The peroxide process is a method for the industrial production of hydrazine.
In this process hydrogen peroxide is used as an oxidant instead of sodium hypochlorite, which is traditionally used to generate hydrazine. The main advantage of the peroxide process to hydrazine relative to the traditional Olin Raschig process is that it does not coproduce salt. In this respect, the peroxide process is an example of green chemistry. Since many millions of kilograms of hydrazine are produced annually, this method is of both commercial and environmental significance. [1]
In the usual implementation, hydrogen peroxide is used together with acetamide. This mixture does not react with ammonia directly but does so in the presence of methyl ethyl ketone to give the oxaziridine.
Balanced equations for the individual steps are as follows. Imine formation through condensation:
Oxidation of the imine to the oxaziridine:
Condensation of the oxaziridine with a second molecule of ammonia to give the hydrazone:
The hydrazone then condenses with a second equivalent of ketone to give the ketazine:
Typical process conditions are 50 °C and atmospheric pressure, with a feed mix of H2O2:ketone:NH3 in a molar ratio of about 1:2:4. [2] Methyl ethyl ketone is advantageous to acetone because the resulting ketazine is immiscible in the reaction mixture and can be separated by decantation. [2] A similar process based on benzophenone has also been described. [3]
The final stage involves hydrolysis of the purified ketazine:
The hydrolysis of the azine is acid-catalyzed, hence the need to isolate the azine from the initial ammonia-containing reaction mixture. It is also endothermic, [4] and so requires an increase in temperature (and pressure) to shift the equilibrium in favour of the desired products: ketone (which is recycled) and hydrazine hydrate. [5] The reaction is carried out by simple distillation of the azeotrope: typical conditions are a pressure of 8 bar and temperatures of 130 °C at the top of the column and 179 °C at the bottom of the column. The hydrazine hydrate (30–45% aqueous solution) is run off from the base of the column, while the methyl ethyl ketone is distilled off from the top of the column and recycled. [5]
The peroxide process, also called the Pechiney–Ugine–Kuhlmann process, was developed in the early 1970s by Produits Chimiques Ugine Kuhlmann. [6] [5] Originally the process used acetone instead of methyl ethyl ketone. [6] Methyl ethyl ketone is advantageous because the resulting ketazine is immiscible in the reaction mixture and can be separated by decantation. [2] [7] The world's largest hydrazine hydrate plant is in Lannemezan in France, producing 17,000 tonnes of hydrazine products per year. [8]
Before invention of the peroxide process, the Bayer ketazine process had been commercialized. In the Bayer process, the oxidation of ammonia by sodium hypochlorite is conducted in the presence of acetone. The process generates the ketazine but also sodium chloride: [1]
In organic chemistry, a ketone is a functional group with the structure R−C(=O)−R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group −C(=O)−. The simplest ketone is acetone, with the formula (CH3)2CO. Many ketones are of great importance in biology and in industry. Examples include many sugars (ketoses), many steroids, and the solvent acetone.
Hydrazine is an inorganic compound with the chemical formula N2H4. It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly toxic unless handled in solution as, for example, hydrazine hydrate.
Butanone, also known as methyl ethyl ketone (MEK), is an organic compound with the formula CH3C(O)CH2CH3. This colourless liquid ketone has a sharp, sweet odor reminiscent of acetone. It is produced industrially on a large scale, but occurs in nature only in trace amounts. It is partially soluble in water, and is commonly used as an industrial solvent. It is an isomer of another solvent, tetrahydrofuran.
Unsymmetrical dimethylhydrazine (UDMH; 1,1-dimethylhydrazine, НДМГ; Несимметричный диметилгидразин (NDMG / NDMH or codenamed гептилheptil) is a chemical compound with the formula H2NN(CH3)2 that is used as a rocket propellant. It is a colorless liquid, with a sharp, fishy, ammonia-like smell typical for organic amines. Samples turn yellowish on exposure to air and absorb oxygen and carbon dioxide. It is miscible with water, ethanol, and kerosene. In concentration between 2.5% and 95% in air, its vapors are flammable. It is not sensitive to shock. Symmetrical dimethylhydrazine, 1,2-dimethylhydrazine is also known but is not as useful. UDMH can be oxidized in air to form many different substances, including toxic ones.
Hydrazones are a class of organic compounds with the structure R1R2C=N−NH2. They are related to ketones and aldehydes by the replacement of the oxygen =O with the =N−NH2 functional group. They are formed usually by the action of hydrazine on ketones or aldehydes.
Methyl ethyl ketone peroxide (MEKP) is an organic peroxide with the formula [(CH3)(C2H5)C(O2H)]2O2. MEKP is a colorless oily liquid. It is widely used in vulcanization (crosslinking) of polymers.
The Wolff–Kishner reduction is a reaction used in organic chemistry to convert carbonyl functionalities into methylene groups. In the context of complex molecule synthesis, it is most frequently employed to remove a carbonyl group after it has served its synthetic purpose of activating an intermediate in a preceding step. As such, there is no obvious retron for this reaction. The reaction was reported by Nikolai Kischner in 1911 and Ludwig Wolff in 1912.
Tollens' reagent is a chemical reagent used to distinguish between aldehydes and ketones along with some alpha-hydroxy ketones which can tautomerize into aldehydes. The reagent consists of a solution of silver nitrate, ammonium hydroxide and some sodium hydroxide. It was named after its discoverer, the German chemist Bernhard Tollens. A positive test with Tollens' reagent is indicated by the precipitation of elemental silver, often producing a characteristic "silver mirror" on the inner surface of the reaction vessel.
Acetone, is an organic compound with the formula (CH3)2CO. It is the simplest and smallest ketone. It is a colorless, highly volatile and flammable liquid with a characteristic pungent odor.
Methyl methacrylate (MMA) is an organic compound with the formula CH2=C(CH3)COOCH3. This colorless liquid, the methyl ester of methacrylic acid (MAA), is a monomer produced on a large scale for the production of poly(methyl methacrylate) (PMMA).
Pyrazole is an organic compound of azole group with the formula C3H3N2H. It is a heterocycle characterized by a 5-membered ring of three carbon atoms and two adjacent nitrogen atoms, which are in ortho-substitution. Pyrazole is a weak base, with pKb 11.5 (pKa of the conjugate acid 2.49 at 25 °C). Pyrazoles are also a class of compounds that have the ring C3N2 with adjacent nitrogen atoms. Notable drugs containing a pyrazole ring are celecoxib (celebrex) and the anabolic steroid stanozolol.
Hydrazides in organic chemistry are a class of organic compounds with the formula R−NR1−NR2R3 where R is acyl, sulfonyl, phosphoryl, phosphonyl and similar groups, R1, R2, R3 and R' are any groups. Unlike hydrazine and alkylhydrazines, hydrazides are nonbasic owing to the inductive influence of the acyl, sulfonyl, or phosphoryl substituent.
The Nicolaou Taxol total synthesis, published by K. C. Nicolaou and his group in 1994 concerns the total synthesis of taxol. Taxol is an important drug in the treatment of cancer but also expensive because the compound is harvested from a scarce resource, namely the pacific yew.
Azines are a functional class of organic compounds with the connectivity RR'C=N-N=CRR'. These compounds are the product of the condensation of hydrazine with ketones and aldehydes, although in practice they are often made by alternative routes. Ketazines are azines derived from ketones. For example, acetone azine is the simplest ketazine. Aldazines are azines derived from aldehydes.
The Wharton olefin synthesis or the Wharton reaction is a chemical reaction that involves the reduction of α,β-epoxy ketones using hydrazine to give allylic alcohols. This reaction, introduced in 1961 by P. S. Wharton, is an extension of the Wolff–Kishner reduction. The general features of this synthesis are: 1) the epoxidation of α,β-unsaturated ketones is achieved usually in basic conditions using hydrogen peroxide solution in high yield; 2) the epoxy ketone is treated with 2–3 equivalents of a hydrazine hydrate in presence of substoichiometric amounts of acetic acid. This reaction occurs rapidly at room temperature with the evolution of nitrogen and the formation of an allylic alcohol. It can be used to synthesize carenol compounds. Wharton's initial procedure has been improved.
This is the list of extremely hazardous substances defined in Section 302 of the U.S. Emergency Planning and Community Right-to-Know Act. The list can be found as an appendix to 40 C.F.R. 355. Updates as of 2006 can be seen on the Federal Register, 71 FR 47121.
Hydrazines (R2N−NR2) are a class of chemical compounds with two nitrogen atoms linked via a covalent bond and which carry from one up to four alkyl or aryl substituents. Hydrazines can be considered as derivatives of the inorganic hydrazine (H2N−NH2), in which one or more hydrogen atoms have been replaced by hydrocarbon groups.
An oxaziridine is an organic molecule that features a three-membered heterocycle containing oxygen, nitrogen, and carbon. In their largest application, oxaziridines are intermediates in the industrial production of hydrazine. Oxaziridine derivatives are also used as specialized reagents in organic chemistry for a variety of oxidations, including alpha hydroxylation of enolates, epoxidation and aziridination of olefins, and other heteroatom transfer reactions. Oxaziridines also serve as precursors to amides and participate in [3+2] cycloadditions with various heterocumulenes to form substituted five-membered heterocycles. Chiral oxaziridine derivatives effect asymmetric oxygen transfer to prochiral enolates as well as other substrates. Some oxaziridines also have the property of a high barrier to inversion of the nitrogen, allowing for the possibility of chirality at the nitrogen center.
Acetone azine is the simplest ketazine. It is an intermediate in some hydrazine manufacturing processes.
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