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ORGANIC REACTIONS. Types of Reactions. Substitution: Polar Non-polar. Rearrangement. Definitions. Mechanism: Complete step-by-step of exactly which bonds break and which bonds form and in what order. - PowerPoint PPT Presentation
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04/20/23 1Dr Seemal Jelani
Substitution:◦ Polar
◦ Non-polar
H
BrHH + KCN
H
NCHH + KBr
CH4 + Cl2 CH3Cl + HCllight (h)
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Mechanism: Complete step-by-step of exactly which bonds break and which bonds form and in what order.
Thermodynamics: The study of the energy changes that occur in chemical transformations. This allows for comparison of stability of reactants and products.
Kinetics: The study of reaction rates, determining which products are formed most rapidly. One can predict how the rate will change with changing conditions.
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rate = kr[A] [B]a b
CH3Br + OH CH3OH + Br
Rate = k[CH3Br][OH ]
second order rate kinetics
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(CH3)3CBr + H2O (CH3)3OH + HBr
Rate = k[(CH3)3CBr]
First order rate kinetics
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Chlorination does not occur at room temperature in the dark.
The most effective wavelength of light is blue that is strongly absorbed by Cl2 gas.
The light-initiated reaction has a high quantum yield (many molecules of product are formed from each photon of light).
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It is the change that occurs in a system when one mole of matter is transformed by a chemical reaction under standard conditions
Bond Dissociation Energy the amount of energy which is required to homolytically fracture a chemical bond
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60%
40%
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C
CH3
CH3
CH3 H HCH3
CH3
CH2
C CH3
CH3
CH3
C.++ Cl
.
.
.
C
CH2
CH3
CH3 H
.C
CH3
CH3
CH3
+ Cl2
+ Cl2 C
CH3
CH3
CH3 Cl
C
CH2Cl
CH3
CH3 H 65%
35%
+ Cl
+ Cl
.
.
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.O3 O2 + Oh
C Cl
F
F
Cl Cl
F
F
C . .
. .
. .
Cl+
Cl + O3 ClO + O2
ClO + O Cl . + O2
O3 + O 2 O2.net reaction
i)
ii)
hultraviolet
a CFC
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ThemeOne Nucleophile is substituted for another nucleophile
General reaction
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A species that loves a nucleusSince nuclei are positively charged, so nucleophiles are negatively charged or bear a partial negative charge
Examples are lone pairs or a hydroxide ion.
Nucleophile is an electron rich species.
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An ion or molecule that is electron deficient and can accept electrons
Electrophiles are often reducing agents and Lewis acids
They are either positive ions (e.g. NO2 +) or
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molecules that have a positive charge on a particular atom(e.g. SO3, which has an electron-deficient sulphur atom)
In organic reactions they tend to attack negatively charged parts of a molecule
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Nucleophiles can be classified according to the kind of atom that forms a new covalent bond.1. Oxygen Nucleophile
(HO-, CH3O)
2. Nitrogen Nucleophiles (NH3,
RNH2…)
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3 Sulfur Nucleophiles (HS-, RS- …)
4 Halogen Nucleophiles (I-..)
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