A procedure for the preparation of simple mixed trialkylborane compounds has been devised. n-Butyldiethylborane and di-n-butylethylborane have been prepared. AI kyl group exchange has been shown to occur when a Grignard reagent is allowed to react with tri-n-butylborane or di-n-butylchloroborane. In one attempt to prepare α,ω-bis(di-n-butylboryl)-alkanes, 1,4-bis(di-n-butylboryl)butane apparently was isolated. This reaction could not be repeated. Failure to isolate α,ω-bis(di-n-butylboryl)alkanes has been attributed to either disproportionation of this product or to exchange of alkyl groups during the reaction. As a result of this, two boron-carbon ring compounds, 1-n-butylboracyclopentane and 1-n-butylboracyclohexane, have been prepared.All reactions were conducted under anhydrous conditions with the maintenance of a nitrogen atmosphere at all times.Boron analyses were determined by oxidation with hydrogen peroxide, accord ing to the method of Erickson (#).Molecular weights were determined cryoscopically by measuring the freezing point depressions of benzene solutions.
n-Butyldiethylborane from Di-n-butylchloroboraneTo a cold (0°C.) ethereal Grignard solution prepared from 12.0 grams (0.5 gramatom) of magnesium and 55.0 grams (0.5 mole) of ethyl bromide were added drop wise 40.0 grams (0.25 mole) of di-n-butylchloroborane (1), dissolved in an equal volume of ether. The reaction mixture, after being heated to reflux for 2 hours, was hydrolyzed at 0°C. with a 10% solution of hydrochloric acid. The ethereal layer was washed with water, 5% sodium bicarbonate solution, and again with water, and finally was dried over anhydrous magnesium sulfate. After the ether had been removed in vacuo, distillation of the residue gave 8.8 grams (28%) of n-butyldiethylborane, boiling point, 45° to 46°C. (15 mm.).Analysis. Calculated for C8H19B: boron, 8.75; molecular weight, 126. Found: boron, 7.73; molecular weight, 125, 126. In addition, 5.5 grams of an impure liquid, boiling point 63° to 73° C. (15 mm.), and 9.5 grams (21%) of tri-n-butylborane were collected.During the course of this work, it became necessary to find a solvent for the