Note that no other reagents are needed in order to complete any of these sequences, you should only be using what is there.

Work in progress, links to closely related examples are provided at this time.

under construction

General common errors:

(1) incorrect formal charges (2) backwards arrows (3) not showing the arrows for all the bonding changes (4) misuse of resonance / equilibrium arrows (5) vague arrows e.g. not starting on a bond or lone pair.


Acid catalysed tautomerisation of an enol to a ketone. For an example, see steps 3 and 4 of alkyne hydration

The alkene reacts via an electrophilic addition mechanism, via protonation to give the more stable carbocation intermediate (there is resonance stabilisation by the oxygen). A base, B:, which could be the alkene, water or HSO4- then removes the H from the O.

Common errors: (1) Using B: to represent a base in a reaction but then not listing what B: could be based on species that are present in the reaction mixture. (2) Using HO- as the base in an acidic medium.


This is a halogenation of an alkene using a simple dihalide, Cl2 which proceeds via a cyclic halonium ion to give an overall anti addition.

Common errors: (1) showing the reaction via a carbocation intermediate. (2) showing a radical reaction.


The starting material has a 1,2-halohydrin and an alcohol, the product is an ether and an alcohol now where the Br was, with specific stereochemistry. The reagent is a base. The reactions will be SN2 (alkoxides as the nucleophuiles). The base will react to remove a proton from the acidic -OH groups.... the deprotonation of the -OH adjacent to the -Br results in the formation of an epoxide from the halohydrin. The epoxide is then attacked by the other oxygen as the nucleophile to give the product shown.

Common errors: (1) SN1 reactions instead of SN2


Diels-Alder reaction of a conjugated diene to give a substituted cyclohexene.

Common errors: (1) The process is not a radical reaction. (2) Not drawing the "diene" in the reactive s-cis conformation. (3) Not drawing a concerted (i.e. one-step) reaction. (4) Not showing the correct regiochemistry (i.e. showing the formation of the 1,4-disubstituted product).

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