Chemistry part 17, Julia Burdge,2e (2009) pps

396 CHAPTER 10 Organic Chemistry The number 66 refers to the fad that there are six C atoms in each monomer. Other nylons, such as nylon 610, are made from various combinations of molecu l es similar to adipic ac id and h examethylenediamine. 6. Each step lengthens the chain of carbon atoms and results in the formation of a new radical , continuing the propagation of the reaction. Reactions such as this are known as chain reactions. They continue until the system runs out of ethylene molecules or until the radical species encounter s another radical species resulting in termination of the reaction. H H ~ / R' C=C / \ H H Initiation step H H I I +. R-C-C' I I H H H H H H I I ___ \ r. / R-C-C / C ,( 'C H H H H I I I I +. R-C-C-C-C' I I / \ H H H H I I I I H H H H Propagation steps H H H H H H H H I I I I I I I 1 ,,- R C-C C-C' ·R I I ' ' • R C-C C-C-R I I I I I I H H H H H H H H n n Termination step Some familiar and important addition polymers are listed in Table lOA. Condensation Polymers Reactions in which two or more molecules become connected with the elimination of a small molecule, often water, are called condensation reactions (Figure 10.12). Condensation polymers form when molecules with two different functional groups combine, with the elimination of a small molecule, often water. Many condensation polymers are copolymers, meaning that they are made of two or more different monomers. . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The first synthetic fiber, nylon 66, is a condensation copolymer of two molecules: one with carboxy groups at each end (adipic acid) and one with amine groups at both ends (hexamethy lenediamine): H2N-(CH2)6-NH2 + HOOC-(CH2)4-COOH Hexamethylenediamine Adipic acid Condensation Further condensation reactions SECTION 10.6 Organic Polymers 397 Name Polytetrafluoroethylene (Teflon) Polyethylene Polypropylene Polyviny1chloride (PVC) Polystyrene o Monomer Unit o Structure F F \ / C~ C / \ F F H H \ / C ~ C / \ n H Hn H H \/ C~ C / \ H CH3 H H \ / C~ C / \ H CI n n II ~ . R-C-OH + HO-R •• •• II +. R-C-Q-R + H 2 0 (a) ~ R-OH + HO-R • • • •• (b) Uses Nonstick coatings Plastic bags, bottles, toys Carpeting, bottles Water pipes, garden hoses, plastic wrap Packing material, insulation, furniture Nylon was first made by Wallace Carothers 2 at DuPont in 1931. The versatility of nylons is so great that the annual production of nylons and related substances now amounts to several billion pounds. Biological Polymers Naturally occurring polymer s include proteins, polysaccharides, and nucleic acids. Proteins, polymers of amino acids, play an important role in nearly all biological processes. The human body contains an estimated 100,000 different kinds of proteins, each of which has a specific physiological function. An amino acid has both the carboxylic acid functional group and the amino functional group. Amino acids are joined together into chains when a condensation reaction occurs between a carboxy group on one molecule and an amino group on another molecule (Figure 10.13). 2. Wallace H. Caro th ers (1896 1937). American chemis t. Be sides its enomlOUS commercial success. Carothers's work on nylon is ranked with that of Staudinger in clearly elucidating macromolecular structure and properties. Depressed by the death of his sister and wrongly believing that his life's work had been a failure, Carothers committed suicide at the age of 41 . Figure 10.12 (a) Condensation reaction between an alcohol and a carboxy lie acid to form an ester. (b) Condensation of two alcohol molecules in the presence of sulfuric acid to form an ether. 398 CHAPTER 10 Organic Chemistry Figure 10.13 Formation of a peptide bond with elimination of wate r. Figure 10.14 The 20 amino acids essential to living organisms. The shaded area represents the R group. H 0 + I II H N-C - C -O - 3 I R j Name Alanine Arginine Asparag in e Aspartic acid Cysteine Glutamic acid Glutamine Gl yc in e Histidine Isoleucine H 0 I II + +H N- C -C-O- 3 I R2 Abbreviation Ala Arg Asn Asp C ys • Glu GIn Gly His Ile • • H 0 H 0 I II I II +H N -C-C-N-C-C-O- 3 I I I R\ H R2 Peptide bond Structure H I H C-C-COO - 3 I NHt H H I I H 2 N -C- N -CH 2 -CH 2 -CH o -C-COO- II - I NH NHt o H II I H N-C -CH -C-COO- 2 2 I NHt H I HOOC-CH 2 -C-COO - I H I NH+ 3 HS-CH -C-COO - 2 I NH+ 3 H I HOOC-CH 2 -CH 2 -C -COO- I NH+ 3 o H II I H 2 N -C-CH 2 -CH 2 -cr -COO - NHt H I H-C-COO- I NHt H I HC=C-CH 2 -C-COO- / \ ~W N~ /NH 3 C H CH3H I I H C-CH -C-C-COO - 3 2 I I H NHt SECTION 10.6 Organic Polymers 399 Name Abbreviation Leucine Leu Ly sine L ys Methionine Met Phenylalanine Phe Proline Pro Serine Ser Threonine Thr - Tryptophan Trp Tyrosine Tyr Valine V al Structure H 3C H . \ I CH- CH -C-COO- / Z I H3C NHj H I H 2N -CH Z -CH Z -CH Z -CH Z -r-COO- NHj I ~ H I H C-S-CH -CH - C- C OO- 3 2 Z I /' ~ NH+ 3 /, ~:::::' " If < )-CH , - C - C OO - \'- - I /. L C::::::::' ./ NHt H I HO-CH , -C-COO- - I NH + 3 OH H I I H 3 C- C I - C- COO- I , H NH i H I C -CH II Z C- COO- I / CH NH + 3 N H H /' " I HO-< >-CH?- C- C OO- - I ,,- ./ NH t I I 1- r: Ie I" ~- I , The bonds that form between amino acids are called peptide bonds. Very long chains of amino acids assembled in this way are called protein s, while shorter chains are called polypeptides. Amino acids consist of a central carbon atom bonded to four different groups: an amino group, a carboxy group, a hydrogen atom, and an additional group (highlighted in Figure 10.14) consisting of carbon, hydrogen, and sometimes other elements such as nitrogen or sulfur. Proteins Peptide bonds are al so calle d amide bonds or amide linka ges be ca use they conta in the am i de functional group. 400 CHAPTER 10 Organic Chemistry _ Multimedia Organic and Biochemistry-mo lecular structure in D NA. • are made essentially from the 20 different amino acids shown in Figure 10.14. The identity of a protein depends on which of the 20 amino acids it contains and on the order in which the amino acids are assembled. Polysaccharides are polymers of sugars such as glucose and fructose. Starch and cellulose are two polymers of glucose with slightly different linkages and very different properties. In starch, glucose molecules are connected by what biochemists call ~ linkages. This enables ani- mals, including humans, to digest the starch in such foods as corn, wheat, potatoes, and rice. Starch In cellulose, the glucose molecules are connected by ex linkages. Digestion of cellulose requires enzymes that most animals do not have. Species that do digest cellulose, such as termites and ruminants (including cattle, sheep, and llamas), do so with the help of enzyme-producing symbi- otic bacteria in the gut. CH 2 0 I OH Cellulose OH I CH20 o HO~~ :V OH Nucleic acids, which are polymers of nucleotides, play an important role in protein syn- thesis. There are two types of nucleic acids: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Each nucleotide in a nucleic acid consists of a purine or pyrimidine base, a furanose sugar (deoxyribose for DNA; ribose for RNA), and a phosphate group. Figure 10.15 shows the building blocks of DNA and RNA. The components of a nucleotide are linked together as shown in Figure 10.16. These molecules are among the largest known-they can have molar masses of up to tens of billions of grams. RNA molecules, on the other hand, typically have molar masses on the order . . of tens of thousands of grams. Despite their sizes, the composition of nucleic acids is relatively simple compared with proteins. Proteins consist of up to 20 different amino acids, whereas DNA and RNA consist of only four different nucleotides each . Found only in DNA Fonnd in both DNA and RNA N '" Q.l H-{ = '"' = N ~ I H 0 til H3 C / H Q.l = N NAo '1:l S H '"' t: I H Thymine OH o H OH H Oeox yriho se NH2 N N H-{ NAH N I Adenine H H H NH2 N / H NAo I H Cytosine o II -O - P-o - I 0 - Ph osphate Figure 10.15 The components of the nucleic acids DNA and RNA. 0- I 0=P-0 -+ -CH 2 I 0 0 - Pho s phate unit H ( / ~N N ) Adenine unit H OH H Deoxyrib ose unit Figure 10.16 Structure of a nucleotide, one of the repeating units in DNA. 0 N /H A N NH2 Guanine SECTION 10.6 Organic Po lymers 401 Fonnd only in RNA 0 H /H N H NAo I H Uracil OH o H H OH OH Ribo se , 402 CHAPTER 10 Organic Chemistry Applying What You've Learned Although it was approved by the FDA in 1998, thalidomide is th e most regulated pre- scription drug in history, because it is known to harm developing fetuses. The drug's manufacturer, Celgene Corporation, has developed the System for Thalidomide Edu- cation and Prescribing Safety (STEPS) program. In order for physicians to prescribe thalidomide to their patients, they must be registered in the STEPS program. Female patients must have a negative pregnancy test within 24 hours of beginning treatment and must undergo periodic pregnancy testing throughout treatment. Both female and male patients must comply with mandatory contraceptive measures, patient registration, and patient surveys. Moreover, new patients must view an informational video in which a thalidomide victim explains the potential dangers of the drug. Problems: a) From the structures given at the beginning of the chapter, identify the functional groups in thalidomide. [ ~ Sample Problem 10.2] b) Write molecular formulas for thalidomide, lenalidomide, and CC-4047. [ ~~ Sample Problem 10.3] c) Thalidomide is converted to the drug CC-4047 by substitution of an amino group for one of the H atoms on the aromatic portion of the molecule. Using curved ar- rows, draw the mechanism for this reaction and all the resonance structures for the carbocation intermediate. [ ~~ Sample Problem 10.7] CHAPTER SUMMARY Section 10.1 o Organic chemistry is the study of carbon-based substances. Although it was once thought that organic compounds could only be produced by nature, thousands of new organic compounds are now synthesized each year by scientists. o Carbon's position in the periodic table makes it uniquely able to fOlm long, stable chains -a process called catenation. o Aromatic compounds contain one or more benzene rings. Aliphatic compounds are organic compounds that do not contain benzene rings. Section 10.2 o Alkyl groups consist of just carbon and hydrogen. They are derived from the corresponding alkane by removing one hydrogen atom and are represented generically in the formulas of organic compounds with the letter R. o Functional groups are specific arrangements of atoms that are responsible for the properties and reactivity of organic compounds. Common functional groups and their formulas include Alcohol ROH Carboxylic acid RCOOH Aldehyde RCHO Ketone RCOR' Ester RCOOR' Amine RNH RNHR ' or RNR 'R" 2, , Amide RCONH 2 , RCONHR ', or RCONR'R" o Many organic compounds contain more than one functional group. A substituent in an alkane is a group other than hydrogen that is bonded to the carbon chain. o An amino acid contains both the carboxy group and the amino group. Section 10.3 o Condensed structural formulas or condensed structures abbreviate a series of repeating units, such as -CH 2 CH 2 CH 2 CH 2 -, into a more compact form, such as - (CH 2 )4 - . Kekule structures are similar to Lewis structures but do not show the lone pairs on a molecule. Skeletal structures use straight lines to represent C-C bonds. The y typically do not show the C atoms explicitly except for the purpose of emphasizing a particular functional group. H atoms are not shown in skeletal structures-again, except to emphasize a functional group. The number of H atoms bonded to a C atom must be infen'ed from the number ofC-C bonds in the structure. Heteroatoms, atoms other than C and H, are always shown explicitly in a skeletal structure. Section 10.4 o Constitutional isomers are molecules in which the same atoms are connected differently. Stereo isomers are molecules in which the same atoms are connected by the same bonds but the bonds are oriented differently. Geometrical isomers arise due to restricted rotation about a carbon-carbon double bond. Cis and trans isomers are geometrical . Isomers. CHAPTER SUMMARY 403 o Molecules that are nonsuperimposable mirror images of each other are optical isomers. They are also refen'ed to as chiral, and each of the mirror images is called an enantiomer. Optical isomers are so called because they rotate the plane of plane-polarized light. The degree of rotation is the same for both enantiomers, but the directions of rotation are opposite each other. An equal mixture of both enantiomers is called a racemic mixture. A racemic mixture does not rotate the plane of plane-polarized light. Section 10.5 o An electrophile generally is a positively charged ion that is attracted to electrons. A nUcleophile is a negatively charged ion or a partially negatively charged atom in a polar molecule. Nucleophiles and electrophiles are attracted to each other. o A carbocation is an intermediate species in which one of the carbon atoms is surrounded by only six electrons and bears a positive charge. o o 0 0 Electrophilic addition reactions and nucleophilic addition reactions involve the addition of a molecule or an ion to another molecule. Substitution reactions occur when an electrophile replaces a hydrogen on an aromatic ring or when a nucleophile replaces a leaving group on a carbon atom. Carbocations are the intermediate species in racemization, a nucleophilic substitution reaction in which a single enantiomer is converted into a racemic mixture. An elimination reaction is one in which a double bond forms and a small molecule, such as water, is eliminated. • o Hydration is the addition of a water molecule across a double bond. o Isomerization reactions convert one isomer into another. Section 10.6 o Polymers are long chains of repeating molecular units called monomers. Polysaccharides are polymers of sugars. Addition polymers form when a radical species attacks a double bond, forming a ne w, longer radical species that attacks another double bond, and so on. o An elimination reaction that joins two molecules is a condensation reaction. Condensation polymers form when molecules with two different functional groups undergo a condensation reaction. o Copolymers are polymers that contain more than one type of monomer. o Proteins and polypeptides are biological polymers in which the monomers are amino acids. Amino acids are joined by peptide bonds, which result from the condensation reaction between the amino group of one amino acid and the carboxyl group of another amino acid. o Nucleic acids are polymers of nucleotides. The two types of nucleic acid are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Each nucleotide in a nucleic acid consists of a purine or pyrimidine base, a furanose sugar (deoxyribose for DNA; ribose for RNA), and a phosphate group linked together . 404 CHAPTER 10 Organic Chemistry I(EY WORDS Addition polym er, 395 Alcohol, 370 Aldehyde, 370 Aliphatic, 365 Alkyl group, 367 Amide, 370 Amine, 370 Amino acid, 370 Aromatic, 365 Carbocation, 387 Carboxylic acid, 370 Catenation, 365 Chiral, 383 Cis, 382 Condensation polymer, 396 Condensation reaction, 396 Ge ometr ical isomer, 382 Heter oatom, 377 Hydration, 391 Condensed structural formula, 376 Isomerization reaction, 394 Condensed structure, 376 Kekule structure, 376 Constitutional i some rism, 382 Ketone, 370 Copolymer, 396 Monomer, 395 Deox yribonucleic acid (DNA), 400 Nucleic acid, 400 Electrophile, 386 Nucleophile, 386 Electrophilic addition, 387 Nucleophilic addition, 388 Elimination reaction, 394 Nucleotide, 400 Enantiomer, 383 Ester, 370 Optical isomers, 383 Peptide bond, 399 QUESTIONS AND PROBLEMS Section 10.1: Why Carbon Is Different Review Questions 10.1 ===== o II (d) H-C-OH (e) CH 3 -CH 2 CH 2 -OH Polymer, 395 Polypeptide, 399 Poly sa ccharides, 400 Protein, 397 Ra ce mic mixture, 384 Racemization, 391 Ribonucleic acid (RNA), 400 Skeletal structure, 376 Stereoisomers, 382 Sub st ituent, 368 Substitution reaction, 388 Trans, 382 Explain why carbon is able to form so many more compounds than any other element. 10.2 Why was Wohler's synthesis of urea so imp ortant for the development of organic chemistry? 10.8 Draw structures for molecules with the following formula s: (a) CH 4 0 10.3 What are aromat ic organic compounds? What are aliphatic organic compounds? Section 10.2: Classes of Organic Compounds Review Questions lOA What are functional groups? Why is it logical and useful to classify organic compounds according to their functional groups? 10.5 Draw the Lewis structure for each of the following functional groups: alcohol, aldehyde, ketone, carboxylic acid, amine. 10.6 Name the classes to which the following compounds belong: (a) C 4 H 9 0H (b) C 2 H s CHO (c) C 6 H s COOH (d) CH 3 NH2 Problems 10.7 Classify each of the following molecules as alcohol, aldehyde, ketone, carboxylic acid, or amine: (a) CH 3 -CH 2 -NH 2 o II (b) CH 3 -CH 2 -C \ H (c) CH 3 - C-CH2-CH 3 II o (b) C 2 H 6 0 (c) C 3 H 6 0 2 (d) C 3 H s O 10.9 Name each of the following compounds: (a) 10.10 Name each of the following compounds: (a) NH ? o 10.11 Give the name of the alkane represented by the model shown. 10.12 The molecular formula corresponding to the model is C s H 9 Cl0 2 . What is the name of the compound? 10.13 Write structural formulas for each of the following based on their systematic names. The names quoted in parentheses are so-called common names. Common names are not systematic and are more difficult, sometimes impossible, to connect with a unique structure. (a) 2,2,4-Trimethylpentane ("isooctane") (b) 3-Methyl-1-butanol ("isoamyl alcohol") (c) Hexanamide ("caproarnide") (d) 2,2,2-Trichloroethanal ("chlora l" ) 10.14 Write structural formulas for each of the following: (a) 3,3-Dimethyl-2-butanone ("pinacolone") 10.15 10.16 (b) 3-Hydroxybutanal ("acetaldol") (c) Ethyl penta no ate ("ethyl va lerate") (d) 6-Methy 1- 2-heptanarnine ("isoocty larnine") Classify the oxygen-containing groups in the plant hormone abscisic acid. a OH Identify the functional groups in the antipsychotic drug haloperidol. F < 10.17 PABA was the active UV-absorbing compound in earlier versions of sunblock creams. What functional groups are present in PABA? QUESTIONS AND PROBLEMS 405 10.18 Lidocaine (C'4H22N20) is a widely us ed local anesthetic. Classify its nitrogen-containing functional groups. Section 10.3: Representing Organic Molecules Problems 10.19 Write structural formulas for the following organic compounds: (a) 3-methylhexane, (b) 2,3-dimethylpentane, (c) 2-bromo-4-phenylpentane, (d) 3,4,S-trimethyloctane. 10.20 Write structural formulas for the following compounds: (a) 1, 1,3-trichloro-2-propanol, (b) 3-methyl-3-pentanamine, (c) 3-bromo-l-chloro-2-butanone, (d) propyl-4-bromobutanoate. 10.21 (a) Convert CH3(CH2)4C(O)CH2C02H to a Kekule structure and to a skeletal (line) structure. 10.22 (b) Convert the following to a condensed structure and to a skeletal (line) structure: o CH 3 II I CH 3 CH 2 CHCH 2 COCCH 3 I I CH 3 CH 2 CH 3 (c) Convert the following to a condensed structure and to a KekuIe structure: H I N ( a) Convert (CH3 )2C =CHC02H to a Kekule structure and to a skeletal (line) structure. (b) Convert the following to a condensed structure and to a skeletal (line) structure: CH 3 CH 2 NCH 2 CH 3 I CH 3 (c) Convert the skeletal structure of the general anesthetic isofiurane to a condensed structure and to a Kekule structure: F F [...]... the entire volume of its container 2 Gases are compressible Unlike a solid or a liquid, a gas consists of particles with relatively large distances between them; that is, the distance between any two particles in a gas is much larger than the size of a molecule or atom Because gas particles are far apart, it is possible to move them closer together by confining them to a smaller volume 3 The densities... volume of its container Like a liquid, a gas consists of particles (molecules or atoms) that do not have fixed positions in the sample [ ~~ Section 1.2] As a result, both liquids and gases are able to flow (Recall from Chapter 1 that we refer to liquids and gases collectively as fluids ) While a sample of liquid will assume the shape of the part of its container that it occupies, a sample of gas will... Gaseous Reactant Determining the Amount of Reactant Consumed Using Change in Pressure Predicting the Volume of a Gaseous Product Gas Mixtures • • • 11.6 • • • 11.7 • • Dalton's Law of Partial Pressures Mole Fractions Using Partial Pressures to Solve Problems The Kinetic Molecular Theory of Gases Application to the Gas Laws Molecular Speed Diffusion and Effusion Deviation from Ideal Behavior Factors That... 1.3] , 4 Gasesform homogeneous mixtures (solutions) with one another in any proportion Some liquids (e.g., oil and water) do not mix with one another Gases, on the other hand, because their particles are so far apart, do not interact with one another to any significant degree unless a chemical reaction takes place between them This allows molecules of different gases to mix uniformly That is, gases... pressure that are more commonly used, Table 11.2 lists the units in which pressure is most commonly expressed in chemistry and their definitions in terms of pascals Which of these units you encounter most often will depend on your specific field of study Use of atmospheres (atm) is common in chemistry, although use of the bar is becoming increasingly common Use of millimeters mercury (mmHg) is common... species being oxidized and the species being reduced 10.74 Draw the structures of the dipeptides that can be formed from the reaction between the amino acids glycine and lysine 410 10.76 CHAPTER 10 Organic Chemistry From the C 4H 9 alkyl groups in Problem 10.77, find the ones that cOlTespond to "R" among the amino acids listed in Figure 10.14 Match the name of the amino acid with the name of the group From... Anion (b) Which of these species is the most nucleophilic? Which is the most electrophilic? (c) Predict which species reacts with water to give HC(CH 3h (d) Write a chemical equation for the reaction in part (c), and use curved alTOWS to show the flow of electrons (HOh P(0)OCH 2 0 10.83 o In each of the following pairs, specify whether the two structural formulas represent constitutional isomers, ... branching on the relative potential energies and stabilities of these isomers? (b) Assume this effect is general to predict which one of the 18 C 8H I8 isomers should be the most stable 412 10.94 Organic Chemistry CHAPTER 10 Carbon dioxide reacts with sodium hydroxide according to the following equation: (c) The overall reaction is the result of two separate reactions - H-O: •• Reaction I: 'tj' + :o=C=o:... flow of electrons in reaction II (c) Classify reaction I as electrophilic addition, nucleophilic addition, electrophilic substitution, or acid-base (d) Classify reaction II according to the choices in part (c) 10.95 10.96 The combustion of 20.63 mg of compound Y, which contains only C, H, and 0, with excess oxygen gave 57.94 mg of CO 2 and 11.85 mg of H 2 0 (a) Calculate how many milligrams of C, H,... ,, CI H CI H CI CI H H CI 10.102 Nylon was designed to be a synthetic silk (a) The average molar mass of a batch of nylon 66 is 12,000 g/mol How many monomer units are there in this sample? (b) Which part of nylon's structure is similar to a polypeptide's structure? (c) How many different tripeptides (made up of three amino acids) can be formed from the amino acids alanine (Ala), glycine (Gly), and . they conta in the am i de functional group. 400 CHAPTER 10 Organic Chemistry _ Multimedia Organic and Biochemistry-mo lecular structure in D NA. • are made essentially from the. compounds shown, using wedges and dashes to show stereochemistry (a) (b) (c) "' ", (d) 408 CHAPTER 10 Organic Chemistry 10.48 Write the structural formulas of the alcohols. of a Gaseous Product 11.5 Gas Mixtures • Dalton's Law of Partial Pressures • Mole Fractions • Using Partial Pressures to Solve Problems 11.6 The Kinetic Molecular Theory