KlementineJBS
commented
8 months ago 30.10.23
Ended up using 1.2 equiv. of PBr3 as it was old and likely to have decomposed - it is possible to distill it but decided this would take too much time.
SM = 115.3 mg (0.512 mmol) PBr3 = 0.615 mmol, 58 uL Dissolved in 2 mL DCM under nitrogen. Had some issues with putting under nitrogen - hotplate turned on randomly and boiled DCM so results may not be entirely accurate.
Set up at about midday and reaction was complete by 3 pm.
Quenched with NaHCO3 (sat., 10 mL) and worked up with DCM (3 x 10 mL) and a wash with NaHCO3 (sat., 10 mL).
Dried over mag sulphate.
Link to HIRAC and master page. Method taken from J. Batten's PhD thesis (2022).
KBS29 - Appel reaction (CBr4).docx
Previous attempt is #63
Previously have had issues with removing PPh3O and with KBr not dissolving in DCM. Could potentially use MeCN instead ref. Could consider solvent free reactions ref.
Also have been looking into alternative reactions. E.g. could use phosphorus tribromide ref, or catalytic P(Ph)3O and LiBr ref. This latter does require addition via syringe pump over 5-7 hours.
Phosphorus tribromide reacts 3 x for every molecule. Should be able to use 0.4 equiv (~= 1.2 equiv.). Consider workup with HBr which apparently improves yields ref.
Can also try triturating with ether to remove PPh3O (doesn't dissolve in ether) or try reaction with iodine instead of CBr4 ref.
Reaction scheme
Outcome