Improvements in and relating to the Preparation of Aromatic Isocyanates

摘要

1,189,556. Aromatic isocyanates. E.I. DU PONT DE NEMOURS & CO. 1 July, 1968 [29 June, 1967; 29 May, 1968], No. 31318/68. Heading C2C. A process for preparing aromatic isocyanates comprises reacting an aromatic nitro-compound wherein the or each nitro group is directly attached to an aromatic ring with carbon monoxide under essentially anhydrous and hydrogen-free conditions at an elevated temperature and pressure in the presence of a palladous salt catalyst e.g. palladous chloride, and a saturated aliphatic nitrile e.g. acetonitrile. The preparations of 2,4-tolylenediisocyanate, 2 - methyl -5- nitrophenylisocyanate, 4-methyl - 3 - nitrophenylisocyanate, mphenylene diisocyanate, 3-nitrophenylisocyanate, 2,21-biphenylylenediisocyanate, 2- isocyanate-21-nitrobiphenyl, p-chlorophenylisocyanate, isopropyl p-isocyanatobenzoate, phenylisocyanate, p-fluorophenylisocyanate, 4-biphenylylisocyanate and 2,4,6,- and 2,4,5-trichlorophenylisocyanate are described. A list of starting materials includes pentafluoronitrobenzene, m-fluoronitrobenzene, 2,4- and 3,5-dinitrobenzonitrile, o,m and p-nitrobenzonitrile, o-nitrophenylphenyl sulphone, bis (o, m and p-nitrophenyl) sulphone, N,N- dimethyl-4-nitroaniline, o, m and p-nitrostilbene, o, m and p-nitrobenzophenone, 1- and 2-nitronaphthalene, 2-,4- and 9-nitrofluorene, 7-nitrobenz[a]anthracene, 2- and 6-nitrochrysene, 3- and 8-nitrofluoranthrene, m-nitrostyrene, 2,3- and 4-bromo-1-nitrobenzene, o and p-nitroanisole, o and p-nitrophenetole, o and p-nitrophenylacetate, methyl o and p-nitrobenzoate, dinitrodurene, dinitroprehnitere, 9,10-dinitroanthracene, 1,3- and 3,6-dinitrophenanthrene, 1,6-dinitropyrene, bis(o, m and p-nitrophenyl)ether, and 2,4- dinitroacetophenone.