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A Level Chemistry > Organic Chemkstry II - Topic 17 > Flashcards

Organic Chemkstry II - Topic 17 Flashcards

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1
Q

Suffix of aldehydes

A

al

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2
Q

Suffix of ketones

A

One

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3
Q

Suffix and prefix of nitriles

A

Suffix - nitrile
Prefix - cyano

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4
Q

Suffix of esters

A
  • yl - oats
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5
Q

Suffix for Acyl chloride

A
  • oyl - chloride
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6
Q

Suffix for amide

A

Amide

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7
Q

Functional group of aldehyde

A

H - C = O

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8
Q

Functional group of ketone

A

C = O

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9
Q

Functional group of amines

A

C - NH2

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10
Q

Functional group of esters

A

O = C - O

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11
Q

Functional group of nitrile

A

C triple bond N

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12
Q

When do we use the prefix oxo to describe an aldehyde

A

The prefix oxo- should be used for compounds that contain a ketone group in addition to a carboxylic acid or aldehyde

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13
Q

When do we use the prefix hydroxy to describe an alcohol (or acid)

A

When there is an OH functional group and an additional functional group

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14
Q

What carbon atom is an aldehyde always on

A

One (hence why they always end in al and no number are used to describe the aldehyde)

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15
Q

When do you label the position of ketones in a compound

A

When there is 5 or more carbons in the carbon chain

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16
Q

What carbon does the C in the nitrile group count as

A

1 (so nitrile groups are never number)

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17
Q

How do you name esters

A

1) the chain after the single bonded oxygen is the alcohol formed so ends in yl and is at the beginning of the word
2) the chain after the double bonded oxygen is the carboxylic acid that is formed and ends in anoate and us at the end of the word

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18
Q

Chain isomers

A

Compounds with the same molecular formula but different structures of the carbon skeleton

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19
Q

position isomers

A

Compounds with the same molecular formula but different structures due to different positions of the same functional group on the same carbon skeleton

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20
Q

Functional group isomers

A

Compounds with the same molecular formula but with atoms arranges to give different
functional groups

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21
Q

Stereoisomers

A

same structural formulae but have a different spatial arrangement of atoms

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22
Q

Two types of stereoisomerism

A
  • E-Z isomerism
  • optical isomerism
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23
Q

Conditions for EZ isomerism

A

1) There is restricted rotation around the C=C double bond.
2) There are two different groups/atoms attached both ends of
the restricted double bond

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24
Q

Which atom is classed as higher priority in EZ isomerism

A

The atom with the higher relative atomic mass

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25
Q

What is the condition for optical isomerism to occur

A
  • it has to contain a carbon compound with 4 different groups of atoms attached to a carbon (called a chiral carbon atom)
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26
Q

Enantiomers

A

Two compounds that are optical isomers of
each other

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27
Q

What are optical isomers

A

Isomers with similar physical and chemical properties, but they rotate plane polarised light in different directions

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28
Q

What is a racemate/racemic mixture

A

A mixture containing a 50/50 mixture of the
two isomers (enantiomers)

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29
Q

Will racemic mixture rotate in light

A

racemic mixture will not rotate plane-polarised light.

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30
Q

How do optical isomers rotate in plane polarised light

A

One optical isomer will rotate light clockwise. The other will rotate it anticlockwise(

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31
Q

How is a racemate formed

A

1) Nucleophilic addition of HCN to aldehydes and ketones when the trigonal planar carbonyl is approached from both sides by the HCN attacking species
2) When any attacking species approaches both sides for a trigonal planar reactant or intermediate
3) electrophilic addition of HBr to an unsymmetrical alkene

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32
Q

Why is racemate formed when attacking species approach both sides of the reactant or intermediate

A

As there is an equal chance of either enantiomer forming so a racemate forms

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33
Q

Draw and explain the SN1 mechanism of the formation of a racemate with 2-bromobutane and an OH ion

A

Pg 8 in chemrevise

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34
Q

Draw and explain the SN2 mechanism of the formation of a racemate with 2-bromobutane and an OH ion

A

Page 8 of chemrevise

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35
Q

Difference between SN1 and SN2 mechanism, for formation of racemate

A
  • In SN2 no intermediates are formed instead the reaction occurs via a transition state (meaning that the molecule flips/turns to one side, which is the side the arrow on the Br is facing) whilst in SN1 intermediates are formed
  • In SN2 If the reactant was chiral then during the reaction the opposite enantiomer would form. The product will rotate light in the opposite direction to the reactant
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36
Q

Draw and explain the electrophilllic addition of HBr to but-1-ene

A

Pg 8 of chemrevise

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37
Q

What are carbonyls

A

compounds with a C=O bond, they can be either aldehydes or ketones

38
Q

What is the oxidizing agent that causes alcohols and aldehydes to oxidize

A

Potassium dichromate K2Cr2O7

39
Q

What is primary alcohols oxidised into

A

Aldehydes

40
Q

What is aldehydes oxidised into

A

Carboxylic acid

41
Q

What is secondary alcohol oxidised into

A

Ketones

42
Q

Test for aldehydes: oxidation using potassium dichromate
1) Reaction
2) Reagent
3) Conditions
4) Observation

A

1) aldehyde —> carboxylic acid
2) potassium dichromate (VI) solution and
dilute sulfuric acid
3) heat under reflux
4) Orange dichromate ion (Cr2O7 2-) reduces to green Cr 3+ ion

43
Q

Test for aldehydes

A
  • Tollens reagent
  • Fehling solution
  • potassium dichromate
44
Q

Test for aldehydes: Tollens reagent
1) Reagent
2) Conditions
3) what happens to the aldehydes
4) observation

A

1) Tollen’s Reagent formed by mixing aqueous ammonia and silver nitrate ( [Ag(NH3)2]+ )
2) heat gently
3) aldehydes are oxidised by Tollen’s reagent into carboxylic acid and silver(I) ions are reduced to silver atom
4) a silver mirror forms coating the inside of the test tube, and there is no change to ketones

45
Q

Test for aldehydes: Fehlings solution
1) Reagent
2) Conditions
3) what happens to the aldehydes
4) observation

A

1) Fehling’s solution containing blue Cu 2+ ions
2) heat gently
3) aldehydes are oxidised by Fehlings solution into a carboxylic acid and the copper ions are reduced to copper(I) oxide
4) aldehydes produce a blue Cu 2+ solution change to a red precipitate of Cu2O and Ketones do not react

46
Q

Equation for the oxidation of aldehydes using Tollen’s reagent

A

CH3CHO + 2Ag+ + H2O —-> CH3COOH + 2Ag + 2H+

47
Q

Equation for the oxidation of aldehydes using Fehlings solution

A

CH3CHO + 2Cu2+ + 2H2O —-> CH3COOH + Cu2O + 4H+

48
Q

Full equation for oxidation of aldehydes using potassium dichromate

A

3CH3CHO + Cr2O72- + 8H+ —-> 3 CH3CO2H + 4H2O + 2Cr

49
Q

Full equation for oxidation of aldehydes using potassium dichromate

A

3CH3CHO + Cr2O72- + 8H+ —-> 3 CH3CO2H + 4H2O + 2Cr

50
Q

Reducing agents that will reduce carbonyls to alcohols

A
  • NaBH4
  • LiAlH4
51
Q

Reduction of carbonyls/ carboxylic acids to primary alcohols
1) Reagent
2) Conditions

A

1) LiAlH4 in dry ether (or NaBH4)
2) Room temperature and pressure

52
Q

Addition of hydrogen cyanide to carbonyls to form hydroxynitriles
1) Reaction
2) Reagent
3) Conditions
4) Mechanism

A

1) carbonyl —> hydroxynitrile
2) HCN in presence of KCN
3) Room temp and pressure
4) nucleophilic addition

53
Q

What does the KCN do in the Addition of hydrogen cyanide to carbonyls to form hydroxynitriles

A

The extra KCN increases the concentration of the CN ion nucleophile needed for the
first step of the mechanis

54
Q

Draw the nucleophilic addition of propanone to hydrogen cyanide

A
55
Q

How do we form hydroxynitriles from carbonyls

A

Throughtnthe addition if hydrogen cyanide

56
Q

What does the Iodoform test test for

A

Carbonyls with a methyl group next to the C=O

57
Q

Iodoform test
1) Reagents
2) conditions
3) observations

A

1) Iodine and sodium hydroxide
2) warm very gently
3) The product CHI3 is a yellow crystalline
precipitate with an antiseptic smell

58
Q

Iodoform equation for propanone

A

CH3COCH3 + 3I2 + 4NaOH → CHI3 + CH3COONa + 3NaI +3H2O

(The 3I2 + 4NaOH —> 3NaI + 3H2O stays the same in all Iodoform equations)

59
Q

Iodoform equation with butan-2-one

A

CH3COCH2CH3+ 3I2 + 4NaOH → CHI3 + CH3CH2COONa + 3NaI +3H2O

60
Q

Reaction to test whether a carbonyl is in an compound (test for both aldehydes and ketones)

A

Reaction with 2, 4-DNP

61
Q

Observation with Reaction with 2,4-dinitro phenylhydrazine

A

An orange precipitate is formed in presence of aldehydes and ketones

62
Q

How to identify what the carbonyl is after using 2, 4 DNP

A

1) differentiate an aldehyde from a ketone by using Tollen’s reagent or Fehlings
2) take the melting point of orange crystals product from 2,4-DNP. Compare melting point with known values in database

63
Q

What happens the the solubility of carboxylic acids as the increase in size

A

Solubility decreases

64
Q

Why do carboxylic acids dissolve in water

A

Due to the hydrogen bonding between the OH and C=O group

65
Q

How do carboxylic acids remain stable (after dissolving in water)

A

When a carboxylic acid is dissolved in water it splits up into a carboxylic ion and a hydrogen ion. The lone pair of electrons from the O- ion and the electrons from the pi bond of the C=O become delocalised across the O=C-O bond and the charge is spread out this makes the ion more stable and makes dissociation more likely to occur

66
Q

Explain the relationship with chain length and strength/ stability of carboxylic acids

A

Increasing chain length pushes electron density on to the COO- ion (as the oxygen are more electronegative) , making it more negative and less stable. This makes the acid less strong since there will be a greater attraction to protons (H+) so less dissociation.

67
Q

Explain the affect of chlorine ions on the strength of carboxylic acids

A

Electronegative chlorine atoms withdraw electron density from the COO- ion, making it less negative and more stable. This make the acid more strong as there will be less attractions to the protons so it can dissociate more protons into the solution

68
Q

Methods of preparing carboxylic acids

A

1) Full oxidation of Primary alcohols
2) oxidation of aldehydes
3) hydrolysis of nitriles

69
Q

Full oxidation of primary alcohols
1) reaction
2) reagent
3) conditions
4) observations

A

1) primary alcohol —-> carboxylic acid
2) potassium dichromate(VI) solution and dilute sulfuric
3) an excess of dichromate, and heat under reflux: (distil off product after the reaction has finished)
4) orange dichromate ion (Cr2O7 2-) reduces to the green Cr 3+ ion

70
Q

Hydrolysis of nitriles
1) Reaction
2) Reagent
3) Conditions
4) Equation with propanenitrile

A

1) Nitrile —> carboxylic acid
2) dilute hydrochloric/ sulfuric acid
3) heat under reflux
4) CH3CH2CN + H+ + 2H2O —-> CH3CH2COOH + NH4+

71
Q

All example of salt formation with (carboxylic) acids

A

Acid + metal —> salt + hydrogen
Acid + alkali —> salt + water
Acid + carbonate —> salt + water + carbon dioxide

72
Q

What is the only oxidizing agent that can oxidise carboxylic acid and why

A
  • Methanoic acid
  • as its structure contains and aldehyde group
73
Q

What is the only oxidizing agent that can oxidise carboxylic acid and why

A
  • Methanoic acid
  • as its structure contains and aldehyde group
74
Q

What is the only oxidizing agent that can oxidise carboxylic acid and why

A
  • Methanoic acid
  • as its structure contains and aldehyde group
75
Q

What does carboxylic acids form when oxidized by methanoic acid

A

Carbonic acid

76
Q

Reaction of carboxylic acid with phosphorus (v) chloride
1) reaction
2) reagent
3) conditions
4) equation with ethanoic acid

A

1) carboxylic acid —> acyl chloride
2) PCl5 (phosphorus (V) chloride)
3) room temp
4) CH3COOH + PCl5 —> CH3COCl + POCl3

77
Q

Test for carboxylic acid

A

Reaction of carboxylic acid with phosphorous (V) chloride - it would produce misty fumes of HCl is carboxylic acids are present

78
Q

How are esters formed

A

When Carboxylic acids react with alcohols, in the presence of a strong acid catalyst, to form
esters and water.

79
Q

Use of esters

A
  • perfume
  • solvents
  • flavouring
80
Q

Reagents and conditions used for hydrolysis of esters

A

Reagents: dilute acid or dilute sodium hydroxide
Conditions: heat under reflux

81
Q

Difference in the hydrolysis of esters with an dilute acid and sodium hydroxide

A

With acid - reaction is reversible and does not give a good yield of products (carboxylic acid and alcohol)
With sodium hydroxide - reaction goes to completion and it produces a carboxylic salt product, which is the anion of carboxylic acid, which is resistant to weak nucleophiles (e.g alcohols) so reaction is not reversible

82
Q

Why are acyl chlorides more reactive than carboxylic acids

A

As the Cl group is a good leaving group

83
Q

Reaction of acyl chlorides with water
1) reaction
2) reagent
3) conditions

A

1) acyl chloride —> carboxylic acid
2) water
3) room temp

84
Q

Reaction of acyl chlorides with alcohol
1) Reaction
2) Reagent
3) Conditions

A

1) acyl —> ester
2) alcohol
3) room temp

85
Q

Reaction of acyl chlorides with ammonia
1) reaction
2) reagent
3) conditions

A

1) acyl —-> primary amide
2) ammonia
3) room temp

86
Q

Reaction of acyl chlorides with primary amines
1) reaction
2) reagent
3) conditions

A

1) acyl —> secondary amide
2) primary amine
3) room temp

87
Q

Two types of condensation polymers

A

1) polyesters
2) polyamides

88
Q

How do we form polymers

A

By reacting compounds with the same functional group on each end of the molecule

dicarboxylic acid + diol —-> poly(ester) + water

diacyl dichloride + diol —-> poly(ester) + HCl

89
Q

How are polyesters hydrolysed

A

By using an acid or alkali
- with HCl a polyester will be hydrolysed and split up in to the original dicarboxylic acid and diol
- With NaOH an polyester will be hydrolysed and split up into the diol and dicarboxylic acid salt.

90
Q

What is meant by a chiral molecules

A

A non superimposable molecule on its mirror image with no plane of symmetry

A Level Chemistry (15 decks)

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