10.2 Functional Group Chemistry Flashcards Preview

Chemistry Chapter 10 - Organic Chemistry > 10.2 Functional Group Chemistry > Flashcards

Flashcards in 10.2 Functional Group Chemistry Deck (38)
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1
Q

What reactions to alkanes undergo?

A

Combustion reactions.

2
Q

What are the products of complete combustion?

A

Carbon dioxide and water.

3
Q

What are the products of incomplete combustion?

A

Incomplete combustion is when there is a limited supply of oxygen and the reaction produces carbon monoxide, carbon and water.

4
Q

Why are alkanes unreactive?

A

There are high strength C-C and C-H bonds.

The C-C and C-H bonds and the overall molecules are essentially non polar.

5
Q

Whta is a substitution reaction?

A

One in which one atom or group is replaced by another atom or group.

6
Q

What are free radicals?

A

Species (atoms or groups of atoms) with an unpaired electron.

7
Q

What is homolytic fission?

A

Where a covalent bond breaks so that one electron goes back to each atom making up the original covalent bond.

8
Q

How is homolytic fission shown?

A

With fish hook arrows showing the movement of one electron.

9
Q

How to alkanes undergo substitution reactions?

A

In the presence of UV light alkanes undergo substitution reactions with halogens, the mechanism for these reactions is FREE RADICAL SUBSTITUTION.

10
Q

What are the steps of free radical substitution for the reaction of methane with chlorine?

A
The first stage is photochemical homiletic fission of the bond between the halogen atoms to produce two free radical:
INITIATION Cl2 ----> 2Cl*
PROPOGATION Cl* + CH4 ----> CH3* + HCl
PROPOGATION CH3* + Cl2 ---> CH3Cl + Cl*
TERMINATION Cl* + Cl* ----> Cl2
TERMINATION Cl* + CH3* ----> CH3Cl
TERMINATION H3C* + CH3* ----> C2H6

The Cl* generated in the second propagation step can go on to react further with another methane molecule so the the cycle of propagation sets starts again - a chain reaction.

11
Q

Why are alkenes more reactive than alkanes?

A
Onw component (the pi bond) of the C=C is weaker than a normal C-C single bond.
The double bond (four electrons) attracts electrophiles (reagents attracted to electrons).
12
Q

What reactions to alkenes undergo?

A

Addition reactions.

13
Q

What happens when alkenes react with halogens?

A

The double bond opens up and the halogens add on.

14
Q

What happens when alkenes react with hydrogen?

A

With a nickel catalyst and 150 degrees Celsius heat, the double bond opens up and hydrogen adds on.

15
Q

What happens when alkenes react with hydrogen and a halogen eg H-Br?

A

If heated the double bond opens up and they add on to the molecule.

16
Q

What happens when alkenes react with water?

A

With a concentrated sulphuric acid catalyst and heat the double bond opens up and the water adds on.

17
Q

How can alkenes and alkanes be distinguished form each other?

A

By shaking them with bromine water.
Alkenes will change from orange to colourless.
Alkanes there will be no change in colour.

18
Q

What are the conditions needed for alkene to undergo addition polymerisation?

A

Require high temperature and pressure and maybe a catalyst.

19
Q

What is the structure put in brackets called?

A

The repeating unit of the polymer, the basic unit form which the whole polymer can be made up.

20
Q

How are addition polymers named?

A

According to the monomer from which they were made.

21
Q

What is the only group that reacts when the polymerisation reaction occurs?

A

Only the C=C group reacts, all other groups attached to the C=C are unaffected.

22
Q

How do you draw or find the repeating unit form part of the polymer chain?

A

Take any two adjacent Cs in the polymer chain to give the repeating unit.

23
Q

How can you make the repeating unit the original monomer?

A

Put a double bond between the 2Cs.

24
Q

How do alcohols combust in oxygen?

A

The produce water and carbon dioxide.

25
Q

How are primary alcohols oxidised?

A

First to an aldehyde which can be oxidised further to a carboxylic acid.

26
Q

What are some oxidising agents that can be used?

A
Acidified dichromate(VI) [Cr2O7^2-/H+]  colour change from orange to green. 
Acidified manganate(VII) [MnO4^-/H+] colour change from purple to colourless.
27
Q

How do you obtain the carboxylic acid as the main product from the reaction mixture?

A

Heat under reflux.

28
Q

How do you obtain the aldehyde as the main product from the reaction mixture?

A

Distillation so that as the aldehyde distils off as soon as it is formed since the aldehyde has a lower boiling pint that the alcohol as there is no hydrogen bonding between aldehyde molecules.

29
Q

How are secondary alcohols oxidised?

A

Ketones which cannot be oxidised any further.

30
Q

How are tertiary alcohols oxidised?

A

Cannot be oxidised.

31
Q

What is the process of esterification?

A

When an alcohol is heated with a carboxylic cis in the presence of a small amount of concentrates sulfuric acid as a catalyst and an ester is formed.

32
Q

What type of reaction is an esterification reaction?

A

Condenstion reaction - two molecules join together with the elimination of water.

33
Q

How can you work out the structure of n ester?

A

Put the OH groups of the alcohol and carboxylic acid together, join the O of the alcohol to the C bearing the C=O and then remove the water.

34
Q

How do you name esters?

A

The carbon chain containing the COO group is named as alkanoate and the other carbon chain as an alkyl group.

35
Q

What is a nucleophile?

A

Species possessing a lone pair of electron which is attracted to an electron deficient region is a molecules and donates a lone pair of electrons to form a coordinate covalent bond.

36
Q

Why are halogenoalkanes more reactive than alkanes?

A

The very electronegative halogen atom makes the C that it is attached to more positive so that it attracts a nucleophile.

37
Q

What type of reactions to halogenoalkanes undergo?

A

Nucleophilic substitution reactions, for example when 1-bromopropane is heated with aqueous NaOH the Br is replaced by an OH.

38
Q

What type of reaction does benzene undergo?

A

Electrophilic substitution reactions a hydrogen atom in the ring is replaced by another atom/group.