Reaction of Alkenes with Hydrogen Chloride gas

Dissolve the alkene in methylene chloride in a closed system. Place a bubbler at the inlet and the outlet to monitor the flow of the gas. Pass the tube from the outlet bubbler into an alkaline solution to capture any unreacted HCl. Stir the mixture gently and bubble in HCl gas at a rate such that no gas is seen at the outlet bubbler. The completion of the reaction is indicated by gas coming through the outlet bubbler. Wash the mixture with aqueous sodium carbonate, then with water. Dried the solution over anhydrous calcium chloride or anhydrous magnesium sulphate. DWD. (B.Pt. of methylene chloride is 42�C)

Reaction of Alkenes with Mercuric Acetate

Prepare a 10% mercuric acetate in 1: 1 water-tetrahydrofuran (ratio by volume). Add in the alkene and stir for about 10 minutes. Neutralise the solution with sodium hydroxide. Finally added in an equivalent amount of 0.5 M solution of sodium boronhydride. Extract with ether and dry. DWD.

Reaction of Alkenes with Bromine

Dissolve the bromine in methylene chloride (ratio by weight 2:50). Stir the alkene gently and drop in slowly the solution of the bromine. The mixture should become colourless showing that the bromine has reacted. Stop adding when the colour of the bromine persists. Wash with sodium carbonate then water, and then dry. DWD.

Reaction of Alkenes with Ozone

Ozone is produced in the laboratory with an "ozonator", a machine that discharge a high voltage (7500 volt) across oxygen flowing through. Dry oxygen gas passing through an ozonator can contain ca 6% of ozone.

The ozonised oxygen is bubbled into a solution of the alkene at ca  − 40�C. (5 parts of calcium chloride and 4 parts of crushed ice is a suitable bath). Suitable solvents are methylene chloride, chloroform, carbon tetrachloride, ethyl chloride, hexane and ethyl acetate. The reaction should be conducted in a closed system with the outlet passing through a potassium iodide/boric acid solution. When the reaction is over the ozone coming out will react with potassium iodide to give iodine. The solution will turn dark blue.

Add the solution into a mixture of zinc dust and 50% aqueous acetic acid and reflux for about an hour. Treat the ether extract with a small portion of potassium iodide to remove any peroxide or ozonide present. Wash with water and dry. DWD

Reaction of Alkenes with Peracid

Prepare the peracetic acid by mixing acetic acid with 30% hydrogen peroxide in a 30:7 volume ratio. Stir the mixture overnight at room temperature. Add the peracetic solution into the alkene gradually so that the reaction mixture does not heat up to more than 40�C. Stir the mixture overnight. Neutralise the mixture with sodium hydroxide, keeping the temperature below 40�C. Extract the glycol with ethyl acetate. Glycols are very likely to be solids. So concentrate the ethyl acetate extract and then allow the compound to crystallise out. PWD.

Reaction of Alkenes with H₂O₂ / OsO₄

An alcohol solution of hydrogen peroxide is prepared by mixing 25ml of a 30% aqueous solution of hydrogen peroxide to 100 ml of tert-butyl alcohol. Add anhydrous sodium sulphate to the mixture in small portions until two layers are obtained. Remove the alcohol layer and dry it with anhydrous magnesium sulphate. The alcohol contains ca 6% of hydrogen peroxide.

Add the alkene into the hydrogen peroxide solution, then add a solution of osmium tetroxide in anhydrous tert-butyl alcohol at 0�C. Allow the mixture to stand overnight. Distill off the solvent under reduced pressure, and then collect the glycol fraction. Allow the compound to crystallise out. PWD.