p-Nitrophenylcyanate—An efficient, convenient, and Nonhazardous substitute for cyanogen bromide as an activating agent for sepharose

Abstract

The reaction of aromatic cyanates with agarose-based resins was investigated. Phenylcyanate yielded aliphatic-aromatic imidocarbonates as the major product, whereasp-nitrophenylcyanate acted as a cyanylating agent, yielding mainly cyanate esters on the resin. Such cyanate esters were recently also shown to be the active group on cyanogen bromide-activated Sepharose; hence, the stable and nonvolatilep-nitrophenylcyanate was found to be a very convenient substitute for the highly hazardous cyanogen bromide. Activations withp-nitrophenylcyanate could be done safely outside a hood. Employing triethylamine instead of the commonly used inorganic bases, an optimized activation procedure was developed that is about 10 times more efficient than conventional cyanogen bromide activation. Since both cyanogen bromide andp-nitrophenylcyanate-activated resins contain cyanate esters as active groups, the coupling of ligands proceeded in an identical fashion in both cases.