A2 Organic Flashcards
(35 cards)
What are the 2 reagents often used for reduction
LiAlH4 in ether (stronger than NaBH4)
NaBH4
Name the mechanism that turns aldehyde/ketones back to alcohols
What are the conditions
Nucleophilic addition
Room temp and pressure
What’s another way carbonyls can be reduced apart from nucleophilic addition
What are the conditions
Catalytic hydrogenation
H2/Ni catalyst
High pressure
What’s the reaction, reagent and condition for carbonyl -> hydroxynitrile
KCN , dilute H2SO4
Room temp and pressure
What is used to show the presence of C=O group
What’s the name of this reaction
2,4-dinitrophenylhydrazine
Nucleophilic addition elimination
What’s the result of adding dinitrophenylhydrazine to c=o groups
Bright orange / yellow ppt forms
What reagent and condition is needed in esterification
CONCENTRATED H2SO4
Heating under reflux
Why is esterification not preferred
It is a reversible reaction, which is quite slow and produces low yield
State a few uses of Ester
Perfumes and flavourings because of its sweet smell
Solvents for polar organic substances
Plasticisers for polymers
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
What does a base hydrolysis form
What’s the condition and reagent
Carboxylate ion (salt) and alcohol
NaOH
Heat under reflux
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
What is biodiesel
A mixture of methyl esters of long chain carboxylic acids
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
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
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
What are the conditions of both acyl chloride and acid anhydride reactions
Room temp
What’s an alternative method of producing esters
Why’s this better
Reacting acyl chloride with alcohol
Produces much higher yield
Observations from acyl chloride reactions
Steamy white fumes of HCL
What is delocalised energy
Extra stability in benzene molecule due to electron delocalisation
Evidence that led scientists to doubt kekule’s theory
- Bond length is different between C=C (short) and C-C (long)
- Enthalpy change of hydrogenation is less exothermic than expected when compared to that for cyclohexane
- Only reacts with Br2 at high temp/presence of halogen carrier
Why is benzene more stable than cyclohexane-1,3,5-triene
Electrons are stabilised
Why wouldn’t benzene undergo addition reactions
It would involve breaking up the delocalised system
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
