4.2.2 Haloalkanes Flashcards

1
Q

What are haloalkanes?

A

Saturated organic compounds that contain carbon atoms and at least one halogen atoms

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2
Q

Are halogenoalkanes soluble in water?

A

Insoluble as C-H bonds are non-polar, not compensated for enough by C-X bond polarity

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3
Q

Do halogenoalkanes have a polar bond? Why?

A

Yes polar, as halogen has a higher electronegativity than C ( halogen is δ-, carbon is δ+)

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4
Q

What type of intermolecular forces do haloalkanes have? Why?

A

Permanent dipole-dipole and london forces of attraction

C-X bond polarity creates permanent dipoles

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5
Q

When would haloalkanes have higher boiling points?

A

Increase carbon chain length

Halogen further down group 7

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6
Q

How would the mass of a haloalkane compare with the mass of an alkane of the same chain length?

A

greater

as mass of halogen > mass of H

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7
Q

What is the most important factor in determining halogen reactivity?

A

The strength of carbon halogen bond

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8
Q

What would bond polarity suggest the order of reactivity would be?

A

C-F would be most reactive as most polar bond

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9
Q

What would bond enthalpies suggest the order of reactivity would be?

A

C-I would be most reactive as lowest bond enthalpy

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10
Q

What is a primary halogen?

A

The halogen atom is present at the end of the chain

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11
Q

Define nucleophile

A

electron pair donor

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12
Q

What is nucleophilic subsitution?

A

A reaction where a nucleophile donates a lone pair of electrons to δ+ C atom, δ- atom leaves molecule (replaced by nucleophiles)

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13
Q

What is hydrolysis?

A

A reaction where water is a reactant

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14
Q

What reactant often produces hydroxide ions for hydrolysis?

A

water

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15
Q

What fission does water undergo to produce OH⁻?

A

Heterolytic fission

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16
Q

What are CFC’s?

A

Chlorine - fluoro - carbons

haloalkanes containing C, F and Cl only (no H)

17
Q

What is the problem with CFC’s?

A

Although unreactive under normal conditions they catalyse the breakdown of ozone in the atmosphere via free radical subsitution

18
Q

What is the main function of ozone layer?

A

Provides protection from harmful UV radiation

19
Q

Does ozone play a protection role in all layers of the atmosphere?

A

No, in the troposphere it contributes towards photochemical smog

20
Q

How do CFCs break the ozone layer down?

A

Free radical subsitution

21
Q

Write an equation for the overall decompostion of ozone into oxygen

A

2O₃ -> 3O₂

22
Q

Write free radical subsitution equation to show how Cl free radicals catalyse the breakdown of O₃

A

Cl₂ -> 2Cl•
Cl• + O₃ -> ClO• + O₂
ClO• + O₃ -> 2O₂ + Cl•

Overall: 2O₃ -> 3O₂

23
Q

Write free radical substitution equation to show how nitrogen monoxide can decompose ozone

A
  • NO + O₃ -> •NO₂ + O₂
  • NO₂ + O -> •NO + O₂

Overall: O₃ + O -> 2O₂