12. Alkene Reactivity
This Study Mind Tutorial covers the following specification points:
Edexcel: 6.18, 6.20, 6.21,6.22(i-v),6.23,6.24(i-iii),6.25
6.18. know the general formula for alkenes
6.20. understand the bonding in alkenes in terms of σ- and π- bonds
6.21. know what is meant by the term ‘electrophile’
6.22. understand the addition reactions of alkenes with:
(i) hydrogen, in the presence of a nickel catalyst, to form an alkane Knowledge of the application of this reaction to the manufacture of margarine by catalytic hydrogenation of unsaturated vegetable oils is expected.
(ii) halogens to produce dihalogenoalkanes
(iii) hydrogen halides to produce halogenoalkanes
(iv) steam, in the presence of an acid catalyst, to produce alcohols
(v) potassium manganate(VII), in acid conditions, to oxidise the double bond and produce a diol
6.23. understand that heterolytic bond fission of a covalent bond results in the formation of ions
6.24. understand the mechanism of the electrophilic addition reactions between alkenes and:
(ii) hydrogen halides, including addition to unsymmetrical alkenes
(iii) other given binary compounds
Use of the curly arrow notation is expected − curly arrows should start from either a bond or from a lone pair of electrons.
Knowledge of the relative stability of primary, secondary and tertiary carbocation intermediates is expected.
6.25. know the qualitative test for a C=C double bond using bromine or bromine water