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Chemistry A Level > Organic 2 - Chapter 13 & 14 > Flashcards

Organic 2 - Chapter 13 & 14 Flashcards

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1
Q

What is a haloalkane

A

It is an alkane with hydrogen atoms substituted by halogen atoms

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2
Q

What are the classifications of haloalkanes

A

Primary
Secondary
Tertiary

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3
Q

What is primary

A

Halogen at the end of the carbon chainn

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4
Q

What is secondary

A

Halogen in the middle of carbon chain

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5
Q

What is tertiary

A

Halogen at junction of 2 carbon chains

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6
Q

What are nucleophiles

A

Electron pair donors

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7
Q

What reactions do haloalkanes do

A

Nucleophilic substitution where the halogen is replaced by an electron pair donor
Elimination reactions

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8
Q

What affects the rate of reaction for haloalkanes

A

The strength of the carbon halogen bonds
The reaction gets quicker down group 7

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9
Q

What are common nucleophiles

A

Hydroxide ion OH-
Cyanide ion CN-
Ammonia NH3-

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10
Q

What is a nucleophilic substitution

A

It is where an electron pair donor replaces another atom or group of atoms during a reaction

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11
Q

What is the general mechanism of nucleophilic substitution

A

The nucleophile attacks the carbon attached to the halogen
The bond breaks between the carbon and halogen towards the halogen
The nucleophile replaces the halogen

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12
Q

What is different about the mechanism with ammonia

A

It requires 2 ammonia’s
It takes 2 stages forming NH2 at the point

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13
Q

What are elimination reaction

A

It is one in which an atom or group of atoms is removed from a reactant

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14
Q

What are the conditions for elimination

A

The reactant must be dissolved in ethanol not water and must be heated

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15
Q

What are the products of elimination reactions

A

Alkene
Halogen with group 1 atom
Water

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16
Q

What is the general mechanism for elimination reactions

A

The hydroxide ion attacks a hydrogen
The bond between the carbon and hydrogen breaks and goes to a carbon carbon bond
This breaks the halogen carbon bond
Forms an alkene

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17
Q

What conditions are there for nucleophilic substitution

A

Aqueous hydroxide ions and warm

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18
Q

What structures favour elimination or substitution

A

Primary - Substitution
Secondary - Both
Tertiary - Elimination

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19
Q

What happens if the haloalkane is unsymmetrical when eliminated

A

Multiple isomeric products

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20
Q

What are alkenes

A

They are unsaturated hydrocarbons with the general formula Cn H2n

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21
Q

What happens to boiling point as Mr rises

A

It rises

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22
Q

What does E and Z stand for

A

E - opposite
Z - together

23
Q

How do you use CIP to assign E/Z

A

Look at the atomic number of the atoms attached directly to the double carbon bond ( or subsequent atoms if they are the same)
Highest values opposite = E
Highest value together = Z

24
Q

Are alkenes soluble

A

They are virtually insoluble in water

25
Q

What reactions do alkenes carry out

A

Combustion
Electrophilic additions

26
Q

How do alkenes combust

A

They burn to form Carbon dioxide and water
They are not used as fuels though

27
Q

Why aren’t alkenes used as fuels

A

Because they are more valuable for other purposes

28
Q

What is electrophilic addition

A

Where the double bond will accept atoms to form an alkane from an alkene

29
Q

How does the addition of hydrogen happen

A

It happens in the presense of the finely divided Ni catalyst at about 150 degrees
Used to make margarine

30
Q

How does the addition of halogens work
What is the mechanism

A

Alkenes react quickly with halogens to produce haloalkanes

Double carbon bond attacks electropositive halogen
This breaks the halogen bond towards the other halogen
This forms a carbocation
The other halogen ion reacts with the carbocation

31
Q

How does the addition of hydrogen halides work
What is the mechanism

A

Hydrogen halides react with alkenes to form haloalkanes

Hydrogen is attacked by double carbon bond
This breaks the hydrogen halide bond towards the halogen
This forms a carbocation
The halide ion attacks the carbocation

32
Q

How does the addition of sulphuric acid work
What is the mechanism

A

Forms and alkyl hydrogensulphate

Double bond attacks hydrogen
Bond breaks between oxygen and hydrogen towards oxygen
Forms a carbocation
OSO3H - attacks carbocation

33
Q

What are alkyl hydrogen sulphates used for

A

They are converted into alcohols by reaction with water (hydrolysis)

34
Q

What happens when unsymmetrical molecules react with unsymmetrical alkenes in an addition reaction

A

You can get more than 1 product

35
Q

What is the trend in stability across the types of carbocation intermediates

A

Primary is the least stable
Tertiary is the most stable

Alkyl groups push electrons towards C+ so more stable

The product formed will be from the most stable carbocation

36
Q

What is polymerisation

A

A process in which lots of small molecules called monomers join together to form a large molecule (polymer) which consists of repeating units

37
Q

What types of polymers are there

A

Naturally occuring or synthetic
Addition or condensation polymers

38
Q

What are addition polymers

A

They are long chain molecules formed when lots of small molecules join together to form a polymer with nothing else formed

39
Q

What affects the properties of polymers

A

Chemical structure and intermolecular forces

40
Q

What are plasticisers

A

They are molecules that push chains apart which means the IMF are weaker and so are more flexible

41
Q

What is the problem with addition polymers

A

They are unreactive and so non-biodegradable

42
Q

What are alcohols

A

A homologous series of compounds with general formula Cn H2n+1 OH

43
Q

What is the trend in BP of alcohols

A

Increases as mr increases

44
Q

Are alcohols soluble in water

A

The short chain alcohols are soluble due to hydrogen bonding

45
Q

What ways can alcohols be made

A

Hydration of ethene - Alkenes react with steam

Fermentation of sugars

46
Q

How does the hydration of ethene work

A

Double carbon bond attacks hydrogen ion (from acid)
This forms a carbocation
Oxygen from water attacks carbocation
Hydrogen bonded onto oxygen breaks bond

47
Q

What conditions are required for fermentation and Hydration of ethene

A

35 degrees
anaerobic

300 degrees
high pressure

48
Q

What is dehydration

A

It is the removal of water

49
Q

What alcohols can be dehydrated

A

That have a hydrogen atom on the Carbon next to the carbon with the OH group

50
Q

What does the dehydration of alcohols produce

A

alkene
Water
hydrogen ion

51
Q

What mechanism is used to dehydrate alcohol and how

A

elimination
The lone pair on the oxygen attacks the H+ ion (from the acid) and bonds
The hydrogen next to the OH breaks off towards C-C bond
The positively charged oxygen breaks off from carbon towards oxygen

52
Q

What conditions are used for the dehydration of alcohols

A

sulfuric acid or phosphoric acid
180 degrees

53
Q

What is dehydration used for

A

Produces alkene from a renewable source
Makes polymers

54
Q

What is electronegativity

A

The (relative) tendency of an atom to attract a pair of electrons/ the electrons/ electron density in a covalent bond

Chemistry A Level (20 decks)

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