Topic 6 Reactions Flashcards Preview

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Flashcards in Topic 6 Reactions Deck (33):
1

What are the reagents and conditions needed to convert an alkene to an alkane?

Reagent: Hydrogen
Catalyst: Nickel
Conditions: 150 degrees centigrade and 5 atmospheres.

2

The hydrogenation of a double bond involves which reaction mechanism?

Electrophilic Addition

3

What are the reagents and conditions needed to convert an alkane to a halogenoalkane?

Reagent: Halogen (e.g. Bromine)
Catalyst: None
Conditions: UV light.

4

The conversion of an alkane to a halogenoalkane involves which reaction mechanism?

Free radical substitution

5

In the process of producing a halogenoalkane from alkane, what does the UV light cause?

Homolytic bond fission to produce halogen free radicals. [Note: Radicals are denoted by small dots.]

6

How would you produce an alkene from a halogenoalkane?

Add hot ethanolic potassium hydroxide.

7

From a halogenoalkane how would you produce a nitrile?

Add potassium cyanide in ethanolic solution under reflux.

8

The production of nitriles from halogenoalkanes involves what mechanism?

Nucleophilic substitution. [Note: The cyanide ion acts as a nucleophile].

9

What are the reagents and conditions needed to produce an amine from a nitrile?

Reagents: Hydrogen
Catalyst: Nickel
Conditions: 150 degrees centigrade and 5 atmospheres.
[Alternatively lithium aluminium hydride (ether) can be used.]

10

Amines can be produced directly from halogenoalkanes using which reagents and conditions?

Reagent: Concentrated ammonia.
Conditions: Heat in a sealed tube.

11

Halogenoalkanes can be produced from alkenes using hydrogen halides. What conditions are need for this?

Conditions: Room temperature
The hydrogen halide needs to be aqueous.

12

What process is used to produce alkenes from alkanes?

Cracking.

13

Alcohols can be can be produced from halogenoalkanes using what reagent?

Aqueous potassium hydroxide under reflux. [The hydroxide acts as a nucleophile and hydrogen halides are produced].

14

What are the conditions and reagents needed to produce an alkene from an alcohol?

Add concentrated sulphuric acid under reflux.

15

What are the conditions and reagents needed to produce an alcohol from an alkene?

Reagent: Steam
Catalyst: Concentrated phosphoric acid.
Conditions: 300 degrees centigrade and 60 atmospheres.

16

What are the conditions and reagents needed to produce an ether from an alcohol?

Heat with sulphuric acid. [Can only be used with primary alcohols.]

17

What are the conditions and reagents needed to produce an aldehyde from an alcohol?

Heat under distillation with acidified potassium dichromate. [Primary alcohols only]

18

What are the conditions and reagents needed to produce a ketone from an alcohol?

Heat under reflux with acidified potassium dichromate. [Secondary alcohols only]

19

What are the conditions and reagents needed to produce a carboxylic acid from an alcohol?

Heat under reflux with acidified potassium dichromate. [Primary alcohols only].

20

What are the conditions and reagents needed to produce an alcohol from a carboxylic acid?

Add lithium aluminium hydride in dry ether.

21

What are the conditions and reagents needed to produce an alcohol from a ketone?

Add lithium aluminium hydride in dry ether.

22

What are the conditions and reagents needed to produce an alcohol from an aldehyde?

Add aqueous sodium borohydride and heat.

23

What are the conditions and reagents needed to produce an alkyl hydrogensulphate from an alkene?

Add concentrated sulphuric acid.

24

What are the conditions and reagents needed to produce an alcohol from an alkyl hydrogensulphate?

Add warm water.

25

How can hydrogen bromide be produced?

By mixing 50% sulphuric acid with potassium bromide.

26

Chloroalkanes can be prepared from alcohols using phosphorus (v) chloride. Other than the chloroalkane, what products are formed?

Phosphoryl chloride (POCl3) liquid and hydrogen chloride gas.

27

Both phosphorus (III) bromide and phosphorus (v) bromide can be used to produce bromoalkanes from alcohols. Other than the bromoalkane, what products are formed when phosphorus (III) bromide is used?

H3PO3 liquid (Phosphorous acid).

28

Hydrogen iodide cannot be used to produce iodoalkanes from alcohols. Why is this so?

Hydrogen iodide is unstable and is easily oxidised to iodine.

29

Phosphorus (III) iodide can be used to produce iodoalkanes from alcohols but how must it be produced?

It must be produced in situe using a mixture of red phosphorus and iodine, as phosphorus (III) iodide it is unstable.

30

Which of the following cannot be oxidised using acidified potassium dichromate:
a) propan-2-ol
b) ethanol
c) 2-methylpropan-2-ol
d) 3-methylbutan-2-ol

The answer is c.
Tertiary alcohols cannot be oxidised.

31

Why is concentrated phosphoric acid preferred to concentrated sulphuric acid in the dehydration of alcohols?

Phosphoric acid produces a purer product.

32

There are two ways of producing amines from halogenoalkanes. One produces a pure product and the other an impure product. Identify the synthesis of both.

1. Pure product from substitution using cyanide ions under reflux.
2. Impure product from substitution using ammonia as an impure product can form from further substitution.

33

How can a diol be formed from an alkene and what would you observe in the reaction?

Add acidified potassium permanganate. The solution would go from pink to colourless.