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Flashcards in A2 Organic Deck (35):
1

What are the 2 reagents often used for reduction

LiAlH4 in ether (stronger than NaBH4)
NaBH4

2

Name the mechanism that turns aldehyde/ketones back to alcohols

What are the conditions

Nucleophilic addition

Room temp and pressure

3

What’s another way carbonyls can be reduced apart from nucleophilic addition

What are the conditions

Catalytic hydrogenation

H2/Ni catalyst
High pressure

4

What’s the reaction, reagent and condition for carbonyl -> hydroxynitrile

KCN , dilute H2SO4
Room temp and pressure

5

What is used to show the presence of C=O group
What’s the name of this reaction

2,4-dinitrophenylhydrazine

Nucleophilic addition elimination

6

What’s the result of adding dinitrophenylhydrazine to c=o groups

Bright orange / yellow ppt forms

7

What reagent and condition is needed in esterification

CONCENTRATED H2SO4

Heating under reflux

8

Why is esterification not preferred

It is a reversible reaction, which is quite slow and produces low yield

9

State a few uses of Ester

Perfumes and flavourings because of its sweet smell

Solvents for polar organic substances

Plasticisers for polymers

10

What is the name of reaction when esters -> alcohol and carboxylic acid

What reagents and condition is needed

Acid hydrolysis

H2O
Dilute HCL

heat under reflux

11

What does a base hydrolysis form

What’s the condition and reagent

Carboxylate ion (salt) and alcohol

NaOH
Heat under reflux

12

What’s the difference between acid and base hydrolysis and which one is better

Base hydrolysis is NOT reversible and so it produces a much higher yield

13

What is biodiesel

A mixture of methyl esters of long chain carboxylic acids

14

Is biodiesel carbon neutral

Can be thought of as carbon neutral because when crops absorb the same amount of co2 as they produce when burned
But
Energy is used in making fertilisers to grow crops, and used in planting, harvesting etc
Also if energy comes from burning fossil fuels then its not carbon neutral

15

What can acyl chloride react with and what are the products

What’s the name of this mechanism

Water - carboxylic acid and Hcl
Ammonia - amide and Hcl
Alcohol - Ester and Hcl
Primary amine - amide and Hcl

Nucleophilic addition elimination

16

What can acid anhydrides react with
What are the products
What’s the name of reaction

Water - carboxylic acid x2
Ammonia - amide and cooh
Alcohol - Ester and cooh
Primary amine - amide and cooh

Nucleophilic addition elimination

17

What are the conditions of both acyl chloride and acid anhydride reactions

Room temp

18

What’s an alternative method of producing esters
Why’s this better

Reacting acyl chloride with alcohol

Produces much higher yield

19

Observations from acyl chloride reactions

Steamy white fumes of HCL

20

What is delocalised energy

Extra stability in benzene molecule due to electron delocalisation

21

Evidence that led scientists to doubt kekule’s theory

1. Bond length is different between C=C (short) and C-C (long)
2. Enthalpy change of hydrogenation is less exothermic than expected when compared to that for cyclohexane
3. Only reacts with Br2 at high temp/presence of halogen carrier

22

Why is benzene more stable than cyclohexane-1,3,5-triene

Electrons are stabilised

23

Why wouldn’t benzene undergo addition reactions

It would involve breaking up the delocalised system

24

What’s the toxicity of benzene

What is less toxic, why?

Carcinogen (cancer causing molecule)

Methylbenzene is less toxic and reacts more readily because the methyl group releases electrons into the delocalised system making it more attractive to electrophiles

25

Reagents , conditions and mechanism for nitration

Electrophilic substitution
Conc H2SO4 and HNO3
Done at ~60degrees. Of higher temp is used, a second nitro group can be substituted

26

State the change in functional group in fried elf crafts acyl action

State the reagents conditions and mechanism for this

Benzene to phenyl ketone
Reagents : acyl chloride with anhydrous AlCL3 catalyst
Conditions : heat under reflux (50degrees)
Mechanism: electrophilic substitution

27

What’s the mechanism for nitroarene-> phenylamine

Reagent?
Condition?

Reduction reaction
Sn + Hcl or Fe + Hcl
Conditions : heating

28

What does delocalisation do to a phenol

Makes C-O bond stronger and O-H bond weaker

Thus it is more acidic cuz it’s more likely to give away proton

29

What does delocalisation do to phenylamine

Less basic than chained amines as the lone pair is delocalised onto the ring, making it less available to accept proton

30

What forms when amine reacts with acid
CH3NH2 + H+ ->

What could you add to convert it back

Ammonium salt CH3NH3+

Arden NaOH to convert it back

31


In this reaction
CH3CH2Br + NH3 -> CH3CH2NH3+ +Br-
CH3CH2NH3+ + NH3 -> CH3CH2NH2 + NH4Br
Why should excess ammonia be used

It can limit the further subsequent reactions and will maximise the amount of primary amine formed

32


What can quaternary salts be used as?

And what does that do?

Cationic surfactants

Surfactants reduce the surface tension of liquids.
Helps in their uses as fabric softener, hair conditioner etc

33


Reactants for halogenoalkane to amine (heat under reflux)

Haloalkane to nitrile - KCN in ethanol (heat under reflux)

Nitrile to amine - LiAlH4 in ether with Ni catalyst

34


What’s the disadvantage of the reaction of producing amine from haloalkane

It is 2 stepped thus low yield

KCN is toxic

35


Reagent condition and mechanism for nitrobenzene-> phenylamine

Reagent : Sn and Hcl
Condition: heating
Reduction