Organic 2 - Chapter 13 & 14

Question 1

What is a haloalkane

Answer 1

It is an alkane with hydrogen atoms substituted by halogen atoms

Question 2

What are the classifications of haloalkanes

Answer 2

Primary
Secondary
Tertiary

Question 3

What is primary

Answer 3

Halogen at the end of the carbon chainn

Question 4

What is secondary

Answer 4

Halogen in the middle of carbon chain

Question 5

What is tertiary

Answer 5

Halogen at junction of 2 carbon chains

Question 6

What are nucleophiles

Answer 6

Electron pair donors

Question 7

What reactions do haloalkanes do

Answer 7

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

Question 8

What affects the rate of reaction for haloalkanes

Answer 8

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

Question 9

What are common nucleophiles

Answer 9

Hydroxide ion OH-
Cyanide ion CN-
Ammonia NH3-

Question 10

What is a nucleophilic substitution

Answer 10

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

Question 11

What is the general mechanism of nucleophilic substitution

Answer 11

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

Question 12

What is different about the mechanism with ammonia

Answer 12

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

Question 13

What are elimination reaction

Answer 13

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

Question 14

What are the conditions for elimination

Answer 14

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

Question 15

What are the products of elimination reactions

Answer 15

Alkene
Halogen with group 1 atom
Water

Question 16

What is the general mechanism for elimination reactions

Answer 16

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

Question 17

What conditions are there for nucleophilic substitution

Answer 17

Aqueous hydroxide ions and warm

Question 18

What structures favour elimination or substitution

Answer 18

Primary - Substitution
Secondary - Both
Tertiary - Elimination

Question 19

What happens if the haloalkane is unsymmetrical when eliminated

Answer 19

Multiple isomeric products

Question 20

What are alkenes

Answer 20

They are unsaturated hydrocarbons with the general formula Cn H2n

Question 21

What happens to boiling point as Mr rises

Answer 21

It rises

Question 22

What does E and Z stand for

Answer 22

E - opposite
Z - together

Question 23

How do you use CIP to assign E/Z

Answer 23

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

Question 24

Are alkenes soluble

Answer 24

They are virtually insoluble in water

Question 25

What reactions do alkenes carry out

Answer 25

Combustion Electrophilic additions

Question 26

How do alkenes combust

Answer 26

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

Question 27

Why aren't alkenes used as fuels

Answer 27

Because they are more valuable for other purposes

Question 28

What is electrophilic addition

Answer 28

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

Question 29

How does the addition of hydrogen happen

Answer 29

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

Question 30

How does the addition of halogens work What is the mechanism

Answer 30

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

Question 31

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

Answer 31

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

Question 32

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

Answer 32

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

Question 33

What are alkyl hydrogen sulphates used for

Answer 33

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

Question 34

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

Answer 34

You can get more than 1 product

Question 35

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

Answer 35

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

Question 36

What is polymerisation

Answer 36

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

Question 37

What types of polymers are there

Answer 37

Naturally occuring or synthetic Addition or condensation polymers

Question 38

What are addition polymers

Answer 38

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

Question 39

What affects the properties of polymers

Answer 39

Chemical structure and intermolecular forces

Question 40

What are plasticisers

Answer 40

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

Question 41

What is the problem with addition polymers

Answer 41

They are unreactive and so non-biodegradable

Question 42

What are alcohols

Answer 42

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

Question 43

What is the trend in BP of alcohols

Answer 43

Increases as mr increases

Question 44

Are alcohols soluble in water

Answer 44

The short chain alcohols are soluble due to hydrogen bonding

Question 45

What ways can alcohols be made

Answer 45

Hydration of ethene - Alkenes react with steam Fermentation of sugars

Question 46

How does the hydration of ethene work

Answer 46

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

Question 47

What conditions are required for fermentation and Hydration of ethene

Answer 47

35 degrees anaerobic 300 degrees high pressure

Question 48

What is dehydration

Answer 48

It is the removal of water

Question 49

What alcohols can be dehydrated

Answer 49

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

Question 50

What does the dehydration of alcohols produce

Answer 50

alkene Water hydrogen ion

Question 51

What mechanism is used to dehydrate alcohol and how

Answer 51

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

Question 52

What conditions are used for the dehydration of alcohols

Answer 52

sulfuric acid or phosphoric acid 180 degrees

Question 53

What is dehydration used for

Answer 53

Produces alkene from a renewable source Makes polymers

Question 54

What is electronegativity

Answer 54

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