3.3 Halogenoalkanes Flashcards

1
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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2
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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3
Q

Which intermolecular forces do they have? why?

A

Permanent dipole-dipole and van der Waals forces of attraction C-X bond polarity creates permanent dipoles

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4
Q

When would they have higher boiling points?

A

Increase Carbon chain length

Halogen further down group 7

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5
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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6
Q

What is the most important factor in determining their reactivity?

A

Carbon-halogen bond enthalpy

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7
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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8
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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9
Q

What is a nucleophile?

A

A negatively charged ion/δ− atom with a lone pair of electrons which can be donated to an electron deficient atom

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10
Q

Give 3 examples of nucleophiles

A

:OH-
:CN-
:NH3

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11
Q

What is nucleophilic substitution?

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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12
Q

What are CFCs?

A

Chlorine-fluoro-carbons - haloalkanes containing C, F and Cl only (no H)

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13
Q

What is the problem with CFCs?

A

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

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14
Q

What are CFCs being replaced with?

A

HCFCs (hydrogen, chlorine, fluorine, carbon)

HFCs (hydrogen, fluorine, carbon)

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15
Q

What are the conditions/reactants needed for the

elimination reaction of haloalkanes?

A

NaOH or KOH dissolved in ethanol (no water present)

Heated

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16
Q

What is formed in the elimination reaction of haloalkanes?

A

An alkene, water and halogen ion