Preparation of di- and/or triisocyanates

摘要

Preparation of diisocyanates and triisocyanates comprises feeding diamines and/or triamines in vapor form at mean flow velocity of 20-150 m/s to tubular reactor via concentric annular gap formed between walls of double-walled guide tube extending centrally in direction of axis of rotation of reactor; and feeding phosgene to reactor over remaining cross-sectional areas of reactor at mean flow velocity of >=1 m/s. Preparation of diisocyanates and triisocyanates of formula R(NCO) n comprises gas phase phosgenating the corresponding diamines and/or triamines of formula R(NH 2) n by providing a tubular reactor (1); heating the diamines and/or triamines in vapor form and phosgene separately from one another to 200-600[deg]C; feeding the diamines and/or triamines (A) in vapor form to the tubular reactor via a concentric annular gap at a mean flow velocity of 20-150 m/s; and feeding the phosgene (B) to the tubular reactor over the remaining cross-sectional areas of the tubular reactor at a mean flow velocity of >=1 m/s. R : (cyclo)aliphatic or aromatic not >15C hydrocarbon; and n : 2 or 3. At least 2 carbon atoms are arranged between two isocyanate (NCO) groups. At least 2 carbon atoms are arranged between two amino (NH 2) groups. The tubular reactor has a double-walled guide tube (6) extending centrally in the direction of the axis of rotation (8) of the tubular reactor. A concentric annular gap is formed between the inner and outer walls of the double-walled guide tube. The ratio of the cross-sectional area of the tubular reactor bound by the inner wall of the guide tube to the cross-sectional area of the tubular reactor bound by the wall of the tubular reactor and the outer wall of the guide tube is 1:0.5-1:4.