Haloalkanes

Question 1

Free radical substitution

Answer 1

Definition of free radical: a species with a single, unpaired electromn
Requires UV light to break Cl-Cl bond- by homoliticfission.
Initiation of reaction between methane and chlorine
Cl2–> 2cl•
Propagation
Step 1: CH4 + Cl•—> •CH3 + HCl
Step 2: •CH3 + CL2–> CH3CL + Cl•
Termination:
Cl• + Cl•—> Cl2
Cl• +•CH3–> CH3Cl
•CH3 + •CH3–> C2H6
For further substitution use reagents in excess

Question 2

Nucleophile definition

Answer 2

An electron pair diner
OH-= hydroxide
CN-= nitrile ion
NH3= ammonia

Question 3

Strength of C=C bond

Answer 3

C=C bond is stronger than a single bond because it has more electrons. A pie bond is weaker than a sigma bond. A pie bond is more reactive. Allene is more reactive. Can’t react because the pie bond is formed by an overlap of p orbitals and this would be lost resulting in a break of bond.

Question 4

Definition of an electro Phil’s

Answer 4

Accepts a electron pair

Question 5

Major and minor products

Answer 5

X is made from a 2º carbocation whereas Y is made from a 1º carbocation. 2º is more stable due to a more positive inductive effect.

Question 6

Why does bromine react in electro Philip addition even though its a non-polar molecule

Answer 6

C=c is electron rich, this induces a dipole across the Br2 molecule. The d+ Br atom accepts an electron pair.

Question 7

Test for Alkenes

Answer 7

Bromine water
Allene= orange to colourless
Anything else-nvc
CH2=CH2 +Br2 —> CH2BrCH2Br

Question 8

Aldehyde

Answer 8

Structural formula: CHO
Ending: al
Carbonyl bonded to at least 1H atom

Question 9

Ketone

Answer 9

Carbonyl bonded to 2 carbon atoms
Structural formula: CO
Ending: one

Question 10

Carboxylic acid

Answer 10

Carbonyl bonded to an OH group
Ending: oic acid
Structural: COOH

Question 11

Oxidation of alcohols

Answer 11

Acidified K2Cr2H7 and conc sulfuric acid
Turns orange to green
Reagent. O used H20 produced. Product. Conditions
Primary alcohol. 1. 1. Aldehyde Distillation
Aldehyde. 1. 0. Carboxylic acid Reflux
Primary alcohol 2. 1. Carboxylic acid. Reflux
Secondary alcohol. 1. 1. Ketone. Reflux or distillation

Question 12

Oxidation statements

Answer 12

Features of condenser: open at both ends, cold water flows around outside
Purpose of condenser: cool hot vapour condenses it to a liquid
Anti bumping granules used to prevent formation of larger bubbles

Question 13

Test for aldehyde

Answer 13

Tollens: forms silver mirror
Equation: [Ag(NH3)2]+ +e- —> Ag (s) +2NH3
Fehling’s: forms brick red precipitate
Equation: Cu2+ +e- —> Cu+

Question 14

Test for Carboxylic acid

Answer 14

Na2CO3- forms effervescence
Equation: CO32- +2H+ —> CO2 + H20