This document discusses organic reactions including substitution, elimination, addition, and rearrangement reactions. It provides details on: - The components and mechanisms of nucleophilic substitution reactions including SN1 and SN2 pathways. - The key differences between SN1 and SN2, including rate determining steps and order of reaction. - Elimination reactions including E1 and E2, and the differences in their mechanisms and requirements. - Addition reactions including electrophilic addition and examples like hydrogenation, halogenation, and hydration. - Rearrangement reactions where the carbon skeleton is rearranged to form structural isomers.

1. GENERAL CHEMISTRY
PAGADIAN CITY SCIENCE HIGH SCHOOL

2. Organic reactions are chemical
processes in which one or more
organic compounds undergo
transformations to form new
organic compounds. Organic
compounds primarily consist of
carbon and hydrogen atoms,
with some exceptions that may
also include elements like oxygen,
nitrogen, sulfur, and others.

3. Organic reactions require the
breaking of strong covalent
bonds, which takes a
considerable input of energy. In
order for relatively stable organic
molecules to react at a
reasonable rate, they often must
be modified with the use of
highly reactive materials or in the
presence of a catalyst.

4. Substitution
Reactions
01 02
Elimination
Reactions
04
Rearrangement
Reactions
03
Addition
Reactions

5. SUBSTITUTION
REACTIONS
A substitution reaction is a reaction
in which one or more atoms in a
molecule are replaced with another
atom or group of atoms attached to a
carbon atom in a compound.
To recognize: two compounds react
to form two products.

6. COMPONENTS OF
SUBSTITUTION REACTIONS
• Nucleophile (Nu): the electron-rich species
donating a pair of electrons to carbon.
• Electrophile: the electron-deficient species
accepting a pair of electrons.
• Product: the species that is formed from a
substitution reaction.
• Leaving group (LG or X): the group that leaves
the compound; typically an anion (e.g. Cl-) or a
neutral molecule (e.g. H2O).

7. It is a reaction which strong nucleophile
replace the weak nucleophile.
Having a nucleophile and a carbon atom
connected to an electronegative atom
is not enough for a substitution to
happen.
1. NUCLEOPHILIC SUBSTITUTION
TYPES OF SUBSTITUTION REACTIONS

8. What makes a good leaving group?
Good leaving group are the ones that
stabilized negative charge, so the weaker
the LG as a base, the better it is as
leaving group.
Types of Nucleophilic Substitution
• SN2 reaction (Bimolecular
Nucleophilic reaction)
• SN1 reaction (Unimolecular
Nucleophilic reaction)

9. The nucleophile attacks and kicks out the leaving
group. In other words, this happens simultaneously
(concerted mechanism) - as one comes, the
other one leaves.
BIMOLECULAR NUCLEOPHILIC
REACTION (SN2)

10. TRANSITION STATE
All chemical transformations go
via an unstable structure known
as the transition state, which
exists between the chemical
structures of the substrates and
products.
BIMOLECULAR NUCLEOPHILIC
REACTION (SN2)

11. The word “bimolecular” indicates a second-
order reaction because the rate of reaction
depends on both of the concentration of alkyl
halide and nucleophile.
The rate of the reaction is based on the
concentrations of the reactants involved in
the slowest step in the mechanism (Rate
Determining Step).
A second-order reaction indicates that both
reactants collide/participate in the transition
state of the reaction.
BIMOLECULAR NUCLEOPHILIC
REACTION (SN2)

12. BIMOLECULAR NUCLEOPHILIC
REACTION (SN2)

13. UNIMOLECULAR NUCLEOPHILIC
REACTION (SN1)
The leaving group leaves first, and only after this step, the
nucleophile can attack. This is the stepwise - S1
mechanism, Let's discuss both mechanisms one-by-one.
The nucleophile does not appear in the rate equation
which means it has no impact on the rate of the SN1
reaction.

14. Step [1] Breaking the C – LG bond.
In this rate-determining step, a
carbocation intermediate is formed.
Step [2] A nucleophilic attack. The
carbocation is highly electron-
deficient and the nucleophile
attacks as a Lewis base using its
lone pairs
TWO STEPS IN SN1 MECHANISM

15. The rate determining (slowest), step
in Sn1 mechanism is the loss of the
leaving group. When the leaving
group is gone, there is a carbocation
formed. This is the intermediate.
Sn1 is a unimolecular (first order)
mechanism and the rate of the
reaction depends only on the
concentration of the substrate.
UNIMOLECULAR NUCLEOPHILIC
REACTION (SN1)

16. UNIMOLECULAR NUCLEOPHILIC
REACTION (SN1)

17. ELIMINATION REACTIONS
Involve the removal of two adjacent
atoms/substituents from a molecule.
This results in the formation of a double
bond and the release of a small molecule.
E1 Elimination
(Unimolecular)
TYPES:
E2 Elimination
(Bimolecular)

18. • E1 reaction is particularly common in
secondary and tertiary alkyl halides
in absence of a strong base.
+ X + H-B
Byproduct/s

19. • Leaving group (Br)
leaves, forming a
carbocation (C+)
intermediate.
2. A base (H2O)
deprotonates an
H atom to form a
pi bond.

20. • E2 reaction occurs when an alkyl halide is
treated with a strong base such as
hydroxide ion (OH-).
+ X + H-B

22. E1 Reaction E2 Reaction
Mechanism Two-steps One-step
Base Usually weak (H2O, ROH, R2NH) Strong (OH–, RO–, R2N–)
Leaving group Essential and must be good Not important
Steps
• Leaving group leaves, forming a
carbocation (C+).
• Base removes a proton, forming
the alkene.
• Simultaneous removal of the
leaving group and hydrogen
atom in presence of a base
to form C=C bond.

23. ADDITION REACTIONS
Alkenes and alkynes are unsaturated
hydrocarbons containing carbon-
carbon double (C=C) and triple (C≡C)
bonds, respectively.
Alkenes and alkynes exhibit higher
reactivity compared to alkanes.

24. ADDITION REACTIONS
The Addition Reaction is an organic
reaction where two or more molecules
combine to form a larger one. Addition
reactions can only occur on reagents
that have multiple bonds.
Is essentially the reverse of the
Elimination Reaction.

25. 2 TYPES OF ADDITION
REACTIONS
Electrophilic Addition Reactions
Electron deficient species and can
accept an electron pair from electron
rich species.
Unsaturated
Reactants
Electrophile
Saturated
Product
+ →

26. Hydrogenation
a chemical reaction that adds
molecular hydrogen (H2) to a
compound.
Catalysts: Ni, Pd, Pt, etc.
DIFFERENT FORMATIONS
OF ADDITION REACTIONS

27. Halogenation
a chemical reaction that occurs
when halogens are added to a
substance.
DIFFERENT FORMATIONS
OF ADDITION REACTIONS
Haloalkane
Unsaturated
Reactants
Halogen
+ →

28. Hydrohalogenation
a chemical reaction that adds
hydrogen halides to a molecule.
DIFFERENT FORMATIONS
OF ADDITION REACTIONS
Haloalkane
Unsaturated
Reactants
Hydrogen -
Halogen
+ →

29. MARKOVNIKOV’S RULE
“Hydrogen is added to the carbon with
the most hydrogens and the halide is
added to the carbon with the least
hydrogens”.

30. DIFFERENT FORMATIONS
OF ADDITION REACTIONS
Hydration
a chemical reaction that occurs
when water molecules are
added to a substance.
Alcohol
Unsaturated
Reactants
Water
(H2O)
+
→
ACID

31. REARRANGEMENT
REACTIONS
A Rearrangement Reaction is a broad
class of organic reactions where the
carbon skeleton of a molecule is
rearranged to give a structural isomer
of the original molecule.
GOOD BYE
Often a substituent moves
from one atom to another
atom in the same molecule.

32. REARRANGEMENT
REACTIONS
Rearrangement
reactions can
accompany many of
the reactions such as
substitution, addition,
and elimination
reactions.
GOOD BYE

33. NUCLEOPHILIC SUBSTITUTION
ACCOMPANIED BY REARRANGEMENT
GOOD BYE

34. ALKENE ADDITION ACCOMPANIED BY
REARRANGEMENT
GOOD BYE

35. ELIMINATION (E1) ACCOMPANIED BY
REARRANGEMENT
GOOD BYE

36. HUMANA JUDDDDD!!!!!!!!!!
PAGADIAN CITY SCIENCE HIGH SCHOOL