Chemical Properties
colorless or light yellow liquid. soluble in ethanol, ether, ethyl acetate and petroleum ether, insoluble in water. Decomposes when exposed to light. It is used in organic synthesis.
Uses
1-Bromooctadecane is used in the preparation of shortened single-walled carbon nanotubes (s-SWCNTs). It is utilized to prepare octadecane in the presence of sodium borohydride as a catalyst. It is involved as a raw material for the preparation of dimethyldistearylammonium bromide, which is a bentonite modifier.
Preparation
1-Bromooctadecane is synthesized by the reaction of stearyl alcohol with hydrogen bromide. The alcohol is heated to 100°C, dry hydrogen bromide is introduced, and the reaction temperature is maintained at 100-120°C until the solution no longer absorbs hydrogen bromide. The bromide is layered, the organic phase is washed with concentrated sulfuric acid, the bromide after the acid solution is separated and mixed with an equal volume of 90% methanol, washed with ammonia to make the bromide alkaline, then washed with 90% methanol, and anhydrous Dry calcium chloride. Finally, vacuum distillation, collecting 209-211 ℃ (1.33kPa) fraction is 1-bromooctadecane, and the yield is 90%.
Purification Methods
Twice recrystallise bromooctadecane from the melt, then distil it under vacuum three times using the middle cut. Alternatively, wash the oil with aqueous Na2SO4, then conc H2SO4 (cool) and again with aqueous Na2SO4 and then fractionally distil it. [Meyer & Ried J Am Chem Soc 55 1574 1933, Hoffmann & Smyth J Am Chem Soc 72 171 1950, IR: LeFévre et al. Aust J Chem 12 743 1959, IR: Brini-Fritz Bull Soc Chim Fr 516 1957, Beilstein 1 IV 555.]
