Triphenylphosphine Dibromide

[1034-39-5] C15H18Br2P (MW 389.10) InChI = 1S/C18H15Br2P/c19-21(20,16-10-4-1-5-11-16,17-12-6-2-7-13-17)18-14-8-3-9-15-18/h1-15H InChIKey = OCXGTPDKNBIOTF-UHFFFAOYSA-N (bromination of alcohols,3, 4 phenols,22 and enols;3 cleavage of ethers23, 32, 33 and acetals25 to alkyl bromides; cyclization of amino alcohols34, 35 to cyclic amines; conversion of carboxylic acid derivatives into acyl bromides;36, 37 bromination39 or dehydration38 of carboxamide groups) Alternate Names: bromotriphenylphosphonium bromide; dibromotriphenylphosphorane. Physical Data: adduct:2 colorless crystalline solid; mp 235 °C (dec). Ph3P: mp 80.5 °C; bp 377 °C (in inert gas); d254 1.194 g cm−3; n80D 1.6358. Br2: mp −7.2 °C; bp 59.5 °C; d25:4 3.12 g cm−3. Solubility: adduct: sol CH2Cl2, MeCN, PhCN, DMF; less sol PhH, PhCl. Ph3P: sol ether, PhH, CHCl3, AcOH; less sol alcohol; pract. insol. H2O. Br2: sol H2O (3.58 g/100 mL); very sol. alcohol, ether, CHCl3, CCl4, CS2. Form Supplied in: adduct: hygroscopic solid; commercially available; purity 95–96%. Both parent compounds, Ph3P and Br2, are widely available. Ph3P: odorless platelets or prisms; purity ≈99%; typical impurity Ph3PO ≈1%. Br2: dark reddish liquid, volatile, with suffocating odor; vaporizes rapidly at rt; purity >99.5%. Analysis of Reagent Purity: adduct: 31P NMR (CH2Cl2) +49 ppm (ionic form);2 Raman (solid phase) 239 cm−1 (PBr). Typical impurities, Ph3P and Ph3PO: 31P NMR (various solvents) −5 to −8 ppm and +25 to +29 ppm, respectively. Preparative Method: several preparations are described,2, 23b,32b but in most cases the hygroscopic reagent is prepared just before use by addition of Bromine to Triphenylphosphine in a dry solvent with cooling. Handling, Storage, and Precautions: adduct: corrosive; very hygroscopic; moisture sensitive; incompatible with strong oxidizing agents and strong bases; may decompose on exposure to moist air or water; do not get in eyes, on skin, or on clothing; keep containers tightly closed and store in a cool dry place; these reagents should be handled in a fume hood.