Tests for Cyanogen Compounds

When soluble cyanides or ferro and ferri-cyanides are distilled in the presence of potassium chlorate, with sulphuric acid, free hydro cyanic acid is found in the dislillatc insoluble substances of this nature, such as Prussian and Turnbull s blue, and the spent oxide of gasworks also are decomposed. Acoordingly, when testing for cyanogen compounds, l g. of the scraped match-heads is treated with so c.c. of warm water and filtered, and both the filtrate and the residue distilled separately with dilute sulphuric add. Hydrocyanic acid can be identified in the disttUate by the following reactions... 

The iron salts of ferro and ferricyanic acid are the compounds to which the names cyanogen and cyanide are due. Two of these salts are of deep blue color and the Greek word from which cyanogen and cyanide are derived is cyanos which means blue. The ferric ferro-cyanide, Fe4 "(Fe"(CN6)3, is known as Prussian blue and the ferrous ferri-cyanide, Fe3"(Fe" (CN)6)2, is Turnbull s blue. These compounds are formed when ferric salts in solution are treated with potassium ferro-cyanide and when ferrous salts in solution are treated with potassium ferricyanide. They are common qualitative tests for the two forms of iron salts. The compounds are also used as laundry blueing and are formed in the blue print process of photography. 

Cyanogen derivatives arc numerous and capable of great complexity. Platinous cyanide Pt(CN)3, is obtained as a yellow precipitate when mercuric cyanide is added to a solution of alkali chlorplatinite. Double cyanides of the general formula M 2Pt(CN)4 are formed by such reactions as 6 KCN + PtCL = K2Pt(CN) + 4 KC1 + (CN),. These platino-cyanides do not respond to the ordinary tests for platinum. These compounds yield beautifully colored hydrates, and the barium and calcium hydrates have optical isomeric modifications.2 Certain of these hydrates become remarkably fluorescent under excitation from ultraviolet light or radium. 

Griess was a very careful and accurate experimenter. He discovered quina-zoline derivatives by the action of cyanogen on anthranilic acid, and the colour reaction with nitrites and m-phenylenediamine. He also used mixed solutions of sulphanilic acid and a-naphthylamine as a test for nitrites, this reagent being improved by IloBvay. Griess discovered the diaminobenzoic acids, dinitrobenzoic acids, methyl orange, and various azo-compounds. ... 

These tests demonstrate that rhizomes of johnsongrass have biological activity and that the activity is residual. The allelochemic usually associated with Sorghum species in general, and with johnsongrass in particular, is the cyanogenic glucoside dhurrin (3) or its decomposition product (p-hydroxybenzaldehyde). Whether these compounds act as allelochemics in field situations is unknown and somewhat suspect, since they would surely be immobilized or altered in most soil situations, as was shown for... 

In order to test how far these distances are characteristic distances which occur also in other compounds, the substances allene, C3H4, diacetylene, C4H2, cyanogen, CgNa, and ethylene-oxyde, C2OH4, were investigated. The plane model for allene... 

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