General methods of preparation
From alkyl halide
From organometallic compound
Fatty acids are good source of hydrocarbon, continuous heating of sodium salt of carboxylic acid (R – COONa)
with soda lime (NaOH – CaO) gives hydrocarbon, this process is known as decarboxylation (e.g. replacement of
– COOH group by – H) decarboxylation also takes place on heating only, when compound is gem dicarboxylic
acid or there is keto group or double bond on b carbon
By Reduction
Physical Properties of Alkanes
Characteristic reaction of alkanes are free radical substitution reaction, these reactions are generally chain
reactions which are completed in three steps
Halogenation of higher alkane
Factors determining the relative yields of the isomeric products
Alkylation
Combustion is used as a measurment of stability.
More branched alkanes are more stable and have lower heat of combustion
Alkenes are hydrocarbons with carbon–carbon double bonds, Alkenes are also called as
olefins, a term derived from olefiant gas, meaning "oil forming gas". Alkenes are among the
most important industrial compounds and many alkenes are also found in plants and animals.
Ethylene is the largest–volume industrial organic compound, used to make polyethylene and
a variety of other industrial and consumer chemicals.
Alkenes polymerise to give many important polymers
(A) Alkenes
(1) Alkenes are unsaturated hydrocarbons having at least one double bond
Alkenes and Alkadienes
ISOMERISM
(A) Alkene
(A) Alkenes
Terminal alkynes are much more acidic than other hydrocarbons due to more electronegative sp hybridised
carbon.
Studies of numerous alkenes reveal, pattern of stabilities that related to the number of alkyl groups attached to
the carbon atoms of the double bond.
COMPARATIVE STUDY OF ALKANES, ALKENES, ALKYNES
General Methods of preparation of alkenes
General Methods of preparation of alkenes
General methods of preparation of Alkynes
CHEMICAL REACTIONS OF ALKENES & ALKYNES
Electrophilic addition reaction (Mechanism, Remarks, Reactivity order)
Electrophilic addition reaction (Mechanism, Remarks, Reactivity order)
Many of the reactions of alkynes are similar to the corresponding reactions of alkenes. Like the pi
bond of an alkene, the pi bonds of an alkyne are electron-rich, and they readily undergo addition
reaction. The bond energy of the alkyne triple bond is about 226 kJ (54 kcal) more than the bond
energy of an alkene double bond.
ADDITON OF HALOGEN (HALOGENATION)
Alkene
Alkene
KHARASCH EFFECT OR PEROXIDE EFFECT
ADDITION OF H2O (HYDRATION REACTION)
Alkenes react with mercuric acetate in a mixture of water and tetrahydrofuran (THF) to produce (hydroxyalkyl)
mercury compounds. These can be reduced to alcohols with sodium borohydride and water.
Oxymercuration
If solvent taken is alcohol product will be ether & process is called alkoxymercuration demercuration
In the first step, boron and hydrogen undergo syn addition to the alkene in the second step, treatment with
hydrogen peroxide and base replaces the boron with – OH with retention of configuration. The net addition of – H
and – OH occurs with anti Markovnikov regioselectivity and syn stereoselectivity.
Alkynes undergo acid–catalyzed addition of water across the triple bond in the presence of mercuric ion as a
catalyst. A mixture of mercuric sulfate in aqueous sulfuric acid is commonly used as the reagent
(A) Alkenes (Heterogeneous hydrogenation)
MISCELLANEOUS REACTIONS OF ALKENE
MISCELLANEOUS REACTIONS OF ALKENE
Dienes are of three types
Preparation and Properties of alkenes
Preparation and Properties of alkynes
