Transcript Introduction of Organic Chemistry

Introduction of Organic Chemistry
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Syllabus
 Introduction of Organic chemistry
 Classification
 Sources
 Types
 Functional Groups
(Aldehydes,Ketone,Acids,Alccohols)
 Application
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Chemistry
 Chemistry is the study of the substances,
specially their structure, properties,
transformations and the energy changes
accompanying these transformation.
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Branches
 Organic Chemistry
 Inorganic Chemistry
 Physical Chemistry
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Discipline Branches of Chemistry
 Analytical Chemistry
 Industrial Chemistry
 Instrumental Chemistry
 Agriculture Chemistry
 Medicinal Chemistry
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Organic Chemistry
 The study of Carbon Compounds or better
to say the chemistry of hydrocarbons and
their derivatives.
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ATOMIC STRUCTURE
 Atom: Smallest indivisible particle of an
element
 Molecule: Smallest particle of matter
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Types of Bonding

Ionic bonding
– electron is fully transferred from metal to non-
metal
– binding is by electrostatic attraction.
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Ionic Bonding
Na
Sodium Atom
F
Fluorine Atom
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Ionic Bonding (2)
Na
Sodium ion
F
Fluoride ion
Attraction between the two ions is electrostatic -Ionic Bond
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A SIMPLE COVALENT BOND
A pair of electrons is shared between the two bonded atoms.
H.
.H
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A SIMPLE COVALENT BOND
Bonded pair
H H
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A LEWIS DIAGRAM
H
..
O
..
CONSTRUCTED
FROM LEWIS
DOT SYMBOLS
H.
(note use of lines for bonds)
H
COVALENT
BONDS
..
.O .
..
.H
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DRAWING CONVENTIONS
1. A shared pair (bond) is drawn as a line.
C
O
2. An unshared pair is shown as a pair of dots.
N:
3. The diagram includes formal charges (later).
H
.. +
O
H
H
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Bonding patterns
 Carbon
 Nitrogen
(phosphorus)
 Oxygen (sulfur)
 Halogen (F, Cl, Br, I)
 Hydrogen
4 bonds
3 bonds
2 bonds
1 bond
1 bond
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Normal bonding patterns
Carbon (4 bonds)
Nitrogen (3 bonds)
C
N
C
C
C
N
N
(Phosphorus)
Oxygen (2 bonds)
O
O
(Sulfur)
Halogen (1 bond)
X
(F, Cl, Br, I)
Hydrogen (1 bond)
H
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Common Bonding Patterns -- Cations
+
C
+
.. +
O
N +
+
O
..
N
+
N
+
O:
+
N
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Common Bonding Patterns -- Anions
_
B
..
C
_
.. _
N..
..
N
..
.. _
O:
..
_
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Types of Carbons
Primary (1°) – attached to only one other carbon
Secondary (2°) – attached to two other carbons
Tertiary (3°) – attached to three other carbons
Quaternary (4°) – attached to four other carbons
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Hydrocarbons
Aliphatic
alkanes – contain only single bonds
(saturated)
alkenes – contain at least one double bond
(unsaturated)
alkynes – contain at least one triple bond
Aromatic
contain a benzene ring
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Hydrocarbons
 Alkanes contain only single ( ) bonds and have the
generic molecular formula: [CnH2n+2]
 Alkenes also contain double ( + ) bonds and have
the generic molecular formula: [CnH2n]
 Alkynes contain triple ( + 2) bonds and have the
generic molecular formula: [CnH2n-2]
 Aromatics are planar, ring structures with alternating
single and double bonds: eg. C6H6
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Types of Hydrocarbons
Each C atom is tetrahedral with sp3 hybridized orbitals. They only have single bonds.
Each C atom is trigonal planar with sp2 hybridized orbitals.
There is no rotation about the C=C bond in alkenes.
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Types of Hydrocarbons
Each C atom is linear with sp hybridized orbitals.
Each C--C bond is the same length; shorter than a C-C bond: longer than a C=C bond.
The concept of resonance is used to explain this phenomena.
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Alkanes
1 meth
2 eth
3 prop
4 but
5 pent
6 hex
7 hept
8 oct
9 non
10 dec
methane
ethane
propane
butane
pentane
hexane
heptane
octane
nonane
decane
CH4
C 2 H6
C 3 H8
C4H10
C5H12
C6H14
C7H16
C8H18
C9H20
C10H22
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Naming Alkanes
C1 - C10 : the number of C atoms present in the chain.
-
Each member C3 - C10 differs by one CH2 unit. This is called a homologous series.
Methane to butane are gases at normal pressures.
Pentane to decane are liquids at normal pressures.
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Nomenclature of Alkyl Substituents
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Constitutional Isomers

Substances which have the same molecular
formula but a different structural formula.

Isomers differ in connectivity.
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• A compound can have more than one name, but a
name must unambiguously specify only one compound
A C7H16 compound can be any one of the following:
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Functional Groups




An atom or group of atoms which makes an organic
compound reactive and decides its functions (properties)
is called a Functional group.
In an organic compound, the alkyl group determines the
physical properties whereas the functional group
determines the chemical properties of the compound.
A Functional group can be introduced by displacing
hydrogen of the hydrocarbon.
The functional groups are directly attached to the carbon
of the organic compound.
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The basic structure of testosterone (male hormone) and estradiol
(female hormone) is identical.
 Both are steroids with four fused carbon rings, but they differ in the
functional groups attached to the rings.
 These then interact with different targets in the body.
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 6 functional groups, all hydrophilic
 In a hydroxyl group (-OH), a hydrogen atom forms a polar covalent bond
with an oxygen which forms a polar covalent bond to the carbon skeleton.
 Because of these polar covalent bonds hydroxyl groups improve the
water solubility of organic molecules.
 Organic compounds with hydroxyl groups are alcohols and their names
typically end in -ol.
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A carbonyl group (-CO) consists of an oxygen atom joined to the carbon
skeleton by a double bond.
 If the carbonyl group is on the end of the skeleton, the compound is an
aldelhyde.
 If not, then the compound is a ketone.
 Isomers with aldehydes versus ketones have different properties.
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A carboxyl group (-COOH) consists of a carbon atom with a
double bond with an oxygen atom and a single bond to a hydroxyl
group.
Compounds with carboxyl groups are carboxylic acids.
A carboxyl group acts as an acid because the combined
electro-negativities of the two adjacent oxygen atoms increase
the dissociation of hydrogen as an ion (H+).
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An amino group (-NH2) consists of a nitrogen atom attached to two
hydrogen atoms and the carbon skeleton.
Organic compounds with amino groups are amines.
The amino group acts as a base because amino groups can pick up
a hydrogen ion (H+) from the solution.
Amino acids, the building blocks of proteins, have amino and
carboxyl groups.
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A sulfhydryl group (-SH) consists of a sulfur atom bonded to a
hydrogen atom and to the backbone.
This group resembles a hydroxyl group in shape.
Organic molecules with sulfhydryl groups are thiols.
Sulfhydryl groups help stabilize the structure of proteins.
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A phosphate group (-OPO32-) consists of phosphorus bound to four
oxygen atoms (three with single bonds and one with a double
bond).
A phosphate group connects to the carbon backbone via one
of its oxygen atoms.
Phosphate groups are anions with two negative charges as two
hydrogens have dissociated from the oxygen atoms.
One function of phosphate groups is to transfer energy
between organic molecules.
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Functional Groups
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Functional Groups
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Classes of Organic Compounds
R
H
R
Alkane
R
O
R
R'
Ether
R
R
C
R
H
Aldehyde
C
R'
C
R
OH
Carboxylic Acid
C
Ketone
O
O
O
R
O
R
Alkene
R
OH
Alcohol
NH2
O
C
R
R
Amine
R
C
X
Alkyl Halide
C
Alkyne
R'
C
O
R
R'
Ester
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C
NH2
Amide
R
C
Nitrile
N
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ALCOHOL FUNCTIONAL GROUP
R –O H
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Classification
 Monohydric Alcohols
 Polyhydric Alcohols
- Dihydric Alcohols (Ethylene Glycol)
- Trihydric Alcohols (Glycerol)
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Monohydric Alcohols
 Devided in Primary, Secondary and tertiary
alcohols.
 CH3OH, CH3CH2OH
 Methanol
Ethanol
 CH3CH(OH)CH3
 Isopropyl Alcohol
 CH3C(OH)(CH3)

t-Butyl Alcohol
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Physical Properties
 Lower
are
colorless,
neutral
substances
with
characteristic sweet alcoholic smell and burning taste.
Higher are waxy solids.
 Lower are readily soluble in water & organic solvents but
it decreases as M.W. increases.
 B.P. are higher than corresponding alkanes. e.g.
Methanol-338 K and Methane-112K
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Preparation of Alcohol
 By Hydrolysis
R-X + NaOH→ R-OH + NaX
 By Hydration
CH2=CH2 → CH3CH2OH
 Hydrolysis of Esters
CH3COOC2H5 → CH3COOH + C2H5OH
 Reduction of Aldehyde/Ketone
CHO/C=O → 1-Alcohol/2-alcohol
 Grignard Reagent
R-Mg-X →R-O-MgX →R-OH
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Chemical properties
 Displacement of –OH gr. By Halogen(X)
R-OH + HX → RX + H2O
 Action of Alkali Metals
2ROH + 2Na → 2RONa + H2
 Dehydration
C2H5OH → CH2=CH2 + H2O
 Oxidation of Alcohol(K2Cr2O7/H2SO4)
1-alcohol → Aldehyde → Acid
 Reduction of Alcohols(Red P )
C2H5OH + 2HI → CH3CH3+H2O + I2
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METHANOL
H
H
H
C
OH
Methanol (methyl alcohol) or wood alcohol
a. Made by the destructive distillation of wood
b. Or by… CO + 2H2  CH3OH
c. Used as a solvent
d. Possible replacement for gasoline
e. Forms formaldehyde in body causing blindness
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ETHANOL
H
H
C
H
H
C
H
OH
Ethanol (ethyl alcohol) or grain alcohol
a. Made from the fermentation of grain, fruit, or sugar
b. C6H12O6 + yeast  2C2H5OH + CO2
c. The alcohol that is in beverages
d. Added to automotive fuels – 10% as gasohal
e. 1 pint of pure alcohol will kill most people
f. caused deterioration of the liver, memory loss
and is harmful to unborn babies
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ISOPROPYL ALCOHOL
OH
H
H
C C
H
H C H
H
H
Isopropyl alcohol (rubbing alcohol)
a. Alcohol used for cuts and cleaning
b. Will not be absorbed by the skin
c. Toxic if taken internally
d. Sold as a 70% solution – 140 proof
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Ethylene glycol
H
Ethylene glycol
a. Used for antifreeze in cars
b. Very sweet tasting
c. Toxic – caused kidney failure and death
H
H C C H
HO
OH
H
H
H C C H
HO
OH
O O
Liver
C C
HO
Kidney
CaC 2O4
OH
Oxalic acid
Calcium Oxalate
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GLYCEROL
H
H H
H C C C H
HO
OH OH
Glycerol
a. Used in lotion to keep skin soft
b. Food additive that keeps cookies soft
c. Can add to nitric acid to form nitroglycerin
Nitroglycerin (nitro) taken to relieve angina
heart pain
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Carbonyl Compounds
If an oxygen atom is attached to carbon by a double bond
the functional group –C=O is called carbonyl group.
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ALDEHYDE
O
R C H
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Physical Properties
 Formaldehyde is a gas at room temp. All other members
are colorless liquids at ordinary temp. The higher
members are solids.
 Lower aldehydes have unpleasant smell but as one goes
up in the series the smell becomes more fruity. Ketones
are generally pleasant smelling liquids.
 Solubilities
 Lower members are highly soluble in water. Solubilities
decreases with increasing molecular mass.
 B.P. are higher than those of non polar alkanes.
 B.P. of aldehydes/Ketones are lower than the B.P. of
alcohols.
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Chemical Properties

Addition Across C=O bond
CH3CHO + HCN
Acetaldehyde
-

HCH(OMgBr)CH3
CH3CH=NNH2 + H2O
Oxidation
CH3CHO

CH3CH=N-OH + H2O
With Hydrazine (Phenyl Hydrazine)
CH3CHO + H2NNH2

CH3CH2OH + Mg(OH)Br
With Hydroxyl Amine
CH3CHO + H2NOH

CH3CH(OH)COOH
2-hydroxy propanoicAcid
Addition of Grignard Reagent
HCHO + CH3MgBr

CH3CH(CN)OH
Cyanohydrins
CH3COOH
Reduction (Pt / Ni)
CH3CHO + H2
CH3CH2OH
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FORMALDEHYDE
Formaldehyde
O
C
H
H
a.
b.
c.
d.
Soluble in water
40% solution is called formaline
Used in some plastic manufacturing
Makes a good disinfectant
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BENZALDEHYDE
O
Benzaldehyde
a. called synthetic oil of almond
b. used as flavoring – maraschino cherries
c. used in perfumes
C H
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Ketones
O
R
C
R
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ACETONE
O
Acetone
a. Made from Isopropyl alcohol
CH3
O
OH
H 3C CH
H3C
C
CH 3
-H
H 3C
C
CH 3
b. Used as a solvent for fats, rubber, plastics, and varnishes
c. Used as fingernail polish remover
d. Will not mix with water
Washes water off of glassware after cleaning
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CARBOXYLIC ACID
O
R
C
OH
R COOH
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Physical Properties



The first nine mono carboxylic acids are colorless liquids, while
the higher ones are colorless wax like solids.
Solubility: The first four (formic, acetic, propeonic, butiric) are
soluble while fifth (valeric) is slightly soluble and acids above
six carbon are insoluble in water.
B.P. & M.P.: They have abnormally high b.p., even higher than
those of alcohols of similar molecular weights.
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Chemical Properties
Reaction with alkalies
R-COOH + NaOH
R-COONa + H2O
Decarboxylation
CH3COOH + NaOH
soda lime
CH3COONa + H2O
CH3COONa + NaOH
sodalime
CH4 + Na2CO3
Reduction
R-COOH
LiAlH4/ 2H2
R-CH2OH
Reaction with Carbonates
R-COOH + Na2CO3
R-COONa + H2O + CO2
Dehydration
2R-COOH
R-COOCOCH3 + H2O
Acid Anhydride
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FORMIC ACID
O
H
C
OH
Formic Acid
a. Irritant to skin
b. Part of the venom in ants, bee’s, or wasps
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ACETIC ACID
The acid in vinegar
O
CH 3 C
OH
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BENZOIC ACID
O
C
OH
Benzoic acid
Used to make benzene type compounds in organic synthesis
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ESTERS
O
R C O
R
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O
O
Apricot (pentyl buterate)
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O
O
Orange (Octyl acetate)
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O
CH3 C O
Jasmine (benzyl acetate)
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O
C O CH3
Wintergreen (methyl salicylate)
OH
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ETHER
R O R
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DIETHYL ETHER
O
Diethyl ether
a. Used as a solvent
b. Used for thinning paints
c. Boils at 36 C (dries quickly)
d. Used as anesthetic or as a drug
e. Dissolves organic compounds readily
f. Reacts with oxygen to form unstable peroxides
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TERT-BUTYL ETHER
CH3
CH3 O C CH3
CH3
Tert-butyl ether (MTBE)
a. Gasoline additive
b. Reduces CO emissions
c. Replaced lead as the antiknock compound
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ETHYLENE OXIDE
H
H
Ethylene Oxide
a. Very toxic gas
b. Used in the formation of ethylene glycol
c. Ethylene glycol is used in antifreeze and in polyester fibers.
C C H
H
O
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AMINES
R
primary
H N
H
H
R
H N
R N
H
H
amonia
secondary
R
R N
tertiary
R
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H
CH2 CH2 N
Amphetamine (stimulant drug)
H
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H
N
Analine (used in dyes)
H
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CH3
CH3 N
H
Dimethyl amine
used in volcanizing rubber, tanning hydes
and making of soaps
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CH2CH3
CH3CH2
N
CH2CH3
Triethyl amine
attracts insects
warning agent in natural gas
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