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Review
Organic Chemistry
Chemistry 203
Goal of atoms Filled valence levelNoble gases
(Stable)
Bonding
1. Ionic bonds
2. Covalent bonds
Ionic bonds
result from the transfer of electrons from one element to another.
Bonding
Metals: lose 1, 2 or 3 e- Cation (Y+)
Nonmetals: gain 1, 2 or 3 e- Anion (X-)
Ions
Cation (Y+): Na+ Li+ Ca2+ Al3+
Anion (X-): Cl- F- O2-
Bonding
Ionic bonds
Metal-Nonmetal
Na: 1s2 2s2 2p6 3s1 Cl: 1s2 2s2 2p6 3s2 3p5
AnionCation
Na+: 1s2 2s2 2p6 Cl-: 1s2 2s2 2p6 3s2 3p6
Ne Ar
Bonding
Covalent bonds
result from the sharing of electrons between two atoms.
Nonmetal-NonmetalMetalloid-Nonmetal
Sharing ofvalence electrons
Lewis Dot Structure
H He Li CAl N Cl
H H Or H H
Or Cl H
Lewis Structure
HCl
Cl: 1s2 2s2 2p6 3s2 3p5
H: 1s1 He: 1s2
Ar: 1s2 2s2 2p6 3s2 3p6
Intermolecular Forces
London dispersion forces
Dipole-dipole interaction
Hydrogen bonding
Ionic bondsCovalent bonds<
Intramolecular (Bonding) Forces
Intermolecular Forces
London dispersion forces
Attractive forces between all molecules
Only forces between nonpolar covalent molecules
2+
No PolarityOriginal Temporary
Dipole
δ- δ+
+2+
HeHe
Original Temporary Dipole
Induced Temporary Dipole
__ _ _
He He
2+_ ___ 2+
δ- δ+He
__ 2+
δ- δ+He
__ 2+
London dispersion forces
T ↓ Kinetic energy ↓Move slower
Attractive forcesbecome more important liquid
He: T = -240°C (1 atm) → liquid
Dipole-Dipole Interactions
Attractive forces between two polar molecules
stronger than London dispersion forces
boiling point ↑
Hydrogen bonding
Between H bonded to O, N, or F (high electronegativity) → δ+and a nearby O, N, or F → δ-
Stronger than dipole-dipole interactions & London dispersion forces
H2O
H O
H
H
O
H
- +
hydrogenbond
hydrogenbond
- +
(a) (b) (c)
Hydrogen bonding
CH3COOH
Acetic acidδ-
δ+
H-bonding in our body
DNA
H-bond
Protein (α-helix)
H-bond
Intermolecular Forces
Solubility
polar dissolves polar
Nonpolar dissolves nonpolarlike dissolves like
octane CCl4octane + CCl4
Organic Compounds
Hydrocarbons
Large family of organic compounds
Composed of only carbon and hydrogen
Saturated hydrocarbons
Alkanes
Unsaturated hydrocarbons
Alkenes, Alkynes & Aromatics
C - C C = C C CC
CC
C
CC
H
H
H
H
H
H
A Kekulé structureshowing all atoms
A Kekulé structureas a line-angle formula
Alkanes
Chemical reactions of Alkanes
Low reactivity
1- Combustion:
• Alkanes react with oxygen.
• CO2, H2O, and energy are produced.
• Alkane + O2 CO2 + H2O + heat
CH4 + 2O2 CO2 + 2H2O + energy
2- Halogenation:
Alkanes react with Halogens.
CH4 + Cl2 CH3Cl + HCl
Heat or light
Chemical reactions of Alkanes
Low reactivity
CH3Cl+ Cl2 CH2Cl2 + HCl
CH2Cl2+ Cl2 CHCl3 + HCl
CHCl3+ Cl2 CCl4 + HCl
Heat or light
Heat or light
Heat or light
Chloromethane
Dichloromethane
Trichloromethane
Tetrachloromethane
Alkenes & Alkyens
Chemical properties of Alkenes & Alkynes
More reactive than Alkanes
Addition of Hydrogen (Hydrogenation-Reduction)
Addition of Hydrogen Halides (Hydrohalogenation)
Addition of water (Hydration)
Addition of Bromine & Chlorine (Halogenation)
Chemical properties of Alkenes & Alkynes
Addition reactions
Exothermic reactions
–C = C – – C – C–
Products are more stable (have the lower energy).
• A hydrogen atom adds to each carbon atom of a double bond.
• A catalyst such as platinum or palladium is used (Transition metals).
H H H H
│ │ Pt │ │
H–C=C–H + H2 H– C – C– H
│ │
H H
Ethene Ethane
1. Hydrogenation (Reduction):
Pt
More reactive than Alkanes
Chemical properties of Alkenes & Alkynes
• A hydrogen halide (HCl, HBr, or HI) adds to alkene to
give haloalkane.
H H H H
│ │ │ │
H–C=C–H + HCl H– C – C– H
│ │
H Cl
Ethene Chloroethane
2. Hydrohalogenation:More reactive than Alkanes
Chemical properties of Alkenes & Alkynes
2. Hydrohalogenation:
- reaction is regioselective.
- Markovnikov’s rule: H adds to double bonded carbon that has the greater number of H and halogen adds to the other carbon.
CH3CH=CH2 HCl CH3CH-CH2
HClCH3CH-CH2
ClH
1-Chloropropane(not formed)
2-ChloropropanePropene
+
The rich get richer!
Chemical properties of Alkenes & Alkynes
3. Hydration (addition of water):
• Water adds to C=C to give an alcohol.
• Acid catalyst (concentrated sulfuric acid).
• A regioselective reaction (Markovnikov’s rule).
CH3CH=CH2 H2OH2SO4
CH3CH-CH2
HOH
Propene 2-Propanol+
CH3C=CH2
CH3
H2OH2SO4 CH3C-CH2
CH3
HO H2-Methyl-2-propanol2-Methylpropene
+
Chemical properties of Alkenes & Alkynes
• A halogen atom adds to each carbon atom of a double bond.
• Usually by using an inert solvent like CH2Cl2.
H H H H
│ │ │ │
CH3–C=C–CH3 + Cl2 CH3– C – C– CH3
│ │
Cl Cl
2-Butene 2,3-dichlorobutane
4. Halogenation:
CH2Cl2
More reactives than Alkanes
Chemical properties of Alkenes & Alkynes
Aromatic Hydrocarbons
Halogenation
Nitration
Sulfonation
No addition reactions (almost unreactive)
Chemical properties of aromatics
Aromatic substitution: One of the H atoms is repalecd by some groups.
Chemical properties of benzene
1. Halogenation:
H Cl2FeCl3 Cl HCl+ +
ChlorobenzeneBenzene
Cl and Br react rapidly with benzene in the presence of an iron catalyst.
2. Nitration:
H HNO3H2SO4
NO2 H2O++
Nitrobenzene
Chemical properties of benzene
In presence of concentrated nitric acid and sulfuric acid, one of the H atoms is replaced by a nitro (-NO2) group.
3. Sulfonation:
Chemical properties of benzene
H H2SO4 SO3H H2O+
Benzenesulfonic acid
+
In presence of concentrated sulfuric acid and heat, one of the H atoms is replaced by sufonic acid (-SO3H)
group.
Heat
OH NaOHH2O
O-Na+ H2O+
Phenol Sodium phenoxide(a water-soluble salt)
+OH
Alcohols
Chemical Properties of Alcohols
1. Acidity of Alcohols:
2. Acid-Catalyzed Dehydration:
CH3CH2OH CH2 = CH2 + H2OH2SO4
180°C
3. Oxidation of Alcohols:
C = C + H20Dehydration
Hydration- C – C -
H OH
OH NaOHH2O
O-Na+ H2O+
Phenol Sodium phenoxide(a water-soluble salt)
+
Alkene having the greater number of alkyl groups on the double bond
generally predominates.
Acid-Catalyzed Dehydration
CH3CH2CHCH3
OH H3PO4 CH3CH=CHCH3 CH3CH2CH=CH2
1-Butene (20%)
2-Butene (80%)
2-Butanol
+-H2O
CH3CHCHCH3OH
CH3 H2SO4CH3C=CHCH3
CH3
CH3CHCH=CH2
CH3
3-Methyl-1-butene2-Methyl-2-butene (major product)
3-Methyl-2-butanol
+-H2O
In the oxidation [O] of a primary alcohol 1, one H isremoved from the –OH group and another H from the Cbonded to the –OH.
primary alcohol aldehyde
OH O │ ║ CH3─C─H CH3─C─H + H2O │ H
ethanol ethanal (ethyl alcohol) (acetaldehyde)
Oxidation of 1° Alcohols
K2Cr2O7
H2SO4
[O]
The oxidation of 2 alcohols is similar to 1°, except that a
ketone is formed.
secondary alcohol ketone
OH O │ ║
CH3─C─CH3 CH3─C─CH3 + H2O │
H
2-propanol 2-propanone
Oxidation of 2° Alcohols
[O]
K2Cr2O7
H2SO4
Tertiary 3 alcohols cannot be oxidized.
Tertiary alcohol no reaction
OH │
CH3─C─CH3 no product │
CH3 no H on the C-OH to oxidize
2-methyl-2-propanol
Oxidation of 3° Alcohols
K2Cr2O7
H2SO4
[O]
Thiols
Chemical Properties of Thiols
1. Thiols are weak acids (react with strong bases).
CH3CH2SH + NaOH CH3CH2S-Na+ + H2OH2O
2. Oxidation to disulfides: -S-S- disulfide
2HOCH3CH2SH + O2 HOCH2CH2S-SCH2CH2OHOxidation
Reduction
Sodium ethanethiolate
CH3-NH2 CH3-NH-CH3
CH2CH3 CH3 CH=CH2
TolueneEthylbenzene Styrene
NH2
Amines
Chemical properties of Amines
They are weak bases (like ammonia): react with acids.
N
H
H
CH3 .. + H – O – H....N
H
H
CH3 H+
O – H......
-
(to form water-soluble salts)
(CH3CH2)2NH HCl
NCH3COOH
NH
(CH3CH2)2NH2+Cl-
CH3COO-
Diethylammoniumchloride
+Pyridinium acetate
+(a)
(b) +
Aldehydes & Ketones
Chemical properties of Aldehydes and Ketones
1. Oxidation: only for aldehydes (not for ketones).
K2Cr2O7
H2SO4
CH3─CH2─CH2─CH2─C─OH
=
O
CH3─CH2─CH2─CH2─C─H
=
O
Pentanal Pentanoic acidK2Cr2O7: Oxidizing agent
CH
O
Benzoic acidBenzaldehyde
+ O2
COH
O
2 2Liquid aldehydes
are sensetive to oxidation.
No oxidizing agent
Chemical properties of Aldehydes and Ketones
2. Reduction:
Like reducing the alkene (C = C) to alkane (C – C):
– Reduction of an aldehyde gives a primary alcohol (-CH2OH).
– Reduction of a ketone gives a secondary alcohol (-CHOH-).
H2
tran sition
metal catalyst+
1-Pen tan ol
CH3─CH2─CH2─CH2─C─ H
=
O
PentanalCH3─CH2─CH2─CH2─CH2─ OH
H2
tran si tion
metal cataly st+CH3─C─CH2─CH3
=
O
CH3─CH─CH2─CH3
-OH
2-butanol2-butanone
3. Addition of alcohols (hemiacetals):
CH
OO-CH2CH3
HC OCH2CH3
H
O-H+
Benzaldehyde Ethanol A hemiacetal
H of the alcohol adds to the carbonyl oxygen and
OR adds to the carbonyl carbon.
unstable
Chemical properties of Aldehydes and Ketones
Chemical properties of Aldehydes and Ketones
O-CH2CH3H C OCH2CH3
H
O CH2CH3
+
Ethanol An Acetal
C OCH2CH3
H
O-H
A hemiacetal
+H2OAcid
3. Addition of alcohols (Acetals):
H
O
O-HC
O O
H
H
O O-H
H
4-Hydroxypentanal A cyclic hemiacetal
123
45
1345
redraw to show the -OH and -CHO close
to each other2
3. Addition of alcohols (hemiacetals):
If –OH is part of the same molecule that contains C=O.
Chemical properties of Aldehydes and Ketones
Carboxylic Acids
carbonyl group O
CH3 — C—OH hydroxyl
Carboxyl group
COOH NaOHH2O
COO- Na
+H2O+ +
Benzoic acid(slightly soluble in water)
Sodium benzoate(60 g/100 mL water)
COOH NH3H2O
COO- NH4
++
Ammonium benzoate(20 g/100 mL water)
Benzoic acid(slightly soluble in water)
1- Reaction with bases:
Chemical properties of Carboxylic Acids
2- Reduction:
Chemical properties of Carboxylic Acids
Resistant to reduction
Using a powerful reducing agent: LiAlH4 (Lithium aluminum hydride).
1° alcohol
COH
=OLiAlH4, ether
H2OCH2OH
3-cyclopentene-carboxylic acid
4-Hydroxymethyl-cyclopentene
Chemical properties of Carboxylic Acids
3- Fischer Esterification:
- A carboxylic acid reacts with an alcohols to form an ester.
- Using an acid catalyst such as concentrated sulfuric acid.
CH3C-OHO
H-OCH2CH3
H2SO4CH3COCH2CH3
OH2O
Ethanoic acid(Acetic acid)
++
Ethyl ethanoate(Ethyl acetate)
Ethanol(Ethyl alcohol)
The best way to prepare an ester.
4- Decarboxylation:
Chemical properties of Carboxylic Acids
Loss of CO2 from a carboxyl group.
decarboxylation +O
RCOH RH CO2Heat
Esters & Amides
CH3 — C — NH2
O
Amide group
Formation of Esters
RCOHO
A carboxylic acid
=
Fischer Esterification
RCOR'O
RC-OHO
H- O R '
==
An alcoholA carboxylic acid An ester
H2SO4
+ H2O
Chemical Reactions of Esters
1. Hydrolysis: reaction with water.
(breaking a bond and adding the elements of water)
RCOR 'O
RC-OHO
H- O R '
= =An alcoholA carboxylic acidAn ester
+ H2O +Heat
Acid
2. Saponification (Hydrolysis): an ester reacts with a hot aqueous base.
RCOR'O
RCO-NaO
H- O R '
= =
An alcoholA sodium saltAn ester
+ NaOH +H2O
Heat - +
CH3COCH2CH3
OCO-NaO
CH3CH2OH
= =EthanolSodium acetateEthyl Ethanoate
+ NaOH +- +
CH3
Chemical Reactions of Esters
3. Esters react with ammonia and with 1° and 2° amines to form amides.
Thus, an amide can be prepared from a carboxylic acid by first converting the carboxylic acid to an ester by Fischer esterification and then reaction of the ester with an amine.
OCH2CH3
O
+ NH3 NH2
O
+ CH3CH2OH
Ethyl 2-phenyl acetate 2-Phenylacetamide
Chemical Reactions of Esters
Formation of Amides
RCOHO
A carboxylic acid
=
RCNHR'O
RC-OHO
H- N HR
==
An AmineA carboxylic acid An amide
Heat+ H2O'
H2OCH3C-NHCH2CH3
OHHNCH2CH3CH3C-OH
O+ +
Acetic acid Ethanamine N-ethylethanamide
Chemical Reactions of Amides
Such as esters:
Hydrolysis in hot aqueous acid or base.
CH3CH2CH2CNH2
OH2O HCl
H2OCH3CH2CH2COH
ONH4
+Cl
-
Butanoic acidButanamide
++ +heat
CH3CNHO
NaOHH2O
CH3CO-Na+O
H2N
AnilineSodiumacetate
Acetanilide
++heat
Amides do not react with ammonia or with amines.
Chemical Reactions of Amides
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