Patent ID: 6916953

Claim:
A process for preparing organic isocyanates, which comprises (a) introducing a first partial amount of chlorine, wherein the first partial amount of chlorine has a content of free and bound bromine and iodine of at least 50 ppm and less than 400 ppm; (b) introducing a second partial amount of chlorine; (c) reacting the first and second partial amounts of chlorine with carbon monoxide to form phosgene; (d) reacting the phosgene with one or more primary amines to form an isocyanate and hydrogen chloride; (e) separating off and optionally purifying the isocyanate; (f) separating off and optionally purifying the hydrogen chloride; (g) catalytically oxidizing at least part of the hydrogen chloride separated off and optionally purified in step (e) with a gas comprising oxygen to form chlorine; (h) separating off the chlorine formed in step (g) wherein the second partial amount of chlorine in step (b) comprises at least a partial amount of the chlorine formed in step (g).