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Chemistry A Level > Synthesis > Flashcards

Synthesis Flashcards

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1
Q

What is the mechanism used to convert an alkene to an alkane and what are the reagents and conditions required?

A
  • Mechanism- Hydrogenation
  • Reagents- H2
  • Products- Alkane
  • Conditions- 150ºC and a nickel catalyst
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2
Q

What is the mechanism used to convert an alkene to a dihaloalkane?

A
  • Mechanism- Halogenation
  • Reagents- Br2
  • Product- Dihaloalkane
  • Conditions- None
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3
Q

How can you test for an alkene?

A

Bromine water is normally orange, if you add bromine water to an alkene then the bromine water will decolorise as an addition reaction occurs

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4
Q

What is the mechanism used to convert an alkene to an alcohol and what are the reagents and conditions?

A
  • Mechanism- Hydration
  • Reagents- H2O
  • Products- Alcohol
  • Conditions- H3PO4 catalyst, 300ºC, 65atm
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5
Q

What is a primary carbocation?

A

A carbocation that is connected to two hydrogen atoms and one R group

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6
Q

What is a secondary carbocation?

A

A carbocation that is connected to one hydrogen atom and two R groups

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7
Q

What is a tertiary carbocation?

A

A carbocation connected to three R groups and no hydrogen atoms

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8
Q

How do you produce a haloalkane from an alkene?

A

React the alkene with HBr, if you react with Br2 then a dihaloalkene with be produced

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9
Q

How do you produce an ester?

A

React a carboxylic acid and an alcohol, the OH of one molecule and the H from the OH group on the other molecule are removed as a water molecules, this forms an ester linkage. The mechanism is esterification and an H2SO4 catalyst is required as well as heat

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10
Q

What does the reaction of propanoic acid and butan-1-ol produce?

A

Butyl propanoate

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11
Q

What is the mechanism used to convert an alcohol to an alkene?

A
  • Mechanism- Dehydration
  • Reagents- none
  • Products- Alkene + H2O
  • Conditions- 170ºC and H2SO4 catalyst, heat under reflux
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12
Q

What is the mechanism used to convert an alcohol to a haloalkane?

A

Halide substitution, the halide ion takes the place of the OH group, a water molecule is produced as the OH that is removed bonds with the H from the H-X molecule

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13
Q

What is the mechanism used to convert a haloalkane to an alcohol?

A
  • Mechanism- Hydrolysis/Nucleophilic substitution
  • Reagents- H2O/NaOH/anything that releases an OH- ion as a nucleophile
  • Products- Alcohol + HX or NaX etc.
  • Conditions- 50ºC
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14
Q

What is the mechanism to convert an alkane to a haloalkane?

A
  • Mechanism- Free radical substitution
  • Reagents- A halogen molecule
  • Products- Multiple products
  • Conditions- UV light
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15
Q

What is the mechanism to convert an alkene to a polymer?

A

Addition polymerisation

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16
Q

What is the mechanism to convert an alkane to an alkene?

A

Cracking

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17
Q

What is the mechanism to convert an alcohol to an aldehyde?

A
  • Mechanism- Oxidation
  • Reagents- Primary alcohol
  • Products- Aldehyde + H2O
  • Conditions- Heat and distil, K2Cr2O7 / H+ as [O] oxidising agent, observe colour change orange to green
  • CH3CH2CH2OH + [O] → CH3CH2COH + H2O
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18
Q

What is the mechanism to convert an alcohol to a carboxylic acid?

A
  • Mechanism- Oxidation
  • Reagents- Primary alcohol
  • Products- Carboxylic acid + H2O
  • Conditions- Heat under reflux, 2[O] as K2Cr2O7 / H+, observe colour change of orange to green
  • CH3CH2CH2OH + 2[O] → CH3CH2COOH + H2O
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19
Q

What is the mechanism that is used to convert an alcohol to a ketone?

A
  • Mechanism- Oxidation
  • Reagents- Secondary alcohol
  • Products- Ketone + H2O
  • Conditions- Heat under reflux, [O] as K2Cr2O7 / H+, observe colour change of orange to green
  • CH3CH(OH)CH2CH3 + [O] → CH3COCH2CH3
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20
Q

How would you prepare a primary amine?

A
  • React ammonia with a haloalkane, CH3CH2CH2Cl + NH3 → CH3CH2CH2NH3+Cl-
  • The ammonium salt reacts with an additional ammonia molecule in a reversible reaction, CH3CH2CH2NH3+Cl- + NH3 ⇌ CH3CH2CH2NH2 NH4+Cl-
  • The haloalkane, ammonia and ethanol are all heated together
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21
Q

How do you prepare a secondary amine?

A

CH3CH2CH2Cl + CH3CH2CH2NH2 ⇌ (CH3CH2CH2)2NH + HCl

22
Q

How do you produce a tertiary amine?

A

(CH3CH2CH2)2NH + CH3CH2CH2Cl ⇌ (CH3CH2CH2)3N+HCl

23
Q

How do you produce a quaternary amine salt?

A

(CH3CH2CH2)3N + CH3CH2CH2Cl ⇌ (CH3CH2CH2)4N+Cl-

24
Q

To produce a primary amine or a quaternary ammonium salt which reactant would you add in excess?

A
  • For primary amine add excess NH3

- For quaternary salt add excess haloalkane

25
Q

How do you prepare an aromatic amine?

A
  • Nitrobenzene can be reduced to produce phenylamine
  • The reducing agent is produced in situ from a mixture of HCl and tin
  • The reaction mixture is heated under reflux at around 110ºC and after around 30 mins, sodium hydroxide is added to neutralise any excess HCl
  • The aromatic amine has to be separated in a multi-stage process involving steam distillation, solvent extraction and further distillation
  • C6H5NO2 + 6[H] → C6H5NH2 + 2H2O
26
Q

What does the hydrolysis of a polyester with H+/H2O produce?

A

A diol and a carboxylic acid, the acid hydrolysis of has a slow rate of reaction

27
Q

What does the hydrolysis of a polyester with NaOH/H2O produce?

A

The salt of the carboxylic acid and a diol, the rate of reaction with basic hydrolysis is much faster than acid hydrolysis

28
Q

What does acid hydrolysis of a polyamide produce?

A

A dicarboxylic acid and a diammonium salt, the H+ joins on to the NH2 group, forming NH3+ on both sides of the salt

29
Q

What does the basic hydrolysis of a polyamide produce?

A

A salt of the dicarboxylic acid and the diamine

30
Q

What is the difference between a cyanide ion and a nitrile?

A

A nitrile is a molecule containing the -CN functional group such as ethanenitrile CH3CN, a cyanide ion is a CN- ion, this can be ionically bonded to sodium to form Na+-CN

31
Q

How is the carbon chain length extended?

A

The haloalkane is reacted with potassium cyanide using ethanol as the solvent. The CN- ion attacks the delta positive carbon, this joins the CN- ion to the delta positive carbon, this forms a nitrile and extends the carbon chain length. K-X is formed (potassium halide)

32
Q

What is the equation for the reaction between CH3CH2CH2Br and KCN?

A

CH3CH2CH2Br + KCN → CH3CH2CH2CN + KBr

33
Q

What is is the equation for the reduction of CH3CN using hydrogen?

A

CH3CN +2H2 →CH3CH2NH2

34
Q

Why is ethanol used as the solvent in the nucleophilic substitution of a haloalkane with a cyanide ion?

A

As if water is used then the hydroxide ion would be the nucleophile and the carbon chain would not increase in length

35
Q

Other than hydrogen, what can be used as the reducing agent for the reduction of a nitrile?

A

Li+[AlH4]-, the oxidation number of hydrogen in this compound is -1

36
Q

What is the equation of the reaction for the reduction of propanenitrile using LiAlH4?

A

CH3CH2CN + 4[H] →CH3CH2CH2NH2

37
Q

What does hydrolysis of a nitrile produce?

A

A primary amide and then an ammonium salt, the rate of this reaction is so slow that is completely negligible (unimportant). Therefore an acid catalyst has to be used

38
Q

What does the acid hydrolysis of a nitrile produce?

A

CH3CN + 2H2O + HCl → CH3COOH + NH4Cl

39
Q

What is the equation for the reaction between benzene and CH3Cl?

A
  • C6H6 + CH3Cl → C6H5CH3 + HCl
  • FeCl3 + CH3Cl → CH3+ (acts as electrophile) + FeCl4- (reacts with H on benzene)
  • FeCl4- + H+ → FeCl3 + HCl
  • Overall: CH3Cl + H+ → CH3+ + HCl
40
Q

What is the equation of the reaction between C6H6 and CH3COCl (ethanoyl chloride)?

A

C6H6 + CH3COCl → C6H5COCH3

- A strong Lewis acid catalyst is required

41
Q

What is the role of anti-bumping granules in reflux and distillation?

A

To make the mixture boil more calmly

42
Q

What is the process of filtration to purify an organic solid?

A
  • Connect thick-walled rubber tubing to the vacuum pump and check there is suction
  • Put a Buchner funnel into the top of a filter flask
  • Connect the tubing that is connected to the vacuum pump to the side of the filter flask and start the suction
  • Put a piece of filter paper into the top of the funnel
  • Use the solvent from your organic synthesis to dampen the filter paper so it sticks over the holes of the funnel
  • Pour the reaction mixture into the centre of the funnel
  • Wash out the reaction vessel with the solvent and rinse the collected soli with more solvent and maintain suction for a minute after all the washings have been added
  • Turn off the suction ad removed the rubber tubing from the side arm of the filter flask
  • Invert the solid onto a watch glass and collect the organic solid
43
Q

Describe the process of recrystallisation

A
  • Recrystallisation is a technique that is used to purify an organic product from catalysts, unreacted starting materials and side products
  • The crude product is dissolved into the minimum amount of hot solvent (hot solvent is used as a larger amount of solid will dissolve when the solvent is hot)
  • Activated charcoal can be used to remove coloured impurities if the product is coloured
  • The hot solution should then undergo gravity filtration using fluted filter paper, the residue of insoluble impurities and activated charcoal can be disposed off
  • Filtrate should now be allowed to cool and crystals of the organic product should begin to form, cooling the mixture in an ice bat can speed up this stage, ay soluble impurities should remain dissolved
  • The purified organic product can then be collected using vacuum filtration, the crystals should then be washed with a small amount of cold solvent to remove any filtrate that contains dissolved impurities, a drying oven can then be used to obtain dry crystals
44
Q

How can the purity of an organic product be checked?

A

All pure compounds have distinct melting and boiling points, by measuring the melting and boiling points of the known organic product produced the purity can be determined by comparing the melting point of the organic product to a data book. The more impure the product is, the lower the melting and boiling points will be

45
Q

How is an ester produced from an acyl chloride?

A

CH3COCl + CH3CH2OH → CH3COOCH2CH3 + HCl

46
Q

How is a carboxylic acid produced from an acyl chloride?

A

CH3COCl + H2O → CH3COOH + HCl

47
Q

How is a primary amide produced from an acyl chloride?

A

CH3COCl + 2NH3 → CH3CONH2 + NH4Cl

48
Q

How is a secondary amide produced from an acyl chloride?

A

CH3COCl + CH3CH2NH2 → CH3CONHCH2CH3 + HCl

49
Q

What is CH3COCl called?

A

Ethanoyl chloride

50
Q

What is CH3COOCOCH3 called?

A

Ethanoic anhydride

51
Q

How are acyl chlorides produced?

A

CH3COOH + SOCl2 → CH3COCl + SO2 + HCl

52
Q

How is an acid anhydride produced?

A
  • Two carboxylic acids are reacted together

- CH3COOH + CH3COOH → CH3COOCOCH3 + H2O

Chemistry A Level (15 decks)

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