3.3.3 Halogenoalkanes

Question 1

Haloalkane

Answer 1

Alkane skeleton and one or more halogens instead of a hydrogen
General formula rcnh2n+1 x
If contains multiple it is listed in alphabetical order

Question 2

Properties haloalkanes

Answer 2

Bond c-halogen is polar as the halogen is more electronegative ethan the carbon
Halogen carbon bond is not polar enough to be soluble in water
Has dipole - dipole bonding and van der waals
Bp increases with chain length and bp increases as you go down the group
More electrons more van der waals

Question 3

Bond polarity of haloalkanes

Answer 3

Because the halogen makes the c partial electron deficient it means attcked by nucleophiles
Polarity increases as you go up the group

Question 4

Nucleophile

Answer 4

Electron pair donar, it is partially or fully negatively charged

Question 5

Bond empathy of haloalkanes

Answer 5

Bonds get weeker as you go down as the atoms get larger meaning less attraction between the nucleus and shared electrons
Bond enthalpy decrease as you go down

Most important factor meaning reactivity increases as you go down the group.

Question 6

Nucleophilic substitution (with ammonia) mechanism

Answer 6

1. n nucleophile attacks the delta + of the carbon attached to the halogen - arrow 1
2. arrow from bond between c and halogen to halogen - arrow 2
3. arrow from one of the h-n bonds to the n - 3rd arrow
4. nucleophile secind amine attacks the h - arrow 4
5. amine formed primary amine (2H and h and line pair )
   and a ammonium ion and a halogen ion

Question 7

Nucleophilic substitution mechanism

Answer 7

arrow 1 - nucleophile attack the c connected to the halogen
arrow 2 - from the carbon halogen bond to the halogen

the nucleophile replaces the halogen

Question 8

Elimination in haloalkanes

Answer 8

Organic molecule losing a smaller molecule
Hydrogen halide is removed
Double bond replaces the hydrogen halide making it an alkene
Oh is acting as a bace
Removes the h+ ions from the haloalkane
Heterolytic fission

Question 9

Elimination (mechanism)

Answer 9

1. the OH- ions use ist lone pair to form bond with one of the H on carbon next to the carbon halogen bond as delta pos
2. electron pair form c-H become part of c=c - arrow from c-h bind to c-c bond
3. the br halogen takes lone pair in the c-x bond and leaves as ion

Question 10

Elimination in haloalkanes conditions

Answer 10

The na/k hydroxide is dissolved in ethanol and mixed with the haloalkane
Mixture is heated
(test for it with bromine as makes an alkene)
Happens in reflux

Question 11

Reflux

Answer 11

Heated into gas and collected as a liquid

Question 12

Oh as a nucleophile or base rules

Answer 12

Elimination if
High temp -dissolved in ethanol - reflux
Tertiary or secondary

Substitution if
Room temp - aq
Primary or secondary structure