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TETRAZINES

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Originally appearing in Volume V26, Page 672 of the 1911 Encyclopedia Britannica.
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TETRAZINES , in organic See also:

chemistry, a See also:group of compounds containing the See also:ring See also:system C•N•N CNN C•N•C C•NN,Or &.Nt, Or &.N.&; only derivatives of the first two types are known. The members of the first See also:series may be prepared by oxidizing osazones (i.e. dihydrazones of a-See also:diketones), dihydrotetrazines resulting. Dihydro-derivatives of the second type are formed from See also:hydrazine and imino-See also:ethers (A. Pinner, Ber., 1893, 26, p. 2126; 1894, 27, p. 984); these easily oxidize to the corresponding tetrazines, which are See also:stable towards acids; their dihydro-derivatives, however, are decomposed, the group—NH.NH—being eliminated as hydrazine and replaced by See also:oxygen, with consequent formation of the five membered oxybiazole ring. Concentrated acids convert the dihydro-tetrazines into isodihydrotetrazines, thus:-- R•C•NH•NH R•C N?i'•N N•N :C•R N•NH•C•R, the N-alkyl derivatives of which type may be prepared by the See also:action of alcoholic potash and See also:chloroform on aromatic hydrazines. Much discussion has circulated about the decomposition of diazo-acetic ester, from which A. Hantzsch and 0. Silberrad (Ber., 1900, 33, p. 58) obtained what they considered to be a dihydrotetrazine, thus: CH•CO2R H02C•CH•N:N HC•NH•N N:N •CH•See also:CO2H N•NH•CH. which it is connected by a See also:chain See also:bridge (1855) and two railway See also:bridges.

The handsome See also:

chateau of the See also:counts of See also:Thun (built in 1667–73 and restored in 1788), which occupies a rocky height above the See also:town, was at one See also:time fortified, and was a See also:place of some importance during the Seven Years' See also:War. It contains a magnificent library, with many valuable See also:MSS. and fne collections of coins and See also:armour. In addition to being the See also:principal See also:emporium for the See also:Austrian See also:traffic on the See also:Elbe, See also:Tetschen has a considerable See also:industry, its products comprising chemicals, oil, See also:soap, See also:cotton stuffs, See also:plaster of See also:Paris, glazed and coloured See also:paper, See also:cellulose, See also:beer, See also:flour and preserved See also:fish. The town of Tetschen originally See also:lay on the See also:south See also:side of the See also:castle See also:rock, but after its destruction by a See also:flood, it was moved in 1059 to its See also:present site. In 1305 it came into the hands of the knights of Wartenberg, who held it for two See also:hundred years. In 1534 the Saxon lords of Biinau obtained it and introduced the See also:Protestant See also:religion, which was exterminated when, after the See also:battle of the See also:White See also:Hill (1620) the Bunau See also:family was driven out. The lordship was bought from them in 1628 by the Freiherr von Thun, by whose descendants, the Counts Than, it is still held.

End of Article: TETRAZINES

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