Organic Reactions
1. Addition
The pattern: break a C-C multiple bond (also called a π bond) and form two new
single bonds. The reaction occurs only at the carbons that are a part of a multiple
bond, C1 and C2
Alkene with Hydrogen  an alkane
Alkene with steam  an alcohol
Alkene with HX  a halogenoalkane
Alkene with X2  1,2 halogenoalkane
2. Elimination
The pattern: Formation of a π bond (double bond). Breaking of bonds at C1 and C2
Identify alpha carbon, which is the one with the leaving group attached to it. Identify the beta
carbon, which is the one next to the alpha carbon. Choose the carbon which has the least
number of hydrogens attached to it and this will be where the bond will form.
Halogenoalkane with ethanolic sodium hydroxide  an alkene
3. Substitution
Halogenoalkane & sodium hydroxide  an alcohol [reactivity I>Br>Cl>F
Halogenoalkane & Cyanide  alkanenitrile
Halogenoalkane & ammonia  alkylamine
See Sn1 and Sn2 reactions below
Alcohol & hydrogen halide  halogenoalkane & water
Alcohol & sulfur dichloride oxide  halogenoalkane & HCl & Sulfur dioxide
Alcohol & Phosphorus(v)chloride  halogenoalkane & HCl + POCl3
Alcohol & phosphorus(III)halide  halogenoalkane & H3PO3
4. Hydrolysis
The breakdown of a molecule of water, usually accompanied by an acid or base to speed up the
reaction.
(Nucleophile)
Alkyl halide + Mg in dry ether(ethoxyethane) alkyl halideMg + water  alkane +
Mg(OH)halide
5. Oxidation
The addition of oxygen atoms to a molecule and/or the removal of hydrogen atoms from a
molecule. The [O] refers to an oxidation reaction, such as by using Acidified Potassium
Dichromate.
Alkene & cold acidified potassium manganate VII  alkane -1,2 –diol (a.k.a. glycol)
Alkene & hot acidified potassium manganate VII  Carbon Dioxide(carbon bonded to 2
hydrogens), Carboxylic acid(carbon bonded to one hydrogen and one alkyl group) or a
Ketone(carbon bonded to 2 alkyl groups)
Alcohol & potassium dichromate(VI) acidified with dilute sulfuric acid 
Primary alcohol  aldehyde [orange to green] & water
Secondary alcohol  ketone [orange to green] & water
Tertiary alcohol  no reaction
6. Reduction
The removal of oxygen atoms from a molecule and/or the addition of hydrogen atoms to a
molecule. The [H] refers to a reduction reaction, such as by using Sodium Tetrahydridoborate,
[NaBH4] , Lithium Aluminum Hydride[ LiAlH4] or H2/Platinum
Aldehyde & [H]  primary alcohol
Ketone & [H]  secondary alcohol
Tests:
A) 2,4 DNPH (dinitrophenylhydrazine) will form a deep orange precipitate if either are present.
This is a condensation reaction, where the 2 molecules combine and release a molecule of
water.
B) Tollens’ Reagent (aqueous silver nitrate in excess ammonia). An aldehyde will display a
mirror image in the test tube as the silver is reduced. The ketone test tube will remain
colorless.
C) Fehling’s solution (Copper(II) Sulfate a blue solution). An aldehyde will display a brick red
color. The ketone test tube will remain colorless.
Mechanisms of Organic Reactions
1. Homolytic Fission – Both atoms leave with an electron that formed the covalent bond. The
species produced are called free radicals. They go through an initiation (free radical formation),
propagation (chain reaction) and termination (combination) steps. Alkanes with halogens in
sunlight.
2. Heterolytic Fission – The more electronegative atom takes both the electrons in the covalent
bond. All of the following reactions encompass this type of fission.
Lewis Acids and Bases
A Lewis acid is an electron-pair acceptor, which is also known as an electrophile (electron-loving) in
Organic Chemistry. The electrophile has a vacant orbital in its valence shell and is electron poor.
Examples are: H2 , Br2 , I2 , H2O, HBr, NH4+ , BH3 HCN, CH2 I2, H3O+, OsO4 and anything with a positive
charge.
A Lewis base is an electron-pair donor, which is also known as a nucleophile (electron-loving) in Organic
Chemistry. The nucleophile has an unshared pair of electrons or pi bond (seen in double and triple
bonds) available for bonding and are electron rich. Examples are: RS, I, CN- , Br- , OH- , NH, CH3CO2 ,
CH3O, HS , NH3 , H2O. A nucleophile with a negative charge is more reactive than one without and is a
stronger base.
The only way to truly understand this concept is of course to draw out the Lewis structures, showing the
un-bonded pairs of electrons.
[Nucleophile] [Electrophile]
In the diagram above notice Ammonia has available electrons for bonding and the Boron Trifluoride has
a vacant orbital in its valence shell. The curved arrow shows the donation of the pair of electrons from
Nitrogen to Boron to form a covalent bond.
Nucleophilic substitution reactions
The nucleophile [Nu] which is electron rich will react with the electron poor compound and substitute
itself forming a new bond. This causes a bond to be broken as the species leaves, known as the leaving
group [LG]. Notice the leaving group takes the electrons with it. This is displayed in the reaction of
halogens in sunlight.
Nucleophilic addition reactions
The attack is by the CN which is a nucleophile. Notice the positive carbon and negative oxygen ,as it is
more electronegative than the carbon, in the carbonyl group. The cyanide ion which is negative attacks
the positive carbon and the negative oxygen then attacks the positive hydrogen. Also note there is
regenerated cyanide ions present in the solution. This can then be further reduced by LiAlH4 to yield a
primary amine or hydrolyzed ay an acid to yield a carboxylic acid.
Halogenoalkanes, aka Alkyl halides
There are two different reaction mechanisms possible for alkyl halides, Sn1 and Sn2.
Sn1 Mechanism
Refers to a substitution, nucleophic, unimolecular (1 molecule) reaction. If the nucleophile doesn’t have
a charge it will likely happen by this reaction. The rate of this reaction depends only on the
concentration of one reactant. For the reaction to occur
1) the carbocation must be stable and stability increases with substitution on the carbon. tertiary
> secondary >> primary
2) The solvent must be polar protic such as water, alcohols, and carboxylic acids.
Tertiary carbon is a carbon bonded to three carbon atoms.
Secondary carbon is a carbon bonded to two carbon atoms.
Primary carbon is a carbon bonded to one carbon atom.
It has a two step process:
1) Slow loss of the leaving group, which generates a carbocation intermediate then
2) Rapid attack of a nucleophile on the electrophilic carbocation to form a new bond.

Note the attack can occur from either side so half of the product will have original
conformation and the other half will be inverted.
Sn2
Refers to a substitution, nucleophilic, bimolecular (2 molecules) reaction. The rate is dependent on both
the concentration of the substrate and the nucleophile. Charged nucleophiles proceed through this
reaction. This reaction is favored by polar aprotic solvents (polar enough to dissolve the substrate and
nucleophile but do not hydrogen bond with the nucleophile such as: Acetone, DMSO, Acetonitrile and
DMF. This reaction is completed in one step as a rapid attack of a nucleophile on the electrophile(bond
forms) and removal of the leaving group (bond breaks), the product is inverted. The rate of reaction is
as follows: Primary > Secondary >> Tertiary
Extra information
Molecular formula – shows actual numbers of each type of atom in a molecule
Displayed formula – shows actual bonds present in a molecule
Skeletal formula – only shows lines up and down where each point indicates a carbon
Single bonds – Alkanes, are known to have a sigma bond present, 120 degrees
Double bonds – Alkenes, are known to have a sigma bond and pi bond present, 109.5 degrees
Triple bond – Alkynes, are known to have a sigma bond and two pi bonds present.
Structural isomers – compounds with the same molecular formula but different structural formula
Positional isomers – compound whose functional group is in a different location.
Functional isomers – compound whose functional group is altogether different.
Chain isomers – compound whose has the same molecular formula but the carbon skeleton is different.
Sterioisomers – cis – same atoms bonded on the same side
Trans – same atoms bonded on the opposite side
Optical isomers – a molecule that exhibits chiralty does not have a plane of symmetry and is not
superimposable on its mirror image. It is also known as an enantiomers.
chiral center – a molecule that contains a carbon atom bonded to four different atoms, which are mirror
images of each other. The maximum number of stereoisomers that are possible for a compound with a
chiral center is 2n
Alkanes
Structural Formula – Cn H2n +2
They are non-polar or weakly polar molecules, which are attracted to each other by weak Van der
Waal’s forces. They will not be attacked by nucleophiles or electrophiles. They are soluble in all nonpolar solvents (like dissolves like) such as benzene, ether, chloroform and carbon tetrachloride. The
boiling point, melting point, density and viscosity increase as the length of the carbon chain increases.
Branched chains will have lower boiling points than straight chains. Oil is made up of alkanes,
cycloalkanes and aromatic compounds. Fractional distillation involves breaking down the alkane by
boiling points. The heavier alkanes are further broken down by “cracking”. This will yield a lower
molecular weight alkane(for fuel) and and an alkene (for starting products such as plastics).
Alkenes
Structural Formula – Cn H2n
They are also known as olefins, having a lower density than water. C1 to C4 are gases, C5 to C15 are
liquids and >C16 are solids. The boiling point, melting point and viscosity increase with an increase in the
length of the carbon chin. Branched chains will have lower boiling points than straight chains. They are
colorless and have a higher reactivity than alkanes.
Alkyl halides
Structural Formula – Cn H2n+1 X
They are also known as halogenoalkanes. The boiling points increase with increasing atomic
weight of the halide and are much higher than an alkane with the same carbon skeleton. They
are insoluble in water but are soluble in organic solvents. They are colorless when pure and
have a pleasant odor. Go through Sn1 and Sn2 reactions (see above). Used to produce PVC and
hydrofluorocarbons.
Alcohols
Structural formula – R-OH
The boiling point and solubility in water increase with the number of hydroxyl groups (OH). They tend to
have a high boiling point. They are used to make esters. Methanol is and anti-freeze. Ethanol is the
alcohol in alcoholic beverages.
Primary – OH group is attached to the primary carbon (straight chain)
Secondary – OH group is attached to a secondary carbon (1 branch). Naming is either prefixed by 2- or
secTertiary – OH group is attached to a tertiary carbon(branched on every side of the carbon). Naming is
either prefixed by 3- or tertCarboxylic acids
Structural formula R-COOH
The central carbon of the functional group is doubly bonded to one oxygen and singly bonded to
another and is sp2 hybridized.
They are polar molecules and can form hydrogen bonds with other relavent molecules. Acids containing
more than 6 carbons are not soluble in water due to the hydrogen bonding. They have a high boiling
point which increases with the amount of carbons present. They are soluble in less polar molecules such
as ether, alcohol and benzene. Acidity increases with the increasing negativity of the electron
withdrawing group.
Acidity – RCOOH > HOH > ROH > HC ≡ CH > NH3 > RH