The Dow process is the electrolytic method of bromine extraction from brine, and was Herbert Henry Dow's second revolutionary process for generating bromine commercially.
Also Dow's Process may refer to the hydrolysis of chlorobenzene in the preparation of Phenol.Benzene can be easily converted to chlorobenzene by Electrophillic Aromatic Substitution.After that,dilute Sodium Hydroxide(NaOH) is used at adverse conditions:623Kelvin temperature and 300atmosphere pressure to convert it into a Sodium Phenoxide which can be easily hydrolyzed to form Phenol.This process has now been discontinued at the industrial level.
Before Dow got into the bromine business, brine was evaporated by heating with wood scraps and then crystallized sodium chloride was removed. An oxidizing agent was added, and bromine was formed in the solution. Then bromine was distilled. This was a very complicated and costly process.
His first process involved eliminating the heating. First he oxidized the bromine with a bleaching agent, then dripped it onto burlap, and blew air under the burlap. The air had bromine gas, which was then reacted with iron (or alkalis) producing ferrous bromide.