Halogenoalkanes - Organic 1 Flashcards

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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 is the order of reactivity of halogenoalkanes?

A

Although C-F is the most polar bond, the bond enthalpy of C-X decreases down the group, so reactivity increases down the group

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8
Q

Give 3 examples of
nucleophiles

A

:OH- :CN- :NH3

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8
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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9
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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10
Q

Draw the mechanism for the reaction of bromoethane with NaOH (aq).

A

check google

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11
Q

Draw the mechanism for the reaction of bromoethane with KCN

A

check google

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12
Q

Draw the mechanism for the reaction of bromoethane with NH3

A

check google

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13
Q

Draw a mechanism for the reaction of bromoethane with NaOH in ethanol

A

check google

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14
Q

What are CFCs?

A

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

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15
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

16
Q

What are CFCs being
replaced with?

A

HCFCs (hydrogen, chlorine, fluorine, carbon) HFCs (hydrogen, fluorine, carbon)

17
Q

What are the conditions/ reactants needed for the elimination reaction of haloalkanes?

A

NaOH or KOH dissolved in ethanol (no water present)
Heated

18
Q

What is formed in the elimination reaction of haloalkanes?

A

An alkene, water and halogen ion