Abstract
THE introduction of a new insoluble blue pigment by Imperial Chemical Industries, Ltd., is of much more than passing interest. Monastral Fast Blue BS has none of the various drawbacks of the long-known Prussian blue and ultramarine or the more recently discovered blue lakes derived from coal tar colours, and will inevitably replace them in paints, distempers, varnishes, enamels, in textile printing and in the pigmentation of rubber, plastics and cements. As it is a very close approximation to a true ‘minus red’, the new pigment allows much brighter greens and purples to be obtained by admixture. The remarkable stability and inertness of the pigment are manifest in its exceptional fastness to light, heat, acid or alkali, and its complete insolubility in water, oil, spirit and nitrocellulose solvents. This new pigment belongs to a class of coloured substances to which the name ‘phthalocyanine’ was applied by Linstead, who first made clear their chemical nature (1934). The first phthalocyanine was obtained fortuitously as a by-product during the production of phthalimide at the Grangemouth Works of Scottish Dyes in 1928. It was a compound containing iron united with four molecules of phthalonitrile. Monastral Fast Blue BS is the corresponding copper derivative. Structurally, it is an aggregation of four isoindole units linked in a 16-membered ring of alternate carbon and nitrogen atoms around a central copper atom. The metal is held by two covalent and two co-ordinate bonds to four nitrogen atoms. The phthalocyanines are closely related to the porphyrins, which form the basis of some naturally-occurring colouring matters such as chlorophyll. Apart, therefore, from the value of the pigment in the arts, its chemical nature confers upon it a considerable scientific interest.
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A New Blue Pigment. Nature 136, 862 (1935). https://doi.org/10.1038/136862c0
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DOI: https://doi.org/10.1038/136862c0