Hydrazine, properities

Materials of Construction. In choosing the proper materials of constmction for storing and using hydrazine, it is necessary to consider both the effects of the material on the stabiUty and quaUty of the hydrazine as well as the effect of the hydrazine on the material of constmction. Hydrazine is thermally stable, storable for years without adverse effects either to the product or the storage container provided the recommended materials are used, all systems are clean, and an inert gas, ie, nitrogen, is maintained over the system at all times. Table 10 is a brief listing of materials compatibiUty (125). 

Pyrazolines can be prepared from the reaction between a hydrazine and two carbonyl compounds, one of them having at least one hydrogen atom a to the carbonyl group. Formally, these reactions correspond to the [NN + C + CC] class. However, if one considers the different steps in the ring formation, they more properly belong to the [CNN + CC] (Section 4.04.3.1.2(ii)), the [CCNN + C] (Section 4.04.3.1.2(i)), or the formation of one bond (Section 4.04.3.1.1) classes. 

Oxygen corrosion is often underestimated. Studies have shown that the corrosion can be limited when proper oxygen scavengers are used. Hydrazine leads the group of chemicals that are available for oxygen removal. Because of... 

Most reactions with hydrazine are carried out with aldehydes and ketones in the presence of alkali. The reduction proper is preceded by formation of hydrazones that decompose in alkaline medium at elevated temperatures to nitrogen and compounds in which the carbonyl oxygen has been replaced by two hydrogens. The same results are obtained by alkaline-thermal decomposition of ready-made hydrazones of the carbonyl compounds. Both reactions are referred to as Wolff-Kizhner reduction [280]. 

The essential difference between the hydroxylamine reaction and the hydrazine reaction appears to be that silver nuclei are formed in the solution much more readily by hydrazine than by hydroxylamine. At sufficiently low pH and in the absence of copper, hydroxylamine does not readily form nuclei in the solution, and the catalytic reduction of the silver chloride occurs essentially at a solid interface with the silver nuclei. Hydrazine, on the other hand, readily forms nuclei in the solution and an important fraction of the total reaction involves the catalytic reduction of dissolved silver chloride. This would account for the well-known photographic properties of the two agents. Hydroxylamine is a cleanworking developer which, under proper conditions, yields little fog. Hydrazine shows much less selectivity and, although it develops an image, it also yields a relatively high fog density. 

Purification of hydrazine by pervaporation techniques could be an alternative process. Since hydrazine is highly alkaline, the proper selection of the polymer for the pervaporation membrane is important. 

In general, the stable thermodynamic products of ordinary flames have little worth, but many of the uncommon flames have products of value. The chlorination of hydrocarbons may be carried out in a flame process which was recently announced (A4). A most fascinating example is the formation of boron nitride from the flame reaction between diborane and hydrazine, two compounds which are ordinarily thought of as fuels (B2, VI). The stabilization of this flame depends upon the proper preparation of the premixed gases, since a solid adduct between the reactants prevents flame stabilization if the preflame residence time is too great. 

Appropriate /Lchlorovinylaldehydcs 1 or 3 (1 mmol) and hydrazine hydrate (4 mmol) or phenylhydrazine (1.25 mmol) were introduced in a beaker (50 mL). A small amount of p-TsOH (100 mg) was added and properly mixed with the help of glass rod. The so-obtained paste was irradiated in a microwave oven at a power output of 300 W for the appropriate time. After irradiation, cold water (25 mL) was added. The obtained solid was collected, washed with water, dried and recrystallized from adequate solvent to afford the desired products in good yields (78-97%). 

The chemistry of these very electron-deficient rings mostly concerns nucleophilic attack and displacement of leaving groups such as Cl by nucleophiles such as alcohols and amines. To introduce this subject we need to take one heterocyclic synthesis at this point, though these are properly the subject of the next chapter. The compound maleic hydrazide has been known for some time because it is easily formed when hydrazine is acylated twice by maleic anhydride. 

Hazards Use caution when handling concentrated hydrazine solutions never boil them alone, and keep them away from strong oxidizers. Use proper ventilation when handling concentrated hydrochloric acid fumes and liquid are very irritating and corrosive. 

Hazards Handle 99% anhydrous hydrazine with care. Never distill it in the presence of air, and keep it out of contact with strong oxidizers. Wear gloves, and use proper ventilation when handling cyanogen bromide. Cyanogen bromide is highly poisonous, and inhalation of vapors, or skin absorption can be fatal toxic effects are similar to hydrogen cyanide. 

Aromatic sym-disubstituted hydrazines are obtained by reduction of azo compounds, which in turn are intermediates in properly controlled reductions of nitro compounds. The over-all reduction can be accomplished with zinc dust and alkali or electrolytically. For example, hydrazobenzene, the simplest member, is made by both procedures. Chemical reduction is carried out on o-nitrobromobenzene to form 2,2 -dibromohydrazobenzene (57%), the halo groups remaining intact. Many examples of the electrolytic procedure have been cited the yields vary from 50% to 95%. To a limited extent, a magnesium-magnesium iodide system has been employed as a reducting agent for the azobenzenes. ... 

P11-13b (Seargemt Ambercromby) Capt. Apollo is piloting a shuttle craft on his way to space station Klingon. Just as he is about to maneuver to dock his craft using the hydrazine system discussed in Example 11-3, the shuttle craft thrusters do not respond properly and it crashes into the station, killing Capt. Apollo. An investigation revealed that Lt. Darkside prepared the packed beds used to maneuver the shuttle and Lt Data prepared the hydrazine-helium gas mixture. Foul play is suspected and Sgt. Ambercromby arrives on the scene to investigate. 

You may be exposed to significant amounts of hydrazines if you work in a place that makes, processes, or uses hydrazines, especially if you do not use proper protective equipment. People who live near these places, or near accidental spills or hazardous waste sites contaminated with hydrazines, may also be exposed. However, since hydrazines stay in air, water, and soil only briefly, most people are not exposed to them from these sources. 

---