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Chapter 23: Organic Chemistry, Polymers, and Biochemicals

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1 Chapter 23: Organic Chemistry, Polymers, and Biochemicals
Chemistry: The Molecular Nature of Matter, 6E Jespersen/Brady/Hyslop

2 Carbon Chemistry Bonding
Strong covalent bonding to itself and to other non- metal elements Capable of forming extremely long carbon-carbon chains Multiple arrangements of identical molecular formulas lead to numerous isomers.

3 Structural Formula Representations
Lewis Structure of Pentane Condensed Structural Formula CH3CH2CH2CH2CH3 pentane

4 Structural Formula Representations
Lewis Structure of Pentan-1-ol Condensed Structural Formula CH3CH2CH2CH2CH2OH 1-pentanol

5 Chiral Isomers of Carbon
Chirality exists when carbon has four unique constituents bond to itself | Non-superimposable mirror images

6 Chiral Isomers of Butan-2-ol

7 Abbreviated or Bond-Line Structure
Carbon atoms occur at intersection but no symbol used CH3–CH2–CH3 would appear as: Non-carbon atoms would appear as symbols CH3–CH2–CH2–OH would appear as:

8 Abbreviated or Bond-Line Structure Open-Chain Compounds
Examples butane butane-1-ol

9 Abbreviated or Bond-Line Structure of Ring Compounds
Chair Form of Cylcohexane Cyclohexane Cyclopropane Benzene

10 Abbreviated or Bond-Line Structure Heterocyclic Compounds
Piperazine Pyridine Pyrazole Furan Tetrahydropyran

11 Learning Check 1. Draw at least two geometric isomers of C4H10 using abbreviated structures. 1. Draw the four carbon chain first 2. Now rearrange CH3 groups

12 Your Turn! When a chemical formula is written in the following form, CH3CH2CH2COOH, the representation is known as an abbreviated structure a Lewis dot structure a condensed formula an optical isomer

13 Functional Groups in Organic
Organic families can be defined by functional groups. Frequently use “R” as a place holder for alkane- like hydrocarbon groups R–OH alcohol R–COOH organic acid R–O–R’ ether

14 Functional Groups in Organic

15 Learning Check 1. Write the abbreviated structure for benzoic acid.
2. What family does C6H5NH2 belong to? amine family

16 Your Turn! Which of the following is an example of an ester?
CH3CH2CH2OH B. C. D.

17 Hydrocarbons Hydrocarbon compounds only contain C and H
Alkanes CnH2n CH3CH2CH3 propane Alkenes CnH2n CH3CHCH2 propene Alkynes CnH2n-2 CH3CCH propyne Aromatic C6H benzene Characterized by cyclic delocalized π bonding

18 Hydrocarbons Alkanes are defined as saturated compounds.
All singles bond to carbon Cannot add more hydrogen atoms Alkenes and alkynes are unsaturated compounds. Alkenes have double bonds and H atoms can be added to the double bond to create a saturated compound. Alkynes have triple bonds and H atoms can be added to create a saturated compound. CH2=CHCH3 + H CH3CH2CH3

19 Aromaticity Characterized by conjugated bonds in a ring such as benzene. π electrons are delocalized over the ring Leads to greater stability than expected Properties are different than those of other hydrocarbon families Polycyclic examples:

20 Hydrocarbon Nomenclature
Rules for naming alkanes Established by IUPAC 1. Name ends in “-ane” 2. Complete name uses that of parent compound with constituent groups added. 3. Parent is longest continuous carbon chain. 4. Name of longest chain based on the number of carbons. 5. Carbon atoms are numbered starting at the end that gives the lowest number for the first branch.

21 Straight Chained Alkanes
Table 22.1

22 Alkyl Groups Alkane type groups added to parent chain are known as alkyl groups. Consist of alkane, minus one H atom. Name always ends in –yl Example CH4 : now remove one H which yields –CH3 Naming of –CH3 Start with parent name, which is methane Drop –ane and add –yl So methane becomes methyl group

23 Alkyl Groups CH3CH2CH3 yields –CH2CH2CH3 when one H atom is removed from the end carbon. The name of the aryl group is propyl. Note, you can have another isomer of propyl. The other isomer’s aryl group is 1-methylethyl, or isopropyl, and is created when the H atom is removed from the non-terminal carbon.

24 Nomenclature 6. Aryl groups names are prefixed to parent name. 7. Multiple aryl groups on a parent are numbered and named alphabetically. 8. When there are multiple identical groups add di, tri, tetra to the aryl name. 9. If multiple, identical aryl groups are attached to the same carbon repeat the carbon number.

25 Examples What is the name of the compound shown?
The longest carbon chain (parent) is four. Parent name is butane. Start numbering from the left to get the smallest number for the attached group.

26 Examples 3. The attached alkyl group is a methyl group.
Thus, the correct name is: 2-methylbutane What is the name of the following compound?

27 Examples The parent chain contains five carbons.
Thus, the parent name is pentane. Number from the left to obtain the smallest number for the first alkyl group. The alkyl groups are at the 2 and 3 positions. The 2 and 3 positions each contain a methyl group.

28 Examples Thus, the correct name is: 2,3-dimethylpentane
Let’s consider an alkane with two substituents on the same carbon.

29 Examples The parent chain is six carbons long.
The lowest correct numbering of positions is shown below. There are methyl and ethyl groups attached to carbon 3.

30 Examples The correct name is: 3-ethyl-3-methylhexane

31 Your Turn! What is the correct name for the molecule shown below?
A. 3-butylpentane B. 1,1-diethylpentane C. 3-ethylheptane D. 5-ethylheptane

32 Your Turn! What is the name of the compound shown below?
A. 3-methyl-3-methyloctane B. 3,3-dimethyloctane C. 2-ethyl-2-methylheptane D. 6,6-dimethyloctane

33 Chemical Properties of Alkanes
Alkanes are relatively unreactive Not reactive in conc. NaOH or H2SO4 at room temperature. React with hot HNO3 Will react with Cl2 and Br2 to form halogenated hydrocarbons. Examples are CH3Cl, CH2Cl2 and CHCl3 Can crack molecules like ethane under controlled conditions to form CH2CH2 Will react with O2 to form CO2, CO, and H2O

34 Alkenes and Alkynes Alkenes contain one or more double bonds
General form: CnH2n Alkynes contain one or more triple bonds General form: CnH2n-2 Non-polar compounds are not water soluble Examples: Ethene or ethylene Ethyne or acetylene

35 Alkenes and Alkynes Nomenclature
The parent chain must contain the multiple bond even if it is a smaller chain length than one without a multiple bond Number from end that gives the lowest number to the first carbon of the multiple bond The number is given as -x- and placed just before the –ene or –yne of the parent name. For example, but-2-ene. The double bond starts on carbon 2 of the chain.

36 Alkene Examples Start numbering from the left to get the lowest number for the first carbon with the double bond The parent is heptene and the correct naming including the double bond location would be hep-2-ene

37 Alkene Example The parent chain is four carbons 2,3-dimethylbut-2-ene
We would not name this 2-methyl-3- methylbut-2-ene

38 Naming Polyenes How do we name compounds such as the following?
This compound contains two double bonds and is known as a diene We want the lowest number for the first carbon of each of the double bonds Start numbering from the right

39 Naming Polyenes The correct name would be hex-1,3-diene
Three double bonds would be a triene hex-1,3,5-triene

40 Cyclic Alkenes Number ring to obtain lowest number for first carbon of the double bond

41 Cyclic Alkenes Correct name is 1,6-dimethylcyclohex-1-ene
Other ring examples Cyclopentene Cyclooctene

42 Your Turn! What is the correct name for the compound shown below?
A. 1,4-dimethylcyclopent-1-ene B. 1,3-dimethylcyclopent-1-ene C. 1-methyl-4-methylcyclopent-1-ene D. 1,3-dimethylcyclo-1-pentene

43 Your Turn! What is the correct structure for 3,3-dimethylpro-1-ene? A. B. C. D.

44 trans-1,2-dibromoethene
Geometric Isomers Groups cannot freely rotate about a double bond Therefore, it is possible to have geometric isomers Examples: trans-1,2-dibromoethene cis-1,2-dibromoethene

45 Reactions of Alkene Alkenes readily add across the double bond
Examples of an addition reaction: CH2CH2 + H CH3CH3 hydrogenation CH2CH HCl → CH3CH2Cl CH2CH H2O → CH3CH2OH CH2CH Cl2 → CH2ClCH2Cl

46 Aromatic Hydrocarbons
The most common aromatic compound is benzene and its derivatives Representation of bonding Delocalized π bonds create unique stability, called resonance stabilization. The circle in the ring represents delocalization.

47 Reactions Substitution reactions maintain benzene’s resonance structure. Addition reactions, like those of alkenes, destroy resonance structure Substitution reaction:

48 Addition Reaction Notice that you have reduced the double bonding in the ring and altered the resonance stabilization of the ring

49 Learning Check: What product would form if benzene reacted with
nitric acid using an appropriate catalyst? Sulfuric acid is the catalyst A substitution reaction occurs

50 Your Turn! Which product is most likely formed when sulfuric
acid reacts with benzene? A. B. C. D.

51 Organic Compounds Containing Oxygen
Important functional groups: Alcohol Ether Aldehyde Ketone Carboxylic acid Ester

52 Alcohols and Ethers Common alcohols: names end in –ol CH3OH methanol
CH3CH2OH ethanol CH3CH2CH2OH propan-1-ol If the –OH group was attached to the central carbon then the alcohol would be propan-2-ol Alcohols form hydrogen bonds, causing their boiling points to be higher than predicted.

53 Alcohols and Ethers Primary alcohols: Secondary alcohols:
Tertiary alcohols:

54 Alcohols and Ethers Common ethers: CH3OCH3 dimethyl ether
CH3CH2OCH2CH3 diethyl ether CH3OCH2CH3 methyl ethyl ether No hydrogen bonding occurs, thus, boiling points are lower than corresponding alcohols Like alkanes, ethers are not very reactive

55 Reactions of Alcohols Alcohols can undergo oxidation to form a variety of products. Oxidation removes an H atom from the alcoholic carbon as well as the H on the –OH group. Primary alcohols can be oxidized to aldehydes and carboxylic acids

56 Reactions of Alcohols Aldehydes are more readily oxidized than alcohols Secondary alcohols can be oxidized to ketones

57 Reactions of Alcohols Ketones are not further oxidized
Tertiary alcohols have no H atom on the alcoholic carbon and thus, do not undergo oxidation Alcohols undergo elimination reactions in the presence of concentrated H2SO4 forming water and alkenes –OH group readily accepts a proton from sulfuric acid

58 Elimination Reaction Dehydration of an alcohol
During the reaction a very unstable carbocation is formed. This ion eliminates a proton to form the alkene.

59 Substitution Reactions of Alcohols
Using heat and concentrated HBr, HI, or HCl, a halogen will replace the –OH group A proton adds to the –OH forming –OH2+ Water leaves and the halogen ion attaches to the carbon site where the –OH was attached 2-bromo-2-methylpropane

60 Aldehydes and Ketones Naming aldehydes
Parent name ends in –al, replacing –e in the alkane name The aldehyde group is always at the end of a chain and numbering starts with that end of the chain Aldehyde group Keto group

61 Naming Aldehydes Number from the aldehyde end
Do not use -1- for aldehyde: 3-methylpropan-1-al, or 3-methyl-1-propanal would be wrong 3-methylpentanal

62 Learning Check What is the name of the following aldehyde?
4-ethylhexanal

63 Naming Ketones Parent name ends in –one
Parent chain must contain carbonyl group Numbering so carbonyl carbon has lowest possible number 4-ethylheptan-3-one NOT: 4-ethylheptan-5-one

64 Your Turn! What is the correct name for the aldehyde shown below?
A. 2,4-dimethylpentanal B. 2,4-dimethyl-1-pentanal C. 2-methyl-4-methylpropanal D. 2,4-dimethyl-5-pentanal

65 Your Turn! - Solution Aldehydes are numbered from the aldehyde end of the molecule There are two identical groups, (methyl) so we use –di in the naming 2,4-dimethylpentanal

66 Your Turn! What is the correct name for the ketone shown below?
A. 4-methyl-3-ethylhexan-2-one B. 4-ethyl-3-methylhexan-5-one C. 3-ethyl-4-methylhexan-2-one D. 3,4-diethylpentan-2-one

67 Your Turn! - Solution Number to give lowest number to keto group so you start from the right Alkyl groups are ordered alphabetically so ethyl comes before methyl

68 Reactions of Aldehydes and Ketones
Aldehydes and ketones add hydrogen across the C=O bond Process is hydrogenation or reduction

69 Carboxylic Acids and Esters

70 Naming Carboxlic Acids
Name ends in –oic, replacing –e in the parent name Numbering begins with carboxyl group –COOH or –CO2H is the condensed form CH3COOH is ethanoic acid (acetic acid)

71 Naming Carboxylic Acids
Benzoic acid Propanoic acid

72 Naming Esters Name begins with alkyl group attached to the –O
Name of parent acid is separate from the alkyl group name and –oic is replaced with –ate Ethyl propanate

73 Learning Check What is the name of the following ester?
Alkyl group is propyl Number, starting with the ester carbon Propyl 4-methylpentanate

74 Your Turn! What is the correct name for the product when 3- methylbutan-1-ol is completely oxidized? A. 3-methylbutanoic acid B. 2-methyl-1-butanoic acid C. 2-methlybutan-1-oic acid D. 3-methylbutan-1-oic acid

75 Reactions of Carboxylic Acids
The –COOH is weakly acidic and therefore reacts with base RCOOH + OH– → RCOO– + H2O

76 Formation of Esters Esters give fruits their characteristic odor

77 Saponification Strong base reacts with an ester to form alcohol and the ester’s anion forms pentanoate ion

78 Your Turn! Name the ester formed when methanol reacts with hexanoic acid. A. 1-methyl hexanoate B. methylhexanoate C. methyl hexanoate D. methyl hexan-1-oate

79 Organic Derivatives of Ammonia
Amines are derived from ammonia with one or more H atoms replaced with organic groups Like ammonia, amines are weakly basic Amines react with acids

80 Acid Property of Protonated Amines
Ethylmethylammonium ion is the conjugate acid of ethylmethylamine pKa = pKb= 3.24

81 Amides General form Where (H)R indicates either an H atom or an R group attached Naming The name of the parent acid is amended dropping the –oic ending and replacing it with –amide

82 Example Names of Amides
Propanamide 4-ethylhexamide These are examples of simple amides

83 Synthesis of Simple Amides
An organic acid reacts with aqueous NH3 to form an amide 2-methylpropanoic acid yields 2-methylpropanamide

84 Amide Reactions Amides can be hydrolyzed back to their acid form producing ammonia in the process

85 Amide Reactions Urea, an amide, ultimately hydrolyzes to NH3, CO2 and water Carbonic acid is formed, which then decomposes to carbon dioxide and water The overall reaction is:

86 Basicity of Amides Amides are not basic like amines
The lone pair on the N atom is delocalized and thus not readily available for donation to a proton Amides are neutral in an acid-base sense

87 Your Turn! What is the correct name for the molecule shown below?
A. 4,5-dimethylhexanamide B. 2,3-dimethyl-6-hexanamide C. 4-methyl-5-methylhexanamide D. 4-isopropyl-4-methylpropanamide

88 Organic Polymers Macromolecule made up of small, repeating units
Example, polypropylene Starting material

89 Polymers Repeating unit is called a monomer
The reaction to create a polymer is known as polymerization Chain Growth Polymers Polymers created by the addition of one monomer to another monomer Polypropylene is an example of a chain growth polymer

90 Common Polymers

91 General Repeat Unit for Polyvinyl Chloride
This unit is repeated n times to create the polymer

92 Step-Growth Polymers Condensation reaction
A small molecule such as water is eliminated when the monomers are joined: Nylon 6,6, for example Nylon is a copolymer, two different molecules combined

93 Dacron-A Polyester Another example of a condensation copolymer

94 Physical Properties Dependent on how polymers pack
Branching polymers create non-crystalline, amorphous solids

95 Physical Properties Amorphous polymer of polyethylene is known as low density polyethelene or LDPE Low molecular mass and low structural strength Used to make plastic grocery bags Non-branching polyethylene forms high density polyethylene or HDPE Strong London forces between chains Strong fibers are formed

96 Physical Properties HDPE is lightweight, water repellent, resists tears Common uses Strong mailing envelopes Tyvek Ultrahigh molecular weight polyethlene 3 to 6 million molar mass UHMWPE Used to make very strong polymers Sails, bullet proof vests, bike helmets

97 Biochemical molecules
Carbohydrates Structures of glucose, a monosaccharide Building unit for cellulose and starch

98 Disaccharide Sucrose

99 Disaccharide Reactions
Disaccharide molecules split into monosaccharides Gal-O-Glu + H2O → galactose + glucose Polysaccharides Starch is a large polymeric sugar molecule Can be broken down into glucose, which is used for energy in biochemical reactions Amylose is the structurally simpler glucose polymer portion of starch

100 Disaccharide Reactions
Amylose Amylose +n H2O → n glucose

101 Polysaccharides The majority of starch is made up of a more complex polysaccharide known as amylopectin

102 Cellulose A polymer of glucose with different oxygen bridge orientations We lack an enzyme to digest cellulose

103 Lipids Water insoluble natural products Dissolve in non-polar solvents
Relatively non-polar with large segments that are hydrocarbon-like Cholesterol

104 Lipids Fats and oils Triacylglycerols-esters of glycerol and long chain carboxylic acids (fatty acids)

105 Fatty Acids

106 Triacylglycerols Triacylglycerol example

107 Reactions of Triacylclycerols
Digestion Breaks down the triacylclycerol into its three component fatty acids and glycerol. Takes place in base so in fact the fatty acids are in their anion form Hydrogenation The addition of hydrogen to the double bonds Turns oils into solids

108 Soap Castile soap is made from olive oil
Olive oil has many different fatty acids Two major fatty acid constituents are oleic acid, %, and linoleic acid, 4-20% Saponification of triacylglcerols using NaOH or other base, and heat, results in salts of the fatty acid components plus glycerol Sodium oleate and sodium linoleate, for example This product mixture, soap, is thus the result of saponification of triacylglcerols

109 Cell Membranes Glycerophospholipids
Diacylclcerols with phosphate unit which is attached to a amino alcohol unit Contain a hydrophobic, water avoiding, unit and a hydrophilic, water loving, unit Aggregate together to form lipid bilayers with hydrophilic layers oriented to the outside and inside layers of the membrane

110 Cell Membranes

111 Cell Membranes Membrane also contains protein units, some which act as ion channels to move select ions in and out of cells Other proteins act as molecular recognition sites for hormones and neurotransmitters

112 Proteins Polypeptides made up of α-amino acids
Serve as hormones, neurotransmitters, and enzymes Essential amino acids are those the body does not synthesize Basic amino acid structure:

113 Amino Acids Lysine Cysteine

114 Amino Acids Isoleucine Alanine

115 Polypeptides Formation of peptide bond

116 Polypeptides Combining two amino acids forms a dipeptide
Often the amino acids are abbreviated Glycine – Gly Alanine – Ala A dipeptide of these would then be shown as: Gly-Ala A few amino acids can be arranged in a very large number of orders leading to many different proteins Gly-Ala-Arg Gly-Arg-Ala Ala-Gly-Arg Plus three more

117 Polypeptides and Proteins
How many ways can you arrange n different objects? n ! Therefore 3 amino acids have 6 arrangements You can also use the same amino acid more than once in a polypeptide Proteins Consist of polypeptides and usually small organic molecules They may also incorporate metal ions into their structure

118 Structure of Hemoglobin

119 Nucleic Acids RNA – ribonucleic acid DNA – deoxyribonucleic acid
The chemical of a gene Chemical basis of inherited characteristics

120 Nucleic Acid Sugars

121 Basic Nucleic Acid Structure
Where G is a placeholder for a unique nucleic acid side chain The sugars are ribose for RNA and deoxyribose for DNA The groups, G, are: adenine (A), thymine (T), uracil (U), guanine (G), and cytosine(C)

122 DNA - Double Helix Structure
A unique arrangement of amino acids maximized hydrogen bonding resulting in a pairing of strands to form a double helix Base Pairing A only with T C only with G

123 DNA Replication Enzyme catalyzed process unzips the two strands
Arrangement of base pairs dictates replication pattern

124 Polypetide Synthesis Controlled formation of peptide bonds to make a polypeptide Repeated many times to form polypeptides and proteins Genetic information is transcribed from DNA in the nucleus onto RNA (m RNA) This messenger RNA moves outside the nucleus and through a complex process, using other RNA types, synthesizes a specific protein The order of amino acid synthesis is coded so that the correct amino acids are made available in the proper sequence


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