Hydrazine and its Salts

Hydrazine and its salts can be titrated in solution using manganese(lll) solutions. Saits of hydrazine generally act as reductants and they can be titrated by suitable redox titrations. Under Andrews titration conditions, iodate is reduced to ICI (I2 is initially liberated). Hydrazine salts can be titrated against standard KIO3 solution. 

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In humans, the vapor is immediately irritating to the nose and throat and causes dizziness and nausea itching, burning, and swelling of the eyes develop over a period of several hours. Severe exposure of the eyes to the vapor causes temporary blindness, lasting for about 24 hours. The liquid in the eyes or on the skin causes severe burns. Hydrazine and its salts will also produce skin irritation and allergic reactions in humans. 

Many syntheses of (benzo)pyridazines involve the use of hydrazine and its derivatives, and the safe handling and disposal of these materials should be given careful consideration. Hydrazine and its salts are potential carcinogens and many hydrazine derivatives have, or are likely to have, toxic properties and all should be handled with care. In addition, hydrazine can react violently with oxidizing agents and the explosive decomposition of hydrazine vapor in air can be catalyzed by, for instance, rust. 

Hydrazine and its salts are powerful reducing agents. Hydrazine is oxidised to nitrogen. 

Hydrazine and its salts reduce ammoniacal solutions of cupric salts ... 

Hydrazine and its salts react with oxidants in different molar ratios under different conditions. It is therefore necessary to establish the stoichiometry of its reaction with Mn(Ill) sulphate solution. 

Some reductants are rarely used in preparative coordination chemistry and others have only limited application. Such reductants are discussed here. Hydrazine and its salts are strong reductants capable of generating noble metals from their coiriplexes. However, if the amount of reductant is carefully controlled, the metal center in a noble metal complex can be reduced to a lower oxidation state. For example, the synthesis of potassium tetrachloroplatinate(II) by reduction of K2[PtCl6l with hydrazine sulfate, N2HfH2S04, is well known. Grinberg has shown, 63 in his classic experiments, that the reaction mechanism involves the formation of platinum black which reacts with potassium hexachloroplatinate(IV), Eq. 9.46 ... 

Numerous explosives are based on hydrazine and its derivatives, including the simple azide, nitrate, perchlorate, and diperchlorate salts. These are sometimes dissolved in anhydrous hydrazine for propeUant appUcations or in mixtures with other explosives (207). Hydrazine transition-metal complexes of nitrates, azides, and perchlorates are primary explosives (208). 

Azo compounds and hydrazines, azo alkanes, azo aromatics, aminoazobenzenes, dia-zonium salts, diazomethane, hydrazine and its methyl derivatives... 

As reaction is preceded by a certain delay, this induction period was reduced by the addition of copper salts, e.g. potassium cuprocyanide K3Cu (CN)4. This substance was supplied to the system dissolved in the hydrazine hydrate. It was found that potassium cuprocyanide reacts with hydrazine even at room temperature to form metallic copper which, if deposited in the pipelines, may cut off the flow of hydrazine into the combustion chamber. To prevent this the system was modified so that hydrazine hydrate flowed from the tank into the combustion chamber through a cartridge containing cupric nitrate, which dissolved in hydrazine hydrate in a sufficient quantity to accelerate the reaction (hydrazine and its reaction with H202 will be discussed in more detail further on). 

Heat stabilizers - [HEAT STABILIZERS] (Vol 12) -m electric insulation [INSULATION, ELECTRIC] (Vol 14) -hydrazine derivatives as [HYDRAZINE AND ITS DERIVATIVES] (Vol 13) -lead compounds [LEAD COMPOUNDS - LEAD SALTS] (Vol 15) -metal soaps [DRIERS AND METALLIC SOAPS] (Vol 8) -for PVC foam [FOAMED PLASTICS] (Vol 11)... 

Both 1- and 2-fluoronaphthalenes are reduced to naphthalene by a mixture of hydrazine and its sodium salt, in 39 and 60% yield, respectively.63 As in the case of other monofluoroarenes, more efficient reduction is achieved by lithium aluminum hydride combined with cerium(III) chloride in refluxing tetrahydrofuran.1011 1,2,3,4-Tetrafluoronaphthalene (6) is monoreduced by lithium aluminum hydride at C2 with complete regioselcctivity to give trifluoronaphthalene... 

Pyrylium salts also react with hydrazine and its derivatives to give the N-aminoazonium salts (Eq. 3), although the reaction takes other courses in some cases.50,70,80-93 The reaction involves the formation of intermediate hydrazones by nucleophilic attack at the a-position of pyrylium rings. The hydrazones undergo ring closure followed by dehydration. This method has been utilized for the preparation of highly substituted pyridine AT-imines. 

Benzaldehyde and other aromatic aldehydes condense with hydrazine or its salts to form water-insoluble colorless aldazines. Owing to its greater solubility in water, salicylaldehyde (I) is especially useful as specific reagent. It reacts with hydrazine ... 

Procedure. The test is conducted on a spot plate. A drop of the test solution is treated with one drop each of a 1 % solution of 4-pyridylpyridinium dichloride in water, 1 N sodium hydroxide, and concentrated hydrochloric acid. It is imperative that this order be followed. If hydrazine or its salts are present, an orange to red color is formed. 

The analytical chemistry of Mn(III) solutions and its reactions with ascorbic acid and with hydrazine and hydrazinium salts are discussed in 112(1987)511. The reference also gives... 

Hydrazine [302-01-2] (diamide), N2H4, a colorless liquid having an ammoniacal odor, is the simplest diamine and unique in its class because of the N—N bond. It was first prepared in 1887 by Curtius as the sulfate salt from diazoacetic ester. Thiele (1893) suggested that the oxidation of ammonia (qv) with hypochlorite should yield hydrazine and in 1906 Raschig demonstrated this process, variations of which constitute the chief commercial methods of manufacture in the 1990s. 

Numerous references for the preparation of aminoguanidine bicarbonate and other salts can be found in the excellent review article, The Chemistry of Aminoguanidine and Related Substances by Lieber and Smith. More recently, it has been prepared by treating a cyanamide solution at 20-50° with hydrazine and carbon dioxide, ... 

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