Carbon Carbon Multiple Bond
CARBON CARBON MULTIPLE BOND
PRESENTED BY: WASIQUE AZHAR MSC CHEM (2 SEM)
Some basic concept
Electrophile : a species with a region of positive or partial positive charge electron-poor
Nucleophile: a species with a region of negative or partial negative charge electron-rich
TO LERN OBJECTIVE :
Elecrophilic Addition to carbon-carbon double bond Stereochemistry of Elecrophilic addition reaction Hydrogenation of double and triple bond Nucleophilic Addition to carbon-carbon double bond Regio and chemoselectivity
Addition Reactions
• Reaction involving the addition of a molecule or an ion to another molecule • Electrophilic addition – adding species is an electrophile • Nucleophilic addition – adding species is a nucleophile
Elecrophilic Addition to carbon-carbon double bond
• The characteristic reaction of alkenes is addition—the π bond is broken and two new σ bonds are formed.
• Alkenes are electron rich, with the electron density of the π bond concentrated above and below the plane of the molecule. • Because alkenes are electron rich, simple alkenes do not react with nucleophiles or bases, reagents that are themselves electron rich. Alkenes react with electrophiles.
Electrophilic Addition Energy Diagram:
• The mechanism of electrophilic addition consists of two successive Lewis acid-base reactions. In step 1, the alkene is the Lewis base that donates an electron pair to H—Br, the Lewis acid, while in step 2, Br¯ is the Lewis base that donates an electron pair to the carbocation, the Lewis acid.
Stereochemistry of electrophilic addition reaction
NUCLEOPHILIC ADDITION CARBON CARBON DOUBLE BOND • There is a pi electron cloud above and below the plane • Nucleophile cannot attack easily if electron withdrawing substrate such as –CHO, -COR, are present on the multiple bond . They will decreases the electron density on c=c double bond and so nucleophilic addition take place .
HYDROGENATION OF DOUBLE AND TRIPLE BOND
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PRESENTED BY: WASIQUE AZHAR MSC CHEM (2 SEM)
Some basic concept
Electrophile : a species with a region of positive or partial positive charge electron-poor
Nucleophile: a species with a region of negative or partial negative charge electron-rich
TO LERN OBJECTIVE :
Elecrophilic Addition to carbon-carbon double bond Stereochemistry of Elecrophilic addition reaction Hydrogenation of double and triple bond Nucleophilic Addition to carbon-carbon double bond Regio and chemoselectivity
Addition Reactions
• Reaction involving the addition of a molecule or an ion to another molecule • Electrophilic addition – adding species is an electrophile • Nucleophilic addition – adding species is a nucleophile
Elecrophilic Addition to carbon-carbon double bond
• The characteristic reaction of alkenes is addition—the π bond is broken and two new σ bonds are formed.
• Alkenes are electron rich, with the electron density of the π bond concentrated above and below the plane of the molecule. • Because alkenes are electron rich, simple alkenes do not react with nucleophiles or bases, reagents that are themselves electron rich. Alkenes react with electrophiles.
Electrophilic Addition Energy Diagram:
• The mechanism of electrophilic addition consists of two successive Lewis acid-base reactions. In step 1, the alkene is the Lewis base that donates an electron pair to H—Br, the Lewis acid, while in step 2, Br¯ is the Lewis base that donates an electron pair to the carbocation, the Lewis acid.
Stereochemistry of electrophilic addition reaction
NUCLEOPHILIC ADDITION CARBON CARBON DOUBLE BOND • There is a pi electron cloud above and below the plane • Nucleophile cannot attack easily if electron withdrawing substrate such as –CHO, -COR, are present on the multiple bond . They will decreases the electron density on c=c double bond and so nucleophilic addition take place .
HYDROGENATION OF DOUBLE AND TRIPLE BOND
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