Chapter 11: Bonding and Molecular Structure: Carbon – More Than Just Another Element Chapter 11 Problem Set Pages 531-535 2, 3, 4, 5, 6, 7, 11, 12, 13 11.1 THE UNIQUENESS OF CARBON Why is carbon so unique? What is kinetic stability? The Diversity of Bonds Formed by Carbon Carbon forms four bonds: 4 single bonds 2 single and 1 double bond 2 double bonds 1 triple bond and 1 single bond When carbon forms four single bonds, it has a tetrahedral structure. When carbon atoms form a double bond, there is the possibility of forming cis and trans isomers. The diversity of carbon is illustrated by the allotropes of carbon. Stability of Carbon Compounds The Importance of Bond Dissociation Energy (refer to Chap 9 sec 5) The C-C bond energies are quite strong. Compare some carbon bond energies with those of silicon. Kinetic Stability of Carbon Compounds What is kinetic stability? An example of kinetic stability is the fact that ethylene doesn't undergo spontaneous polymerization. 1 11.2 HYDROCARBONS What are hydrocarbons? Alkanes What is the general formula for alkanes? Alkanes, which have more than three carbon atoms, can form structural isomers. For example, consider the two structural isomers for C4H10 Each alkane is a framework of tetrahedral carbon atoms, and each carbon atom must have four single bonds. EXAMPLE 11.1 Page 489 Drawing Structural Isomers of Alkanes Draw structures of the five isomers of C6H14.Using Appendix E, name each of the structures. 2 EXERCISE 11.1 Page 487 Drawing Structural Isomers of Alkanes Draw and name the 9 isomers having the formula C7H16 Hint: one heptane, two hexanes, five pentanes, one butane Cycloalkanes, CnH2n Cyclohexane has two less hydrogen atoms that hexane. The six carbon atoms in cyclohexane do not lie in a plane. Properties of Alkanes What are some common alkanes? Small alkanes are gases 3 11.3 ALKENES AND ALKYNES What is stereoisomerism? One form of stereoisomerism is geometric isomerism. EXERCISE 11.2 Page 495 Drawing Structural Isomers of Alkenes From a Formula There are 17 possible isomers with the formula C6H12. Draw structures for the five isomers in which the longest chain has six carbons. Properties of Alkenes and Alkynes Addition Reactions of Alkenes and Alkynes EXERCISE 11.3 Page 497 Reactions of Alkenes 1. Draw the structure of the compound obtained from the reaction of HBr with ethylene 2. Draw the structure for the compound that comes from the reaction of Br2 with cis—2-butene. Give a reasonable name for the structure. 4 What are unsaturated compounds? Aromatic Compounds Benzene is a key molecule in chemistry. A source of many aromatic compounds in coal tar The Structure of Benzene It is an unsaturated compound. Substitution Reactions of Aromatic Compounds It is possible to substitute a halogen atom, a nitro group, or an alkyl or other hydrocarbon group for one or more hydrogen atoms of benzene. Difference between substitution and addition EXERCISE 11.4 Page 500 Isomers of Substituted Benzenes Draw a structure for the compound p-dichlorobenzene – one of the 2 aromatic compounds used in moth balls. Properties of Aromatic Compounds Benzene molecules have unusual stability that is associated with the unique pi bonding in molecules. The extra stability is termed resonance stabilization. 11.4 ALCOHOLS AND AMINES What is a functional group? 5 Alcohols What is an alcohol functional group? What are some uses of methanol? How is industrial ethanol made? EXERCISE 11.5 Page 505 Structural Isomers of Alcohols Draw the structures and name the 4 isomers with the formula C4H9OH. (two have framework of butane and two are derived from 2-methyl-propane.) Properties of Alcohols Account for the fact that methane is essentially insoluble in water, whereas methanol is completely miscible with water. What is an ether? 6 Amines What are primary, secondary, and tertiary amines? Properties of Amines The smallest amines are water-soluble. All amines are bases. 11.5 COMPOUNDS WITH A CARBONYL GROUP The C = O group is called the carbonyl group aldehydes, ketones, and carboxylic acids are oxidation products of alcohols The oxidation of primary alcohols yields an aldehyde The oxidation of secondary alcohols yields a ketone Aldehydes and Ketones Aldehydes and ketones have pleasant odors and are often used as the basis for fragtances. For example benzaldehyde is responsible for odor in cherries and almonds SEE Table 11.9 7 EXERCISE 11.6 Page 512 Aldehydes and Ketones Draw structural formulas for 2-pentanone. Draw structures for a ketone and two aldehydes that are isomers of 2-pentanone, and name each of these compounds. EXERCISE 11.7 Page 512 Aldehydes and Ketones Draw structures and name the aldehyde or ketone that is formed upon oxidation of the following alcohols: 1-butanol, 2-butanol, 2-methyl-1-propanol Are the 3 compounds isomers? Carboxylic Acids (Organic Acids) What is the most common organic acid? What are some naturally occurring organic acids? In an organic acid, what hydrogen atom is the acidic hydrogen? Esters What is esterification? hydrolysis 8 EXERCISE 11.8 Page 516 Esters Draw the structure and name the ester formed from each of the following reactions. 1. propanoic acid and methanol 2. butanoic acid and 1-butanol 3. hexanoic acid and ethanol Amides What is a structural formula of an amide? 11.6 FATS AND OILS Fats and Oils are triesters made from glycerol and long chain fatty acids. A fatty acid may be unsaturated, monounsaturated, polyunsaturated What is saponification? (soap making) 11.7 Synthetic Organic Polymers Classifying Polymers What is a polymer? What is a monomer? What is a thermoplastic? What is a thermosetting plastic? 9 Addition Polymers Polyethylene and Other Polyolefins The equation for the production of polyethylene can be represented by the Equation nH2C = CH2 (-CH2CH2-)n What is the difference between high density polyethylene and low density polyethylene? Polymers formed from substituted ethylenes have a range of properties and uses…. Natural and Synthetic Rubber Rubber is a naturally occurring polymer whose monomers are 2-methyl-1,3-butadiene (isoprene). What are elastomers? What are copolymers? Condensation Polymers What is a condensation reaction? Polyesters Consider the formation of polyethylene terephthalate… 10 Polyamides What is Nylon-6,6? New Polymer Materials What are composites? Proteins, Natural Polymers What is a peptide bond? What are polypeptides? What is a primary structure of a protein? 11