Topic 31: Organic Synthesis and Analysis

Question 1

Considerations when synthesising

Answer 1

• Starting materials
• Conditions
• Economics
• Safety

Question 2

Acid anhydride functional group

Answer 2

R(CO)O(CO)R
zigzag one

Question 3

Good Oxidising agent

Answer 3

Acidified Potassium Dichromate
K2Cr2O7
Good guess in exam

Question 4

Strong oxidising agent

Answer 4

Potassium permanganate
KMnO4
Very strong oxidising agent, not a good guess in an exam

Question 5

Reducing agents

Answer 5

Sodium Tetrahydridoborohydrate
NaBH4
Hydrogen with Nickel
H2/Ni
Tin with HCl
Sn/H+
Lithium aluminium hydride
LiAlH4

Question 6

Sodium Tetrahydridoborohydrate
NaBH4

Answer 6

Used in aqueous solution
Reduced POLAR bonds (don’t use if non-polar)
Reacting species :H-

Question 7

Hydrogen with Nickel
H2/Ni

Answer 7

Used for non polar bonds

Question 8

Tin with HCl
Sn/H+

Answer 8

Reduces NO2 to NH2

Question 9

Lithium aluminium hydride
LiAlH4

Answer 9

Very strong and reactive
Anhydrous conditions
Expensive
Used to reduce amide or nitrile to amine

Question 10

Dehydrating agent

Answer 10

Conc. H2S04
Elimination reactions
Heated Al2O3
alcohols to alkenes

Question 11

Memorise the maps of synthesis

Answer 11

Do it

Question 12

Test for alkene

Answer 12

Shake with bromine water
Red-brown colour disappears

Question 13

Test for haloalkane

Answer 13

• Add NaOH(aq) and warm
• Acidify with HNO3
• Add AgNO3

Ppt of AgX

Question 14

Test for aldehyde

Answer 14

Warm with tollens solution
Silver mirror
or
Warm with Fehling’s solution
Blue colour to red ppt
or
Add acidified K2Cr2O7
Orange turns green

Question 15

Test for alcohol

Answer 15

Add acidified K2Cr2O7
Orange turns green with primary/secondary alcohol (also aldehydes)

Question 16

Test for carboxylic acid

Answer 16

Add NaHCO3
effervesces as CO2 given off