Halogenoalkanes Flashcards

1
Q

Halogenoalkanes:

What’s meant by Halogenoalkanes?

A

When H in Alkanes are replaced w Halogens

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2
Q

Halogenoalkanes:

What are Halogenoalkanes reacted with?

A

Nucleophiles

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3
Q

Halogenoalkanes:

What are Nucleophiles?

A

Species that donate electron pairs

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4
Q

Halogenoalkanes:

What charge are Nucleophiles?

A

δ- or -

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5
Q

Halogenoalkanes: Primary,Secondary & Tertiary Structures

What are Primary Halogenoalkanes?

Carbon-cation is found by breaking Halogen away from C

A

Carbon-cation is attached to 1 Alkyl Group & 2 Hydrogens

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6
Q

Halogenoalkanes: Primary,Secondary & Tertiary Structures

What are Secondary Halogenoalkanes?

Carbon-cation is found by breaking Halogen away from C

A

Carbon-cation is attached to 2 Alkyl Groups & 1 Hydrogen

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7
Q

Halogenoalkanes: Primary,Secondary & Tertiary Structures

What are Tertiary Halogenoalkanes?

Carbon-cation is found by breaking Halogen away from C

A

Carbon-cation is attached to 3 Alkyl Groups & no Hydrogens

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8
Q

Halogenoalkanes: Primary,Secondary & Tertiary Structures

Which Halogenoalkanane Structure is most stable?

A

Tertiary

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9
Q

Halogenoalkanes: Bond Enthalpy

How do you break Halogenoalkane?

A

Break halogen away from Carbon chain attaching the chain to something else

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10
Q

Halogenoalkanes: Bond Enthalpy in terms of IMFs

What’s the trend of Halogenoalkanes in terms of Bond Enthalpy & IMFs?

A
  • Down G7, atomic radius increases
    ↳ more electrons
    ↳ more IMFs
    ↳ higher mp/bp : more energy needed to break it down

Hence C-I has the highest mp/bp
↳ hardest to break

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11
Q

Halogenoalkanes: Bond Enthalpy in terms of NC

What’s the trend of Halogenoalkanes in terms of Bond Enthalpy & NC?

A
  • Down G7, atomic radius increases
    ↳ outer e- = further away shielded by inner e-
    ↳ ionise quicker : nuclear charge is reduced
    ↳ lower mp/bp : less energy needed to break it down

Hence C-I has the lowerst mp/bp
↳ easiest to break

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12
Q

Halogenoalkanes: Bond Enthalpy IMFs VS NC

Which one takes priority?

A

Nuclear Charge

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13
Q

Halogenoalkanes: Bond Enthalpy IMFs VS NC

Why does NC take priority?

A

Weaker Carbon-Hydrogen (e.g C-I) bonds break first
↳ they react the fastest

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14
Q

Halogenoalkanes: Halogenoalkane Hydrolysis using Water

What’s formed when a Halogenoalkane is hydrolysed w water?

A

An alcohol

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15
Q

Halogenoalkanes: Halogenoalkane Hydrolysis using Water

What’s the equation for this reaction?

A
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16
Q

Halogenoalkanes: Halogenoalkane Hydrolysis using Water

What type of Fission occurs?

A

Heterolytic Fission
↳ bond breaks unevenly, an atom receives both radicals forming 2 ions

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17
Q

Halogenoalkanes: Halogenoalkane Hydrolysis using Water

What’s the Nucleophile in this reaction?

A

Water

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18
Q

Halogenoalkanes: Halogenoalkane Hydrolysis using Water

How would you identify the Halide formed in this reaction?

A

Add Silver Nitrate into solution

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19
Q

Halogenoalkanes: Halogenoalkane Hydrolysis using Water

Why would you add Silver Nitrate to the solution?

A

Silver Halide precipitate is formed at different rates
↳ undissolved solid

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20
Q

Halogenoalkanes: Halogenoalkane Hydrolysis using Water

How would you identify the Halide?

A

Identify colour change

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21
Q

Halogenoalkanes: Halogenoalkane Hydrolysis using Water

What colour is the AgCl Precipitate?

A

White

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22
Q

Halogenoalkanes: Halogenoalkane Hydrolysis using Water

What colour is the AgBr Precipitate?

A

Cream

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23
Q

Halogenoalkanes: Halogenoalkane Hydrolysis using Water

What colour is the AgI Precipitate?

A

Pale Yellow

24
Q

Halogenoalkanes: Primary,Secondary & Tertiary have diff reactivities

What’s the relationship between the Type of Structure the Halogenoalkane forms & Reactivity?

A
  • Down the table, the faster the Halogenoalkane is broken
    ↳ more Alkyl groups = more stable
    ↳ more reactive it is : quicker it breaks
25
Q

Halogenoalkanes: Nucleophiles

What are 4 examples of Nucleophiles?

A
  • Hydroxide (OH-)
  • Water (H2O)
  • Ammonia (NH3)
  • Cyanide Ions (CN-)
26
Q

Halogenoalkanes: Nucleophiles

What is considered a Nuclophile?

A

Anything with a lone pair of e-
↳ H2O & NH3 are neutral nucleophiles

27
Q

Halogenoalkanes: Nucleophillic Substitution

What occurs in this Reactions?

A

Nuc replaces X

28
Q

Halogenoalkanes: Nucleophillic Substitution

What does a Nucleophillic Substitution mechanism look like?

A
29
Q

Halogenoalkanes: Nucleophillic Substitution

What does the ‘Nuc’ represent?

A

Nucleophile

30
Q

Halogenoalkanes: Nucleophillic Substitution

What does the ‘X’ represent?

A

Halogen

31
Q

Halogenoalkanes: Nuclophillic Substitution

What’s Nucleophillic Substitution?

A

When halogenoalkanes are hydrolysed to alcohols

32
Q

Halogenoalkanes: Nucleophillic Substitution

What’s the 1st Step of Nucleophillic Substitution?

A

Nuc provides a pair of electrons to the C (δ+)

33
Q

Halogenoalkanes: Nucleophillic Substitution

What’s the 2nd Step of Nucleophillic Substitution?

A

C-X bond breaks heterolytically
↳ bond breaks unevenly, a species gains both electrons (Halogen) forming 2 ions

34
Q

Halogenoalkanes: Nucleophillic Substitution

What’s the 3rd Step of Nucleophillic Substitution?

A
  • Nuc bonds to C
  • Halogen takes both electrons
35
Q

Halogenoalkanes: Forming Alcohols

What do Halogenoalkanes react w to form an Alcohol?

A

Aqueous KOH
↳ provides OH- group

36
Q

Halogenoalkanes: Forming Alcohols

What’s the Equation for this Reaction?

A
37
Q

Halogenoalkanes: Forming Alcohols

What’s meant by Reflux?

A

Continuously heating over a long period of time

38
Q

Halogenoalkanes: Forming Alcohols

What is used in Reflux?

A

Warm Alkali (NaOH)

39
Q

Halogenoalkanes: Forming Alcohols

What’s a Reflux substitute?

A

Water (neutral nuclophile)
↳ reaction is slower

40
Q

Halogenoalkanes: Forming Alcohols

Why’s Water used as a substitute?

A
  • Reaction is slower
  • OH- can be dissolved in water
41
Q

Halogenoalkanes: Forming Nitriles

What do Halogenoalkanes react w to form Nitriles?

A

Potassium Cyanide (CN-)
↳provides Cyanide Ions which are triple bonded

42
Q

Halogenoalkanes: Forming Nitriles

What’s the Equation for this reaction?

A
43
Q

Halogenoalkanes: Forming Nitriles

What’s a Reflux Substitute for this reaction?

A

Ethanol
↳ Potassium Cyanide is insoluble in water but soluble in ethanol

44
Q

Halogenoalkanes: Forming Amines (NH2)

What do Halogenoalkanes react w to form Amines?

A

Excess Ethanolic Ammonia
↳ ammonia dissolved in ethanol

45
Q

Halogenoalkanes: Forming Amines (NH2)

Why’s the Ethanolic Ammonia in Excess?

A

Ammonia reacts twice in this reaction

46
Q

Halogenoalkanes: Forming Amines (NH2)

What’s the Reaction mechanism for this?

A
47
Q

Halogenoalkanes: Forming Amines (NH2)

What’s the 1st Reaction w Ammonia?

A

Attacks the Halogen
↳ e- donated to C (δ+) which later passes it to X

48
Q

Halogenoalkanes: Forming Amines (NH2)

What happens after the 1st Reaction w Ammonia?

A
  • Dative bond is formed
  • N is +
49
Q

Halogenoalkanes: Forming Amines (NH2)

Why does the 2nd Reaction w Ammonia occur?

A

You can’t have a + on a compound

50
Q

Halogenoalkanes: Forming Amines (NH2)

What happens in the 2nd Reaction w Ammonia?

A

Ammonia takes a proton from N+
↳ removes a H from it creating an Amine

51
Q

Halogenoalkanes: Forming Amines (NH2)

How would you Identify an Amine?

A

Smells fishy

52
Q

Halogenoalkanes: Elimination Reactions

What is an Elimination Reaction?

A

When a Halogenoalkane reacts w Ethanolic Alkali instead of Aqueous

53
Q

Halogenoalkanes: Elimination Reactions

What’s the Equation for this reaction?

A
54
Q

Halogenoalkanes: Elimination Reactions

Why’s Reflux required for this Reaction?

A

Otherwise volatile stuff will be lost

55
Q

Halogenoalkanes: Elimination Reactions

What occurs in this Reactions?

A
  • Alkene formed
  • Reactants are dehydrated