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Transcript of Chapter 22 Organic and Biochemical Molecules. Chapter 22: Organic and Biochemical Molecules 22.1...
Chapter 22Chapter 22
Organic and Biochemical Organic and Biochemical MoleculesMolecules
Chapter 22: Organic and Biochemical Molecules
22.1 Alkanes: Saturated Hydrocarbons
22.2 Alkenes and Alkynes
22.3 Aromatic Hydrocarbons
22.4 Hydrocarbon Derivatives
22.5 Polymers
22.6 Natural Polymers
Computer model of a globular protein
The Position of Carbon in the Periodic Table
“I am Carbon and I am Special”
1. I can form strong and short C-C bonds.
2. The C-C bond is short enough to allow sideways overlap of the unused p orbitals, resulting in bonding. I gladly form carbon- carbon double bonds, and I can even form carbon-carbon triple bonds.
3. I have no problem bonding to other elements (H, O, N, S, etc.– I love them all). Given where I am in the periodic table, I typically form four bonds, except in carbon monoxide.
I Am Special -- Try Comparing Me to My Brother, Si
1. The C-C bond is much stronger than the Si-Si bond. (Atomic size increases down the group: bonds between atoms become longer and weaker.)
2. For me BE (C-C) ~ BE (C-O). For Si, BE (Si-O) >> BE (Si-Si). With availability of oxygen in nature, Si will exist mostly with Si-O bonds.
3. I have no d - orbitals to worry about. CH3-CH3 is stable while SiH3-SiH3 is very susceptible to species with a pair of lone pairs of electrons to donate into the vacant d orbitals.
You can spend your whole life learning about me!
Bond Energy and the Stability ofCarbon Chains
I Can Amaze You With Diversity
Consider the number of compounds with the formula C4H8O.
These are called structural isomers–compounds with the same chemical formulas, but different ways of connecting the atoms together to form different functional groups, or different compounds with completely different chemical and physical properties.
Chemical Diversity of Organic Compounds
Reactivity & Polarity of Bonds in Organic CompoundsC C Bonds are nonpolar, no difference in the EN values of the atoms. They are relatively short (200 pm). Result: UnreactiveC H Bonds are nearly nonpolar and short (109 pm) EN (C-H) = 2.5 – 2.1 = 0.4 Result: UnreactiveC O Bonds are highly polar, with the oxygen end very electron rich EN (C-O) = 2.5 – 3.5 = 1.0 Result: ReactiveC Br Bonds are nearly nonpolar: EN (C-Br) = 2.5 – 2.8 = 0.3 Result: Relatively unreactiveC S Bonds are exactly nonpolar: EN (C-S) = 2.5 – 2.5 = 0.0 Result: Relatively unreactiveEven though the EN differences are small for Br & S with carbon, theatoms are so large that their bonds to carbon are long, weak, and reactive.
Certain Parts of Me Make Me Behave in Certain Predictable Ways
Functional Groups – atoms or specific groups of atoms that impart given characteristics.
The secret to learning organic chemistry.
As the periodic table is to inorganic chemistry, functionalgroups are the easy way to learn organic chemistry.
A Polarized Marriage Does Not Last Very Long
“ I am no different. I am quite reactive at the sites (bonds)that have the high polarity.”
Figure 22.1: C-H bonds in methane
Figure 22.2: (a) Lewis structure of ethane ( C2H6 ). (b) molecular structure of ethane
Figure 22.3: Structures of (a) propane (b) butane
Alkanes
• Methane CH4
• Ethane C2H6 CH3CH3
• Propane C3H8 CH3CH2CH3
• Butane C4H10 CH3CH2CH2CH3
• Pentane C5H12 CH3CH2CH2CH2CH3
• Hexane C6H14 CH3CH2CH2CH2CH2CH3
• Heptane C7H16 CH3-(CH2)5-CH3
• Octane C8H18 CH3-(CH2)6-CH3
• Nonane C9H20 CH3-(CH2)7-CH3
• Decane C10H22 CH3-(CH2)8-CH3
Table 22.1 (P1014) Selected properties of the First 10 Normal Alkanes Number of Molar Melting Boiling structuralName Formula Mass Point (oC) Point(oC) isomers
Methane CH4 16 -182 -162 1Ethane C2H6 30 -183 -89 1Propane C3H8 44 -187 -42 1Butane C4H10 58 -138 0 2Pentane C5H12 72 -130 36 3Hexane C6H14 86 -95 68 5Heptane C7H16 100 -91 98 9Octane C8H18 114 -57 126 18Nonane C9H20 128 -54 151 35Decane C10H22 142 -30 174 75
Figure 22.4: (a) normal butane (b) branched isomer
n-Butane
Isobutane
Pentane
n - Pentane
CH3-CH2-CH2-CH2-CH3
Isopentane2-Methyl Butane
CH3-CH-CH2-CH3 CH3
Neopentane
2,2-Dimethyl Propane
CH3
CH3 – C – CH3
CH3
Boiling Points of Hydrocarbons
Rules for Naming Alkanes (P 1016-1017)-I1) The names of the alkanes beyond butane are obtained by adding the suffix –ane to the Greek root for the number of carbon atoms (pent- for five, hex- for six, and so on). For a branched hydrocarbon, the longest continuous chain of carbon atoms determines the root name for the hydrocarbon. For example in the alkane: The longest chain contains 6 carbon atoms. CH3 The compound is named hexane. CH2 CH2 CH3-CH2-CH-CH2-CH3 2) When alkane groups appear as substituents, they are named by droping the –ane and adding –yl. For example, -CH3 is obtained by removing a hydrogen from methane and is called methyl, -C2H5 is called ethyl, -C3H7 is called propyl, and so on. The compound above is therefore an ethylhexane. (see table 22.2)
Longest Chain 6 carbons
Rules for Naming Alkanes (P 1016-1017)-II
3) The positions of aubstituent groups are specified by numbering the longest chain of carbon atoms sequentially, starting at the end closest to the branching. For example, the compound CH3 CH3-CH2-CH-CH2-CH2-CH3 1 2 3 4 5 6 is called 3-methylhexane. Note that the set of numbers is correct since the left end of the molecule is closest to the branching, and this gives the smallest number for the position of the substituent. Note that a hyphen is written between the number and the substituent name. 4) The location and name of each substituent are followed by the root alkane name. The substituents are listed in alphabetical order, and the prefixes di-, tri-, and so on, are used to indicate multiple, identical substituents.
Naming Saturated Hydrocarbons
Based on the longest chain of carbon atoms
Prefix + root + suffix
Location and nature of substituents on chain
Indicator of the # of C’s in the longest chain
Class of organic compound -ane for alkanes
Numerical Roots for Carbon Chains and Branches
Root Number of Carbon Atoms
meth- 1eth- 2prop- 3but- 4pent- 5hex- 6hepta- 7oct- 8non- 9dec- 10
Like Example 22.2 (P 1017-18)-I
Draw the structural isomers for the saturated hydrocarbon heptane C7H16 .name each of the isomers.
Solution: Straight chain: CH3-CH2-CH2-CH2-CH2-CH2-CH3 n-Heptane
One methyl group: CH3-CH-CH2-CH2-CH2-CH3 2-Methylhexane CH3 3-Methylhexane CH3-CH2-CH-CH2-CH2-CH3
CH3 Two methyl groups: CH3-CH-CH2-CH-CH3 CH3 CH3 2,4-dimethyl pentane
CH3 CH3-CH-CH-CH2-CH3 CH3-C-CH2-CH2-CH3 CH3 CH3 CH3 2,2-dimethylpentane 2,3-dimethylpentane
Like Example 22.2 (P 1017-18)-IITwo methyl groups cont. CH3 CH3-CH2-C-CH2-CH3 CH3
CH3CH2-CH-CH2-CH3 3,3-dimethylpentane CH2 3-ethylpentane CH3 CH3
2,2,3-trimethylbutane CH3-CH-C-CH3 CH3 CH3
Reactions of Alkanes - Chlorination
The Stepwise Chlorination of Methane by Chlorine:
CH4 (g) + Cl2 (g) CH3Cl(g) + HCl(g)
CH3Cl(g) + Cl2 (g) CH2Cl2 (g) + HCl(g)
CH2Cl2 (g) + Cl2 (g) CHCl3 (g) + HCl(g)
CHCl3 (g) + Cl2 (g) CCl4 (g) + HCl(g)
CH4 (g) + 4 Cl2 (g) CCl4 (g) + 4 HCl(g)
Figure 22.5: (a) molecular structure of cyclopropane (b) overlap of sp3 orbitals
Figure 22.6: (a) chair (b) boat forms
Figure 22.7: Bonding in ethylene
Figure 22.8: Bonding in ethane
Figure 22.9: The two stereoisomers of 2-butene
Figure 22.10: Bonding in acetylene
Hydrocarbons C + H
Compounds containing only carbon and hydrogen with only single bonds and no multiple bonds - Saturated hydrocarbons - Alkanes CnH2n+2
Compounds containing only carbon and hydrogen with only single bonds and no multiple bonds, but a ring structure - Saturated hydrocarbons - Cycloalkanes CnH2n
Compounds containing only carbon and hydrogen with double bonds - Unsaturated hydrocarbons - Alkenes CnH2n
Compounds containing only carbon and hydrogen with triple bonds - Unsaturated hydrocarbons - Alkynes CnH2n–2
Conformations from rotation of single bonds–isomers exist as a resultof rearrangements of the atoms in different structural formulas.
Drawing Hydrocarbons–I Problem: Draw structures for hydrocarbons that have different structures with: a) seven C atoms, no multiple bonds, and no rings. b) five C atoms, one double bond, and no rings. c) five C atoms, no multiple bonds, and one ring.Plan: In each case, we draw the longest carbon chain and then work down to smaller chains with branches at different points along them. The process typically involves trial and error. Then we add H atoms to give each C atom a total of four bonds.Solution: (only the carbon backbone will be shown here) a) compounds with seven C atoms: (9) [C7H16]
C-C-C-C-C-C-C C-C-C-C-C-C C
C-C-C-C-C-C C
CC-C-C-C-C C
C-C-C-C-C C C
C-C-C-C-C C C
CC-C-C-C-C C
C-C-C-C-C C C
CC-C-C-C C C
Drawing Hydrocarbons–II
b) compounds with 5 C atoms and one double bond: (5) [C5H10]
C=C-C-C-C C=C-C-C C=C-C-C
C-C=C-C-C
C-C=C-C
c) compounds with 5 C atoms and one ring: (5) [C5H10]
C-C-C-C C
C-C-C-C C
CC-C-C C
C-C-CC-C
C-CC C C
C CC
Naming and Drawing Alkanes, Alkenes, and Alkynes–I
Problem: Give the systematic name for each of the following, indicate the chiral center in part (d), and draw two geometric isomers for part (e).(a) CH3 (b) CH2-CH3
CH3 - CH - CH-CH3 CH3-CH2-CH2-CH-CH-CH3
CH3 CH2
CH3
(c) CH3 CH3
(d) CH3-CH2-CH-C-CH3
CH3 CH3
(e) CH3-CH2-CH=C-CH-CH3
CH3
Plan: For (a) to (c), we refer to Table 15.2. We first name the longest chain (root- + -ane). Then we find the lowest branch numbers by counting C atoms from the end closer to a branch. Finally, we name each branch (root- + -yl) and put them alphabetically before the chain name.
H2H2
H2
H2
CH3
CH2-CH3
Naming and Drawing Alkanes, Alkenes, and Alkynes–II
Plan:Cont. For (e), the longest chain that includes the multiple bond is numbered from the end closer to it. For (d), the chiral center is the C atom bonded to four different groups. In (e), the cis isomer has larger groups on the same side of the double bond, and the trans isomer hasthem on opposite sides.Solution:
(a) CH3
CH3
CH3 - CH - CH - CH3
1 2 3 4
2,3-Dimethylbutane
CH2 - CH3
H(b) CH3
CH3 - CH2 - CH2 - C - C -
CH2
CH31
234567
3-Methyl-4-ethylheptane
Naming and Drawing Alkanes, Alkenes, and Alkynes–III
(c)
CH3
H2
H2
H2
H2
CH2 - CH3
1
2
3
1-Ethyl-3-methylcyclohexane
(d) CH3 CH3
CH3 - CH2 - C - C - CH3
H CH3
12345
2,2,3-Trimethylpentane
chiral center
(e)
CH3 - CH2 - C = C - CH - CH3
H CH3
CH3
CH3 - CH2 - C = C - CH - CH3
H
CH3
CH3
cis-2,3-Dimethyl-3-hexene trans-2,3-Dimethyl-3-hexene
Alkenes
Alkenes–Carbon compounds that contain at least one C=C double bond. Alkenes have the general formula: CnH2n
Alkenes are called unsaturated hydrocarbons The names of alkenes differ from those of alkanes in two respects: 1) The root chain must contain both C atoms of the double bond, even if it is not the longest chain. The chain is numbered from the end closer to the C=C bond, and the position of the bond is indicated by the number of the first C atom in it. 2) The suffix for alkenes is -ene. Examples: Ethylene, C2H4; Propene, C3H6; Butene, C4H8
H2C=CH2
EthyleneH2C=CH-CH3
Propylene =
H2C=CH-CH2-CH3
1-ButeneH3C-CH=CH-CH3
2-Butene
H3C-CH2-CH=CH2
1-ButeneH3C-CH=CH2
Propene
H2C=C-CH3
2-Methyl propene CH3
Alkenes
C2H4 Ethylene H2C=CH2
C3H6 Propylene H2C=CH–CH3
C4H8 Butene H2C=CH–CH2–CH3
C5H10 Pentene H2C=CH–CH2–CH2–CH3
C6H12 Hexene H2C=CH–CH2–CH2–CH2–CH3
C7H14 Heptene H2C=CH–( CH2)4–CH3
C8H16 Octene H2C=CH–( CH2)5–CH3
The Initial Chemical Event in Vision
Alkynes
Alkynes –Hydrocarbons that contain at least one C C bond Alkynes have the general formula: CnH2n–2
Alkynes are named the same way as alkenes, except that the suffix is -yne. Examples:
HC CHAcetylene
HC C-CH3
PropyneH3C-C CH Propyne
HC C- CH2-CH3
1-ButyneH3C-C C-CH3
2-ButyneH3C-CH2-C CH 1-Butyne
HC C-CH2-CH2-CH3
1-PentyneH3C-C C-CH2-CH3
2-Pentyne
R-Group Names and Chemical Formulas
methyl - CH3
ethyl - CH2 - CH3 or - C2H5
n-propyl - CH2 - CH2 - CH3 or - C3H7
isopropyl - CH - CH3
CH3
n-butyl - CH2 - CH2 - CH2 - CH3 or - C4H9
isobutyl - CH2 - CH - CH3
CH3
CH3
tert-butyl - C - CH3 CH3
H2 H2
H2
H2H2
Hcyclohexyl
H2 H2
H2
H2
cyclopentyl H
H2
H2
H2
cyclobutylH
H2
H2H
cyclopropyl
Figure 22.11: The structure of benzene
Figure 22.12: Some selected substituted benzenes and their names
Compounds containing aromatic rings are often used in dyes, such as these for
sale in a market in Nepal
Source: Getty Images
Some Reactions of Alcohols–I
1) The reaction of an alcohol with an alkali metal to form an alkoxide ion:
As with water: 2 Na(s) + 2 H2O(l) 2 NaOH(aq) + H2 (g)
With alcohols a similar reaction occurs, forming an alkoxide ion:
2 Na(s) + 2 CH3-CH2-OH(l) 2 CH3-CH2-O-(aq) +2 Na+
(aq) + H2 (g)
2 Li(s) + 2 CH3-OH(l) H2 (g) + 2 CH3-O-(aq) + 2 Li+
(aq)
2) Dehydration of alcohols yields an unsaturated compound–an alkene or an ether (R-O-R). An example of the formation of an alkene:
OH
+ H2OH2SO4
Phenol Cyclohexene
Some Reactions of Alcohols–II2) cont., Formation of an ether:
2 CH3-OH(l) CH3-O-CH3 (g) + H2O(l)
H2SO4
CH3-CH2-OH(l) + HO-CH2-CH3 (l) H2O(l) + CH3-CH2-O-CH2-CH3
Dimethyl ether
H + HO-Diethyl ether
H2SO4
OHCH3-CH2-CH2-CH2-CH2-CH2-OH(l) + CH3-CH-CH2-CH3 (l)
H2SO4
CH3
H-C-O-CH2-CH2-CH2-CH2-CH2-CH3 (l) CH2
CH3
2-Butyl n-hexyl ether
n-Hexanol 2-Butanol
Ethyl alcohol Ethanol
Methanol
Some Reactions of Alcohols–III
3) Oxidation - Yields an aldehyde, acid or, for some alcohols, a ketone.
Primary alcohols Aldehyde Organic Acid
Secondary alcohols Ketone
Tertiary alcohols no oxidation
O OCH3-CH2-OH(l) CH3-C-H CH3-C-OH
K2Cr2O7
H2SO4
= [O] = “Oxidation”
[O][O]
Ethanol Ethanal Acetic acid
OH OCH3-CH-CH2-CH3 (l) CH3-C-CH2-CH3 (l)
2-Butanol Ethyl methyl ketone
[O]
-H2O -H2O
-H2O
Ethanol is being tested in selected areas as a fuel for automobiles
Source: AP/Wide World Photos
Some Molecules with Alcohol Functional Group
Cinnamaldehyde produces the characteristic odor of cinnamon
Source: Visuals Unlimited
Aldehydes
Formaldehyde Methanal
H C H
O
Acetaldehyde Ethanal
H3C C H
O
Benzaldehyde
CH
CCH
CHCH
CH
C H
O
Dimethyl ketoneH3C C CH3
O
Acetone
Ethyl methyl ketone
H3C CH2 C CH3
O
Diethyl ketone
H3C CH2 C CH2 CH3
O
Ketones
Some Common Aldehydes and Ketones
Figure 22.13: Some common ketones and akdehydes
The CarbonylGroup
Carboxylic Acids
Formic acidH C O H
O
Acetic acid
H3C C O H
O
Propionic acid
H3C CH2 C O H
O
Butanoic acid
H3C CH2 CH2 C O H
O
Figure 22.14: Some carboxylic acids
Some Molecules with the Carboxylic Acid Functional Group
Which Reactant Contributes Which Group to the Ester?
Isotopic labeling shows that the oxygen atom in the ester comes from the alcohol, not the acid, and that the oxygen found in thewater formed as a byproduct comes from the acid.
Alcohol + Organic Acids Esters–I
Ethyl alcohol + Acetic acid = Ethyl acetate
H3C CH2 OH + H3C C O H
H3C CH2 O C CH3 + H2O
O
O
Ethanol Acetic acid
Ethyl acetate Water
Methyl alcohol + Formic acid = Methyl formate
H3C O H + H O C H H3C O C H + H2O
O O
Methyl alcohol + Butyric acid = Methyl butyrate
H3C O H + H3C CH2 CH2 C O H
O
H3C CH2 CH2 C O CH3H2O +
O
Alcohol + Organic acid Esters–II
Methyl formate H C O CH3
O
Methyl acetateH3C C O CH3
O
Ethyl acetate H3C C O CH2 CH3
O
Ethyl butyrateH3C CH2 CH2 C O CH2 CH3
O
Pineapples
Alcohol + Organic acid Esters–III
Some Lipid Molecules with the Ester Functional Group
Esters are the Flavoring in Fruits–IBenzyl acetate C9H10O2 –oil of jasmine O
CH3-C-O-CH2-Isoamyl acetate C7H14O2–ripe apples
O CH3
CH3-C-O-CH2-CH2-CH-CH3
Ethyl 2-methylbutanoate C7H14O2–ripe apples
CH3 OCH3-CH2-CH-C-O-CH2-CH3Isoamyl acetate C7H14O2–bananas
Ethyl butyrate C6H12O2–pineapple
Ethyl formate C3H6O2–rum
O CH3
CH3-C-O-CH2-CH2-CH-CH3
OCH3-CH2-CH2-C-O-CH2-CH3
OH-C-O-CH2-CH3
Esters are the Flavoring in Fruits–II
Amyl butyrate C9H18O2–apricot
Methyl salicylate C8H8O3–oil of wintergreen
Ethyl formate C3H6O2–lemonade
n-Octyl acetate C10H20O2–oranges
OCH3-CH2-CH2-C-O-CH2-CH2-CH2-CH2-CH3
OH-C-CH2-CH3
OCH3-C-O-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3
OC-O-CH3
OH
Computer-generated space-filling model of acetylsalicylic acid (aspirin)
Source: Photo Researchers, Inc.
Amines–I
NH3 Ammonia
CH3NH2 Methyl amine
(CH3)2NH Dimethyl amine
(CH3)3N Trimethyl amine
N
CH3
CH3
CH3
N
H
. .. .
CH3
CH3
. .N
HH
H
. .N
H
H CH3
Figure 22.15: The general formulas for primary, secondary, and tertiary amines:
Amines–II
CH3-CH2-NH2 Ethyl amine
CH3-CH2-CH2-NH2 n-Propyl amine
CH3-CH2-CH2-CH2-NH2 n-Butyl amine
CH
CCH
CHCH
CH
NH2
Phenyl amine
Soybeans
Source: AP/Wide World Photos
Benzoyl Peroxide
O
O
O
OO
O
.2
Heat
A “free radical” is a molecule with an unpaired electron.
Polymerization of Ethylene–IO
O . + H2C CH2
O
O
CH2
CH2
.
EthyleneBenzoyl peroxideradical
Adduct
Polymerization of Ethylene–II
O
O CH2
CH2
.
+ H2C CH2
O
O
CH2
CH2 CH2
CH2 CH2
CH2
.
2
Structures and Applications of Some Major Addition Polymers (Based upon the Ethylene Molecule)–I
Monomer Polymer ApplicationsH H C CH H
F F C CF F
H H C CH CH3
H H C CH Cl
Polyethylene Plastic bags, bottles, toys
Polytetrafluoroethylene Cooking utensils (e.g. Teflon)
Polypropylene Carpeting (indoor-outdoor), bottles
Poly(vinyl chloride) Plastic wrap, garden hose, indoor plumbing
Structures and Applications of Some Major Addition Polymers (Based upon the Ethylene Molecule)–II
Monomer Polymer ApplicationsH H C CH Phenyl
H H C CH C N
H H C C OH O C CH
H Cl C CH Cl
H CH3
C CH C O CH3
O..
Polystyrene Insulation, furniture
Polyacrylonitrile Yarns, fabrics, wigs, (e.g. Orlon, Acrilon)
Poly(vinyl acetate) Adhesives, paints, textile coatings, computer disks
Poly(vinylidene chloride) Food wrap (e.g. Saran)
Poly(methyl methacrylate) Glass substitute (e.g. Lucite, Plexiglas), bowling balls, paint
Poly(Vinyl Chloride) (PVC) and Teflon
H Cl
C C
H H
C C C C C C C C
H H H H H H H H
H Cl H Cl H Cl H Cl n
Vinyl chloride PVC
C C
F F
F F
Tetrafluoroethylene
C C C C C C C C
F F F F F F F F
F F F F F F F F
Teflon
n
Polystyrene
C C
H
H
H
H
H
HHH
H
C C C C C C C C C
H H
H H
H
H HH
n
Styrene
Figure 22.17: Major use of HDPE is for blow-molded objects such as bottle for soft
drinks, shampoos, bleaches, and so on
Important Polymer Linkage Groups
• Linkage -COO- -CONH- -C-O-C-
• Name Ester Amide Ether
• Precursors Acid + Acid + Alcohol +
• Alcohol Amine Alcohol
• Polymer
• Type
• Polyesters Polyamides Cellulose
• Proteins Starch
Nylon netting magnified 62 times
Source: Corbis
Colored water drops are shown beading onKevlar fabric treated with a non-scale
water-resistant coating.
Source: AP/Wide World Photos
Condensation Polymers Polyamides–Nylon-66
HOOH
O
OH2N
NH2
+Adipic acid
Hexamethylenediamine
NN
H
HO
O n
The formationof nylon - 66
Figure 22.16: The reaction to form nylon can be carried out at the interface of two immiscible liquid layers in a beaker
Wallace H. Carothers
Source: Dupont - Wilmington, Delaware
Two Molecules with the Same Functional Group at Both Ends of Each Molecule–
Two Different Monomers
Nylon-66 Adipic acid and Hexamethylenediamine
Kevlar Terephthalic acid and Phenylenediamine
Polyesters Terephthalic acid and Ethylene glycol
Kevlar
C
C
O
O
HO
OH
H2N
NH2Terphthalic Acid Phenylenediamine
+
HO C
C
O
O
N
H
NH2
+ H2O
E TC
Polyesters ( PET )
Polyethylene Terphthalate
C
C
O
O
HO
HO
CH2
O
OH C C OH
H H
Ethylene GlycolTerphthalic acid
+
C
C
O
O
O
CH2
n
H H
+ H2O
Polyurethane
NC
O
H3C N C O
C O H
C O H
C O H
H
H
H
H
H
+
NC
O
H3C N C O C C C O H
H H
H HO
H
O
H
Toluene diisocyanateGlycerol
Polymer
Plastic Recycling–I
1) PET Polyethyleneterephthalate Soft drink bottles, blister packs, photographic film, oven proof trays,
fiberfill (Dacron)
2) HDPE High density polyethylene Milk jugs, many types of containers (food, liquid detergent, shampoos, etc.)
3) PVC Poly(vinyl chloride) “Synthetic leather” upholstery, water pipes, house siding, flooring, bottles for cooking oils, shrink wrap, meat & poultry wrap, garden hoses, phonographic records, laboratory tubing
4) LDPE Low density polyethylene Films (food wrappings, plastic bags, etc.), flexible containers such as squeeze bottles for mustard, etc.
Plastic Recycling–II
5) PP Polypropylene Appliances, autos, pipe, drinking straws, bottle caps, luggage, bread and cheese wrap, cereal box liners,
wrap for clothing
6) PS Polystyrene Styrofoam, hot-drink cups, plastic plates & silverware, egg cartons, food trays, and fast food containers
7) Other plastics–addition polymers Teflon Lucite, plexiglass Poly(vinyl acetate) Natural rubber Neoprene rubber Styrene butadiene rubber
A scanning electron microscope image showing the fractured plane of a self-healing
material with a ruptured microcapsule in a thermosetting matrix
Source: University of Illinois Urbana-Champaign
Macromolecules in Living Organisms
Nucleic Acids
Carbohydrates
Proteins - The molecular machinery of the cell
* Polyamides made from the condensation reactions of amino acids. Each amino acid contains a carboxyl group at one end and an amino group at the other end.
* Nine amino acids have nonpolar character and are found inside of proteins.
* Eleven amino acids have polar side chains, are more polar, and found on the outside of a protein where they may be in contact with water.
Figure 22.18: The 20 α-amino acids found in most proteins. [ Nonpolar R Groups ]
Figure 22.18: The 20 α-amino acids found in most proteins. [ Nonpolar R Groups ] (cont’d)
Figure 22.18: The 20 α-amino acids found in most proteins. [ Polar R Groups ]
Figure 22.18: The 20 α-amino acids found in most proteins. [ Polar R Groups ]
Figure 22.18: The 20 α-amino acids found in most proteins. [ Polar R Groups ]
Figure 22.18: Alpha-amino acids, Polar R groups (continued).
Amino Acids–The Building Blocks of Proteins
R OIn general, amino acids have the form: H2N - C - C - O - H H
Amino acids are normally charged, because the carboxyl grouptransfers an H+ ion to H2O to form H3O+, which transfers the H+
to the amine group.
R OH2N - C - C - O - H H
R OH3N+- C - C - O -
H
H3O+
+ H2O- H2O
Polypeptides
• A macromolecule made up of amino acids;• All proteins are polypeptides;• A small protein (polypeptide) consists of 50-100
amino acids;• A large protein may contain up to thousands;
myosin, a muscle protein, has approximately 1750 amino acids.
Tripeptide containing glycine, cysteine, and alanine
Source: Photo Researchers, Inc.
Figure 22.19: The amino acid sequences in (a) oxytocin and (b) vasopressin
Figure 22.20: Hydrogen bonding within a
protein chain
Figure 22.21: Ball-and-stick
model of a portion of a protein chain
Figure 22.22: Hydrogen bonding
Figure 22.23: (a) collagen (b) pleated sheet arrangement of many proteins bound together to from
the elongated protein found in silk fibers
Figure 22.24: Protein myoglobin
Figure 22.25: Summary of the various types of interactions that stabilize the tertiary
structure of protein
Figure 22.26: Permanent waving of hair
Figure 22.27: Schematic representation of the thermal denaturation of a protein
Carbohydrates
• General formula = Cx(H2O)y
• Carbohydrates are an important food source for organisms.
• Some important ones are:– Glucose C6H12O6
– Fructose C6H12O6
– Sucrose C12H22O11
• Oligosaccharides - Disaccharides– Two simple sugars (monosaccharides) linked together
• Polysaccharides–biopolymers– Starch–cellulose
Figure 22.28: Tetrahedral carbon atom has four different substituents
Self-tanning products
Figure 22.29: The mirror image optical isomers of glyceraldehyde
Figure 22.30: The cyclization of D-fructose
Figure 22.31: The cyclization of glucose
Figure 22.32: Sucrose is a disaccharide formed from α-D-glucose and fructose
Polysaccharides
• Glycogen–produced in the livers of animals– ~1000 Monomers
– Many branches on the main chain, but their average length is less than 30 monomer units
– Branches are fairly frequent with them occurring every 8-12 monmer units
• Starch–produced in plants– Glucose polymers: amylose and amylopectin
• Cellulose–produced in plants– ~ 2000-3000 Glucose units long, but glucose units are
combined as cellobiose units which have a beta linkage
Figure 22.33: Polymers amylose and cellulose
Amylose -
Cellulose -
A Portion of the Structure of Glycogen, the Major Storage Polysaccharide in Animals
3 Important Building Blocks of Nucleic Acids
• 1) A pentose sugar–In RNA the sugar is ribose, and in DNA it is deoxyribose, in which one hydroxy group has been replaced by a hydrogen.
• 2) A nitrogen containing organic base:– Adenine– Guanine– Thymine– Cytosine– Uracil
• 3) A phosphate linkage derived from phosphoric acid
Figure 22.34: Pentoses
DNA
RNA
Figure 22.35:
The organic bases found inDNA/RNA
Figure 22.36: Adenosine reaction
Figure 22.37: Nucleic acid chain
Figure 22.38: DNA double helix
Prize-Winning Work on Nucleic Acids and DNA
• 1940’s British chemist Alexander Todd– (Nobel Prize)– Discovered the basic composition of DNA.
• 1950’s Edwin Chargaff (Columbia Univ.)– Found that different species had different numbers of bases.
– Found that the molar ratio of guanine to cytosine and adenine to thymine was always very close to 1.0, suggesting that somehow, adenine and thymine are paired in DNA and so are guanine and cytosine.
• 1953 James D. Watson , Francis Crick and Maurice Wilkins–Nobel Prize– Found the double helix structure of DNA.
Figure 22.39: Cell division of DNA
Figure 22.40: mRNA molecule
Four of the Functional Groups
C O H
Alcohol
Alcohol group - Hydroxyl group
..
..Ether group
C O C....
Ether
Carboxylic acid group Ester group
.. ..
C O C
O
..
..
.. ..
C O H
O
Carboxyl
..
..
....
Ester
More Functional Groups
Alkenes
Alkynes
Thiols and Disulfides
Amines (primary, secondary, tertiary)
Aldehydes
Ketones
Amides
Suggested “Must Learn Items”
Functional Group Compound Type Suffix or Prefix ofname
Example Systematic Name(Common Name)
alkene -ene ethene(ethelene)
alkyne -yne ethyne(acetylene)
alcohol -ol methanol(methyl alcohol)
ether ether dimethyl ether
haloalkane halo- chloromethane(methyl chloride)
amine -amine ethylamine
C C C C
HH
HH
C C C C HH
C O H....
Important Functional Groups in Organic Compounds-I
H
H C O H
H
..
..
C O C
H H
H C O C H
H HC X
....
......
H
H C Cl
HC N
H H
H C C N H
H H H
Functional Group Compound Type Suffix or Prefix ofName
Example Systematic Name(Common Name)
aldehyde -al ethanal(acetaldehyde)
ketone -one 2-propane(acetone)
carboxylic acid -oic acid ethanoic acid(acedic acid)
ester -oate methyl ethanoate(methyl acetate
amide -amide ethanamide(acetamide)
nitrile -nitrile ethanenitrile(acetonitrile,methyl cyanide)
Important Functional Groups in Organic Compounds - II
O
C H
H O
H C C H
H O
C C C
H O H
H C C C H
H H O
C O H
H O
H C C O H
H O
C O C
H O H
H C C O C H
H HO
C N
H O
H C C N H
H HC N H
H C C N
H
....
....
..
..
..
....
......
.. ........
.. ......
.. ..
....
..
..
.... ..
....
Some Five-Carbon Skeletonsone double bond one simple ringsaturated carbon cpds.
Adding the H-Atom Skin to the C-Atom Skeleton
Xylenes–The Three Isomers of C8H10
CH3
CH3
CH3CH3
CH3
CH3
1,2-Dimethylbenzene (o-xylene) bp = 144.4°C
1,3-Dimethylbenzene (m-xylene) bp = 139.1°C
1,4-Dimethylbenzene (p-xylene) bp = 138.3°C
TNT and its Decomposition (Explosion!)
CH3
NO2
NO2
O2N
2,4,6-Trinitromethylbenzene (trinitrotoluene, TNT) C7H5N3O6
4 C7H5N3O6 (s) + 33 O2 (g)
28 CO2 (g) + 10 H2O(g) + 12 NO2 (g) + Energy
Naphthalene and Benzo[a]pyrene Aromatic Carcinogens
Napthelene C10H8
Benzo[a]pyrene C20H12
(P 621)
Isomers
Structural Stereoisomers
Geometric Optical
Optical Isomerism and Chiral Molecules
Stereoisomerism: Molecules with the same sequence of atoms, but different orientations of groups in space.
Optical isomerism: A type of stereoiosmerism that occurs when an object and its mirror image cannot be superimposed on each other.
Chiral: An asymmetric organic molecule that contains at least one carbon atom that is bonded to four different groups.
An Analogy for
Optical Isomers
Consider carbon bonded to A, B, C, and D. There are two possible structures.
Optical Isomers
A
D
B
C
A
D
C
B
B a
nd C
do
not s
uper
impo
se The two structures are mirrorimages of each other. Theyare optical isomers of each other.
Each of the two forms is asymmetric - noplane of symmetry. An organic molecule ischiral if it has a carbon atom that is bondedto four different groups.
The Rotation of Plane-Polarized Light by an Optically Active Substance
Some Reactions of Alcohols–IV
4) Substitution reaction of an alcohol with hydrohalic acids to form haloalkanes and water:
CH3-OH(l) + HCl(aq) CH3-Cl(g) + H2O(l)
CH3-CH2-CH2-OH(l) + HI(aq) CH3-CH2-CH2-I(l) + H2O(l)
General formula: R-OH + HX R-X + H2O
Examples:
5) Esterification: Alcohol + Organic Acid = Ester + Water
O OCH3-OH(l) + HC-OH H-C-O-CH3 (l)
[H+]
Methanol Formic acid Methyl formate
O OCH3-CH2-OH(l) + CH3-C-OH(l) CH3- C-O-CH2-CH3 (l)
Ethanol Ethanoic acid Ethyl ethanoate
[H+]
Optical Isomerism
How different are optical isomers? They have the exact same chemical formula, chemical and physical properties, but they are different in two ways:
1) They rotate the plane of polarized light (Fig 15.11): rotation to the right detrorotatory ( d or + ) rotation to the left levorotatory ( l or - ) 2) In their chemical properties, optical isomers differ only in a chiral environment. dform of A + dform of B product. dform of A + lform of B no reaction.
Example: Of d-glucose and l-glucose, only d-glucose is metabolizedin humans–a good example of the important selectivity of life forms.
The Binding Site of an Enzyme
The Basis of Proton Spin Resonance
Fig. 15.B (p. 622)
The 1H-NMR Spectrum of Acetone
Fig. 15.C (p. 623)
1H-NMR Spectrum of Dimethoxymethane
Fig. 15.D (p. 623)
Fig 15.EMRI ofthe HumanBrain(P 623)
R-Group Names and Chemical Formulas
methyl - CH3
ethyl - CH2 - CH3 or - C2H5
n-propyl - CH2 - CH2 - CH3 or - C3H7
isopropyl - CH - CH3
CH3
n-butyl - CH2 - CH2 - CH2 - CH3 or - C4H9
isobutyl - CH2 - CH - CH3
CH3
CH3
tert-butyl - C - CH3 CH3
H2 H2
H2
H2H2
Hcyclohexyl
H2 H2
H2
H2
cyclopentyl H
H2
H2
H2
cyclobutylH
H2
H2H
cyclopropyl
Types of Organic Reactions–I
1) Addition Reactions: These reactions occur when an unsaturated compound containing a double or triple bond becomes saturated by adding a compound. This reaction occurs for C=O, C=C and C=C bonds. X YGeneral form: R-CH=CH-R + X-Y R-C-C-R H H
Examples:
CH3-CH=CH-CH3 + H2 CH3-CH2-CH2-CH3
Br BrH-CH=CH-CH2-CH3 + Br2 H-C-C-CH2-CH3
H H
H ClH2C=CH2 + HCl H-C-C-H H H
A Color Test for the C=C Bonds
Fig. 15.14 (P 624)
Types of Organic Reactions–II
2) Elimination Reactions: These are the opposite of addition reactions. A saturated reactant becomes an unsaturated compound, and another molecule is formed.
X YGeneral form: R-CH-CH2 R-CH=CH2 + X-Y
Examples: OH H H2SO4
CH3-CH-CH2 CH3-CH=CH2 + H2O
OH Cr2O72- O
CH3-CH2-CH-CH3 CH3-CH2-C-CH3 + H2O H2SO4
Cl HCH3-CH-CH-CH2-CH3 CH3-CH=CH-CH2-CH3 + HCl
Types of Organic Reactions–III
3) Substitution Reactions: These reaction occur when an atom (or group) from an added reagent substitutes for one in the organic reactant.
General form: R-C-X + Y R-C-Y + X
Examples: CH3-OH + HBr CH3-Br + H2O
O CH3 CH3-C-Cl + CH3-CH-CH2-CH2-OH HCl + O CH3
CH3-C-O-CH2-CH2-CH-CH3
CH3-CH2-CH2-Br + CH3-CH2-ONa NaBr + CH3-CH2-CH2-O-CH2-CH3
CH3-CH2-CH2-Br + NaOH CH3-CH2-CH2-OH + NaBr
Recognizing the Type of Organic ReactionProblem: State whether each of the following reactions is an addition, elimination, or substitution reaction: a) CH3-CH2-OH + CH3-OH CH3-CH2-O-CH3 + H2O b) CH3-CH2-CH=CH-CH3 + H2 CH3-CH2-CH2-CH2-CH3
c) CH3-CH2-CH2-CH2-Cl CH3-CH2-CH=CH2 + HClPlan: We determine the type of reaction by examining the change in the number of atoms bonded to carbon. a) More atoms bonded to carbon is an addition. b) Fewer atoms bonded to carbon is an elimination. c) Same number of atoms bonded to carbon is a substitution.Solution: a) Substitution–the C-OH in both reactant molecules is converted into C-O bonds in the product molecule, so the same number of atoms are bonded to carbon.b) Addition–two C-H bonds form in the product, so more atoms are bonded to carbon.c) Elimination–two bonds in the reactant (C-H,C-Cl) are not in the product, so fewer atoms are bonded to carbon in the product.
The Redox Process in Organic Reactions
Oxidation numbers are not relied upon as much in organic reactions.
Instead, organic chemists note the movement of electron density around the carbon atom by counting the number of bonds to more electronegative atoms (normally oxygen) or to less electronegative atoms (normally H).
An oxidation-reduction (redox) reaction involves both oxidation and reduction, but organic chemists normally focus on the organic reactant only. Therefore:
When a C atom in the organic reactant forms more bonds to O or fewer bonds to H, the reactant is oxidized and the reaction is anoxidation.When a C atom in the organic reactant forms fewer bonds to O ormore bonds to H, the reactant is reduced and the reaction is a reduction.
Organic Oxidation and Reduction Reactions
An example of an organic reaction that involves oxidation-reductionis the reaction that occurs with ethanol and acidic potassium dichromateto yield acetic acid: O
CH3-CH2-OH CH3-C-OHK2Cr2O7 (acid)
In ethanol the C-2 has 2 bonds to hydrogen, and 1 bond to oxygen, whereas in the product (acetic acid) C-2 has three bonds to oxygen and no bonds to hydrogen. Thus, in this reaction the ethanol is oxidized toform acetic acid, so this reaction is an oxidation.
Another reaction is the addition of hydrogen to the double bond in propylene to form propane:
CH3-CH=CH2 + H2 CH3-CH2-CH3
Pd
Note that the C-2 and C-3 have more bonds to hydrogen than in the reactant propylene, so this the reactant is reduced , and the reaction isa reduction.
Alcohols
CH3OH Methyl alcohol-Methanol
C2H5OH Ethyl alcohol-Ethanol CH3CH2OH
C3H7OH Propyl alcohol-Propanol
H3C CH2 CH2 OH H3C CH OH
n-Propyl alcoholCH3
2-Propyl alcoholH3C CH2 CH2 CH2 OH
n-Butyl alcohol
Ethers
Dimethyl ether H3C–O–CH3
Ethyl methyl ether H3C–O–CH2–CH3
Diethyl ether H3C–CH2–O–CH2–CH3
Diphenyl etherC
CH CH
CH
CH
C CH
CH CH
CH
CH
CH O
Reactions of Alkyl Halides with Anions
CH3-CH2-CH2Cl + NaCN CH3-CH2-CH2CN + NaCl
CH3-CH2-Br + NaSH CH3-CH2-S-H + NaBr
CH3-CH2I + NaO-CH3 CH3-CH2-O-CH3
1-Chloropropane 1-Cyanopropane
1-Iodoethane Methylethyl ether
Bromoethane Ethylmercapton
CH3-CH2-Cl + NaNH2 CH3-CH2-NH2 + NaCl
Chloroethane Ethylamine
CH3-CH2-CH2-CH2-Br + NaOH CH3-CH2-CH2-CH2-OH + NaBr
1 - Bromobutane 1-Butanol1-Butyl alcohol
Polychlorinated Biphenyls (PCBs)
.. Cl.... ..Cl..
..
..Cl...... Cl..
..
Until recently, halogenated aromatics were used as insulating fluidsin electrical transformers and were discharged in waste water. Because of their low solubility, they accumulated for decades in river and lakesediment and were eaten by microbes and invertebrates. Fish ate the invertebrates, and birds and mammals, including humans, ate the fish. PCBs become increasingly concentrated in body fat at each stage. As a result of their health risks, PCBs in natural waters present a real problem.
PCBs
Some Biomolecules with the Amine Functional Group
General Structures of Amines
Reactions of Alcohols, Alkyl Halides and Amines
Problem: Determine the reaction type and predict the products of the following chemical reactions: ( a) CH3-CH2-CH2-OH
(b) CH3-CH2-Br + KOH
(c) CH3-CH2-OH + CH3-OHPlan: We examine the reactant(s) and other reagent(s) to decide on thepossibilities for each functional group, keeping in mind that, in general,one functional group changes into another.Solution:
Cr2O7-2
H2SO4
H2SO4
(a) Elimination (oxidation):
(b) Substitution:
(c) Elimination:
OCH3-CH2-C-OH Propanoic acid
CH3-CH2-OH + KBr Ethyl alcohol
CH3-CH2-O-CH3 Methylethyl ether
Hydrolysis-SaponificationThe Reverse Reaction of Ester Formation
Animal fats and/or vegetable fats which are “triglycerides” were broken down using a strong base such as lye (NaOH) to produce a “soap”.
OR- C-O-CH2
OR’-C-O-CH OR”-C-O-CH2
A triglyceride
+ 3 NaOH
OR-C-O- Na+
OR-C-O- Na+
OR-C-O- Na+
+
HO-CH2
HO-CH
HO-CH2
3 Soapmolecules
Glycerol
Amides
Formation of amides: Amides may be formed by the reaction between an organic acid or ester and amine in a dehydration-condensation reaction.
General formation: O H O H R-C-OH + H-N-R’ R-C-N-R’ + H2O
Examples:
O O HCH3-C-O-CH3 + H2N-CH2-CH3 CH3-C-N-CH2-CH3 + CH3-OH
Methyl ethanoate + Ethylamine N-Ethylethanamide + Methanol
O H O HCH3-CH2-C-OH + H-N-CH3 CH3-CH2-C-N-CH3 + H2O
Propionic acid Methyl amine N-Methylpropylamide
O CH3 O CH3
CH3-CH2-CH2-C-OH + H-N-CH2-CH3 CH3-CH2-CH2-C-N-CH2-CH3Butanoic acid Methylethylamine N-Ethyl-N-methylbutanamide
Some Molecules with the Amide Functional Group
The Formation of Anhydrides
Image to come.
Rules for Naming an Organic Compound–I
1. Naming the longest chain (root) (a) Find the longest continuous chain of carbon atoms. (b) Select the root that corresponds to the number of carbon atoms in this chain.2. Naming the compound type (suffix) (a) For alkanes, add the suffix -ane to the chain root. (Other suffixes appear in Table 15.5 with their functional group and compound type.) (b) If the chain forms a ring, the name is preceded by cyclo-.3. Naming the branches (prefix) (a) Each branch name consists of a subroot (number of C atoms) and the ending -yl to signify that it is not part of the main chain. (b) Branch names precede the chain name. When two or more branches are present, name them in alphabetical order.
Rules for Naming an Organic Compound-II
3. continued: (c) To specify where the branch occurs along the chain, number the main-chain C atoms consecutively, starting at the end closer to a branch, to achieve the lowest numbers for the branches. Precede each branch name with the number of the chain C atom to which that branch is attached. (d) If the compound has no branches, the name consists of the root and suffix. 6 carbons hex-
hex- + -ane = hexane CH3
CH3 CH CH CH2 CH3 CH3
CH2 CH3
methyl
ethyl
1 2 3 4 5
ethylmethylhexane
3-ethyl-2-methylhexane
6
Condensed vs. Expanded Formulas
Look at the formulas of 3-ethyl-2-methylpentane:
H
H C H H H H H
H C C C C C H
H H H H H C H
H C H
H
CH3
CH3 CH CH CH2 CH3
CH2
CH3
ExpandedFormula
Condensed Formula
Structure of a Cationic Detergent