Hydrazine handling

The reactor effluent, containing 1—2% hydrazine, ammonia, sodium chloride, and water, is preheated and sent to the ammonia recovery system, which consists of two columns. In the first column, ammonia goes overhead under pressure and recycles to the anhydrous ammonia storage tank. In the second column, some water and final traces of ammonia are removed overhead. The bottoms from this column, consisting of water, sodium chloride, and hydrazine, are sent to an evaporating crystallizer where sodium chloride (and the slight excess of sodium hydroxide) is removed from the system as a soHd. Vapors from the crystallizer flow to the hydrate column where water is removed overhead. The bottom stream from this column is close to the hydrazine—water azeotrope composition. Standard materials of constmction may be used for handling chlorine, caustic, and sodium hypochlorite. For all surfaces in contact with hydrazine, however, the preferred material of constmction is 304 L stainless steel. 

Concern for personnel exposure to hydrazine has led to several innovations in packaging to minimize direct contact with hydrazine, eg, Olin s E-Z dmm systems. Carbohydrazide was introduced into this market for the same reason it is a soHd derivative of hydrazine, considered safer to handle because of its low vapor pressure. It hydrolyzes to release free hydrazine at elevated temperatures in the boiler. It is, however, fairly expensive and contributes to dissolved soHds (carbonates) in the water (193). In field tests, catalyzed hydrazine outperformed both hydrazine and carbohydrazide when the feedwater oxygen and iron levels were critical (194). A pubUshed comparison is available (195) of these and other proposed oxygen scavengers, eg, diethyUiydroxylarnine, ydroquinone, methyethylketoxime, and isoascorbic acid. 

NOTE - Petrochemical plants also generate significant amounts of solid wastes and sludges, some of which may be considered hazardous because of the presence of toxic organics and heavy metals. Spent caustic and other hazardous wastes may be generated in significant quantities examples are distillation residues associated with units handling acetaldehyde, acetonitrile, benzyl chloride, carbon tetrachloride, cumene, phthallic anhydride, nitrobenzene, methyl ethyl pyridine, toluene diisocyanate, trichloroethane, trichloroethylene, perchloro-ethylene, aniline, chlorobenzenes, dimethyl hydrazine, ethylene dibromide, toluenediamine, epichlorohydrin, ethyl chloride, ethylene dichloride, and vinyl chloride. 

Sodium azide (Eastman, 97-99%) is activated by dissolving 100 g of the salt in 400 ml of distilled water and stirring with 14 ml of hydrazine hydrate for 15 min. The solution is filtered and added dropwise to 4 liters of rapidly stirred, dry acetone. The solid is collected by filtration and washed with 150 ml of dry acetone. The fine powder (57-85 g) is dried under vacuum at 50° for 2 hr. Sodium azide is extremely toxic and the fine powder should be handled with care to avoid breathing the dust. 

Yield of the crude product according to the NMR spectra. In parentheses yield of the isolated pure hydrazine. Hydrazines arc known to be prone to air oxidation and unstable upon storage or handling on silica gel. This might be the reason for the considerable loss of yield during purification. 

Uses It is one active ingredient present in water which has been purified by chlorination (Ref 6). It is used as an intermediate for.the prepn of hydrazine and substituted hydrazines. Recentiy there has been a renewed interest in chloramine as a possible intermediate for the prepn of UDMH (see Vol 7, H203-R) which avoids handling the highly carcinogenic dimethyl-nitrosamine (Refs 5 7)... 

Carbohydrazide was the first novel oxygen scavenger of any significance to provide a safe handling replacement for hydrazine it was patented as an oxygen scavenger as Nalco ELIMIN-OX in 1981. 

CAUTION NOTE Hydrazine is toxic, and suitable precautions for its handling should be observed. Its use is usually prohibited in hospitals, the food manufacturing industry, and where steam may come into contact with food or beverages. The use of sodium sulfite may also be unacceptable in some of these applications. The existence of any regulations governing the use of either should be ascertained and observed. 

Until recently the atmospheric chemistry of nitrogen-containing compounds such as the hydrazines, which are widely used as fuels in military and space vehicles, has received comparatively little attention. N,N-dimethyIhydrazine (also UDMH = unsymmetrical dimethylhydrazine) is used in liquid-fueled rockets, and thus there Is a possibility that its use, storage, and handling could result in its release in the atmosphere. 

Use of rusty tweezers, rather than the glass rod specified to handle specimens being immersed in hot 64% hydrazine, caused the hydrazine vapour to ignite. 

In any apparatus for handling anhydrous hydrazine, all connections must be made through tightly fitting corks which are covered with tin foil. 

Hydrazide method, for covalent ligand immobilization, 6 396t Hydrazine, 70 727 73 562-607. See also Anhydrous hydrazine analytical methods for, 73 588-589 aqueous grades of, 73 585 chemical properties of, 73 566-576 as a corrosion inhibitor, 73 595 economic aspects of, 73 584-585 electrode potentials of, 73 566t explosive limits of, 73 566 handling and storage of, 73 586-588 as a hazardous material, 73 585... 

The survey of hazards and safety procedures involved in handling rocket fuels and oxidisers includes liquid hydrogen, pentaborane, fluorine, chlorine trifluoride, ozone, dinitrogen tetraoxide, hydrazine, methyl hydrazine and 1,1-dimethyl hydrazine [1]. The later volume [2] is a bargain compendium of five NFPA publications ... 

Fuel cells using directly liquid fuels are advantageous in this aspect. Methanol, formaldehyde (water solution), formic acid (water solution) and hydrazine are among fuels relatively easy to oxidize electrochemically. Alcohol and hydrocarbon with larger molecular weight are much harder to oxidize completely to C02- Other qualifications to be considered are price, availability, safety, energy density and ease of handling. 

The first task was to design a linker between the primary amine functionality on the resin and the hydrazine function that ultimately binds the macrocyclic aldehyde. As mentioned above, the employed resin (PEGA1900) features a primary amino group at the end of a PEG spacer connected to the polyacrylamide backbone. To assure monofunctionalization, the amino group was monobenzylated, thereby preventing possible proximity problems. Subsequently, the resulting secondary amine was provided with a handle for the introduction of the hydrazine functionality (see Scheme 29). 

All initiators are potentially explosive compounds and must be stored and handled with care. 2,2 -AIBN is obtained from the reaction of acetone with potassium cyanide and hydrazine hydrochloride. As shown in equation 17.51, the reaction produces hydrogen cyanide and hydrazine. The latter reacts with acetone forming acetone dihydrazone, which reacts with... 

Caution. Anhydrous hydrazines and solutions containing hydrazines are corrosive and can cause burns. They are also suspected to be carcinogens. All handling must be done with protective clothing and gloves, and must be carried out in a well-ventilated hood. 

The authors [48] numerical data are collected in Table 67. They are valuable indications of the safety measures which should be observed in the storage, transportation and handling of hydrazine. It can be contained in vessels of glass and stainless steel, but under no circumstances in those made of iron. Aluminium containers are also acceptable. 

They remain liquid under normal, ambient operating conditions (moderate temperature, atmospheric pressure). Safety in storage and handling should also be considered. A storable liquid propellant should not have an excessively high vapour pressure at ambient temperature. The leading storable propellant uses dinitrogen tetroxide as oxidizer and a 50/50 mixture of hydrazine-unsymmetrical dimethylhydrazine (UDMH) as fuel [71], Nitrogen tetroxide and UDMH is another storable propellant mixture in use [73],... 

CAUTTON Hydrazine hydrate is a poison upon ingestion and by intravenous routes. It is an experimental carcinogen and is a corrosive irritant to the eyes, skin, and mucous membranes. Appropriate safety precautions and procedures should be taken during all stages of its handling and disposal. 

Tertiary phosphite complexes of platinum(O) can be prepared by the hydrazine reduction of PtCl2 P(OR)3 2 (equation 384), or by replacement of triphenylphosphine in Pt(PPh3)3 (equation 385).1233 Alternatively the complexes can be prepared from Pt(j73-C3H5)(r/5-Cp) and the phosphite.1268 Heteronuclear INDOR measurements show that 2/(PP) has a value of +81 Hz in Pt P(OMe)3 4. A detailed synthesis of Pt P(OEt)3 4 has been published from K2PtCl4 and triethyl phosphite with KOH (equation 386).1267 The product is obtained as colorless crystals which can be handled in air. 

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