Hydrazine dithione

Hydrazine Ditfaionate, N2H4.H2S2Oa, a polymer of amidosul-phonic acid, may be prepared by the interaction of hydrazine sulphate and barium dithionate. It is obtained as large crystals. On evaporation over sulphuric acid it decomposes with separation of sulphuric anhydride and is converted into a mixture of hydrazine sulphate and secondary hydrazine dithionate, (N3H4)2.H3S306.a... 

Alkylthio, arylthio, and thioxo. The thioxo group in pyrimidine-2,4-dithione can be displaced by amines, ammonia, and amine acetates, and this amination is specific for the 4-position in pyrimidines and quinazolines. 2-Substitution fails even when a 5-substituent (cf. 134) sterically prevents reaction of a secondary amine at the 4-position. Acid hydrolysis of pyrimidine-2,4-dithione is selective at the 4-position. 2-Amination of 2-thiobarbituric acid and its /S-methyl derivative has been reported. Under more basic conditions, anionization of thioxo compounds decreases the reactivity 2-thiouracil is less reactive toward hot alkali than is the iS-methyl analog. Hydrazine has been reported to replace (95°, 6 hr, 65% 3deld) the 2-thioxo group in 5-hexyl-6-methyl-2-thiouracil. Ortho and para mercapto- or thio- azines are actually in the thione form. ... 

The thiazine dithiones also react with hydrazine, hydroxylamine, semi-carbazide, and thiosemicarbazide. Hydrazine gives 3-aminopyrimidine-2,4-dithiones (214) (Scheme 87) [80JCR(S)148]. Thiosemicarbazide reacts in the same way as diamines to give [l,2,4]triazolo[l,5-a]pyrimidines (215) (Scheme 88). 

In a one-pot reaction, a,a-disubstituted a-halo carbonyl compounds 1 (R, potassium thiocyanate, acetic acid, and monosubstituted hydrazines 3 are transformed into dihydro-lfT-imidazo[l,5- 7][l,2,4]triazole-2,5 (3H,6H)dithiones 8 (Scheme 1) (93TH, 01TH). With R =H, the reaction takes a different course (cf. Section 2.3). 

Disulfanylquinoxaline [quinoxaline-2,3(1 f/,4//)-dithione] reacts with hydrazine hydrate in refluxing ethanol to afford 3-hydrazinoquinoxaline-2(l//)-thione. ... 

Dithiocarbazates (CCXV), which are themselves the reaction products of hydrazines with carbon disulfide, can react further with another carbon disulfide molecule. In this manner l,3,4-thiadiazolidine-2,5-dithiones (CCXXXI) are formed 57, 58, 66, 69, 71). 1,3,4-thiadiazolidine-... 

Various 3-substituted aminoquinoxaline-2-thiones have been prepared from quinoxaline-2,3-dithione. For example, treatment of the dithione with methylamine yields 3-methylaminoquinoxaline-2-thione, and the corresponding reaction with hydrazine hydrate yields 3-hydrazino-quinoxaline-2-thione. The latter compound is also obtained by treatment of 2,3-dichloroquinoxaline with thiourea and then with hydrazine hydrate. When 2-chloroquinoxaline 1-oxide is heated with thiourea in methanol at room temperature, an unidentified solid m.p. 184-185° is obtained alkaline hydrolysis of methanol-soluble products gives quinoxaline-2-thione in 41% yield. A method of some general applicability is illustrated by the preparation of the thioxo compound 4 from o-anilinoaniline (3). °... 

The interaction of l,2-dihydro-4//-benzo[with acid hydrazides provides very satisfactory yields of 5-substituted 3-(o-amino-phenyl)-l,3,4-thiadiazoles (94), undoubtedly by way of the intermediate iV-(2-aminothiobenzoyl)-N -acyl-hydrazines (93). ... 

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