Boiling points of BF3 are determined by the interaction of a promoter and BF3. The simplest form of oligomerization is a two-step process, in which the water-soluble promoter is first extracted from the washwater and then dissolved in the BF3 hydrate. Other types of promoters include fatty acids, ketones, aldehydes, phosphoric acid, ethers, and organic esters.
When using a water-soluble promoter, it should be able to form azeotropes with water. This means that it should have a boiling point below BF3’2H20. Generally, a range of 10-20 parts per 100 parts of oligomer is recommended. If the oligomerization is carried out at a pressure of less than 10 psig, the water washing can be done at higher pressures.
After the oligomerization, a second water wash was conducted. It was mixed with the first wash and added to the reaction mixture. Agitation and stirring were done at 30C for 0.5 hours. In this way, a decene oligomer was formed.
After a few hours, 15 parts of n-butanol were also added. These were subsequently distilled to remove a residual liquid. Approximately 61 weight percent of BF3 was recovered. However, more than 16.1 weight percent of BF3 was retained in the residual liquid. By analysis, the residual product contained approximately 50 weight percent of BF3 in the BF3 hydrate form.
Another method for obtaining BF3 is to catalyze an oligomerization of an -olefin. This can be carried out in a closed vessel under BF3 pressure. As a result, the amount of BF3 in the reaction mixture should be greater than the amount needed to complex with the promoter. Alternatively, BF3 can be continuously bubbled through the reaction mixture, which increases the amount of BF3 that is present.