4.1 & 2 Flashcards
(135 cards)
1
Q
Homologous series
A
A series of organic compounds having the same functional group with each successive member differing by CH2
2
Q
Functional group
A
A group of atoms responsible for the characteristic reactions of a compound
3
Q
Aliphatic
A
A compound containing carbon and hydrogen joined together in straight chains, branched chains or non-aromatic rings
4
Q
Alicyclic
A
An aliphatic compound arranged in a ring or without side chains
5
Q
Aromatic
A
A compound containing a benzene ring
6
Q
Saturated
A
Single carbon-carbon bonds only
7
Q
Unsaturated
A
The presence of multiple carbon-carbon bonds, including double and triple carbon bonds and aromatic rings
8
Q
Structural isomers
A
Compounds with the same molecular formula but with different structural formulae
9
Q
Homolytic fission
A
In terms of each bonding atom, receiving one electron from the bonded pair, forming two radicals
10
Q
Heterolytic
A
In terms of one bonding atom receiving both electrons from the bonded pair
11
Q
Radical
A
A species with an unpaired electron
12
Q
Alkanes
A
Saturated hydrocarbons containing single C-C and C-H bonds as sigma-bonds (with free rotation)
13
Q
Sigma-bonds
A
Overlap of orbitals directly between the bonding atoms
14
Q
Molecular orbital theory
A
Covalent bonds are formed by the overlap of atomic orbitals
15
Q
Why can we draw alkanes in different ways
A
There is free rotation around these sigma bonds
16
Q
Why do branched alkanes have low boiling points
A
Branched alkanes cannot pack together as well as linear alkanes
Less surface area of contact
So induced dipoles are less strong
Lower bp
17
Q
Why do alkanes have low reactivity
A
Due to their high bond enthalpy
Not attracted to nucleophiles or electrophiles
C-C and C-H bonds are non polar
No partial charge anywhere
18
Q
Shape of alkanes
A
Tetrahedral
19
Q
Alkenes
A
Unsaturated hydrocarbons containing a double carbon bond comprising a pi-bond (restricted rotation) and a sigma-bond
20
Q
Pi-bond
A
Sideways overlap of adjacent p-orbitals above and below the bonding C atoms
21
Q
Shape of alkenes
A
Trigonal planar
22
Q
Naming of alkenes
A
Stem, position of double bond, suffix
23
Q
Stereoisomerism
A
Same structural formula but diff. arrangement of atoms in space
24
Q
E/Z isomerism
A
Stereoisomer
Results from restricted rotation about the double bond
Requires 2 diff. groups to be attached to each carbon atom in the C=C group
25
Z isomers
Same group attached to both carbons, top and bottom
26
E isomers
Diff. group attached to both carbons, top and bottom
27
Formation of pi-bonds
P- orbitals perpendicular to C-C
| Overlapping of orbitals
28
Cis isomerism
Usually Z isomers
Have higher bp
Polar
Have permanent dipole-dipole forces
29
Trans isomers
Non polar
Usually E isomers
Have higher mp
Pack more efficiently so IM forces maximise potential strength
30
Why are alkenes reactive
Exposed areas of high electron density that is attractive to electrophiles
Pi-bonds have a low bond enthalpy
Sigma-bonds in alkanes have higher bond
31
Addition reaction
When a reactant is added to an unsaturated molecule to make a saturated molecule
Breaks pi-bonds and forms sigma-bonds
32
Hydrogenation
H2 gas at high temp with Ni catalyst
| 1 mole of H2 per double bond
33
Alkenes react with:
```
H2
Halogens
Hydrogen halides (HF/HCl/HBr/ HI)
Other H-X molecules e.g. H2SO4
Steam
```
34
Hydration
Reaction with water
35
Conditions of hydration
Steam
H3PO4 catalyst
300 degrees
60 atm
36
Where do curly arrows start
A lone pair
| Existing covalent bond
37
Markownikoff's rule
H atoms/ least electro-ve atoms join the carbon which already has the most H atoms directly bonded (most stable carbocation)
38
Most stable carbocation intermediate
Tertiary (3') - 3 alkyl groups
Secondary (2') - 2 alkyl groups, 1 H
Primary (1') - 1 alkyl group, 2 H
39
What happens when you add an alkyl group
Donate electrons to positive charge and minimise strength
40
General formula of alcohols
CnH(2n+2)O
41
Functional group of alcohols
Hydroxyl group: -OH
42
Naming of alcohols
The no. of the carbon to which the hydroxyl group is attached is written before the -ol
43
Making ethanol
Ethene (g) + water (g) --> ethanol (l)
| Fermentation of sugar - C6H12O6 —> 2C2H5OH + 2CO2
44
Conditions to make ethanol
Phosphoric acid catalyst - dipole of water isn't a strong enough electrophile
300 degrees
60 atm
45
Why does solubility of alcohols decrease with chain length
They behave more like hydrocarbons and the LF's have a greater influence on solubility than the -OH group
46
Primary alcohols
OH bonded to C with 1 alkyl group
47
Secondary alcohols
OH bonded to C with 2 alkyl groups
48
Tertiary alcohols
OH bonded to C with 3 alkyl groups
49
Why do alcohols have high mp and bp
Hydrogen bonding
50
Which alcohols can be oxidised
Primary and secondary alcohol using a suitable oxidising agent e.g. acidified dichromate ions (Cr2O7 ^2-/ H^1)
51
What is the colour change in acidified dichromate ions when oxidised
Orange to green
52
Partial/mild oxidation of primary alcohols
Primary alcohol + [O] --> Aldehyde and water
53
Aldehydes
End in -al
| C=OH functional group (always at the end; don't need numbers)
54
Conditions of partial/mild oxidation of primary alcohols
K2Cr2O7/H2SO4
| Distil immediately
55
Complete oxidation of primary alcohols
Primary alcohol + 2[O] --> Carboxylic acid + water
56
Conditions of complete oxidation of primary alcohols
K2Cr2O7/H2SO4
| Reflux
57
Complete oxidation of secondary alcohols
Secondary alcohols + [O] --> Ketone + water
58
Conditions of complete oxidation of secondary alcohols
K2Cr2O7/H2SO4
| Reflux
59
Ketones
End in -one
| C=O carbonyl functional group
60
Can ketones be oxidised
No
61
Can tertiary alcohols be oxidised
No
62
Dehydration reaction
Alcohol --> alkene (in the presence of acid catalyst (conc. H3PO4/ H2SO4)), heated under reflux
63
Forming halogenoalkanes
Substitution with halide ions in the presence of acid (NaBr/H2SO4)
NaBr + H2SO4 ---> HBR + NaHSO4
CH3CHOHCH3 + HBr --> CH3CHBRCH3 + H2O
64
Nucleophile
Electron pair donor
65
Examples of nucleophiles
OH ^-
Cl ^-
H2O
66
Haloalkanes
Compounds in which a halogen has replaced at least one hydrogen (CnH2n+1X)
67
Classification of haloalkanes
Primary, secondary and tertiary depending on no. of alkyl groups
68
What dictates the reactions of haloalkanes
The polarity of the C-halogen bond
69
What happens as a result of the carbon atom on the C-halogen bond being electron deficient
The partial positive charge attracts species with lone pairs (nucleophiles)
70
Nucleophilic substitution
Nucleophile replaces a halogen
| CH3CH2I + OH --> CH3CH2OH + I
71
Ozone layer
O3
72
What do CFC's do
Deplete the ozone layer
| O3 + O (oxygen radical) --> 2 O2
73
Rates of hydrolysis in haloalkanes
Increase from F to I due to the decrease in bond enthalpies so ppt is formed faster in iodoalkanes and slowest in chloroalkane
74
Heterolytic fission
The breaking of a covalent bond to form an anion and cation as both electrons go to one species
75
Homolytic fission
The breaking of a covalent bond to form 2 radicals, with each species receiving one electrons
Happens in the presence of UV light
76
Equipment for reflux
```
Pear shaped flask
Condenser
Rubber tubing
Stand and clamp
Heat source
```
77
Why are anti-bumping granules used
So the contents boil smoothly without large bubbles forming, which will cause the glassware to vibrate
78
Apparatus for distillation
```
Round bottom or pear shaped flask
Condenser
Rubber tubing
Heat source
Stand and clamp
Screw cap adaptor
Receiver adaptor
Thermometer
```
79
In samples of organic liquids, how do you identify the organic layer
Add water to the mixture. The layer that gets bigger is the aqueous layer
80
How to use a separating funnel
Ensure the tap is closed
Pour the mixtures in and put on a stopper before inverting
Allow layers to settle and identify the organic layer
Place conical flask under the separating funnel, remove the stopper and open the tap until the whole lower layer has left
Do the same for the second layer
81
How to purify products with any acid impurities
Add NaH/CaCO3 (aq) and shake the mixture in the separating funnel
82
Drying agent
Anhydrous inorganic salt that readily takes up water to become hydrated e.g. CaCl2, CaSO4, MgSO4
83
Which fragment ion has a m/z of 15
CH3 +
84
Which fragment ion has a m/z ratio of 29
C2H5+
85
Which fragment ion has a m/z ratio of 57
C4H9 +
86
Which fragment ion has a m/z ratio of 43
C3H7 +
87
Which fragment ion has a m/z ratio of 31
CH2OH
88
Which fragment ion has a m/z ratio of 45
C2H5O +
89
Using M and M + 1 peaks
Height of M + 1 peak/height of M peak * 100 = no. of carbon atoms
90
What does the amount that a bond stretch or bends depends on
Mass of atoms in the bond - heavier atoms vibrate more slowly than lighter ones
The strength of the bond - Stronger bonds vibrate faster than weaker bonds
91
Advantages of oil companies using cyclic alkanes
Lower boiling point so will burn more efficiently
91
What is the greenhouse effect of carbon dioxide dependent on
Abundance in atmosphere
| Ability to absorb IR
91
CCS
Reacting CO2 and metal oxides (CaO)
| Deep in oceans
92
CIP priority rules
If both high priority groups are at the top it’s a (Z) isomer
If they are diagonal, (E)
93
Benefits of developing biodegradable and photodegradable polymers
Reduced dependency on finite resources
| Alleviating problems from disposal of persistent plastic waste
94
Cis-trans isomerism
Special case of E/Z isomerism in which 2 of the substituent groups attached to each carbon of the C=C group are the same
95
Disposal of waste polymers
Combustion which can produce energy
Use as organic feedstock for production of plastics
Dissolving halogenated plastics (PVC) so toxic HCl isn’t released
96
What does IR cause
Covalent bonds to vibrate more and absorb energy
97
Which bonds absorb IR
C=O
O-H
C-H
98
What is infrared spectroscopy used for
Monitor gases causing air pollution (CO and NO from cars)
| Measure ethanol in the breath (breathalysers)
99
What is the M+1 peak caused by
Small proportion of carbon-13
100
When do we use cis/trans isomers
When each carbon in the double bond is attached to one H
101
Why does the bp of cycloalakanes increase
More carbons —> stronger London Forces
| More energy need to overcome imf
102
Why do cycloalkanes get added to straight chain alkanes in petrol
So it burns more efficiently
103
What is the greenhouse effect of CO2 dependent on
Abundance in atmosphere
| Ability to absorb IR
104
Why do we do reflux
To keep the product reacting in the reaction flask until collection
105
Liebig condenser
Allows the product to distill off and be collected
106
Why is ethanol used in the investigation about carbon-halogen bond enthalpy
So the reaction with AgNO3 is slow enough to be observed
107
What happens to bromine water in the presence of alkenes
Decolourises
108
Process of mass spectrometry
The IR causes the molecule to become charged and they are then accelerated through a capillary and detected
109
Heating under reflux
Boiling a liquid in a vertical container to prevent loss of products
110
How to remove acidic impurities
Shaking with potassium hydrogen carbonate ions
111
M/z peak of 45
COOH +
112
Why can cracking produce a variety of alkanes and alkanes w/ diff chain lengths
C-C bonds can break anywhere
113
Steps in purifying an organic liquid
Allow mixture to cool
(If reflux decant reaction mixture from the anti-bumping granules)
Use a separating funnel and discard aq layer
Dry using an anhydrous salt e.g. MgSO4 then filter off and discard
Redistillation - collect distillate in range just below (and up to) the bp of product
114
Why are there many products in free radical substitution
More than one C-H bond can be substituted
Lots of termination steps
Termination steps can give products that will also react w/ radicals
115
Feedstock recycling
Chemical or thermal processes which can use waste polymers to regenerate monomers, oils or gases so that new polymers can be produced
118
Why are there still concerns about ozone depletion
CFC’s are still being used
| Other ozone depleting substances
119
Miscible with
Soluble in
120
Purifying a liquid that is miscible with water
Allow mixture to cool
Decant reaction mixture from anti-bumping granules, if reflux
Use separating funnel and keep aq layer
If acid is present use Na2CO3 (aq) until effervescence stops
Redistil
121
Purifying a solid product
Allow reaction mixture to cool
Filter under reduced pressure and leave impure product to dry
Recrystallise
Filter under reduced pressure, rinse w/ ice-cold water and leave the crystals to dry
Measure mp to assess purity
Repeat 2 previous steps if required
122
Filtering under reduced pressure
Using a Buchner funnel
123
Process of recrystallisation
Transfer impure solid to a boiling tube
Dissolve in minimum quantity of hot solvent (usually water)
Filter hot solution to remove any solid impurities
Allow filtrate to cool slowly to room temp, and then in an ice bath
Crystals will form
124
Determining mp of an organic solid
Ensure sample is dry
Add about 3mm of the sample to a sealed glass capillary tube
Measure mp using a Thiele tube setup
125
Mp of pure vs impure product
Pure products should have fairly narrow mp range
| Impure products will have a LOWER and WIDER mp range
126
Experiment plan for rate of hydrolysis of haloalkanes
Measure 1cm^3 of each haloalkane and place in separate test tubes
Add 1cm^3 of ethanol solvent to each tube
Place in a water bath at 60 degrees
Once all tt have reached the same temp, add 1cm^3 of aq AgNO3 to one of the test tubes she use a stopwatch to time how long it takes for the ppt to form
Repeat w/ other two solutions
127
Heating alcohols under reflux
Place 2 cm^3 of acidified dichromate and 1 cm^3 alcohol (in excess) in a pear shaped flask and attach condenser
Heat sol. under reflux w/ a heating mantle
128
Distillation to form an aldehyde
Place the dichromate, acid and 1’ alcohol (in excess) in a pear shaped flask and attach a condenser
Use thermometer to ensure temp is below 100
Solution will turn green as the aldehyde is produced
-al can’t H bond and has the lowest bp
Collect distillate in the range just below (and up to) the bp of the -al. It will condense in the receiver
129
Carrying out TLC
Take a TLC plate and draw base line 1cm from one end of plate
Use a capillary tube and spot a small amount of sol onto base line
Prepare chromatography tank
Place the prepared TLC plate in the beaker, making sure that the solvent does not cover the spot
Cover the beaker w/ watchglass
130
Making a chromatography tank
This can be made from a small beaker w/ watchglass on top
| Pour solvent into beaker to a depth of about 0.5 cm
131
Determining conc using gas chromatography
Measure the peak integration value of desired peak from compound X
Prepare some standard solutions of diff, known conc. of the compound X
Run these through the GC and ensure your peak integration values
Plot a calibration graph of peak integration value vs conc. and plot LOBF
Find the peak integration value and read off corresponding conc.
132
Limitations of free radical substitution
Further substitution occurs, producing a variety of products
Substitution can occur at different positions in the carbon chain
Produces several by-products lowering atom economy
133
Bond enthalpy of 1’, 2’ and 3’ haloalkanes
Tertiary has the lowest bond enthalpy so shortest time to react with silver nitrate
134
How is infrared spectroscopy used in identifying air pollutants
Indentifies bonds in pollutant
Match spectrum to known pollutants
Measures conc of pollutant
135
Naming esters
Stem is -ol attached to rhs
| Suffix is -COOH attached to lhs
