Zinc cobalticyanide

Coordinate initiation routes to principally amorphous polymer have been found that do offer certain advantages, although these routes have been slow to be adopted, probably due to the apparently complicated structures of the initiators. One of these processes employs zinc with a complex anion promoted with a low-molecular-weight polyether such as dioxane or diglyme (109). The initiator system is based on zinc cobalticyanide (hexacyanocobaltate), Zn3[Co(CN)6]2, or zinc ferricyanide (hexacyanoferrate), Zn3[Fe(CN)6]2, (110-113). 

Zinc cobalticyanide can be obtained as an amorphous precipitate (114) from zinc chloride and potassium or calcium cobalticyanide in water. The product has a formula... 

Titrate (1) against (2) and dilute (1) with 80% ethanol until 1 mL of the resulting solution is equivalent to 1 mL of (2) after making allowance for the lather factor (the amount of standard soap solution required to produce a permanent lather in 50 mL of distilled water). One mL of the adjusted solution after subtracting the lather factor is equivalent to 1 mg of CaCO. See also Soap solution. Cobalticyanide paper (Rinnmann s test for Zn). Dissolve 4 g of K3Co(CN)g and 1 g of KCIO in 100 mL of water. Soak filter paper in solution and dry at 100°C. Apply drop of zinc solution and burn in an evaporating dish. A green disk is obtained if zinc is present. 

This test is affected by large amounts of ammonium salts they should be removed beforehand. Aluminum, in not too great excess, lead, zinc, and antimony salts do not interfere. Solutions of copper and nickel salts can be decolorized by adding potassium cyanide, whereas cobalt salts form the Light yellow soluble potassium cobalticyanide K3[Co(CN) ], which does not interfere with the recognition of the blue of the quinalizarin compound. Iron salts may be masked by means of tartrates. However, tartrates interfere if aluminum is present because a red color is formed in the caustic alkaline solution of quinalizarin. If both iron and aluminum are present, the test solution should be treated with 5 ml of 1 iV NaOH, cooled, diluted to 15 ml, and then filtered if necessary. The dear solution contains any beryllium as beryllate and can be tested as described below. 

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