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Topic 10 Organic chemistry
Essential ideas:
- Organic chemistry focuses on the chemistry of compounds containing carbon.
- Structure, bonding and chemical reactions involving functional group interconversions are key strands in organic chemistry.
10.1 Functional groups
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Identifying functional groups
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Applications and skills:
Identification of different classes: alkanes, alkenes, alkynes, halogenoalkanes, alcohols, ethers, aldehydes, ketones, esters, carboxylic acids, amines, amides, nitriles and arenes. Identification of typical functional groups in molecules eg phenyl, hydroxyl, carbonyl, carboxyl, carboxamide, aldehyde, ester, ether, amine, nitrile, alkyl, alkenyl and alkynyl. Guidance: The distinction between class names and functional group names needs to be made. Eg for OH, hydroxyl is the functional group whereas alcohol is the class name. |
10.1 Homologous series
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Understandings:
A homologous series is a series of compounds of the same family, with the same general formula, which differ from each other by a common structural unit. |
10.1 Classification of organic compounds
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Applications and skills
Identification of primary, secondary and tertiary carbon atoms in halogenoalkanes and alcohols and primary, secondary and tertiary nitrogen atoms in amines. |
10.1 Structural formulas
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Understandings:
Structural formulas can be represented in full and condensed format. Applications and skills: Distinction between empirical, molecular and structural formulas Guidance: Skeletal formulas should be discussed in the course. |
10.1 Structural isomers
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Understandings:
Structural isomers are compounds with the same molecular formula but different arrangements of atoms. |
10.1 Naming alkanes (straight-chain and cyclic alkanes)
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Understandings:
Saturated compounds contain single bonds only and unsaturated compounds contain double or triple bonds. Guidance: The general formulas of alkanes, alkenes, and alkynes acids should be known. The following nomenclature should be covered: alkenes up to hexene and alkynes up to hexyne. |
10.1 Naming organic compounds (alkanes, alkenes and alkynes)
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Understandings:
Saturated compounds contain single bonds only and unsaturated compounds contain double or triple bonds. Guidance: The general formulas of alkanes, alkenes, and alkynes acids should be known. The following nomenclature should be covered: alkenes up to hexene and alkynes up to hexyne. |
10.1 Naming branched-chain alkanes
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This video covers how to name simple branched-chain alkanes.
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10.1 Naming alkenes
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Understandings:
Saturated compounds contain single bonds only and unsaturated compounds contain double or triple bonds. Guidance: The general formulas of alkanes, alkenes, and alkynes acids should be known. The following nomenclature should be covered: alkenes up to hexene and alkynes up to hexyne. |
10.1 Naming alkynes
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Understandings:
Saturated compounds contain single bonds only and unsaturated compounds contain double or triple bonds. Guidance: The general formulas of alkanes, alkenes, and alkynes acids should be known. The following nomenclature should be covered: alkenes up to hexene and alkynes up to hexyne. |
10.1 Naming alcohols
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This video covers naming straight-chain alcohols with up to six carbon atoms in the longest carbon chain.
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10.1 Naming carboxylic acids
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This video covers naming carboxylic acids with up to six carbon atoms in the longest carbon chain.
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10.1 Naming aldehydes and ketones
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Guidance:
The following nomenclature should be covered: compounds up to six carbon atoms (in the basic chain for nomenclature purposes) containing only one of the classes of functional groups: alcohols, ethers, aldehydes, halogenoalkanes, ketones, esters and carboxylic acids. |
10.1 Naming amines
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This video covers how to name amines.
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10.1 Naming ethers
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This video covers how to name ethers.
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10.1 Naming halogenoalkanes
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This video covers how to name halogenoalkanes with up to six carbon atoms in the longest chain.
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10.1 Diols and dicarboxylic acids
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This video covers diols and dicarboxylic acids.
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10.1 Boiling points of organic compounds
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Applications and skills:
Explanation of the trends in boiling points of members of a homologous series. |
10.1 Structure of benzene
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Understandings
Benzene is an aromatic, unsaturated hydrocarbon. Applications and skills: Discussion of the structure of benzene using physical and chemical evidence. |
10.2 Homolytic and heterolytic bond fission
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This video looks at homolytic and heterolytic bond fission.
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10.2 Reactions of benzene
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Understandings:
Benzene does not readily undergo addition reactions but does undergo electrophilic substitution reactions. |
10.2 Combustion reactions of the alkanes
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Applications and skills:
Writing equations for the complete and incomplete combustion of hydrocarbons. |
10.2 Free radical substitution reactions of the alkanes
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Understandings:
Alkanes have low reactivity and undergo free-radical substitution reactions. Applications and skills: Explanation of the reaction of methane and ethane with halogens in terms of a free-radical substitution mechanism involving photochemical homolytic fission. Guidance: Reference should be made to initiation, propagation and termination steps in free-radical substitution reactions. Free radicals should be represented by a single dot. |
10.2 Test for unsaturation
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Understandings:
Bromine water can be used to distinguish between alkenes and alkanes. |
10.2 Addition reactions of the alkenes
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Understandings:
Alkenes are more reactive than alkanes and undergo addition reactions Application and skills: Writing equations for the reactions of alkenes with hydrogen and halogens and of symmetrical alkenes with hydrogen halides and water. Note that the conditions for the hydrogenation of alkenes include a nickel catalyst and high pressure and temperature.
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10.2 Addition polymerisation
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Applications and skills:
Outline of the addition polymerisation of alkenes. Relationship between the structure of the monomer to the polymer and repeating unit. |
10.2 Combustion reactions of the alcohols
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Applications and skills:
Writing equations for the complete combustion of alcohols. |
10.2 Reactions of the alcohols (oxidation)
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Understandings:
Some alcohols undergo oxidation reactions. Applications and skills: Writing equations for the oxidation reactions of primary and secondary alcohols (using acidified potassium dichromate(VI) or potassium manganate(VII) as oxidizing agents). Explanation of distillation and reflux in the isolation of the aldehyde and carboxylic acid products. |
The aldehyde can be distilled off because it has a lower boiling point than the alcohol or carboxylic acid (aldehydes do not form hydrogen bonds between molecules). If the aldehyde is left in contact with the oxidising agent, then the carboxylic acid is formed.
An alternative oxidising agent is acidified potassium manganate(VII) solution which changes colour from purple to colourless.
An alternative oxidising agent is acidified potassium manganate(VII) solution which changes colour from purple to colourless.
10.2 Esterification/condensation reactions of alcohols and carboxylic acids
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Understandings
Alcohols undergo nucleophilic substitution reactions with acids (also called esterification or condensation) Applications and skills: Writing the equation for the condensation reaction of an alcohol with a carboxylic acid, in the presence of a catalyst (eg concentrated sulfuric acid) to form an ester. |
10.2 Reactions of the halogenoalkanes
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Understandings:
Halogenoalkanes are more reactive than alkanes. They can undergo (nucleophilic) substitution reactions. A nucleophile is an electron-rich species containing a lone pair that it donates to an electron-deficient carbon. Applications and skills: Writing the equation for the substitution reactions of halogenoalkanes with aqueous sodium hydroxide. Guidance: The mechanisms of SN1 and SN2 and electrophilic substitution reactions are not required. |