The Chemical reaction on Tri-o-tolylphosphine

To a solution of magnesuim turnings (3.11 g, 128 mmol, 3.5 equiv) in THF (50 ml), a small amount of 2-bromotoluene (1 ml) and a iodine crystal was added. The reaction vessel was heated until initiation occurred when a solution of the remaining 2-bromotoluene (20 g, 117 mmol, 3.2 equiv total) in THF (100 mL) was added. The reaction was was refluxed for 2 hours (color change to black solution), after which it to 0 ° C and a solution of phosphorus trichloride (5.01 g, 36.5 mmol, 1 equiv) in THF (30 ml) was cooled adjusted dropwise. Upon addition completion of the reaction was adjusted under reflux for 18 hours. The reaction was were allowed to cool to room temperature, whereupon NH4Cl solution was added cautiously. The resulting solution was washed with ether (3 × 100 ml), dried over MgSO 4, filtered and concentrated in vacuo. The resulting white solid was recrystalised from ethanol to give Tri-o-tolylphosphine was obtained as a white solid. (6.8 g, 62%)

Although Tri-o-tolylphosphine is commercially available, it is relatively expensive because it is so easy to prepare. The Grignard reaction is a bit temperamental and may need a little encouragement to initiate. A word of warning, do not add all the bromotoluene in one portion, as this will flood the magnesium and the reaction will never work. Furthermore, if you find that the iodine is not sufficient to initiate the reaction, we have found that a micro spatula of mercury chloride and other Grignard reactions help for this. This reaction was carried out at different scales and has shown that about 60% of the desired product in all cases.
Read more>>Tri-o-tolylphosphine online