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a level chemistry > 6.2 nitrogen compounds, polymers and synthesis > Flashcards

6.2 nitrogen compounds, polymers and synthesis Flashcards

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1
Q

What are amines

A

They are a class of compounds related to ammonia NH3
They are organic chemicals where one or more of the hydrogen atoms on ammonia have been replaced by alkyl chains

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2
Q

What are teh3 types of amine

A

primary - one hydrogen atom has been substituted RNH2
secondary - 2 hydrogen atoms have been substituted RNHR
tertiary - All three hydrogen atoms have been substituted RNR’R’’

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3
Q

How would you name a primary amine

A

adding the suffix amine

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4
Q

How would you name secondary amines

A

write the alkyl chains in alphabetical order and add the suffix amine
Secondary amines are often called N-substituted and is given as a prefix to the name

N-methyl propylamine

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5
Q

How would you name tertiary amines

A

name the alkyl chains in alphabetical order and add suffix
the prefix is N.N-

N,N-diethyl propylamine

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6
Q

define lewis base

A

has a lone pair of electrons for donation

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7
Q

Define Bronsted-Lowry base

A

A proton acceptor

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8
Q

How does an amine act as a lewis base

A

ammonia and amines have a lone pair of electrons on the nitrogen atom that they are able to donate mking them a lewis base

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9
Q

How do amines act as Bronsted-Lowry bases

A

Ammonia and amines can accept protons on the nitrogen atom

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10
Q

Describe the reaction between an amine and dilute inorganic acid

A

An alkylammonium salt is made and this is formed by the proton in the acid being replaced by an alkyl ammonium ion

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11
Q

give the symbol equation for the reaction of ethylamine with hydrochloric acid

A

CH3CH2NH2 +HCl → CH3CH2NH3+ +Cl- Ethyl ammonium chloride

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12
Q

How do you prepare amines

A

Heat in a sealed tube but not reflux as it is too volatile
heat the haloalkane with ammonia and ethanol

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13
Q

How do you prepare aromatic amines

A

Heat under reflux nitrobenzene with tin and conc. HCl which acts as the reducing agent at 100C
After about half an hour a strong alkali is added which undergoes a neutralisation reaction to remove excess hydrochloric acid and produce the amine

Producing aromatic amines is a multi-stage process that includes steam distillation solvent extraction and futher distillation

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14
Q

Give the equation for the reduction of nitrobenzene

A

nitrobenzene +6[H] → phenylamine +2H2O

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15
Q

Give the stricture of an amino acid

A

RCH(NH2)COOH

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16
Q

Describe the properties of an amino acid

A

it is a weak acid that will partially ionise in water
The nitrogen has a lone pair of electrons so it can act as a base meaning amino acids are amphoteric

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17
Q

Define zwitterion

A

an internal salt with no charge formed by the donation of a proton from a carboxylic acid funtional group to the amine functional group

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18
Q

What is the isoelectric point

A

when there is no net charge due to the zwitterion having an internal balance of charge

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19
Q

What happens to an amino acid at a low pH

A

The amino acid is acting as a base and accept a proton from the acid
the carboxylic acid functional group becomes COOH and the NH2 group becomes charged NH3

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20
Q

What happens to an amino acid at a high pH

A

The amino acid is acting as an acid and donates a proton to the hydroxide ion
The NH2 group remains the same while the carboxylic acid group becomes the charged COO-

21
Q

Describe the reaction between an amino acid and a metal oxide

A

It is a neutralisation reaction so it will react with the carboxylic acid to form a metal salt and water

22
Q

Describe the reaction between an amino acid and an alkali

A

It is a neutralisation reaction so it will react with the carboxylic acid to form a salt and water

23
Q

Describe the reaction between an amino acid and carbonate

A

It is a neutralisation reaction so it will react with the carboxylic acid to form a salt, co2 and water

24
Q

Describe the reaction between an amino acid and alcohol

A

Will produce an ester and water

25
Q

Describe the reaction between an amino acid and acid

A

The amine group will act as a base and the result will be an ammonium salt

26
Q

Describe an amide

A

They are a class of compounds with a functional group made out of an acyl group attached to an amine group

27
Q

How do you name amides

A

the suffix amide
ethanamide

28
Q

Define optical isomerism

A

Molecules which are non-super imposable mirror images of each other, they have the same chemical properties but interact with polarised light differently

29
Q

What is another name for two optical isomers

A

enantiomers

30
Q

Define chiral

A

A carbon with 4 different groups attached to it

31
Q

What prefixes do enantiomers have

A

+ rotates light in the clockwise direction
- rotates the light in the anti clockwise direction

32
Q

Define racemic mixture

A

A 50/50 mixture of enantiomers
the rotations of the 2 isomers cancel out

33
Q

Give the formula for the acid hydrolysis of nitriles

A

CH3CN + 2H2O + HCl = CH3COOH + NH4Cl

34
Q

What are the conditions for hydrolysing nitriles

A

Nitriles will undergo hydrolysis with an acid catalyst and heat under reflux

to initially form an amide and ammonium salt

35
Q

Why is a carboxylic acid formed during acid hydrolysis of nitriles rather than an organic ammonium salt

A

This is because the strong acid fully ionises in solution forming hydrogen and chloride ions
Once the amide is formed the bond between the nitrogen and carbon is broken making the ethanoate ion and then reacts with the proton from the strong acid to form the carboxylic acid

36
Q

define repeat unit

A

arrangement of atoms that occurs many times in a polymer

37
Q

Define condensation polymerisation

A

the chemical reaction to form a long-chain molecule by elimination of a small molecule such as water

38
Q

Define addition polymers

A

where monomers have atleast one C=C which breaks and joins the other monomers together

39
Q

How are polyesters formed

A

Condensation reaction between dicarboxylic acid and diol

40
Q

How are polyamides formed

A

Dicarboxylic acid and diamine

41
Q

Describe acid hydrolysis of polyesters

A

when a polyester is reacted with a strong aqueous acid the reaction produces a diol and a dicarboxylic acid
slow rate of reaction

42
Q

Describe the alkali hydrolysis of polyesters

A

when a polyester is reacted with hot sodium hydroxide the reaction produces the diol and the salt of the carboxylic acid

43
Q

Describe the acid hydrolysis of polyamides

A

When reacted with strong aqueous acid the reaction produces a diammonium salt and dicarboxylic acid

44
Q

Describe the alkali hydrolysis of polyamides

A

when reacted with sodium hydroxide solution the reaction produces the diamine and the salt of the dicarboxylic acid

45
Q

What is the mechanism used to extend carbon chain length

A

nucleophilic substitution- haloalkane
nucleophilic addition - carbonyl

46
Q

Describe how carbon chain length would be extended

A

The haloalkane is mixed with potassium cyanide and heated under reflux in an ethanol solvent and nucleophilic substitution occurs where cyanide takes place of the halogen creating a new c-c bond

47
Q

Why is ethanol used as the solvent when extending carbon chain length

A

This ensures the nucleophile is the cyanide ion not the hydroxide ion so an alcohol isn’t made and ensures carbon chain length extension

48
Q

describe how carbon chain length is extended using nucleophilic addition

A

Hydrogen cyanide is used
the cyanide ion is attracted to the carbon of the carbonyl group and will form a new covalent bond

49
Q

What can occur during the addition of the cyanide ion on the carbonyl

A

because the C=O is a planar bond there is an equally likely chance that the cyanide ion will attack from either side so a racemic mixture is produced when an unsymmetric ketone or aldehyde is used

a level chemistry (14 decks)

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