Organics 1 Flashcards

1
Q

Give the reactions for producing chloroalkanes from alcohols using Phosphorus Chlorides

A

3CH3CH2OH + PCl3 -> C2H5Cl + H3PO3

CH3CH2OH + PCl5 -> C2H5Cl + POCl3 + HCl

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Give the reactions for forming bromoalkanes from alcohols

A

H2SO4 + 2KBr -> K2SO4 + 2HBr

HBr + CH3CH2OH -> CH3CH2Br + H2O

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Give the reaction to form iodoalkanes from alcohols

A

The alcohol is heated under reflux with a mixture of red phosphorus and either bromine or iodine.

2P + 3I2 -> 2PI3

CH3CH2OH + PI3 -> 3CH3CH2I + H3PO3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Give the general formula for alkanes

A

CnH2n+2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Give the general formula for alkenes

A

CnH2n

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Explain the solubility of alkenes

A

Insoluble due to lack of dipole so not polar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe the bonding a C=C bond

A

Very strong sigma bond between two s orbitals Weaker pi bond between two p orbitals above and below the nuclei

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe how to test to alkenes

A

Bromine Water - Brown to Colourless Acidified Potassium Manganate - Purple to Colourless

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Define Geometrical Isomers

A

Have groups occupy different relative positions in space

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe the Cahn Ingold Prelog System

A

Look at the atomic number of each atom directly bonded to each C in the C=C The highest atomic number takes priority If two are the same then move the next atom along the chain If the priority groups are on the same side (either above or below) then Z isomer If they’re on different sides then E isomer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe Cis/Trans Isomerism

A

Two priority groups are the same. Same side - Cis Different side - Trans

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Draw the mechanism for forming a haloalkane from an alkene with a Hydrogen Halide

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Draw the mechanism for forming a haloalkane from an alkene with a halogen

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

List carbocations in order of stability

A

Tertiary Carbocation - most stable

Secondary Carbocation

Primary Carbocation - least stable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe when a major and minor product will be formed and how to determine which is which

A

Occurs during the electrophilic addition of an asymmetrical alkene

The major product will be formed from the most stable carbocation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe the hydrogenation of alkenes

A

CnH2n + H2 -> CnH2n+2

Ni/Pt catalyst at 150C

Used in food industry to convert unsaturated fats to saturated fats

17
Q

Describe the hydration of Alkenes

A

conc. H3PO4 catalyst > 100C

CnH2n + H2O -> CnH2n+1OH

18
Q

Describe how to deal with waste polymers

A

Recycling - thermosoftening polymers can be remoulded into new products, thermosetting polymers must be chipped and reformed into new products

Incineration - some plastics burnt for energy, halogen-containing compounds release toxics gases, these must be removed

Feedstock - cracked to produce smaller, more useful alkanes + alkenes

Degradable - biodegradable (broken down by enzymes), photodegradable (broken down by UV light)

19
Q

Describe the solubility of haloalkanes

A

Not water soluble - not polar enough

20
Q

Describe how to test for Haloalkanes

A

Reflux with NaOH(aq) in ethanol to produce X- ions

Add excess HNO3 to neutralise excess OH- ions

Add AgNO3

Chloride ions - white precipitate soluble in dilute ammonia

Bromide ions - cream precipitate soluble in concentrated ammonia

Iodide ions - pale yellow - insoluble in ammonia

21
Q

Draw the mechanism for haloalkanes reacting with NaOH and describe the conditions

A

Aqueous NaOH, mixed in ethanol to act as a solvent, heated

22
Q

Describe the mechanism for haloalkanes with cyanide

A

Alcoholic KCN and heat

23
Q

Describe the reaction of a haloalkane and ammonia and draw the mechanism

A

2 Step Mechanism

Use excess concentrated NH3 and high pressure

In ethanol

24
Q

Describe the relative ease of substitution and rates of haloalkanes

A

The ease of substitution depends on the enthalpy of the C-X bond

Bond enthalpy decreases down the group

Therefore easier to substitute C-I than C-F

Therefore iodoalkanes form faster the chloroalkanes

25
Q

Describe the solubility of alcohols

A

Water-soluble due to Hydrogen bonding

26
Q

Describe how alcohols can be produced

A

Nucleophilic substitution of haloalkanes

Hydration of alkenes

Fermentation - Add yeast

27
Q

Compare fermentation and hydration to form alcohols

A

Hydration: non-renewable, fast, high energy input, continuous process, pure product

Fermentation: renewable, slow, low energy input, batch process and alcohol in solution

28
Q

List the benefits and drawbacks of the combustion of alcohols

A

Benefits: biofuels, can be produced from fermentation, carbon neutral potentially

Drawback: not carbon neutral due to CO2 released during manufacture and transport, fermentation is slow and land used for crops has to be used for fuels, less energy released compared to traditional fuels

29
Q

Describe the oxidation of primary alcohols

A

Oxidizes to Aldehydes under distillation

RCH2OH + [O] -> RCOH

Oxidises to Carboxylic Acids under reflux

RCH2OH + 2[O] -> RCOOH

30
Q

Give two common oxidising agents and their colour change

A

Acidified Potassium Managate (VII) - Purple to Colourless

Acified Potasssium Dichromate - Orange to Green

31
Q

Describe the oxidation of Secondary Alcohols

A

Form Ketones under reflux

32
Q

Describe how to test for aldehydes and ketones

A

Tollen’s reagent - heat gently - silver mirror forms in aldehyde present

Fehling’s Solution - mix together Fehlings A + B and heat gently, red precipitate of Cu2O will form in aldehyde present

33
Q

Describe how to test for Carboxylic Acids

A

Add Na2CO3 and positive result if effervescence caused by release of CO2 in neutralisation reaction

34
Q

State the conditions for the dehydration of alcohols

A

Produces Alkene

Use conc. H2SO4 or conc H3PO4

Pass oveer Al2O3

35
Q
A