Ammonia methylhydrazine

It appears that treatment of phenacyl bromides 1239 with methylhydrazine in refluxing acetic acid leads also to 1,4-disubstituted triazoles 1244. Fivefold excess of methylhydrazine is used in these reactions. According to the proposed mechanism, structures 1240-1243, methylhydrazine has a double role, as a condensing agent and an oxidant. In the final account, three molecules of methylhydrazine have to be used to produce one molecule of triazole 1244, two molecules of methylamine and one molecule of ammonia. The basic triazole 1244 (X = Y = H) is separated in 59% yield. The reactions go well with electron-donating substituents (for X = OH, the yield is 81%), but electron-withdrawing substituents can lower the yield dramatically (11% for X = N02) (Scheme 206) <2003JCM96>. 

Regioselectivity was observed when the reaction was extended to the use of substituted hydrazines, where the reaction of 3,4-pyridinedicarboximide derivatives 305 or 306 with methylhydrazine in boiling ethanol gave the corresponding 3-methyl-l,4-dioxo-l,2,3,4-tetrahydropyrido[3,4-r pyridazine 307 and 2-methyl-l,4,5-trioxo-1,2,3,4,5,6-hexahydro analogue 308, respectively, via opening of the imide ring and evolution of ammonia gas... 

Dithiolylium salts may be converted into pyrazoles, pyrazolium salts and isothiazoles (see Section 3.4.1.6.2.ii). For example, 3-phenyl-1,2-thiolylium salt (74) with hydrazine, methylhydrazine or phenylhydrazine yielded the corresponding pyrazoles (75). 3,4-Dimethyl-1,2-dithiolylium perchlorate (76) with ammonia gave 4,5-dimethylisothiazole (77). 

The ene hydrazine 100, prepared from dimedone and methylhydrazine, forms the Michael adduct 101 with dimethyl acetylenedicarboxylate. The adduct is converted into a mixture of pyrrole and pyridone derivatives, 103 and 104, in boiling tetralin. These products arise by a [3.3]sigmatropic shift in the adduct with cleavage of the nitrogen-nitrogen bond to give 102, followed by cyclization and elimination of ammonia and methanol, respectively (equation 42)63. 

Dimethylhydrazine and Derivatives uns-Dimethylhydrazine (UDMH) (1,1-Di-methylhydrazine), code name Dimazine, (H3O2N.NH2 mw 60.10, N 46.62% col flammable liq with ammonia-like odor hygroscopic sp gt 0.791 at 22° ft p minus 58° bp 63° v sol in w, ale, eth in hydrocarbons. Following methods of prepn are listed in Refs 1 11 a) reaction of dimethylamine (DMA) chloramine ... 

Hydrazinoquinoxalines are generally prepared from the corresponding chloroquinoxalines by treatment with hydrazine hydrate in refluxing ethanol. It has been found that displacement reactions with hydrazine can be carried out under milder conditions than the parallel reactions with ammonia or amines, and that when methylhydrazine is reacted with chloroquinoxalines, a 1 1 disubstituted hydrazine is formed, rather than a 1 2 disubstituted product. ... 

A similar example, except one for which the product ions were directly affected by the dopant, was the simultaneous separation of peaks for ammonia, hydrazine, methylhydrazine, and dimethylhydrazine using nonanone. ° The ketone formed cluster ions with each of the available hydrogen atoms, and thus four ketone molecules were clustered on protonated hydrazine, three formed clusters with methylhydrazine, and just two formed them with dimethylhydrazine. The increase in mass and cross section to the core ion from the adducted ketones caused shifts in the drift time of the product ion peaks, so that clustered hydrazine had the longest drift time and dimethylhydrazine the shortest. This change in drift times is shown in Figure 11.2 with nonanone vapors near 1 ppm in the gas atmosphere throughout the drift tube. 

---