with a hydroxide ion to produce an alcohol. Two compounds are converted to two new compounds. TO PREVIOUS SLIDE

Answer on the next slide UNIT 1 Chapter 2: Reactions of Organic Compounds Section 2.1 Learning Check Draw the products of the following substitution reaction. Answer on the next slide TO PREVIOUS SLIDE

Learning Check UNIT 1 The products formed are: Chapter 2: Reactions of Organic Compounds Section 2.1 Learning Check The products formed are: Since it is a substitution reaction of a haloalkane with hydroxide ion, an alcohol is the product. TO PREVIOUS SLIDE

Condensation Reactions UNIT 1 Chapter 2: Reactions of Organic Compounds Section 2.1 Condensation Reactions Two molecules combine to produce a larger organic molecule and another much smaller molecule Water is often the smaller molecule formed Large biomolecules (DNA, fats, carbohydrates, protein) are formed through this type of reaction Condensation reactions typically produce water, in addition to the large organic molecule. This is because these reactions usually involve loss of a –OH group from a carboxylic acid and a hydrogen atom from the second reactant molecule (such as an amine). The next two slides discuss reactions that are very important in biological systems. Condensation reactions and a certain type of condensation reaction, called esterification, are carried out by the cell to synthesize large, complex, biologically important molecules, such as proteins, lipids (fats), carbohydrates, and the genetic material, DNA and RNA. For the synthesis of these very large molecules, the reactions occur repeatedly, building up the molecule with the completion of each reaction. A condensation reaction between a carboxylic acid and an amine produces an amide. TO PREVIOUS SLIDE

Esterification Reactions UNIT 1 Chapter 2: Reactions of Organic Compounds Section 2.1 Esterification Reactions These are a type of condensation reaction A carboxylic acid and an alcohol react to produce an ester and water In what way(s) is an esterification reaction like a condensation reaction? Sample answer to question prompt: a carboxylic acid is one reactant the –OH group of the carboxylic acid becomes part of the second smaller product molecule two molecules combine to form a larger molecule and a much smaller molecule (in this case it is always water) An esterification reaction is between a carboxylic acid and an alcohol. TO PREVIOUS SLIDE

Hydrolysis Reactions UNIT 1 Chapter 2: Reactions of Organic Compounds Section 2.1 Hydrolysis Reactions A molecule is broken apart through the addition of a water molecule (HOH) The –OH is added to one side of a bond, and the H is added to the other side of the bond They are the reverse of condensation reactions The general formula for a hydrolysis reaction is shown in this slide. The term hydrolysis means “splitting apart using water.” This helps to remember that the reaction involves the breaking apart of an organic molecule by water, namely the –OH and –H groups of water. The hydrolysis reaction is the reverse of the condensation reaction (or esterification reaction). Therefore, an ester can undergo hydrolysis to produce a carboxylic acid and an alcohol. In hydrolysis reactions, molecules are broken apart using water as a reactant. TO PREVIOUS SLIDE

Answer on the next slide UNIT 1 Chapter 2: Reactions of Organic Compounds Section 2.1 Learning Check What are the products of the following reaction? Answer on the next slide TO PREVIOUS SLIDE

UNIT 1 Chapter 2: Reactions of Organic Compounds Section 2.1 Learning Check This is an esterification reaction. The products are: TO PREVIOUS SLIDE

Oxidation Reactions UNIT 1 Chapter 2: Reactions of Organic Compounds Section 2.1 Oxidation Reactions In organic chemistry, the term refers to carbon atoms of the organic reactant forming more bonds to oxygen atoms, or forming fewer bonds to hydrogen atoms Common oxidizing agents, [O], are KMnO4 and K2Cr2O7 Oxidation reactions are always accompanied by reduction reactions. Because of this, these reactions are often referred to as oxidation-reduction reactions. Typically, they are discussed in terms of the transfer of electrons. One reactant is oxidized through the loss of electrons and another reactant is reduced by the gain of electrons. This approach is taken in Unit 5. For this unit, only what is occurring to the organic reactant is considered. Therefore, oxidation and reduction reactions are dealt with separately. Also, oxidation and reduction are defined according to changes in the bonds to the carbons of the organic reactant. Organic compounds that have undergone oxidation can be recognized by an increase in the number of bonds to oxygen atoms or decrease in number of bonds to hydrogen atoms. Organic compounds become oxidized when they react with oxidizing agents, indicated by the symbol [O] Some oxidations of organic compounds may also be classified as elimination (e.g., ones that involve formation of C=O, such as the oxidation of alcohols to aldehydes or ketones). Compare the number of C-H and C-O bonds in the reactant and product. TO PREVIOUS SLIDE

Reduction Reactions UNIT 1 Chapter 2: Reactions of Organic Compounds Section 2.1 Reduction Reactions In organic chemistry, the term refers to carbon atoms of the organic reactant forming fewer bonds to oxygen atoms, or forming more bonds to hydrogen atoms Common reducing agents, [H], are LiAlH4 and H2/Pt Organic compounds that have undergone reduction can be recognized by a decrease in the number of bonds to oxygen atoms or increase in number of bonds to hydrogen atoms. Organic compounds become reduced when they react with reducing agents, indicated by the symbol [H] Often C=C and C=O are reduced to C-C and C-O. Therefore, some may be classified as an addition reaction Aldehydes, ketones, carboxylic acids can be reduced to alcohols Alkenes and alkynes can be reduced to alkanes Compare the number of C-H and C-O bonds in the reactant and product. TO PREVIOUS SLIDE

Combustion Reactions UNIT 1 Chapter 2: Reactions of Organic Compounds Section 2.1 Combustion Reactions A compound reacts with oxygen to produce oxides of the component elements The products of the complete combustion of a hydrocarbon are carbon dioxide and water If O2 is insufficient, incomplete combustion occurs Regardless of the hydrocarbon, complete combustion always results in production of carbon dioxide and water. If there is insufficient oxygen available, the incomplete combustion occurs and other products are produced, such as soot, indicated by C(s), and the highly toxic carbon monoxide gas. This occurs in situations such as the orange-yellow flame of a Bunsen burner or burning candle, as well as fuel-burning stoves and heaters when used indoors. TO PREVIOUS SLIDE

Answer on the next slide UNIT 1 Chapter 2: Reactions of Organic Compounds Section 2.1 Learning Check What is the product of the following reaction? + [H] Tips: 1. [H] is shown, which represents a reducing agent. Therefore, this is a reduction reaction. 2. Identify the type of organic compound being reduced. In this case, it is a ketone. 3. What type of organic compound is produced from the reduction of ketones? Alcohols. Therefore, the product must be the alcohol equivalent to the ketone, with the same number of carbon atoms as the ketone. Answer on the next slide TO PREVIOUS SLIDE

UNIT 1 Chapter 2: Reactions of Organic Compounds Section 2.1 Learning Check The reaction is a reduction of propanone (acetone) to produce propan-2-ol (isopropanol) TO PREVIOUS SLIDE

Section 2.1 Review UNIT 1 Chapter 2: Reactions of Organic Compounds TO PREVIOUS SLIDE

2.2 Polymer Equations UNIT 1 Chapter 2: Reactions of Organic Compounds Section 2.2 2.2 Polymer Equations Polymers are very large molecules of repeating monomers. Some are made of one type of monomer Some are made up two or more types of monomers Most are named based on the monomer(s) This polymer is made of two different monomers. Many polymers, such as the plastic that makes up soft drink bottles (polyethylene terephthalate, PET), contain thousands of monomers linked together. Therefore, these molecules are a much larger size than other compounds studied in this chapter. Plastics are polymers that can be heated and molded into specific shapes. The names of polymers is usually based on the name of the monomers it is composed of, with the prefix poly- included. Often, common names of the monomers are used, instead of IUPAC names. For example, the common name for ethene is ethylene. Polyethylene is a plastic used in products such shopping bags and food containers. Polyvinylchloride (PVC) is added to numerous products like adhesives and piping material. PVC is made of vinylchloride monomers (IUPAC: chloroethene). The production of synthetic polymers is a very important industrial process, for the numerous products and ones that other industries heavily rely on. As such, the manufacturing of many of these polymers has been patented and is highly protected by the companies involved. Natural polymers: cotton, wool, protein, DNA Synthetic polymers: plastics, polyester, nylon, rayon TO PREVIOUS SLIDE

Addition Polymerization UNIT 1 Chapter 2: Reactions of Organic Compounds Section 2.2 Addition Polymerization Synthetic polymers can be made using the addition reaction Alkene monomers are joined together through multiple addition reactions Synthetic polymers can be made using the addition reaction, which was discussed in the previous section. The term addition polymerization is used when discussing the synthesis of polymers. Alkene monomers are joined through multiple addition reactions to form the polymer molecule. Note that in the table on this slide, the “…” at each ends of the structures in the third column indicates that the monomers are repeated at both ends. TO PREVIOUS SLIDE

Condensation Polymerization UNIT 1 Chapter 2: Reactions of Organic Compounds Section 2.2 Condensation Polymerization Synthetic polymers can be made using the condensation reaction Monomers are joined together through multiple reactions between two different functional groups on different monomers polyamide Synthetic polymers can be made using the condensation reaction, which was discussed in the previous section. The term condensation polymerization is used when discussing the synthesis of polymers. Polymers that are formed from the reaction between a carboxyl group on one monomer and an alcohol group on another are called polyesters, since ester linkages between monomers are formed. One example of this type of synthetic polymer is polyethylene terephthalate (PET), which is used to make products such as soft drink bottles. Polymers that are formed from the reaction between a carboxyl group on one monomer and an amine group on another are called polyamides, since amide linkages between monomers are formed. Another name for them is nylons. One example of this type of synthetic polymer is polyparaphenylene terephthalamide, or Kevlar®, which is used in products such as bulletproof vests and the hulls of boats. polyester TO PREVIOUS SLIDE

Answer on the next slide UNIT 1 Chapter 2: Reactions of Organic Compounds Section 2.2 Learning Check Identify the monomer(s) of the polymer shown below. Answer on the next slide TO PREVIOUS SLIDE

Learning Check UNIT 1 The monomer is ethene, H2C=CH2 Chapter 2: Reactions of Organic Compounds Section 2.2 Learning Check The monomer is ethene, H2C=CH2 TO PREVIOUS SLIDE

Polymers and Industry UNIT 1 Chapter 2: Reactions of Organic Compounds Section 2.2 Polymers and Industry Many industrial productions of polymers start with petroleum (mix of hydrocarbons) Hydrocarbons of the petroleum are converted to petrochemicals for synthetic reactions (e.g., ethene and propene) The Manufacture of PVC Ethane is an example of an important petrochemical. Large-scale production of it is done by a process called cracking. Ethane from petroleum refineries is heated to 800°C in the presence of a platinum catalyst to produce ethene gas and hydrogen gas. The presence of the double bond makes ethene much more reactive than ethane. The ethene is used in other organic reactions to produce products such as ethylene glycol (used in antifreeze), polyethylene, and polyvinylchloride (PVC). ethene 1,2-dichloroethane vinyl chloride TO PREVIOUS SLIDE

Polymer Production: Risks and Solutions UNIT 1 Chapter 2: Reactions of Organic Compounds Section 2.2 Polymer Production: Risks and Solutions The manufacture of synthetic polymers has given us many useful and life-saving products, but synthetic polymers come with serious risks, such as Workers’ exposure to dangerous chemicals Leaching or release of dangerous chemicals Very slow degradation in the environment What are some possible solutions? Think about the different examples you have heard of or seen that are ways in which polymer waste can be re-used and converted to other useful products. The re-use of such materials is part of the “three R’s”, aimed at lowering the environmental impact: Reduce Re-use Recycle The development of bioplastics is another solution. Bioplastics are designed to degraded much more quickly than polymers made from petrochemicals. Fleece fabric can be produced from the plastic of soft drink bottles. TO PREVIOUS SLIDE

UNIT 1 Chapter 2: Reactions of Organic Compounds Section 2.2 Natural Polymers There are numerous examples of natural polymers, including ones that are essential for life Example of biologically important polymers are polysaccharides, proteins, and DNA polysaccharides contain sugar monomers include starch, cellulose Cellulose provides structure to plants. It is composed of glucose monomers. TO PREVIOUS SLIDE

Natural Polymers (cont’d) UNIT 1 Chapter 2: Reactions of Organic Compounds Section 2.2 Natural Polymers (cont’d) Proteins build muscle act as catalysts in cells (enzymes) Proteins are amide-linked polymers of amino acids. TO PREVIOUS SLIDE

Natural Polymers (cont’d) UNIT 1 Chapter 2: Reactions of Organic Compounds Section 2.2 Natural Polymers (cont’d) DNA genetic material DNA is composed of nucleotide monomers. TO PREVIOUS SLIDE

Answer on the next slide UNIT 1 Chapter 2: Reactions of Organic Compounds Section 2.2 Learning Check Explain why your genetic material (DNA) and soft drink bottle material (PET) are classified as the same type of molecule. Answer on the next slide TO PREVIOUS SLIDE

UNIT 1 Chapter 2: Reactions of Organic Compounds Section 2.2 Learning Check Both are polymers. Both are made of repeating units of monomers. TO PREVIOUS SLIDE

Section 2.2 Review UNIT 1 Chapter 2: Reactions of Organic Compounds TO PREVIOUS SLIDE