1,10-Dibromodecane synthesis
- Product Name:1,10-Dibromodecane
- CAS Number:4101-68-2
- Molecular formula:C10H20Br2
- Molecular Weight:300.07
112-47-0
4101-68-2
The general procedure for the synthesis of 1,10-dibromodecane from 1,10-decanediol is as follows: 1,10-decanediol (1 eq.), 48% aqueous hydrobromic acid (ca. 3 eq./hydroxyl), and octane (ca. 7:1 volume-to-weight ratio to the diol) were added to a single-necked, round-bottomed flask and assembled with a fractionating column/Dean-Stark trap. The reaction mixture was placed in a heated oil bath (145-150°C) with rapid magnetic stirring. The aqueous (lower) layer at the initial boiling point (89-92°C) was condensed and gently separated, and subsequently collected at about half the theoretical volume of water; at this point the temperature of the azeotrope (still at head temperature) began to rise. The condenser was set to full reflux for a few hours, then turned back on and the aqueous-phase material continued to be collected for 1 hour (top temperature 96-100°C). The final volume of the aqueous phase distillate reaches 90-100% of the theoretical value (up to 24% hydrobromic acid in the high boiling distillate). When the octane phase (which is light tan in color) contains dibromides and brominated streptanols (e.g., 6 band 6c), it is washed with cold 85% v/v sulfuric acid (10 mL first, then 5 mL) to remove all color and brominated streptanols. For all three dibromides (3b, 4b, 6b), the neutralized octane solution was passed through a Vigreux column under reduced pressure to remove the solvent, and the residue (which was confirmed to be essentially pure by 1H NMR) was purified by Kugelrohr distillation. Trace amounts of 4-methyltetrahydropyran were detected prior to distillation of 4b.
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4101-68-2
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Yield:4101-68-2 91%
Reaction Conditions:
with hydrogen bromide in octane;water at 145; for 7 h;Dean-Stark;
Steps:
General procedure
General procedure: A one-neck rb flask was charged with diol (1equiv), 48% aq HBr (~3 equiv/OH), octane (~7:1 v/w ratio vs diol), fitted tothe fractionating column/Dean-Stark trap, and heated inan oil bath (145-150 °C) w/rapid magnetic stirring. The aqueous (lower) layer of the initialazeotrope condensate (bp 89-92 °C) was tapped offuntil about half of the theoretical amount of H2O had been collected;the azeotrope temp (still head) then began to rise. The condenser was set to total reflux forseveral h, reopened, and aq material collected for 1h more (head temp 96-100°C). The final volume of aq distillatewas 90-100+% of theory (higher-boiling distillate contained up to 24% HBr). When the (pale tan) octane phase containedboth dibromide and bromoalkanol (6band 6c), washing with cold 85% v/v H2SO4 (10 mL,then 5 mL) removed all color and all bromoalkanol. For all three dibromides (3b, 4b, 6b) the neutralized octane solutionwas stripped of solvent (vigreux column, reduced pressure), and the essentiallypure residue (1H NMR) was kugelrohr distilled. A trace of 4-methyltetrahydropyran was foundin 4b before distillation.
References:
Mekala, Shekar;Hahn, Roger C. [Tetrahedron Letters,2015,vol. 56,# 4,p. 630 - 632] Location in patent:supporting information
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