A Facile Method for the Conversion of Primary Alkyl Chlorides to the Corresponding Bromides

References

• Finkelstein , H. A. 1910 . Ber. Dtsch. Chem. Ges. , 43 : 1528
   Google Scholar
• Posner , G. H. 1975 . Org. React. , 22 : 253 For a review, see
   Web of Science ®Google Scholar
• Willy , W. E. , McKean , D. R. and Garcia , B. A. 1976 . Bull. Chem. Soc. Jpn. , 49 For specific examples, see: 1989, and references therein.
   Web of Science ®Google Scholar
• Yonovich-Weiss , M. and Sasson , Y. 1984 . Synthesis , 34.
   Google Scholar
• Cainelli , G. , Manescalchi , F. , Panunzio , M. and Synthesis . 1976 . An anion-exchange resin has been used to effect this same transformation in 95% yield. See:, 472.
   Google Scholar
• Treatment of 1, 2 - dichloroethane with calcium bromide was reported4 to afford a product mixture containing 39.2% 1-bromo-2-chloroethane.
   Google Scholar
• March , J. 1977 . Advanced Organic Chemistry: Reactions, Mechanisms, and Structure , Second Edition , 323 New York, N. Y. : McGraw-Hill . references therein.
   Google Scholar
• Baker analyzed All reactions were run under a nitrogen atmosphere in a 25-mL flask containing a stirring bar and equipped with a reflux condenser. N, N-Dimethylformamide (DMF), spectrophotometric grade, and dibromomethane (99%) were purchased from Aldrich Chemical Co. and used without further purification. Sodium bromide (“”) was obtained from J. T. Baker Chemical Co.
   Google Scholar
• As a precautionary measure, a small amount of sodium bicarbonate (25 mg/mmol of RCH2Cl) was also added to the reaction mixture in the experiment with 6-chloro-1-(tetrahydropyran-2-yloxy)hexane.
   Google Scholar
• In experiments involving 1-chlorohexadecane as a representative substrate, it was shown that the reaction proceeded more slowly in the presence of only a catalytic amount of sodium bromide. Thus, whereas use of 1 molar equivalent of sodium bromide led to a 97% conversion in this system after 4 hours at 100[ddot]C, the conversion was only 68% in a related experiment utilizing only 0.25 molar equivalent of sodium bromide. We also observed that use of oven-dried (125[ddot]C, several hours) sodium bromide appeared to increase slightly the time required for equilibrium to be reached in this halogen-exchange process [e.g., only 93% (vs. 97%) conversion to 1-bromohexadecane after 4 hours at 100[ddot]C].
   Google Scholar
• The halogen exchange was considerably less facile at lower temperatures. Thus after a reaction time of 5 hours at 70[ddot]C, the conversion of 1-chlorohexadecane to the corresponding bromide was only 38%.
   Google Scholar