4-Fluorophenyl isocyanate

CLEAR LIGHT YELLOW TO AMBER LIQUID

4-Fluorophenyl isocyanate acts as a reagent in the preparation of tris-ureas as transmembrane anion transporters, solid phase combinatorial synthesis of peptides as integrin inhibitors.

Purify the isocyanate by repeated fractionation through an efficient column. If IR indicates that there is too much urea (in the presence of moisture the symmetrical urea is formed), then dissolve it in dry EtOH-free CHCl3, filter, evaporate and distil it. It is a pungent LACHRYMATORY liquid. [See Hardy J Chem Soc 2011 1934, and Hickinbottom Reactions of Organic Compounds Longmans p493 1957.] 4-Fluorophenyl isothiocyanate [1544-68 -9] M 153.2, m 24 -26o, 26 -27o, b 66o/2mm, 2 1 5o/atm, 228o/760mm, n D 1.6116. A likely impurity is the symmetrical thiourea. Dissolve the isothiocyanate in dry CHCl3, filter and distil the residue in a vacuum. It can also be steam distilled, the oily layer is separated, dried over CaCl2 and distilled in vacuo. Bis-(4-fluorophenyl)thiourea has m 145o (from aqueous EtOH). [Browne & Dyson J Chem Soc 3285 1931, Buu Hoi et al. J Chem Soc 1573 1955, Olander Org Synth Coll Vol I 448 1941 ].