The principle of a new electrochromic display based on an oxidation-reduction reaction of an organic compound of the viologen family is described. The result is a display having a built-in memory, high contrast, a low switching voltage, and a low mean power consumption.

The solvent was removed under reduced pressure to give a residue which was treated with water to give 0.2 g of a product which melted at 219°on recrystallization from 2-propanol and was identical with lb described above by mixture melting point, spectral comparison, and tic behavior.iV-Thioformyl derivative 4e was obtained in 71% yield by refluxing 4b with thiophosgene in toluene: mp 236°on recrystallization from methylene chloride-ether; ir 3250, 1660, and 1610 cm-1.

The preparation of 1,4-diethoxy-2-aminobenzene-5-diazoniumborofluoride is described and the structure is proved.room temperature in the dark for 24 hours. The yellow product is then filtered off and dried in a vacuum exsiccator above phosphorus pentoxide. The yield is about 25 g (85 70). 4.8 g is dissolved in a mixture of 25 ml alcohol and 5 ml water at 60" C; a little charcoal is added and the solution filtered; the filtrate is cooled in ice-water and the precipitated diazonium compound filtered off and washed with a little cold alcohol.The yield is 3.5 of fine, yellow crystals. Analysis: Found: C 39.70; H 4.88; N 13.98. Calculated for C,,H,,0,N,BF4(294.96): ,, 40.68; ,, 4.78; ,, 13.92. Eindhoven, October 1952. December 4fh 1952), (Received

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