Alkenes

Question 1

What are single bonds known as and what can they do?

Answer 1

Sigma bonds - overlap and can rotate

Question 2

Define Markownikoff’s Rule

Answer 2

If unsymmetrical alkenes react with unsymmetrical electrophile
H goes to C with most H atoms/most stable

Question 3

What are Double Bonds also known as and what do they do?

Answer 3

Pi bonds - 2 p-orbitals overlap above & below internuclear axis
Can’t rotate

Question 4

Outline the 3 possible electrophiles that can react with Alkenes in electrophilic addition

Answer 4

Hydrogen Halides, Halogens and H2SO4

Question 5

Outline the steps of electrophilic addition of Alkenes + Hydrogen Halides

Answer 5

1. H-X + dipole attacked by e- pair on C=C bond
2. • Halide ion + Carbocation = Haloalkane

Question 6

Outline the steps of electrophilic addition of alkenes and halogens

Answer 6

1. E.g Br-Br has temporary dipole & attacked by C=C dipole
2. • Halide ion + Carbocation = Haloalkane

Question 7

Outline the steps of electrophilic addition (Hydrolisis) of H2SO4 & Alkenes

Answer 7

1. Alkenes attack + dipole H (cold concentrated H2SO4)
2. • OSO2OH group + Carbocation react
3. Warmed & H2O added -> H2SO4 replaced with OH group = alcohol

Question 8

Outline the conditions of the addition of steam of Alkenes (Hydration)

Answer 8

300 degrees, 60 atm & H3PO4 catalyst

Question 9

Outline the steps of hydration of alkenes

Answer 9

1. • dipole of H in H20 attacked by e- pair in C=C
2. • dipole of O attacks Carbocation

Question 10

Define addition polymerisation

Answer 10

Alkenes join together by breaking C=C bond

Question 11

Outline the conditions of addition polymerisation

Answer 11

High Pa & correct catalyst

Question 12

Draw the addition polymerisation of Ethene

Answer 12

n( C=C) -> (-C-C-)n
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(for monomer lines go thru brackets)

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