Chloramine hydrazines

In this reaction hydrazine is an intermediate, but contrary to chloramine, hydrazine reacts rapidly with NH2Br, so that hydrazine can not be isolated as in the NH2CI/NH3 system. 

Hypochlorite solutions are not recommended for decontamination of ammonia and extreme caution should be taken if ammonia is the suspected agent as mixing bleach with this may produce a variety of toxic and carcinogenic compoimds (e.g. chloramine, hydrazine and chlorine gas). 

In a variation of the Raschig process for making hydrazine, amines rather than ammonia ate reacted with chloramine to give the corresponding alkyl hydrazine ... 

The chloramine then reacts with excess ammonia to form hydrazine ... 

This reaction is slow and requires elevated temperatures of 120—150°C under pressure. The kinetics (93,94) and mechanism (95,96) of these reactions have been studied. An undesirable competing reaction is the further oxidation of hydrazine by chloramine ... 

MMHa.nd UDMH. MonomethyUiydrazine and yyz -dimethylhydrazine are manufactured by Olin Corp. using the same Raschig process and equipment employed for anhydrous hydrazine. Chloramine, prepared as described above, reacts with methylamine or dimethylamine instead of with... 

This reaction is catalysed by traces of heavy metal ions such as Cu and the purpose of the gelatin is to suppress reaction (5) by sequestering the metal ions it is probable that gelatin also assists the hydrazine-forming reactions between ammonia and chloramine in a way that is not fully understood. The industrial preparation and uses of N2H4 are summarized in the Panel. 

In contrast to the Raschig hydrazine synthesis, diaziridine formation occurs in solvents of low polarity such as ether and in the absence of strong bases. An ionization of chloramine and the formation of 39 is thus unlikely. 

Hydrazine is produced by the oxidation of ammonia using the Rashig process. Sodium hypochlorite is the oxidizing agent and yields chloramine NH2CI as an intermediate. Chloramine further reacts with ammonia producing hydrazine ... 

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)... 

Diamond LH, Audrieth LF (1955) Preparation of N-substituted hydrazines from amines and chloramine. J Am Chem Soc 77(11) 3131... 

Classically, triazanium chlorides have been prepared by the reaction of hydrazine with mixtures of chloramine and ammonia. If the appropriately substituted hydrazine is available, this is still the method of choice for the synthesis of this class of compounds. 

Hydrazine is prepared by the Raschig process, the first step of which involves the production of chloramine, NH2C1. The process can be summarized by the equations... 

Chloramine is also formed when chlorine is passed into liquid ammonia further reaction with ammonia produces hydrazine ... 

The chloramines formed in the above reaction may further react with the product hydrazine, decomposing the latter to nitrogen. 

In Ketazine processes, hydrazine derivatives are obtained first. Ammonia is oxidized by chlorine or chloramines in the presence of aliphatic ketones. The products are hydrazones and isohydrazones. These are converted to ketazines with excess ketone. The ketazines or the intermediate hydrazine derivatives may be hydrolyzed to hydrazine after all the oxidizing reactants, such as CI2, NaOCl, or NH2CI are consumed. Unlike hydrazine, ketazines do not readily oxidize, and, therefore, the product yield is higher in these processes. 

Hydrazine reacts with chloramines to produce ammonium chloride while decomposing to nitrogen. The reaction is catalyzed hy metal ions at trace concentrations ... 

Then hydrazine is formed by the action of excess ammonia upon chloramine ... 

Diazomethane (called Diazomethan in Ger), C cNiN mw 42.04, N 66.64% poisonous yel gas condensing to a yel liq, bp -24 to -23° and solidifying in pale-yel crysts, fr p -145° explodes violently when heated to a higher temp sol in eth more important methods of prepn are from nitrosomethylurea, nitroso-methylurethane, a mixt of chloroform fit hydrazine hydrate, or l-methyl-l-nitroso-3-nitro-guanidine by reaction with KOH from nitrosyl chloride methylamine by treatment of the Na salt of formaldehyde oxime with chloramine and by other methods... 

In the laboratory, hvdra/iiie can be prepared by convening one-half of a given amount of NFL into chloramine. NILCI. hy sodium hy pochlorite solution in the presence ot a colloid and heating. The remaining one-hulf of the NHi reacts with chloramine to form hydrazine. The product is then cooled to 0 C and HySOj added in amount to react with the hydrazine to form hydrazine sulfate. NTh.SOj. insoluble solid. Hydra/ine hcmisulfate. tN Hsi SOj. is soluble in H 0. It can also be made by the reaction of NH i and hydroxy lamiiteO sulfonic acid. 

Chloramine was widely used in the treatment of water supplies between 1930 44 but many water plants have abandoned this treatment to-day. It has bactericidal props, but against many organisms its action is much weaker than free chlorine. This compd can react, under alkaline condition, with excess ammonia to form hydrazine Refs l)Gmelin, SystNr 6(1927), 418ff 2)... 

Hydrazine is produced commercially by treating ammonia in aqueous solution with sodium hypochlorite to form chloramine, NIL—Cl, and by coupling this with another molecule of ammonia to form hydrazine and hydrochloric acid. Sulfuric acid is added to the liquid, sparingly soluble hydrazine sulfate crystallizes out, and it is in the form of this salt that hydrazine generally occurs in commerce. 

In Eq. (18.2), the reaction rate for chloramine (NH2CI ) formation is rapid relative to the formation of hydrazine in Eq. (18.3). In this step dilute ammonia solution (5% to 15%) is added to the NaOCl at a ratio of 3 1. Use of NaOCl is estimated to be 3.5 pounds per pound of hydrazine. 

The Raschig process can also be used to react amines with chloramine to make monosubstituted or unsymmetrical disubstituted hydrazines. 

The Bayer Ketazine process is based on the reaction of chloramine with ammonia in the presence of acetone at pH 12 to 14. NaOCl, acetone and a 20% aqueous solution of ammonia (at a mole ratio of 1 2 20, respectively) are fed to a reactor at 35°C and 200 kPa to make the aqueous dimethyl ketazine solution. Excess ammonia and acetone are removed in a series of columns and recycled to the reactor. The ketazine solution is distilled to make a hydrazine hydrate containing 64% hydrazine. A sketch of this process is shown in Figure 18.4132. Use of NaOCl is estimated to be 3.5 pounds per pound of hydrazine. 

Hydrazine results from the action of chloramine, CiNH2, on ammonia, this reaction being similar to that used to prepare many organic amines ... 

Since chloramine itself is prepared by chlorination of ammonia, hydrazine is generally prepared by treatment of excess ammonia with chlorine. The similarity to H2O2 is exemplified by the detection of hydrazine at the anode in electrolysis of ammonium salts, just as H2Q2 or its derivatives can result from electrolysis of aqueous acid solutions. 

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