Chapter 6 - Organic chemistry I (L) Flashcards
1
Q
What are hydrocarbons?
A
Compounds that contain only carbon and hydrogen
2
Q
What are saturated hydrocarbons?
A
Hydrocarbons with the maximum amount of hydrogens possible
3
Q
What are unsaturated hydrocarbons?
A
Hydrocarbons without the maximum amount of hydrogens possible
4
Q
What does any compound ending in -ate contain?
A
Oxygen
5
Q
What does a double bond always mean in terms of saturation?
A
The compound is unsaturated
6
Q
What does all single bonds in a compound mean in terms of saturation?
A
The compound is saturated
7
Q
What is a multiple bond?
A
Two or more covalent bonds between two atoms
8
Q
What are displayed formulae?
A
They show every bond and atom separately
9
Q
What are structural formulae?
A
Don’t show individual atoms, and can show bonds but can not. For example:
CH3CH2CH3 and CH3-CH2-CH3 are both structural formula of propane
10
Q
What are skeletal formulae?
A
Each dot represents a carbon atom, and the line between represents the bond between them
11
Q
What is the molecular formula?
A
Shows the actual number of atoms in a molecule
12
Q
What is the empirical formula?
A
Shows the numbers of each atom in the simplest whole number ratio
13
Q
What is a functional group?
A
An atom or group of atoms in a molecule that is responsible for its chemical reactions
14
Q
What is a homologous series?
A
A group of compounds with the same functional group and general formula, which differ by CH2 from the next member
15
Q
What is the general formula of alkanes?
A
Cn H2n+2
16
Q
What is the general formula of alkenes?
A
Cn H2n
17
Q
What is the general formula of halogenealkanes?
A
Cn H2+1 X (X = any halogen)
18
Q
What is the general formula of alcohols?
A
Cn H2n+1 OH
19
Q
What is the equation for the complete combustion of methane?
A
CH4 + 2O2 -> CO2 + 2H2O
20
Q
What is nomenclature?
A
The rules of naming molecules
21
Q
How do I revise nomenclature?
A
Read through the rules and then do practice questions
22
Q
What are structural isomers?
A
Compounds with the same molecular formula but different structural formula
23
Q
What are the two types of structural isomerism?
A
Chain and position isomerism
24
Q
What is chain isomerism?
A
When molecules have different carbon chains e.g. Butane and Methyl-propane
25
What is position isomerism?
When molecules have the same functional group attached in different places e.g. Propan-1-ol and Propan-2-ol
26
Can both position and chain isomerism be present simultaneously?
Yes
27
What is stereoisomerism?
When molecules have the same molecular and structural formula, however a different spatial arrangement
28
What type of isomerism does geometric isomerism come under?
Stereoisomerism
29
What is geometric isomerism also known as?
Cis-trans isomerism
30
Where can geometric isomers occur and not occur?
It can occur in alkenes, but not in alkanes
31
Why can geometric isomers occur in alkenes but not alkanes?
Because the presence of C=C leads to restricted rotation, whereas in alkanes the atoms can rotate freely, without restriction
32
What is cis isomerism?
When the two alkyl groups are on the same side of the C=C
33
What is trans isomerism?
When the two alkyl groups are on opposite sides of the C=C
34
When does cis-trans notation not work and why is this the case?
When there are 4 different groups, because the idea of two identical groups being in a cis- or trans- arrangement does not work, as there are not two groups that are the same
35
In E-Z notation how do you decide which two atoms are the highest priority?
The atom with the highest atomic number on the left of the double bond, and the atom with the highest atomic number on the right of the double bond are the two atoms with the highest priority
36
What are geometric isomers?
Compounds containing a C=C, with the same molecular and structural formula, but with the atoms attached at different positions
37
What is a locant?
A number used to indicate which carbon atom in the chain an atom or group is attached to- e.g. in 2-methyl-propane, the methyl group would be attached to the second carbon (2 is the locant)
38
In E-Z notation, once you have found the two atoms with the highest priority, what do you do?
See whether the two atoms with the highest priority are opposite each other or not- if they are you have an E-isomer, if not you have a Z-isomer
39
Z meaning (German)
Zusammen = Together
40
E meaning (German)
Entgegen = Opposite
41
What are most compounds in crude oil and natural gas?
Alkanes
42
What are the 3 main processes used to convert crude oil into fuels?
- Cracking
- Reforming
- Fractional distillation
43
What is fractional distillation?
The process used to separate a liquid into fractions by boiling and condensing
44
As you go down in fractional distillation, what 4 trends will you see?
```
As you go down, it will be
- hotter
and the molecules will be
- longer chains
- less flammable
- more viscous
```
45
In fractional distillation, where will you find the compounds with the highest boiling points?
At the bottom
46
What happens to the dissolved gases in crude oil during fractional distillation?
They rise to the top of the column without condensing
47
What is cracking?
The breakdown of longer chain molecules into smaller ones by heating with a catalyst
48
Why is the cracking of hydrocarbons important?
Because the demand for longer chain hydrocarbons is much less than the demand for shorter chain hydrocarbons, therefore cracking is used to turn longer chain into shorter chain hydrocarbons
49
What is the process of cracking hydrocarbons?
Longer chain hydrocarbons are passed through a heated catalyst, normally zeolite. This causes larger molecules to break up into at least 2 smaller molecules
50
What is the catalyst usually used in the cracking of hydrocarbons?
Zeolite, which is made up of aluminium, oxygen and silicon
51
Give one good example of cracking of hydrocarbons
Decane -> Octane + Ethene
52
What is the key difference between fractional distillation and cracking?
Fractional distillation involves separating existing compounds, not making new ones in a chemical reaction, which is what cracking does
53
What is reforming?
The conversion of straight-chain hydrocarbons into branched or cyclic hydrocarbons
54
Why is reforming used?
Hydrocarbons with a straight-chain burn less efficiently than cyclic or branched chains, which will then burn more smoothly in an engine
55
What is the process of reforming hydrocarbons?
Straight-chain hydrocarbons are heated with a catalyst, normally platinum.
56
What catalyst is usually used in reforming hydrocarbons?
Platinum
57
Give one good example of reforming of hydrocarbons
Pentane -> Cyclopentane + H2
58
What are the main products of the complete combustion of alkanes?
CO2 and H2O
59
What are the main possible products of the incomplete combustion of alkanes?
CO, Carbon particulates and unburned hydrocarbons
60
How are oxides of sulphur produced?
During the combustion of alkanes, sulfur impurities in the alkane form sulfur dioxide, and then can react with the atmosphere to form sulfur trioxide
61
What is the problem with oxides of sulfur?
They are acidic, and so when they dissolve in water in the atmosphere, they form sulfurous acid and sulfuric acid. This can cause environmental damage
62
How are oxides of nitrogen formed?
Very high temperatures, such as around spark plugs in cars, can cause the nitrogen molecules in the air to react with oxygen molecules
63
What are oxides of nitrogen represented by?
The formula NOx
64
What are the main oxides of nitrogen?
NO and NO2
65
What is the problem with nitrogen dioxide?
It is acidic, and so when it dissolves in water in the atmosphere, it forms nitrous acid and nitric acid. This can cause environmental damage
66
What is complete combustion?
When all the atoms in the fuel are fully oxidised
67
What is incomplete combustion?
When some of the atoms in the fuel are not fully oxidised
68
What three pollutants do three way converters remove?
Carbon monoxide, unburned hydrocarbons and oxides of nitrogen
69
What three products are formed after going through three way catalytic converters?
Nitrogen, Water and Carbon dioxide
70
What always happens to the hydrogen atoms during combustion (including incomplete)?
They are all completely oxidised to water
71
What are biofuels?
Fuels obtained from living matter that has died recently
72
What are renewable energy sources?
Sources that can be continuously replaced
73
What are non renewable energy sources?
Sources that are not being replenished, except over geological timescales
74
What is biodiesel?
A fuel made from vegetable oils obtained from plants
75
What are bioalcohols?
Fuels made from plant matter, often using enzymes or bacteria
76
What is a mechanism?
The sequence of steps in an overall reaction. Each step shows what happens to the electrons involved in bond breaking and forming
77
What is homolytic fission?
The breaking of a covalent bond, in which each of the bonding electrons leaves with one species, forming two radicals e.g. Cl2 -> Cl. + Cl.
78
What is a radical?
A species that contains an unpaired electron
79
In radical mechanisms, what is the initiation step?
When one molecule becomes two radicals e.g. Cl2 -> Cl. + Cl.
80
In radical mechanisms, what is the propagation step?
When a molecule and a radical become a different radical and molecule (there are two reactions in this step)
81
What normally causes the initiation step?
Bond breaking caused by UV radiation
82
In radical mechanisms, what is the termination step?
When two radicals become one molecule
83
When are sigma bonds formed between carbon atoms in alkenes?
When sp2 hybrid orbitals overlap axially/head on
84
When are pi bonds formed in alkenes?
When p orbitals overlap laterally/sideways
85
Which are stronger, sigma or pi bonds?
Sigma bonds are stronger than pi bonds
86
Why are sigma bonds stronger than pi bonds?
Because in pi bonds the negative electrons are further away from the positive nucleus of the carbon atoms than the sigma bonds, meaning the electrostatic attraction is weaker, and the electrons are more available and ready to react
87
What are the two electron orbitals?
p and s orbitals
88
What is hydrogenation?
An addition reaction in which hydrogen is added to an alkene e.g C2H4 (ethene) + H2 -> C2H6 (ethane)
89
What is required for the hydrogenation of ethene to occur?
Heat and a nickel catalyst
90
What is hydration?
An addition reaction in which water is added to an alkene (however think of it as adding a H and an OH)
e.g C2H4 (ethene) + H2O -> C2H5OH (ethanol)
91
What is required for the hydration of ethene to occur?
Steam and a phosphoric acid catalyst (H3PO4). The water must be in gaseous form (steam)
92
What is halogenation?
An addition reaction in which a halogen (e.g. Cl2 or Br2) is added to an alkene (remember it will always be two halogens being added, as they always go around in pairs)
93
What is a hydrogen halide?
Hydrogen with a halogen e.g. HBr or HCl
94
Why can hydrogen halides not be used to test for a double bond?
Because the reactants and products are both colourless
95
What is the test for a double bond and what would you expect to see?
Add bromine and if a double bond is present, the solution will be decolourised (turn from orange to colourless)
96
What catalyst is required for the hydration of ethene?
H3PO4
97
What is a diol?
A compound containing two OH groups
98
During oxidation to diols, what supplies the oxygen?
Potassium manganate (KMnO4)
99
What does [O] mean?
It represents oxygen supplied by an oxidising agent
100
How can you use oxidation to diols to test for the presence of a double bond?
If a double bond is present, the solution will change from purple to colourless
101
What is an electrophile?
An electron pair acceptor
102
What does a curly arrow represent?
The movement of a pair of electrons
103
What is the symbol for slightly (e.g. slightly positive)
Delta (weird looking d)
104
What is heterolytic fission?
The breaking of a covalent bond so that both bonding electrons are taken by one atom
105
What is a carbocation?
Carbon left positive during the transition stage
106
What are primary, secondary and tertiary carbocations?
```
Primary= carbon attached to one carbon
Secondary= carbon attached to two other carbons
Tertiary= carbon attached to three other carbons
```
107
One use of inert compounds
Non-stick coating
108
What does it mean to be inert?
Unreactive
109
What are elimination reactions?
A reaction in which a molecule loses atoms attached to adjacent carbon atoms, forming a C=C bond
110
What is a compound with three alcohols groups called?
A triol
111
What is a primary alcohol?
An alcohol group which is connected to a carbon attached to one other carbon
112
What is a secondary alcohol?
An alcohol group which is connected to a carbon attached to two other carbons
113
What is a tertiary alcohol?
An alcohol group which is connected to a carbon attached to three other carbons
114
What are the products of the complete combustion of alcohols?
H2O and CO2
115
What is halogenation?
Where the hydroxyl group in an alcohol is replaced by a halogen
116
Can you add a halogen to an alcohol?
Yes, but a different method is required for each halogen
117
What are the reaction requirements for the chlorination of an alcohol?
- Phosphorus(V) chloride
| - Mixture does not need heating
118
What are the two (inorganic) products of the chlorination of an alcohol (name and formula)?
```
Phosphorus oxychloride (POCl₃)
Hydrogen chloride (HCl)
```
119
How can tertiary alcohols be chlorinated in a different way to primary and secondary?
Shake the alcohol with concentrated hydrochloric acid at room temperature
120
What are the reaction requirements for the bromination of an alcohol?
- Mixture of potassium bromide and 50% concentrated sulfuric acid
- Warm mixture with alcohol
121
What are the three (inorganic) products of the bromination of an alcohol?
- Hydrogen bromide (HBr)
- Potassium hydrogensulfate (KHSO4) or Potassium sulfate (K2SO4)
- Water (H2O)
122
In the bromination of an alcohol, what are the equations of the two reactions occuring?
KBr + H2SO4 --> K(H)SO4 + HBr
| Alcohol + HBr --> Halogenoalkane + H2O
123
What are the reaction requirements for the iodination of an alcohol?
- Red phosphorus and Iodine
| - Mixture (including alcohol) is heated under reflux
124
What are the two (inorganic) products of the iodination of an alcohol?
- Phosphorus iodide (PI3)
| - Phosphonic acid (H3PO3)
125
What is a dehydration reaction?
A reaction that results in the removal of a hydroxyl group and a single hydrogen atom from an adjacent carbon in an alcohol molecule, forming a C=C bond
126
Why is the dehydration of butan-2-ol special?
There are three possible products:
- but-1-ene
- two isomeric forms of but-2-ene
127
What is produced when a secondary alcohol is oxidised?
A ketone
128
What is produced when a primary alcohol is oxidised?
An aldehyde, then with oxidation of the aldehyde a carboxylic acid is formed
129
What are the reaction conditions for the oxidation of alcohols?
- Heat
| - Oxidising agent
130
What is the common reagent in oxidising alcohols?
A mixture of potassium dichromate and excess of dilute sulfuric acid
131
What apparatus is used to obtain ketones or carboxylic acids in oxidising alcohols?
Heating under reflux
132
What apparatus is used to obtain aldehydes in oxidising alcohols?
Distillation with addition
133
How does distillation with addition in the oxidation of alcohols work?
- Oxidising agent heated
- Alcohol slowly added to oxidising agent
- When aldehyde is formed, it immediately distils off (due to much lower boiling point) and is collected in reciever
134
What is formed when you add water (hydrolyse) to a halogenoalkane?
An alcohol
135
What are the reaction conditions for the hydrolysis of a halogenoalkane?
- Warm
136
What is formed when you add KOH to a halogenoalkane?
An alcohol
137
What are the reaction conditions for the addition of KOH to a halogenoalkane to form an alcohol?
- Heat under reflux
138
What is an ethanolic solution?
A solution in which ethanol is the solvent
139
What are the reaction conditions for addition of KCN to a halogenoalkane?
- Heat under reflux
| - Ethanolic solvent
140
What are the reaction conditions for addition of NH3 to a halogenoalkane?
- Heat in sealed tube
- Ethanolic solvent
- Excess of NH3
141
Why must it be an ethanol solvent in the reaction of KCN and NH3 with halogenoalkanes?
To stop water from acting as a nucleophile
142
What is the organic product of the addition of KCN to a halogenoalkane?
Nitriles
143
What are the inorganic products of the addition of KCN to a halogenoalkane?
A halogen ion (e.g. Br-) or a potassium halogen (KBr)
144
With the addition of KCN to a halogenoalkane, what will the organic product contain that it didn't before the reaction?
One more carbon
145
What does heating NH3 (ammonia) with a halogenoalkane produce?
Primary amines
146
Why is a sealed tube needed in the addition of NH3 to a halogenoalkane?
Because ammonia (NH3) is a gas, so would escape the apparatus before it could react
147
What is the attacking nucleophile in the addition of KCN to a halogenoalkane?
The CN- ion
148
What is the attacking nucleophile in the addition of NH3 to a halogenoalkane?
The NH3 molecule
149
In the addition of NH3 to a halogenoalkane, why would a salt be initially produced?
Because the organic product is a base, so would react with the inorganic product (the acid HI) to form a salt
150
What is the equation for the first step of the conversion of 1-bromoethane to ethyl-amine?
CH3CH2Br + NH3 --> CH3H2NH3⁺ + Br-
151
In the addition of NH3 to a halogenoalkane, what is done to turn the salt into an amine?
There is an excess of ammonia, which reacts with the products of the first reaction
152
What is the equation of the second step of the conversion of 1-bromoethane to ethyl-amine?
CH3H2NH3⁺Br- + NH3 --> CH3CH2NH2 + NH4⁺Br-
153
What are the two final products of the conversion of 1-bromoethane to ethyl-amine?
Ethyl-amine and ammonium bromide
154
What type of mechanism is the addition of NH3 to a halogenoalkane to form an amine?
Nucleophillic substitution
155
What type of mechanism is the addition of KOH to a halogenoalkane to form an alcohol?
Nucleophillic substitution
156
Describe the mechanism for the addition of KOH to bromoethane to form an alcohol
- The Br is delta negative and the C is delta negative
- Curly arrow from C-Br bond to Br, forming Br- ion
- Curly arrow from nucleophile OH- to now positive C, forming covalent bond
- Final products are Ethanol and Br-
157
Describe the first step of the mechanism for the addition of NH3 to bromoethane to form an amine
- The Br is delta negative and the C is delta negative
- Curly arrow from C-Br bond to Br, forming Br- ion
- Curly arrow from nucleophile NH3 to now positive C, forming a C-N covalent bond, with 3 H attached to the N
- The N has a +1 charge, as it has 4 covalent bonds instead of 3
158
Describe the second step of the mechanism for the addition of NH3 to bromoethane to form an amine
- Curly arrow from H to positive N, releasing H+ ion
- Curly arrow from nucleophile NH3 to H+ ion, forming NH4
- Final products are ethyl-amine and NH4 (ammonium)
159
What are the possible products from the addition of NH3 to bromoethane to form an amine?
It is a reversible reaction, so the products will be:
- CH3CH2NH3+ (ethylammonium bromide)
- CH3CH2NH2 (ethyl-amine)
- NH3 (ammonia)
- NH4+ (ammonium)
- Br- (bromine ion)
160
What are nitriles?
Organic compounds containing a C-CN group
161
What are primary amines?
Organic compounds containing the C-NH2 group
162
What is a nucleophillic substitution reaction?
A reaction in which an attacking nucleophile (e.g. OH-) replaces an existing atom or group in a molecule
