Halogenoalkanes (3.3.3-organic)

Question 1

What mechanism is involved with halogenoalkabes?

Answer 1

Nucleophilic substitution

Question 2

What is a nucleophile?

Answer 2

An electron pair donor

Question 3

Order of reactivity

Answer 3

I > Br > Cl > F

Question 4

Conditions of hydrolysis of NaOH

Answer 4

• warm (reflux)

- aqueous ( NaOH dissolved in water and some ethanol)

Question 5

Mechanism for hydrolysis of NaOH

Answer 5

Curly arrows:

Lone pair OH to C with halogen, then from bond to halogen

Question 6

Halogenoalkanes + KCN conditions

Answer 6

• warm (reflux)

- ethanol

Question 7

What are the hazards with adding Potassium Cyanide

Answer 7

• toxic, wear gloves

HCN- funnel cupboard low conc. of CN-

Question 8

KCN and Halogenoalkane mechanism

Answer 8

Curly arrows

• from lone pair CN to C attached to halogen
• from bond to halogen
• triple bond N to C

Question 9

Halogenoalkane + NH3 conditions

Answer 9

• concentrated nh3
• excess concentrated in ethanol
• heat
• sealed container

Question 10

NH3 mechanism ( Ns)

Answer 10

Curly arrows

• from lone pair NH3 to C-X
• from Bond to X
• from NH3 again to H ( attached to N)
• from bond to + N
• final product has NH3 attaches to C

Question 11

Conditions for basic elimination of OH-

Answer 11

-hot (reflux)
- KOH
- solvent- ethanol
[more likely to happen instead of ns if tertiary halogenoalkane]

Question 12

NAOH mechanism for basic elimination

Answer 12

Curly arrows

• from lone pair OH- to H (attached to C bonded to C-X`
• from C-H bond to C-C(-X) bond
• from C-X bond to X
• final product had double bond, removal of H2O and :Br-