13.4 - Electrophilic Addition in Alkenes Flashcards by Haziq Ibrahim

Flashcards in 13.4 - Electrophilic Addition in Alkenes Deck (7)

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Define electrophile

Atom or group of atoms that is attracted to an electron-rich centre where it ACCEPTS a pair of electrons.

- Usually a +ve ion or has partially positive charge

Why does a C=C attract electrophiles?

High electron density (due to pi bond presence), attracts electrophiles to accept an electron pair.

Describe the first step in the mechanism for electrophilic addition.

In the case of butene + hydrogen bromide

- HBr is a dipole due to the difference in electronegativity between the H and Br
1. Electron pair in pi-bond attracted to partially positive H. This breaks the double bond
HBr breaks by heterolytic fission
And the H of the H-Br bonds to the butene chain. This forms a carbocation and a Br-.

Describe the second step in the mechanism for electrophilic addition.

Br- reacts with the carbocation forming a haloalkane.

How is carbocation stability defined?

Primary carbocation - least stable
Secondary
Tertiary carbocation - most stable

What does carbocation stability have to do with electrophilic addition of unsymmetrical alkenes?

- The more stable the carbocation the more likely it is to form.
Markownikoff's rule states: The hydrogen will atack the carbon atom with the most amount of hydrogens attached to it and the least amount of carbons.

If the addition is between an alkene and a halogen, how is the dipole produced?

It is induced by the electron rich density of the pi bond.

13.4 - Electrophilic Addition in Alkenes Flashcards Preview

OCR A Chemistry A Level - Chapter 13 > 13.4 - Electrophilic Addition in Alkenes > Flashcards

Define electrophile

Atom or group of atoms that is attracted to an electron-rich centre where it ACCEPTS a pair of electrons.

- Usually a +ve ion or has partially positive charge

Why does a C=C attract electrophiles?

High electron density (due to pi bond presence), attracts electrophiles to accept an electron pair.

Describe the first step in the mechanism for electrophilic addition.

Describe the second step in the mechanism for electrophilic addition.

Br- reacts with the carbocation forming a haloalkane.

How is carbocation stability defined?

Primary carbocation - least stable
Secondary
Tertiary carbocation - most stable

What does carbocation stability have to do with electrophilic addition of unsymmetrical alkenes?

- The more stable the carbocation the more likely it is to form.
Markownikoff's rule states: The hydrogen will atack the carbon atom with the most amount of hydrogens attached to it and the least amount of carbons.

If the addition is between an alkene and a halogen, how is the dipole produced?

It is induced by the electron rich density of the pi bond.

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13.4 - Electrophilic Addition in Alkenes Flashcards Preview

OCR A Chemistry A Level - Chapter 13 > 13.4 - Electrophilic Addition in Alkenes > Flashcards

Define electrophile

Atom or group of atoms that is attracted to an electron-rich centre where it ACCEPTS a pair of electrons. - Usually a +ve ion or has partially positive charge

Why does a C=C attract electrophiles?

High electron density (due to pi bond presence), attracts electrophiles to accept an electron pair.

Describe the first step in the mechanism for electrophilic addition.

Describe the second step in the mechanism for electrophilic addition.

Br- reacts with the carbocation forming a haloalkane.

How is carbocation stability defined?

Primary carbocation - least stableSecondaryTertiary carbocation - most stable

What does carbocation stability have to do with electrophilic addition of unsymmetrical alkenes?

- The more stable the carbocation the more likely it is to form. Markownikoff's rule states: The hydrogen will atack the carbon atom with the most amount of hydrogens attached to it and the least amount of carbons.

If the addition is between an alkene and a halogen, how is the dipole produced?

It is induced by the electron rich density of the pi bond.

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Atom or group of atoms that is attracted to an electron-rich centre where it ACCEPTS a pair of electrons.

- Usually a +ve ion or has partially positive charge

Primary carbocation - least stable
Secondary
Tertiary carbocation - most stable

- The more stable the carbocation the more likely it is to form.
Markownikoff's rule states: The hydrogen will atack the carbon atom with the most amount of hydrogens attached to it and the least amount of carbons.