Caledon jade green

It is a valuable dyestuffs intermediate. When fused with KOH, two molecules of benz-anthrone combine at the positions marked above to give a dibenzanthrone which is in itself a vat dye. Also used as an intermediate for the preparation of the valuable Caledon Jade Green. 

The alkyl ethers of phenols, naphthols and hydroxyanthraquinones can be prepared, in many cases, by treatment of the halogen compounds with alcoholates at high temperature under pressure (e.g., anisole, page 97). Of course, the phenols themselves can be etherified (cf., page 148), and the cheaper method is used in each case. The dialkyl sulfates serve as active alkylating reagents in certain instances, as in the preparation of Caledon jade green (dimethoxydibenzanthrone). 

The compound is not, itself, used as a vat dye but is important because, when it is fused with caustic potash 2 molecules unite, yielding dibenz-anthrone, (23), from which many vat dyes are derived, the best known example being Caledon Jade Green 3B (C.I. vat green 4), (24). 

In order to check the technique of testing in different laboratories the following standard has been specified. A 40/2 bleached cotton yam is dyed by Method 1 with 5 per cent of Caledon Jade Green XNS Paste Fine. It should give the following results ... 

Caledon Jade Green XBN (ICI) C.I. Vat Green 1,59825, is a green vat dye of unique brilliance of shade and of outstanding fastness properties, especially towards alkali, discovered in 1920 by Davies, Fraser-Thomson and Thomas. The synthesis of this classic is as shown in Figures 2.44 and 2.45. 

Figure 2.45 Synthesis of Caledon Jade Green from bibenzanthrone...

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