FIELD: chemistry.
SUBSTANCE: method includes the following steps: a) providing chlorine; b) providing carbon monoxide; c) reacting said chlorine with said carbon monoxide to obtain phosgene, wherein the carbon monoxide is fed controlled molar excess; d) providing an amine compound and phosgenation of said amine compound using said phosgene to obtain said isocyanate. Molar excess of carbon monoxide is controlled in order to control the colour of the isocyanate, wherein the molar ratio of carbon monoxide to chlorine at step c) lies in the range from more than 1.000:1.000 to 1.025:1.000 inclusively.
EFFECT: method enables to obtain light-coloured di- and polyisocyanates of the diphenyl methane range, wherein the colour of the isocyanate can be controlled or maintained in an acceptable range.
6 cl, 1 tbl, 7 ex
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