3, 5-diamino reaction with alkalis

Reaction with phenylhydrazine hydrochloride141 produces the isolable, ring-opened l-acyl-5-phenyl-diaminoguanidine hydrochloride (58), the free base of which is partly oxidized even by atmospheric oxygen to l-acyl-3-amino-5-phenylformazane. Cyclization of 58 with alkali produces arylhydrazino- or arylazo-1,2,4-triazoles (59) heating 58 in butanol produces 3,4-diamino-l,2,4-triazole (60). 

If S-nitro-2-methylphenylarsinic acid is heated with alkali at 90° C., subsequent treatment with acid yields a mixture of stilbenediarsinic acids, as detailed on p. 194. Reduction with sodium hydrosulphite transforms these into 5 5 -diamino-2 2 -stilbene-l I -diarsinic acid. Further reduction yields the corresponding arseno-compound. 4-Nitro-5-ehlorotolyl-2-arsinic add undergoes a similar series of reactions. o-Phenylenediarsinic acid, ... 

SULFUROUS OXIDE (7446-09-5) SO, Noncombustible liquefied gas under pressure or liquid. Contact with air forms hydrogen chloride fumes. Violent reaction with water or steam, forming sulfurous acid, a medium-strong acid and corrosion hazard. Reacts violently with acetylene, acrolein, alcohols, aluminum powder alkali metals (i.e., potassium, sodium) amines, ammonia, bromine pentafluoride butadiene caustics, cesium acetylene carbide chlorates, chlorine trifluoride chromium powder copper or copper alloy powders chlorine, diethylzinc, fluorine, ethylene oxide lead dioxide lithium acetylene carbide diamino-, metal powders monolithium acetylide-ammonia nitryl chloride potassium acetylene carbide potassium acetylide, potassium chlorate rubidium carbide silver azide sodium acetylide staimous oxide. Decon oses in... 

N-Acetylation of isatin with acetic anhydride yields N-aeetylation whieh undergoes intra molecular rearrangement with alkali to the quinoline eompound 2-hydroxyeinehoninie acid under the name Pfitzinger Reaction. The diamino group is now introdueed under eontrolled condition at room temperature so as to avoid reaction with relatively less reactive 2-ehloro substituent. 

Certain other reactions differ from those discussed in being brought about by acid rather than alkali. Thus, although 2-aminopyridine is unaffected by acid 8 , 2,6-diaminopyridine is converted by hot 10 per cent hydrochloric acid into 2-amino-6-hydroxypyridine 0. The second step, to 2,6-dihydroxypyridine, is more difficult889, 89i, 2,6-Diamino-3-nitroso-pyridine can be converted into the dihydroxy compound with acid or alkali, but with 2,6-diamino-3-nitropyridine alkali is essential s a, The not very convincing explanation usually given for the difference in behaviour between... 

The direct alkylation of aminopyrazines is usually unsatisfactory as a synthetic method because it mainly takes place at the most basic ring nitrogen. However, 3,6-diamino-2,5-dicyanopyrazines are successfully alkylated by treatment with alkyl iodide or bromide in protic solvent in the presence of alkali such as NaOH in dimethylacetamide (DMA) to form bis(dialkylamino)pyrazines <1998DP(39)49>. Reaction of 2,6-diamino-3,5-diarylpyrazine with methylglyoxal in aqueous HCl-ethanol led to -alkylation but no formation of the expected bicyclic imidazolo[l,2- z]pyrazine <2001S768>. 

Diamino-6-hydroxypyrimidine condenses with nitromalonaldehyde in presence of alkali to give 2-amino-4-hydroxy-6-nitropyrido[2,3-d]pyrimi-dine (100) (75%).92 In a similar reaction 2,4-dioxo-l-hydroxy-6-nitro-lf/,3//-pyrido[2,3-d]pyrimidine is formed (101) [Eq. (32)].93... 

The condensation of a, dicarbonyl compounds (49) with aj3-diamino compounds (50), which proceeds through the dihydropyrazine (51), has been much used for the synthesis of alkyl- and arylpyrazines (52). These reactions are usually carried out in methanol, ethanol, or ether in the presence of sodium or potassium hydroxide. The dihydropyrazines may be isolated, or oxidized directly to the pyrazine. Dehydrogenating agents that have been employed include oxygen in aqueous alkali (329), air in the presence of potassium hydroxide (330), sodium amylate in amyl alcohol (330a), alcoholic ferric chloride (24), and copper chromite catalyst at 300° (331) (see also Section 1). Pyrazines prepared by this method and modifications described below are listed in Table II.8 (2, 6, 24, 60, 80,195, 329-382) and some additional data are provided in Sections VI. 1 A, VlII.lA(l), and IX.4A(1). 

Strong parallels exist between the chemistry of 1,2-diamino-1,2-dithioethylenes and that of peraminoethylenes. Many cleavage reactions analogous to equations (6-9) are recognized but it is also common for one of the central C—C bonds to remain intact as in the reaction of 5 with strong alkali. With 2,2-bi(3-methylbenz-thiazoUdine), for example, ammonium iodide yields the salt 46, dimethylsulfate yields 47 and methanol (presumably via initial protonation) gives the adduct 48 . In comparison with this ethylene, the... 

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