Module 6: Chapter 28 - Organic Synthesis Flashcards
1
Q
What is the importance of carbon-carbon bond formation in organic synthesis?
A
It allows you to:
* Lengthen a carbon chain
* Add a side chain to a benzene ring
* Introduce a new functional group which can then be reacted further
2
Q
How can you form a Nitrile from haloalkanes?
A
React haloalkanes with sodium cyanide, NaCN, or with potassium cyanide, KCN, in ethanol
3
Q
What are the conditions to form a Nitrile from haloalkanes?
A
Ethanolic
4
Q
What type of mechanism is the reaction to form a Nitrile from haloalkanes?
A
nucleophilic substitution
5
Q
Draw the complete mechanism for the reaction between a haloalkane and sodium cyanide
A
6
Q
How can you produce an amine from a nitrile?
A
React it with hydrogen in the presence of a nickel catalyst
7
Q
What is the reduction of a nitrile?
A
The reaction of a nitrile with hydrogen in the presence of a nickel catalyst to produce an amine
8
Q
What are the conditions for forming an amine from a nitrile?
A
React with hydrogen in the presence of a nickel catalyst
9
Q
What is the hydrolysis of a nitrile?
A
The production of a carboxylic acid from heating a nitrile with a dilute aqueous acid
10
Q
What is the reaction for the hydrolysis of a nitrile?
A
Nitrile + aqueous acid -> carboxylic acid + ammonium salt
11
Q
How can you produce a carboxylic acid from a nitrile?
A
React it with a dilute aqueous acid
12
Q
What are 2 reactions that increase the length of the carbon chain?
A
- Forming a nitrile from a haloalkane
- Forming a nitrile from aldehydes and ketones
13
Q
What are 2 reactions that add a side chain to a benzene ring?
A
- Alkylation
- Acylation
14
Q
What is filtration under reduced pressure?
A
Filtration under reduced pressure is a technique used for separating a solid product from a solvent or liquid reaction mixture
15
Q
What apparatus is needed for filtration under reduced pressure?
A
- Buchner flask
- Buchner funnel
- Pressure tubing
- Filter paper
- Access to filter or vacuum pump (filter pump used at A level)
16
Q
What is this?
A
A buchner flask
used for filtrating under reduced pressure
17
Q
What is this?
A
A Buchner funnel
used for filtrating under reduced pressure
18
Q
What is this?
A
Filter pump
used for filtrating under reduced pressure
19
Q
Describe the process for filtration under reduced pressure:
A
- Connect one end of the pressure tubing to the filter pump whilst attaching the other end of the rubber tubing to the Buchner flask
- Attach the filter pump to a tap
- Fit the Buchner funnel to the Buchner flask ensuring that there is a good tight fit by using a rubber bung
- Switch on the tap to which the filter pump is attached
- Check for good suction by placing your hand across the top of the funnel
- Place a piece of filter paper inside the Buchner funnel and wet this with the same solvent used in preparing your solid, you should see the paper being sucked down against the holes in the funnel
- Slowly pour the reaction mixture from a beaker into the centre of the filter paper
- Rinse out the beaker with the solvent so that all of the solid crystals collect in the Buchner funnel
- Rinse the crystals in the Buchner funnel with more solvent and lkeave them under suction for a few minutes so that the crystals start to dry
20
Q
What is purification by recrystallisation?
A
A solid product obtained after filtration will contain impurities which can be removed by carrying out recrystallisation. Purification by recrystallisation relies on the desired product and the impurities having different solubilities in the chosebn solvent
21
Q
Describe how to carry out purification by recrystallisation:
A
- Pour a quantity of the chosen solvent into a conical flask. If the solvent is flammable, warm the solvent over a water bath. If it is not flammable (i.e water), place the conical flask on a tripod and gauze over a Bunsen and warm the solvent
- Tip the impure sample into a second conical flask or beaker
- Slowly add the solvent to the impure sample until it dissolves in the solvent. you should add the minimum volume of solvent needed to dissolve the solid
- Once the solid has dissolved, allow the solution to cool. Crystals of the desired product should form in the conical flask or beaker. When no more crystals form, filter the crystals under reduced pressure to obtain the dry crystalline solid
22
Q
How can you determine whether a solid is pure?
A
Determining the melting point:
* A pure organic substance usually has a very sharp melting range of 1 or 2 degrees
* If the compound contains impurities, the solid melts over a wide range of temperatures and an impure sample also has a lower melting point than a pure sample
23
Q
What is the melting range of a substance?
A
The difference between the temperature at which the sample starts to melt and the temperature at which melting is complete
24
Q
What are the 2 methods to determine the melting point of a solid?
A
- Using electrically heated melting point apparatus
- Using an oil bath or Thiele tube method
25
How do you prepare your sample before determining the melting point of a solid?
Bedore taking the melting point of a solid, you should ensure that the sample is completely dry and free flowing:
1. Take a glass capillary tube or melting point tube. Hold one end of the capillary tube in the hot flame of a bunsen burner and rotate the tube in the flame until the end of the tube is completely sealed
2. The capillary tube is allowed to cool, and is then filled with crystals to about 3mm depth. This is usually carried out by pushing the open end of the capillary tube into the solid sample to force some of the solid into the tube
26
How can you use electrically heated melting point apparatus to determine the melting point of a solid substance?
1. Place the capillary tube containing the sample into the sample hole and a 0-300 degrees celcius thermometer in the thermometer hole of the melting point apparatus
2. Using the rapid heating setting, start to heat up the sample whilst observing the sample through the magnifying window
3. Once the solid is seen to melt, record the melting point. Allow the melting point apparatus to cool
4. Prepare a second sample ina. new capillary tube and place in the melting point apparatus and heat up the sample again
5. As the melting point is apporached, set to low and raise the temperature slowly whilst obersving the sample. An accurate determination of the melting point can then be obtained
27
How can you use a Thiele tube or oil bath to determine the melting point of a solid substance?
1. Set up the Thiele tube or oil bath
2. Attach the capillary tube containing the sample to a thermometer using a rubber band
3. Insert the thermometer through a hole in the cork (if using a thiele tube) or clamp the thermometer (if using an oil bath). The end of the thermometer and the end of the capillary tube should dip into the oil
4. Using a micro-burner, slowly heat the side arm of the Thiele tube or the oil bath whilst observing the solid. When the solid starts to melt, remove the heat and record the temperature at which all of the solid has melted. It is important to heat the oil slowly when approaching the melting point, and it is advisable to repeat the melting point determination a second time to ensure that you obtain an accurate value
28
What is this?
A Thiele tube
29
Identify all the functional groups present in aspartame:
30
Identify all the functional groups present within capsaicin:
31
How do you produce a haloalkane from an alkene?
React the alkene with a hydrogen halide
32
What happens if you react an alkene with a hydrogen halide?
A haloalkane is produced
33
How do you produce an alcohol from an alkene?
Hydration of an alkene:
React the alkene with steam in the presence of a phosphoric acid catalyst
34
What happens if you react an alkene with steam in the presence of a phosphoric acid catalyst (hydration of an alkene)?
An alcohol is produced
35
How do you produce an alkene from an alcohol?
React the alcohol with concentrated sulfuric acid
36
What happens if you react an alcohol with concentrated sulfuric acid?
You produce an alkene
37
How do you produce a haloalkane from an alcohol?
React the alcohol with a sodium halide in the presence of a sulfuric acid catalyst
38
What happens if you react an alcohol with a sodium halide in the presence of a sulfuric acid catalyst?
You produce a haloalkane
39
How do you produce an alcohol from a haloalkane?
Reflux the haloalkane with sodium hydroxide
40
What happens if you reflux a haloalkane with sodium hydroxide?
You produce an alcohol
41
How do you produce an ester from an alcohol?
Esterification:
react the alcohol with a carboxylic acid in the presence of a sulfuric acid catalyst
42
What happens if you react an alcohol with a carboxylic acid in the presence of a sulfuric acid catalyst?
You produce an ester
43
How do you produce an alcohol and a salt of a carboxylic acid from an ester?
Alkanline hydrolysis:
React the ester with Sodium hydroxide
44
What happens if you react an ester with sodium hydroxide?
You produce a sodium saly of a carboxylic acid and an alcohol
45
How do you produce a carboxylic acid from an ester?
Dilute acid hydrolysis:
Reflux the ester with a dilute aqueous acid
46
What happens if you reflux an ester with a dilute aqueous acid?
You produce a carboxylic acid
47
How do you produce an ester from a carboxylic acid?
Esterification:
React the carboxylic acid with an alcohol in the presence of a sulfuric acid catalyst
48
What happens if you react a carboxylic acid with an alcohol in the presence of a sulfuric acid catalyst?
You produce an ester
49
How do you produce a nitrile from a haloalkane?
React it with sodium cyanide
50
What happens if you react a haloalkane with sodium cyanide?
You produce a nitrile
51
How do you produce an amine from a haloalkane?
React it with ammonia in ethanol
52
What happens if you react a haloalkane with ammonia in ethanolic conditions?
You produce an amine
53
How do you produce an amine from a nitrile?
Reduction:
React the nitrile with hydrogen in the presence of a nickel catalst
54
What happens if you react a nitrile with hydrogen in the presence of a nickel catalyst (reduction)?
You produce an amine
55
How do you produce an ester from an acyl chloride?
React the acyl chloride with an alcohol
56
What happens if you react an acyl chloride with an alcohol?
you produce an ester
57
What happens if you react an acyl chloride with ammonia?
You produce a primary amide
58
How do you produce a primary amide from an acyl chloride?
React the acyl chloride with ammonia
59
How do you produce a secondary amide from an acyl chloride?
React the acyl chloride with a primary amine
60
What happens if you react an acyl chloride with a primary amine?
You produce a secondary amide
61
How do you produce a carboxylic acid from an acyl chloride?
React the acyl chloride with water
62
What happens when you react an acyl chloride with water?
You produce a carboxylic acid
63
What happens if you react a carboxylic acid with Thionyl chloride?
You produce an acyl chloride
64
What is Thionyl chloride?
SOCl₂
65
How do you produce an acyl chloride from a carboxylic acid?
React the carboxylic acid with thionyl chloride
66
How do you produce a carboxylic acid from an aldehyde?
Reflux the aldehyde with potassium dichromate with a sulfuric acid catalyst
67
What happens if you reflux an aldehyde with potassium dichromate with a sulfuric acid catalyst
You produce a carboxylic acid
68
How do you produce an aldehyde from a primary alcohol?
Oxidation:
Distill the primary alcohol with potassium dichromate with a sulfuric acid catalyst
69
What happens if you distill a primary alcohol with potassium dichromate with a sulfuric acid catalyst
you produce an aldehyde
70
How do you produce a primary alcohol from an aldehyde?
Reduction:
React the aldehyde with aqueous NaBH₄
71
What happens if you react an aldehyde with aqueous NaBH₄
You produce a primary alcohol
72
how do you produce a hydroxynitrile from an aldehyde?
React with NaCN with a sulfuric acid catalyst
73
What happens if you react an aldehyde with NaCN with a sulfuric acid catalyst?
You produce a hydroxynitrile
74
How do you produce a carboxylic acid from a nitrile?
Hydrolysis:
Heat with a dilute aqueous acid
75
What happens if you heat a nitrile with a dilute aqueous acid?
You produce a carboxylic acid
76
How do you produce toluene (methylbenzene) from benzene?
Alkylation:
React benzene with methylchloride in the presence of aluminium chloride
77
What happens if you react benzene with methylchloride in the presence of aluminium chloride?
You produce toluene (methylbenzene)
78
How do you produce bromobenzene from benzene?
Bromination:
React benzene with bromine in the presence of FeBr₃
79
What happens if you react benzene with bromine in the presence of FeBr₃?
You produce bromobenzene
80
How do you produce chlorobenzene from benzene?
React benzene with chlorine in the presence of AlCl₃
81
What happens if you react benzene with chlorine in the presence of AlCl₃?
You produce chlorobenzene
82
How do you produce an aromatic ketone from benzene?
React benzene with an acyl chloride in the presence of an AlCl₃ catalyst
83
What happens if you react benzene with an acyl chloride in the presence of an AlCl₃ catalyst
Your produce an aromatic ketone
84
How do you produce a secondary alcohol from a ketone?
Reduction:
React the ketone with aqueous NaBH₄
85
What happens if you react a ketone with aqueous NaBH₄
You produce a secondary alcohol
86
How do you produce nitrobenzene from benzene?
Nitration:
React benzene with nitric acid and a concentrated sulfuric acid catalyst
87
What happens if you react benzene with nitric acid and a concentrated sulfuric acid catalyst
Your produce nitrobenzene
88
How do you produce phenylamine from nitrobenzene?
Reduction:
React the nitrobenzene with tin and a concentrated acid such as hydrochloric acid and then following this react it with excess sodium hydroxide
89
What happens if you react nitrobenzene with tin and a conecentrated acid (such as hydrochloric acid) follwed by excess sodium hydroxide?
You produce phenylamine
90
What happens if you react phenylamine with bromine?
You produce 2,4,6-tribromophenylamine
91
How do you produce 2,4,6-tribromophenylamine from phenylamine?
React phenylamine with bromine
92
How do you produce 2,4,6-tribromophenol from phenol?
Bromination:
react phenol with bromine
93
What happens if you react phenol with bromine?
You produce 2,4,6-tribromophenol
94
How do you produce 2-nitrophenol/4-nitrophenol from phenol?
Nitration:
React phenol with nitric acid
95
What happens if you react phenol with nitric acid?
You produce 2-nitrophenol and 4-nitrophenol
96
How do you produce sodium phenoxide from phenol?
Neutralisation:
React phenol with sodium hydroxide
97
What happens if you react phenol with sodium hydroxide?
You produce sodium phenoxide
98
How would you synthesise "ethanamide" from "ethanol", for each step name the reagents and conditions
## Footnote
**IMPORTANT**
99
How would you synthesise "butanoic acid" from "propanal", for each step name the reagents and conditions
## Footnote
**IMPORTANT**
100
How would you synthesise "1-(3-aminophenyl) ethanol" from "benzene", for each step name the reagents and conditions
## Footnote
**VERY VERY IMPORTANT**
101
How do you solve a multi-stage synthesis question?
* Identify the functional groups in your starting and target molecules
* Identify a sequence of chemical reactions that could convert the functional groups in the starting molecule into the functional groups of the target molecule and/or increase the length of the carbon chain to the required length
* In the case of aromatic compounds make sure to consider the order of reactions considering directing groups
* State the reagents and conditions for each step
102
What are the conditions for esterification?
* Carboxylic Acid - Sulfuric Acid Catalyst
* Acid Chloride - Does **NOT** require Sulfuric acid catalyst
