More definitions

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  • Created by: Nayeema-A
  • Created on: 05-01-17 14:17
Why is benzene more stable than cyclohexa 1,3,5 triene?
Benzene is less exothermic in hydration meaning more energy is needed to break bonds meaning that it is more stable. This is because the delocalised electrons means electron density is spread between more atoms so the energy of molecule is lowered.
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Two types of electrophillic substitution for benzene
Nitration and Friedel-Crafts Acylation
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Nitration
WARM benzene with conc nitric acid and conc sulfuric acid. Conc sulfuric acid= Catalyst use to produce NO2+ ion . KEEP TEMP BELOW 55 DEGREES
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Uses of nitration reactions
Used in dyes and pharmaceuticals. Also ised in TNT and exploseives as they decompose violently when decomposed
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Friedel-Crafts Acylation
Under reflux with a non-aqeuous solvent (dry ether) and a halogen carrier catalyst (AlCl3). Produces a PhenylKETONE and HCL
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Nitration conditions
Warm benzene and temp below 55 degrees
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Smells slightly fishy?
Amine
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Cationic Surfactant
Positively charges compounds that are partly soluble and partly insoluble in water. These are quarternary ammonium salts that have atleast 1 long chained hydrocarbon.
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Insoluble part of cationic surfactant
Long chain hydrocarbon (non-polar part that binds to grease)
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How grease is removed
Polar head dissolves in water so the grease mixes with water and can be washed away.
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Why do amines act as bases
They are proton acceptors
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Strongest base amine and why?
Primary aliphatic amine as the alkyl group pushes electrons towards the attached group and so increase electron density on nitrogen making it a stronger proton acceptor.
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Carboxylic acid derivative, with functional group -CONH2
Amide
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N-substituted Amide
Alkyl group substitutes a hydrogen on the nitrogen.
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What type of ammonium compound can be used as a cationic surfactant?
Quarternary ammonium salts
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Formation of amine from halogenoalkane
Nucleophillic substitution
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Formation of amine from nitriles
Reduction using a stong reducing agent
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Conditions for formation of amine from nitrile
Strong reducing agent (LiAlH4 or metal catalyst in high temp and pressure in industry) in dry ether with dilute acid
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What mechanism is used to form amides with acyl chloride?
Nucleophillic addition-eliminition between acyl chloride and ammonia/primary amine
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Acid anhydride + Ammonia/primary amine ---> ?
Amide and carboxylic acid
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Formation of aromatic amines
Nitro compound, tin and conc HCL is heated under reflux. This makes a salt. Then add NaOH
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Benzene attracts electrophiles or nucleophiles?
Electrophiles as it has high electron density
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Releases H+ ions when mixed with water. The H+ ions mix to form H3O+ ions.
Bronsted-Lowry Acids
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Dissociation in water
Breaks up into + & - charged ions
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What happens when you add acid to water?
Water acts as a base and accepts protons
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Ionic product of water
Kw= [H+][OH-]
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In pure water Kw=?
Kw=[H+]^2
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pH scale
A measure of the concentration of hydrogen ion in a solution
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pH=
-Log[H+]
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pH of monoprotic acids
[H+]=[Acid]
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Monoprotic Acid
Each molecule of acid releases one proton when it dissociates
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Diprotic Acid
Each molecule of acid releases TWO protons when it dissociates.
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pH of Diprotic acid
2 x [Acid] = [H+]
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finding [H+] from pH
[H+]= 10^[pH]
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Finding pKa from Ka: pKa=
-logKa
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What is a buffer?
A solution that resists change in pH when Small amounts of acid or alkali are added
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Acid Buffer
Buffer less than 7. A mix of weak acids and one of its salts.
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How to acid buffers work? for acid increase
Increase in [H+] means that equilibrium shifts to the left to counteract the increase in conc of H+ and therefore more HA is produced meaning pH stays constant
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How do acid buffers work? For base increase
Increase in OH- means that [H+] decreases as they react with each other so equilibrium shifts right to counteract the decrease [H+] so increases production so pH stays constant.
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How do Base buffers work? increase in acid
H+ reacts with OH- so [OH-] decreases so equilibrium shifts to the right to replace the lost [OH-]. So pH remains constant
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Other cards in this set

Card 2

Front

Nitration and Friedel-Crafts Acylation

Back

Two types of electrophillic substitution for benzene

Card 3

Front

WARM benzene with conc nitric acid and conc sulfuric acid. Conc sulfuric acid= Catalyst use to produce NO2+ ion . KEEP TEMP BELOW 55 DEGREES

Back

Preview of the back of card 3

Card 4

Front

Used in dyes and pharmaceuticals. Also ised in TNT and exploseives as they decompose violently when decomposed

Back

Preview of the back of card 4

Card 5

Front

Under reflux with a non-aqeuous solvent (dry ether) and a halogen carrier catalyst (AlCl3). Produces a PhenylKETONE and HCL

Back

Preview of the back of card 5
View more cards

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