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Organic Chemistry Flashcards

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1
Q

What is a general formula for alkanes?

A

CnHn+2

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2
Q

What are alkanes?

A
  • Hydrocarbons: compound of carbon and hydrogen only
  • Saturated: Contain only single bonds
  • Bonding: Each carbon forms 4 sigma bonds (overlap of orbitals is directly between the bonding atoms)
  • Shape: 4 bond pairs of electrons repel each other equally to get as far apart as possible to form a tetrahedral shape with 109.5 degree bond angle.
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3
Q

Intermolecular forces of alkanes

A
  • London forces
  • Non-polar molecule ( C and H have similar electronegativity)
  • Random movement of electrons lead to uneven distribution of charge -> instantaneous dipole
  • Induces a dipole in a neighbouring molecule
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4
Q

Melting and Boiling points of alkanes

A
  • Low -> methane, ethane, propane and butane are all gases
  • Effect of chain length -> As number of carbons increases, the number of electrons increases and the molecule have more surface contact between them -> more / stronger London forces so more energy is needed to overcome IMF.
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5
Q

How does branching affect the boiling point of alkanes?

A
  • The more branched a compound is, the fewer surface area interactions there are between molecules - this is because molecules cannot fit together as neatly and closely.
  • Therefore branched molecules have fewer induced dipole-dipole attractions compared to the straight-chain isomers.
  • Therefore more branching = lower boiling point.
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6
Q

What is a homologous series?

A
  • A series of organic compounds having the same functional group but with each successive member differing by CH2.
  • They have similar chemical properties and a gradation of physical properties is seen.
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7
Q

What is a functional group?

A
  • A group of atoms responsible for the characteristics reactions of a compound
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8
Q

What is meant by ‘aliphatic’ ?

A
  • Compound containing carbon and hydrogen joined together in straight chains, branched chains or non-aromatic chains.
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9
Q

What is meant by ‘alicyclic’

A
  • An aliphatic compound arranged in non-aromatic rings with or without side chains
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10
Q

What is meant by aromatic?

A
  • A compound containing a benzene ring
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11
Q

What is the functional group for the following?
- Alcohol
- Aldehyde
- Alkane
- Carboxylic acid
- Alkene
- haloalkane
- ketone

A
  • Alcohol -> -OH
  • Aldehyde -> -CHO
  • Alkane -> -C-C
  • Carboxylic acid -> -COOH
  • Alkene -> C=C
  • haloalkane -> -F, -Cl, Br, I
  • ketone -> C-CO-C
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12
Q

What is a general formula?

A
  • The simplest algebraic formula for a homologous series
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13
Q

What is a displayed formula?

A
  • Shows the relative positions of atoms and the bonds between them
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14
Q

What is the structural formula?

A
  • provides the minimum detail for the arrangement of atoms in a molecule
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15
Q

What is an empirical formula?

A
  • The smallest whole-number ratio of atoms of the elements in a compound.
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16
Q

What is a skeletal formula?

A
  • Is a simplified structural formula drawn by removing hydrogen atoms from alkyl chains
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17
Q

What are structural isomers?

A
  • Compounds with the same molecular formula but different structural formulae.
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18
Q

What are the three ways a structural isomer can form?

A
  • The alkyl groups are in different places
  • The functional group can be bonded to different parts of the parents chain.
  • The functional group could be different
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19
Q

What is a molecular formula?

A
  • Shows the number and type of the atoms of each element in a compound
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20
Q

What are stereoisomers?

A
  • Organic compounds with the same molecular formula and structural formula but having different arrangements of atoms in space
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21
Q

What is meant by cis/trans isomerism?

A
  • A type of E / Z isomerism in which the two substituent groups attached to both carbon atoms of the C=C bond are the same.
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22
Q

What is E/Z isomerism?

A
  • Type of stereoisomerism caused by the restricted rotation around a double bond due to pi bonds.
  • Two different groups are attached to both carbon atoms of the C=C
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23
Q

What are the different types of covalent bond fission?

A
  • Homolytic fission -> in terms of each bonding atoms receiving one electron from the bonded pair, forming two radicals
  • Heterolytic fission -> in terms
    of one bonding atoms receiving both electrons from the bonded pair.
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24
Q

What is a radical?

A
  • A species with an unpaired electron
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25
Q

What does a curly arrow mean?

A
  • It represents the movement of electrons showing either heterolytic fission or formation of a covalent bond
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26
Q

What is covalent bond fission?

A
  • A covalent bond fission is a strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms.
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27
Q

Describe the process of Homolytic fission

A
  • A covalent bond breaks and each electron goes to a different bonded atoms
  • This generates two highly reactive, neutral species called radicals.
    <~ ~> (UV)
  • EG : Cl–Cl —> 2Cl’
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28
Q

What are reaction mechanisms?

A
  • They are models that show the movement of electron pairs during a reaction.
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29
Q

Describe the process of Heterolytic fission

A
  • Occurs when a covalent bond breaks and both electrons go to one of the bonded atoms which results in a cation and an anion being formed.
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30
Q

Describe the reactivity of alkanes

A
  • They have a low reactivity with many reagents because:
  • All the covalent bonds in alkane molecules have high bonds enthalpies
  • The carbon-hydrogen sigma bond gave a very low polarity because the electronegativities of carbon and hydrogen are almost the same
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31
Q

What happens during halogenation?

Of alkanes

A
  • Alkanes react with both chlorine and bromine in the presence of UV to form halogenated organic compounds.
  • This process (halogenation) happens by homolytic fission of the halogen molecule, forming radicals.
  • A hydrogen atom in the alkane is substituted by a halogen atom.
  • Under the right conditions this can happen for all of the hydrogens
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32
Q

What are the three stages of the radical substitution mechanism?

A
  • Initiation -> the formation of the radicals
  • Propagation -> two repeated steps that build up the desired product in a side-reaction
  • Termination -> two radicals collide and make a stable product.
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33
Q

EXAMPLE -> Chlorination of methane to form chloromethane

A

Initiation:
- Cl2 -> 2Cl’
- UV or temperature of about 300 degrees Celsius is needed

Propagation:
- CH4 + Cl’ -> ‘CH3 + HCl
- ‘CH3 + Cl2 -> CH3Cl + Cl’
- Step 1 generates an alkyl radical and hydrogen chloride
- Step 2 generates the desired product and regenerates the chlorine radical.

Termination:
- 2Cl’ -> Cl2
- 2’CH3 -> C2H6
- ‘CH3 + Cl’ -> CH3Cl
- A mixture of products is produced by the random collisions between radials. Only one of the products is desirable so this reaction has a low atom economy.

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34
Q

What are some limitations of radical substitution?

A
  • If there is more than two carbon in the alkane you cannot control which carbon the halogen will go on.
  • Further substitution can occur
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35
Q

What are alkenes?

A
  • They have a functional group of C=C
  • They have a general formula of CnH2n
  • They are unsaturated hydrocarbons meaning they are compounds of only C and H which contain a carbon-carbon double bond.
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36
Q

Compare the reactivity of alkanes and alkenes?

A
  • Alkenes are more reactive than alkanes
  • Pi bonds are weaker as they have a lower bond enthalpy than sigma bonds and so break more easily.
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37
Q

Describe the halogenation of an alkene with bromine

A
  • Observations -> Orange bromine is decolourised
  • General Equation ->
    | | | |
    –C=C– + BR2 –> –C–C–
    | | | |
    Br Br
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38
Q

Describe the hydrogenation of an alkene with hydrogen

A
  • Requires -> presence of a nickel catalyst, temperature of 150 degrees Celsius
  • General equation ->
    | | | |
    –C=C– + H2 –> –C–C–
    | | | |
    H H
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39
Q

Describe the halogenation of alkenes with hydrogen halides (in an inert solvent)

A
  • General Equation
    | | | |
    –C=C– + HBr –> –C–C–
    | | | |
    H Br
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40
Q

Describe the hydration of an alkene

A
  • Requires -> Steam at a temperature > 100 degrees Celsius, at 65 atm and with a phosphoric acid catalyst
  • General Equation ->
    | |
    –C=C– + H20 –>
    | |

– C-C–
| |
OH H

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41
Q

What is an electrophile?

A
  • A species attracted to an electron rich centre where it accepts a pair of electrons.
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42
Q

What is meant by an addition reaction?

A
  • A reaction of 2 molecules to produce a single product
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43
Q

What is a carbocation?

A
  • A molecule containing a positive charge on a carbon atom, forming ions
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44
Q

What is heterolytic fission?

A
  • When a covalent bond breaks and one atom takes both electrons from the bonded pair forming ions
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45
Q

Describe the process of Electrophilic addition with the example of ethene and BR2?

A
  • Dipole induced in bromine molecule
  • Slightly positive bromine attracted to C=C
  • Pi bond breaks, new C-BR bond forms and Br-Br breaks
  • Br’ uses lone pair to form a new bond to positive carbon atom.
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46
Q

How can the major product of a Electrophilic addition be determined?

A
  • It will be from the molecule which has the halogen attached to the carbon with the least amount of hydrogens.
  • Carbocations with C’s attached are more stable than carbocations with H’s attached.
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47
Q

Describe the structure of a Double Carbon-Carbon bond

A
  • Sigma Bonds -> Formed by ‘end on’ overlap of orbitals directly between the bonding atoms. They can rotate freely
  • Pi bonds -> formed by ‘sideways’ overlap of p-orbitals above and below bonding atoms. They resist rotation.
  • A double bond consists of both these bonds.
  • The shape of the molecule will therefore be trigonal planar with a bond angle of 120 as there are three sigma bonding pairs.
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48
Q

What is a monomer?

A
  • A small molecule that combines with many others to form a long chain polymer
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49
Q

What is a polymer?

A
  • A long chain molecule made from many monomers
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50
Q

What is addition polymerisation?

A
  • When the monomers are alkene molecules and the pi bonds open up and many of them add together to form a long chain.
51
Q

What are the problems that waste polymers have?

A
  • Landfill
  • Non-biodegradable
  • Made from finite oil based resources
52
Q

How can waste polymers be processed more sustainably?

A
  • Sort and recycle or reuse
  • Combustion and using the energy produced
  • Using them as a feedstock for the production of plastics and other organic chemicals
53
Q

What are some alternatives of plastics?

A
  • Development of biodegradable and photodegradable polymers which would be less dependent on finite resources and alleviate problems of disposing plastics in landfill.
54
Q

What are some properties of alcohols?

A
  • INTERMOLECULAR FORCES
    London forces and hydrogen bonding
  • BOILING POINTS
    Higher than alkanes of a similar mass as H-bonding is stronger than London forces in similar sized molecules. The boiling point will also increase with chain length as there are more electrons and more surface contact
  • SOLUBILITY
    Soluble -> Can form H-bonds with each other. Solubility decreases as chain length increases - the hydrocarbon chain is non-polar and cannot
55
Q

What harmful products could be formed during the combustion of polymers?

A
  • CO -> It is toxic and poisonous as it binds to haemoglobin instead of oxygen reducing the oxygen levels in blood
  • HCL 0> An acidic toxic gas which can be removed from the waste gases produced by alkali scrubbers.
56
Q

What is a pi bond?

A
  • It is the sideways overlap of p-orbitals
  • It has a lower bond enthalpy than sigma bonds because it has a lower electron density and so is a weaker bond
  • It cannot rotate
57
Q

What is a sigma bond?

A
  • A bond that results from a direct end on overlap of two orbitals
  • It has a higher bond enthalpy than pi bond and so is a stronger bond
  • It can rotate
58
Q

What is the shape of alkene molecules?

A
  • Each carbon atom has three areas of electron density
  • two separate covalent bonds between the carbon atoms and two different hydrogen atoms (sigma bonds)
  • the covalent bonds between the two carbon atoms (one sigma and one pi bond)
  • Each of these electron densities repel by the same amount forming bond angles of 120 degrees, which results in a trigonal planar shape.
59
Q

What is an alchohol?

A

A homologous series that:
- are saturated, containing only a single covalent bonds
- gave the general formula CnH2n+1OH
- have a gradation in physical properties
- have similar chemical properties

60
Q

How can alcohols be classified?

A
  • primary
  • secondary
  • tertiary
61
Q

What is a primary alcohol?

A
  • A primary alcohol has the alcohol group attached to the end of a chain.
62
Q

What is a secondary alcohol?

A
  • A secondary alcohol has the alcohol group attached to a carbon atom with two alkyl chains and one hydrogen atom.-
63
Q

What is a tertiary alcohol?

A
  • A tertiary alcohol has the alcohol group attached to a carbon atom with three alkyl chains attached.
64
Q

How does the bpt of alcohols change?

A
  • The boiling points of alcohols increase as the chain length increases.
  • As the molecule gets longer, there are more surface area contacts and so stronger induced dipole-dipole intermolecular forces.
  • This results in more energy needed to overcome these attractive forces hence a higher bpt.
65
Q

What is the difference between bpt of alcohols and corresponding alkanes?

A
  • The bpts of alcohols are higher than the corresponding alkanes.
  • This is because there are hydrogen bonds between the alcohol molecules.
  • Hydrogen bonds are stronger than london forces.
  • As a result more energy is needed to overcome this force of attraction.
66
Q

How is the volatility of alcohols different from corresponding alkanes?

A
  • A substance that is volatile evaporates easily at room temperature and pressure.
  • Volatility increases as the boiling point decreases.
  • Alcohols gave hydrogen bonds and this makes them less volatile than a corresponding alkane
67
Q

Are alcohols soluble?

A
  • Water molecules are polar and so is the alcohol functional group
  • This means that alcohols are soluble in water as their molecule form hydrogen bonds with the molecules
  • This is sometimes described as miscibility
68
Q

How does the solubility of alcohols change with chain length?

A
  • As alkyl chain length increases, the solubility of the alcohol decreases.
  • This is because the aliphatic chain cannot form hydrogen bonds and this becomes the larger part of the molecule
69
Q

Describe how alcohols can be combusted?

A
  • The combustion of alcohols is exothermic and so releases energy and as a result alcohols can be used as fuel
  • They transfer their stored chemical energy to a usable form like thermal energy
  • Combustion is a rapid oxidation reaction that combines oxygen with another substance
  • The products of complete combustion are water and carbon dioxide
70
Q

What are the reagents used in the oxidation of alcohols?

A
  • A reagent is a chemical that takes part in a reaction
  • The reagents used for oxidation of alcohols are a strong acid like sulfuric acid (H2SO4) and an oxidising agent like potassium dichromate (VI) (K2Cr2O7)
  • The species actually involved in the reaction are H+ and Cr2O72-
71
Q

What is oxidation?

A
  • The gain of oxygen
  • The loss of electrons
  • The removal of hydrogen
72
Q

What is the oxidising agent in the oxidation of alcohols?

A
  • Acidified potassium dichromate
  • H2SO4 K2Cr2O7)
  • It is represented at [O] in the equation
73
Q

What happens to the oxidising agent during the reaction of the oxidation of alcohols?

A
  • Changes from orange to green (Cr3+)
74
Q

Describe the oxidation of a primary alcohol

A
  • Gently heat a primary alcohol like ethanol with acidified potassium dichromate (VI), the alcohol group loses its hydrogen atom and is partially oxidised to an aldehyde.
  • The aldehyde must be distilled immediately to prevent any further reaction.
  • If a primary alcohol is heated strongly with excess acidified potassium dichromate (VI) then full oxidation occurs to form to carboxylic acid.
  • To fully oxidise a primary alcohol on purpose, you must use a reflux set-up.
  • The colour will change from orange to green
75
Q

Equation for the first oxidation of a primary alcohol

A

This is the reaction:
H H H
| | |
H - C - C - C - OH + [O]
| | |
H H H

->
H H H
| | |
H - C - C - C = O + H2O
| | |
H H H

76
Q

Equation for the second oxidation of a primary alcohol

A

H H H
| | |
H - C - C - C = O + [O]
| | |
H H H

-> H H H
| | |
H - C - C - C = O + H2O
| | |
H H OH

77
Q

Overall equation for the first primary alcohol

A
  • H H H
    | | |
    H - C - C - C - OH + 2[O]
    | | |
    H H H

-> H H H
| | |
H - C - C - C = O + H2O
| | |
H H OH

78
Q

What is a reflux ?

A
  • Reflux is the constant boiling and condensing of a reaction mixture.
  • This ensures that the reaction goes to completion as fully as possible without losing reactants or products as vapour to the air
79
Q

Describe the oxidation of a secondary alcohol

A
  • Secondary alcohols will oxidise to form a ketone using the oxidising agents.
  • Ketones will not undergo any further reaction.
  • The colour changes from orange to green
80
Q

Equation for oxidation of secondary alcohols

A

H H H H
| | | |
H- C - C - C - C -H + [O]
| | | |
H OH H H

-> H H H H
| | | |
H - C - C - C - C - H
| || | |
H O H H

+H2O

81
Q

What classification of alcohol cannot be oxidised?

A
  • Tertiary alcohol are very resistant to oxidation.
82
Q

What is esterification?

A
  • Chemical reaction used to make an ester.
83
Q

What is an ester?

A
  • Organic compounds that contain a -COOR functional group, where R is an alkyl chain.
  • Esters are widely used in the manufacture of foods because they have a pleasant, fruity smell.
84
Q

How are esters named?

A
  • The first part of the ester’s name comes from the alcohol, with the suffix -anol being changed to -yl.
  • The second part of the ester’s name comes from the carboxylic acid, with the suffix -oic acid replaced by -oate.
85
Q

Describe the esterification of alcohols

A
  • Esters can be made by reacting alcohol with carboxylic acid in the presence of an acid catalyst.
  • It is a reversible reaction
  • The O-H bond in the alcohol and the C-O bond in the carboxylic acid are broken
  • New bonds are made between the H and O-H to form water (condensation reaction)
86
Q

What is a dehydration reaction?

A
  • Dehydration is a chemical reaction in which water is lost from an organic compound.
  • This is a type of elimation reaction
87
Q

How can alcohols be dehydrated?

A
  • Heat (170 degrees) with strong acid (eg concentrated sulphuric acid)
  • Water is eliminated to make an alkene.
  • An -OH group from one carbon atom and an H atom on an adjacent carbon atom lost to form a water molecule.
  • A pi bond forms between the two adjacent carbon atoms
88
Q

What is the general equation for halide substitution in alcohols?

A

ROH + HX -> RX +H2O
when R is an alkyl chain and X is a halide ion.

89
Q

What are the reagents and conditions for halide substitution in alcohols?

A
  • Halide species is directly involved in reaction but the reagent would be hydrogen halide.
  • A acid catalyst such a concentrated sulfuric acid is added and the mixture is warmed to increase the rate of reaction.
  • For iodide phosphoric acid is used because sulfuric acid oxidises iodide ions to iodine so the yield of iodoalkane would be very low
  • Normally for substitution of bromide, a salt like sodium bromide is used which reacts with sulfuric acid to make HBR in situ.
90
Q

What is the definition of an elimination?

A
  • Organic reaction in which one reactant forms two products. Usually a small molecule like water is released
91
Q

What are haloalkanes?

A
  • Saturated organic compounds that contain carbon atoms and at least one halogen atom
92
Q

What is a primary haloalkane?

A
  • Is a haloalkane with the halogen at the end of the chain
93
Q

Describe the bond between carbon and halogen

A
  • Large difference in the electronegativities of carbon and all halogens.
  • Hence, the carbon-halogen bond in haloalkanes is polar
  • The electrons in the C-X spend more time near the halogen atom than the carbon atom .
  • This means that the carbon atom is slightly positive and the halogen atom is slightly negative-
94
Q

How do haloalkanes react?

nucleophilic substitution

A
  • The slightly positive carbon atom is attacked by atoms, molecules or ions that have a partial or full negative charge like H2O, OH- and NH3.
  • These species are called nucleophiles and they are electron-pair donors.
  • The carbon-halogen bond breaks as the two electrons in the covalent bond move to the halogen, forming an halide ion.
  • Two electrons from the nucleophile form a covalent bond with the carbon atom.
95
Q

What are the two factors that affect the reactivity of haloalkanes?

A

Strength of the C-X bond
- Going down the halogen group the atoms get larger. This means that their bonding electrons are further away from the nuclei and feel stronger shielding
- This results in lower mean bond enthalpies and the C-X bonds are easier to break.
- The higher the mean bond enthalpy, the less likely that the halogen will react in a nucleophilic substitution reaction.
The polarity of the C-X bond
- Electronegativity decreases down the group. This means that the polarity of the C-X bond decreases going down the group and it is the molecule with the highest polarity that are more likely to react.

96
Q

What is nucleophilic substitution?

A
  • A reaction where an atom or group of atoms is exchanged for a nucleophile.
  • The nucleophile is attracted to the partial positive charge on the carbon atom and donates its lone pair of electrons to form a new covalent bond.
97
Q

Describe hydrolysis in haloalkanes?

A
  • It is a nucleophilic substitution reaction.
  • Water is often the reactant that provides the hydroxide ion that act as nucleophiles.
  • If water is used, one of the O-H bonds in a molecule undergoes heterolytic fission to produce the nucleophile OH-.
  • This species attacks the electron deficient carbon atom.
  • Once the nucleophile has bonded to the haloalkane, the C-X bond undergoes heterolytic fission to produce a halide ion
98
Q

How can you measure the rate of reaction of hydrolysis of a haloalkane?

A
  • The rate of reaction is measured by the change in concentration of a reactant or product over a given time.
  • One of the products of hydrolysis is a halid ion which can form coloured precipitates of a silver halide when acidified silver nitrate is added.
99
Q

How can haloalkanes produce alcohols?

A
  • It can be heated under reflux with an aqueous solution containing hydroxide ions, an alcohol is made.
  • This is a nucleophilic substitution reaction and also an example of hydrolysis.
  • The rate of reaction is quicker than that using water.
100
Q

What are chlorofluorocarbons?

A
  • CFC
  • Class of organic compounds that contain chlorine and fluorine atoms.
101
Q

What are the properties of CFC’s?

A
  • Inert
  • Non-toxic
  • Non-flammable
  • Volatile
102
Q

What are some uses of CFC’s?

A
  • Fire fighting equipment, refrigerants, aerosols, solvents
103
Q

What problems are there with CFC’s?

A
  • They disperse to upper atmosphere, exposed to UV light, causes bonds to break forming radicals which catalyse the depletion of ozone layer which protects us from harmful UV radiation which increases skin cancer.
104
Q

What is the mechanism for the depletion of the ozone layer?

A

INITIATION
CF2Cl2 -> CF2Cl’ + Cl’ (Cl-Cl bond breaks)
PROPOGATION
Cl’ +O3 -> Cl’O +O2
‘ClO + O -> Cl’ + O2
ClO + O3 -> Cl’ + 2O2
OVERALL EQUATION
O3 + O -> 2O2

105
Q

How can the CFC problem be overcome?

A
  • Phase out CFCs
  • Find replacements eg HFCs (do not contain chlorine, C-F bond stronger and so don’t form radicals as easily)
106
Q

How can the CFC problem be overcome?

A
  • Phase out CFCs
  • Find replacements eg HFCs (do not contain chlorine, C-F bond stronger and so don’t form radicals as easily)
107
Q

What is the mechanism for decomposition of ozone by nitrogen monoxide?

A
  • PROPOGATION
    ‘NO + O3 -> ‘NO2 + O2
    ‘NO2 + O -> ‘NO + O2
  • OVERALL
    O3 + O -> 202
108
Q

Why does the problem continue even if we stop using CFCs?

A
  • CFC’s remain in the atmosphere for >50
  • Some are still being used
  • Other radicals even do the same eg NO catalysing breakdown of ozone
109
Q

What is the test for an unsaturated hydrocarbon?

A
  • Add a few drops of bromine water to the sample and shake
  • Bromine water decolourises
110
Q

What can haloalkanes produce and what can they be made from?

A

THEY CAN MAKE
- Alcohols by hydrolysis.
Conditions -> Hot aqueous sodium hydroxide, heat under reflux.
WHAT ARE THEY MADE FROM
- Alkanes by radical substitution
- Alkenes by halogenation
- Alcohols by halide substitution

111
Q

What can alkanes produce and what can they be made from?

A

THEY CAN MAKE
- Alkenes by cracking
- Haloalkanes by radical substitution.
Conditions -> UV light
Reagents -> halogen and alkane
WHAT ARE THEY MADE FROM
- Alkenes by hydrogenation
Conditions -> nickel catalyst at 150 degrees Celsius

112
Q

What can alkenes produce and what can they be made from?

A

THEY CAN MAKE
- Alkanes by hydrogenation
Conditions -> nickel catalyst at 150 degrees Celsius
- Additional polymers by addition polymerisation
- Haloalkanes by halogenation
- Alcohols by hydration
Conditions -> 65 atm, temperature > 100 degrees Celsius with phosphoric acid catalyst
WHAT ARE THEY MADE FROM
- Alkanes by cracking
- Alcohols by dehydration

113
Q

What can alcohols produce and what can they be made from?

A

THEY CAN MAKE
- Primary alcohols make aldehydes by oxidation
Conditions and reagents -> Acidified potassium dichromate as oxidising agent (changes from orange to green during reaction) and heat. It must be done with a distillation apparatus.
- Primary alcohols make carboxylic acids by oxidation
Acidified potassium dichromate as oxidising agent (changes from orange to green during reaction) and heat. It must be done with under reflux.
- Secondary alcohols make ketones by oxidation
Acidified potassium dichromate as oxidising agent (changes from orange to green during reaction) and heat. It should be done under reflux.
- Haloalkanes by halide substitution
Conditions and reagents -> halide ion (normally reacted with sodium to make a salt) in the presence of an acid.
- Alkenes by dehydration
Conditions -> Acid catalyst and heat under reflux
WHAT ARE THEY MADE FROM
- Haloalkanes by hydrolysis
Conditions (if two halogens in molecule)
-> Hot aqueous sodium hydroxide, heat under reflux.
Conditions (if not) -> Aqueous silver nitrate, ethanol, heat in water bath.
- Alkenes by hydration
Conditions -> 65 atm, temperature > 100 degrees Celsius with phosphoric acid catalyst

114
Q

What can polymers produce and what can they be made from?

A

WHAT ARE THEY MADE FROM
Akenes by addition polymerisation

115
Q

What can aldehydes produce and what can they be made from?

A

WHAT ARE THEY MADE FROM
- Oxidation of primary alcohols
Acidified potassium dichromate as oxidising agent (changes from orange to green during reaction) and heat.
It must be with a distillation apparatus.

116
Q

What can ketones produce and what can they be made from?

A

WHAT ARE THEY MADE FROM
- Secondary alcohols by oxidation.
Acidified potassium dichromate as oxidising agent (changes from orange to green during reaction) and heat. Under reflux.

117
Q

What can carboxylic acids produce and what can they be made from?

A

WHAT ARE THEY MADE FROM
- Oxidation of primary alcohols
Acidified potassium dichromate as oxidising agent (changes from orange to green during reaction) and heat. Under reflux.

118
Q

What can esters produce and what can they be made from?

A

WHAT ARE THEY MADE FROM
- Carboxylic acids by esterification

119
Q

What is mass spectrometry ?

A
  • Determines relative isotopic masses and percentage abundance of elements and so calculate RAM
  • Identifying unknown organic compounds by comparing a spectrum to a database of known compounds
  • Gain information about the structure of a molecule from the molecular ion and fragmentation peaks
120
Q

What happens during mass spectrometry ?

A
  • When an organic molecule is placed in a mass spectrometer some of the molecules lose an electron; resulting positive ion is called a molecule ion.
  • The molecular ion peaks is the one with the highest mass/charge ratio and it tells us the mass of the molecule
121
Q

What is fragmentation?

A
  • molecules can split into fragments
  • the mass of the fragments or the mass lost forming the fragments can be used to help work out the structure
122
Q

What is infrared spectrometry?

A
  • Infrared radiation causes covalent bonds to vibrate more and absorb energy.
  • The frequency of IR radiation absorbed can tell us something about the bond
123
Q

What can infrared spectrometry be used for?

A
  • To monitor gases causing air pollution from car emissions
  • Modern breathalysers measure ethanol in the breath

AS-Level Chemistry (4 decks)

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