Functional Group

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Functional Group

• Functional Group small group of atoms with
  characteristic properties

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Haloalkanes

• At least one halogen atom has replaced a hydrogen
  atom on the hydrocarbon chain
• Nomenclature for haloalkanes
• Name the halogen as a substituent.
• fluoro, chloro, bromo, iodo

CH3CH2C(CH3)ClCH2CHClCH3
CH3CH2CCCBr3
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Halogens on Aromatics
1,2-dichlorobenzene
o-dichlorobenzene
1,4-diiodobenzene
chlorobenzene
1-chloro-1-phenylethane
p-diiodobenzene
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Properties and Uses of Haloalkanes
CFC
Pesticides Refrigerants High toxicity
Lindane
DDT 1,1,1-trichloro-2,2-bis-p-chlorophenylethane
Chlordan
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Reactivity of Haloalkanes
Cl
Polar compound because the electron withdrawing
strength of the halogen
Nucleophilic substitution
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Nucleophilic Substitution

• A reaction in which a nucleophile replaces the
  halogen on the molecule
• nucleophile
• a reactant attracted
• to centers of
• positive charge

N- R X ? N R X-
If N- OH- ? alcohol formation
OR- ? ether formation NH2- ?
amine formation RCOO- ? ester
formation CN- ? nitrile formation
SH- ? mercaptan formation
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Nucleophilic Substitution Mechanisms

• SN1 reaction
• S substitution
• N nucleophilic
• 1 molecularity
• Formation of carbocation
• Following by nucleophile attack
• Forms racemic mixture if molecule is chiral

• SN2 reaction
• S substitution
• N nucleophilic
• 2 molecularity
• Simultaneous nucleophile attack while leaving
  group leaves molecule
• Complex is formed
• Inversion of molecule results in formation of
  opposite enantiomer (if molecule is chiral)

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SN1 reaction (heterolytic dissociation)
Rate determining step is unimolecular

I-
?
carbocation
?
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SN1 reaction (heterolytic dissociation)
?
H3O
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SN2 reaction
Entering group
Leaving group
Rate determining step is unimolecular
?
Complex
?
I-
Inversion of product
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SN1 or SN2?
Why does one of these molecules undergo
substitution by SN1 while the other undergoes
SN2?
Steric hinderance
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Example Problem

• A pure, optically active sample of one isomer of
  CHCl(C6H5)CH3 is hydrolyzed by water, and the
  product is optically inactive.
• Is the mechanism SN1 or SN2?
• Write the formula of the product.

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Example Problem

• The following haloalkane compounds undergo
  nucleophilic substitution by the SN1 mechanism.
  Which of the following would you expect to
  proceed more rapidly
• a) CH3F b) CH3Cl c) CH3Br d) CH3I

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Nomenclature for Functional Groups
If N- OH- ? alcohol formation
OR- ? ether formation NH2- ?
amine formation RCOO- ? ester
formation CN- ? nitrile formation
SH- ? mercaptan formation
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Alcohols
ethanol
methanol
2-propanol
1-propanol
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Alcohols
2-methyl-2-propanol
Tertiary alcohol three carbon chains attached
to carbon with OH functional group
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Phenol
phenol
hydroxybenzene
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Physical Properties of Alcohols

• Boiling Pts of alkanes
• CH4 -162 oC
• C2H6 -88.5 oC
• C3H8 -42 oC
• C4H10 0 oC

• Boiling pts of alcohols
• CH3OH 64.5 oC
• C2H5OH 78.3 oC
• C3H7OH 97.0 oC
• C4H9OH 188 oC

1) BP of alcohols are higher due to hydrogen
bonding 2) BP of molecules increase with
increasing molar mass this results because of
increased London forces
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Ethers
dimethyl ether
ethylmethyl ether
diethyl ether
2-ethoxyethanol
Can also call an O-R alkoxy group O-C2H5 would
be ethoxy
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Physical Properties of Ethers

• Boiling pts of alcohols
• CH3OH 64.5 oC
• C2H5OH 78.3 oC
• C3H7OH 97.0 oC
• C4H9OH 188 oC

• Boiling pts of ethers
• CH3-O-CH3 -24 oC
• C2H5-O-C2H5 34.6 oC

1) BP of alcohols are higher due to hydrogen
bonding
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Amines
methanamine
Ethanamine or aminoethane
aminomethane
dimethylamine (secondary)
trimethylamine (tertiary)
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Physical Properties of Amines

• Boiling pts of alcohols
• CH3OH 64.5 oC
• C2H5OH 78.3 oC
• C3H7OH 97.0 oC
• C4H9OH 188 oC

• Boiling pts of amines
• CH3NH2 -7.5 oC
• C2H5NH2 17 oC
• C3H7NH2 49 oC
• C4H9NH2 78 oC

Amines are generally basic
ethers CH3-O-CH3 -24 oC C2H5-O-C2H5
34.6 oC
Amines have hydrogen bonding not as strong as
alcohols. Ethers do not have hydrogen bonding.
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Functional Groups
-ol
-al
-amine
-amide
-oic acid
-oate
-one
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Esters
methyl ethanoate or methyl acetate
methyl methanoate or methyl formate
ethyl ethanoate or ethyl acetate
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Properties of Esters

• Fragrant odors
• Naturally occurring as fats and oils

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Alkene Preparation

• Elimination Reaction
• Dehydrohalogenation removing a hydrogen and
  halogen atom from the molecule
• CH3CH2CHBrCH3 ? CH3CH CHCH3

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Elimination Reaction
2-butene
1-butene
?
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Elimination Reaction

• Dehydration starting with an alcohol, eliminate
  water and produce an alkene
• Dehydrogenation removing two hydrogen atoms
  from the molecule (difficult)
• CH3CH3 ? CH2 CH2
• Requires a catalyst in which a complex surface
  reaction must occur

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Electrophilic Addition Reactions
Alkenes and alkynes are more reactive than alkanes

• Alkenes (and alkynes) contain double bonds due to
  the formation of p bonds
• p bonds are electron rich regions

What will be attracted to the negative p region?
Electrophile a reactant attracted to the region
of high electron density
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Electrophilic Addition Reactions
Br -
?
Br -
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Types of Addition Reactions

• Hydrogenation H2
• Halogenation Br2, Cl2
• Hydrohalogenation HBr, HCl
• Hydration HOH

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Aromatic Reactions

• Predominant reaction electrophilic substitution
• Benzene rings have a highly dense electron region

Special stability of the benzene ring does not
favor addition reactions aromatics are generally
less reactive than alkenes
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Mechanism for Electrophilic Substitution
Nitration of benzene
HNO3 H2SO4 ? NO2 HSO4- H2O
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Adding a
Second Substituent
Electron withdrawing substituents are meta
directors
The presence of the first substituent will impact
the environment of the overall structure. How?
Example meta directors NO2, COOH, CN, CHO, SO3H
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Adding a
Second Substituent
Electron donating substituents are ortho/para
directors
If phenol were nitrated (NO2), what would the
major product(s) be?
Example o/p directors OH, NH2, Cl, Br,
2 main products are o and p
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Types of Polymerization
Polymer macromolecule made up of a great many
smaller repeating units

• Addition polymerization
• Chain-reaction polymerization
• Freeradical chain reaction polymerization
• Condensation polymerization
• Step-reaction polymerization
• Copolymerization
• Composite material

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Addition polymerization
2

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Plastics
Monomer The repeating unit of a polymer.
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Recycling Plastics
http//www.obviously.
com/recycle/

• Type 1 recycled soda water containers
• Type 2 recycled milk, detergent, oil
  bottles
• Type 3 not commonly recycled PVC
• Type 4 not commonly recycled plastic bags,
  shrink wrap
• Type 5 not commonly recycled bottle tops,
  carpets, containers
• Type 6 not recycled throwaway utensils,
  protective packing
• Type 7 not recycled layered or mixed plastics

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Electrically Conducting Plastics
Electrons move from p bond to p bond
Adding I3- ion to structure enhances the
conductivity
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Electrically Conducting Plastics
Dupont calls this Olight technology
IBM calls this OLED technology
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Flat-Screen Technology

• High brightness and contrast
• Ultra-wide viewing angle
• No backlight required
• Thin, compact form factor
• Fast response time
• Low power consumption

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Condensation Polymerization

• Polyester
• Polyamide
• Combines a carboxylic acid with an amine
• nylon

Alcohol
H2O
Carboxylic acid
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Copolymers
Polymers made up by more than one type of monomer
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Composite

• Consists of two or more materials that have been
  solidified together.
• Seashells
• Bones
• Silicon carbide ceramic embedded with silicon
  carbide fibers
• The fibers are made from the polymer
  dimethylsilane
• Ceramics are brittle, but embedding the polymer
  enhances structural integrity

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Physical Properties of Polymers

• No definite masses chain-lengths
• No definite melting point gradually soften, high
  viscosity
• Strength depends on intermolecular forces if
  substituent groups can form H-bonds, get stronger
  forces if the chain is longer, get stronger
  London forces either results in a stronger
  polymer
• Elasticity ability to return to original state

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Aldehydes, Ketones,
and Carboxylic Acids

• All contain the carbonyl group (C O)

Carboxylic acid
Ketone
Aldehyde
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Aldehydes, Ketones,
and Carboxylic Acids
2-butanone
propanal
propanioc acid
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Oxidation of Alcohols
Primary alcohol
O2 (g) ?
Alcohols can be oxidized into aldehydes, which
can be further oxidized into carboxylic acids
O2 (g) ?
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Oxidation of Alcohols
Secondary alcohol
O2 (g) ?
Can a ketone be further oxidized to produce a
carboxylic acid?
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Intermolecular Interactions

• Why is the solubility, FP, and BP increased?
• Changes in intermolecular interactions
• Alkanes, alkenes, alkynes have low solubility (in
  water), low FP and BP
• London dispersion forces
• Carbonyl compounds have higher solubility (in
  water), higher FP and BP
• Dipole dipole interactions

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Solvents

• Increased solubility in water makes these
  substances good solvents.
• O
• Acetone (propanone) CH3 C CH3
• Completely miscible in water, yet dissolves many
  organic substances

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Carboxylic Acids
Propanal 49 oC Propanoic acid 141 oC

• Hydrogen bonding
• Carboxyl group
• O
• R C OH
• Hydrogen bonding results in high solubilities, FP
  and BP

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Carboxylic Acids

• Weak acids O
• HC2H3O2 acetic acid CH3 - C O H
• Vinegar, very important base product for polymer
  production
• rayon, cellophane
• Acetylsalicylic acid ?

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Organic Bases

• Amines hydrocarbon group with N attached
• Will amines be soluble?

secondary
tertiary
primary
N H bond in the amine results in hydrogen
bonding between molecules these compounds will
be soluble in water when the molecules are small
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Amides

• Formed through a condensation reaction of a
  carboxylic acid and amine (acid/base reaction)
• Salt is an amide

acid
base
salt
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Amide Linkage

• Amide linkage resulting
• from the condensation
• reaction is very important
• biologically.
• When the carboxylic acid and amine compounds are
  both amino acids, the resulting amide linkage is
  a peptide bond.

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Example Amides
LSD
Acetaminophen
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Amide Linkage

• When the amide linkage
• results from the bonding
• of two amino acids, the bond
• is called a peptide bond.

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Peptide Bond

• Bond between two amino acids

dipeptide
a carbon
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Proteins

• Long chain of amino acids bound through repeating
  a-carbon, amide linkage, a-carbon (50 to several
  thousand)
• Many possible sequences of amino acids

SEQUENCE ? SHAPE ? FUNCTION
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Amino acid sequence

• Primary structure determines the proteins
  unique identity
• Three fragments of human hemoglobin
• Leu-Ser-Pro-Ala-Asp-Lys-Thr-Asn-Val-Lys-
• -Val-Lys-Gly-Trp-Ala-Ala-
• -Ser-Thr-Val-Leu-Thr-Ser-Lys-Ser-Lys-Tyr-Arg

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Shape
Hydrogen bonding
a-helix

• Secondary structure
• the arrangement of the
• chain in a regular pattern.
• Dependent on amino
• acid sequence

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Secondary Structure
Triple helix
b-sheet
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Function

• Tertiary structure overall shape
• Globular
• Fibrous
• di-sulfide bonds are examples of forces that help
  to fold proteins into tertiary structures
• Enzymes tertiary structure determines what
  other substances can bind to the enzyme

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Quaternary Structure

• Specific arrangement of neighboring polypeptide
  units
• Denaturation loss of one or any of the four
  structures

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4 Levels of Protein Structure
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Carbohydrates

• Monosaccharides

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Aldopentose
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Aldohexose
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Ketopentose
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Ketohexose
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Forms of Fructose

• ketose ketone sugar
• polyhydroxy ketone

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Forms of Glucose

• Aldose aldehyde sugar
• polyhydroxy aldehyde

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Condensation Reactions

• Disaccharides
• Maltose, lactose, cellobiose, sucrose
• Polysaccharides
• Starch (Glycogen)
• Formed through linkages of the a form
• Cellulose
• Formed through linkages of the b form

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starch
cellulose
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Nucleic Acids

• DNA deoxyribonucleic acid
• RNA ribonucleic acid
• Nucleotide monomer unit of nucleic acid
• Phosphoric acid molecule
• Five-carbon sugar
• Nitrogen-containing organic base

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Nucleotides
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Complementary base pairs