Hydroxylamine phosphate oxime

Dutch State Mines (Stamicarbon). Vapor-phase, catalytic hydrogenation of phenol to cyclohexanone over palladium on alumina, Hcensed by Stamicarbon, the engineering subsidiary of DSM, gives a 95% yield at high conversion plus an additional 3% by dehydrogenation of coproduct cyclohexanol over a copper catalyst. Cyclohexane oxidation, an alternative route to cyclohexanone, is used in the United States and in Asia by DSM. A cyclohexane vapor-cloud explosion occurred in 1975 at a co-owned DSM plant in Flixborough, UK (12) the plant was rebuilt but later closed. In addition to the conventional Raschig process for hydroxylamine, DSM has developed a hydroxylamine phosphate—oxime (HPO) process for cyclohexanone oxime no by-product ammonium sulfate is produced. Catalytic ammonia oxidation is followed by absorption of NO in a buffered aqueous phosphoric acid... 

HPO [Hydroxylamine phosphate oxime] A process for making caprolactam, an intermediate in the manufacture of polyamides. It differs from related processes, such as HSO, in producing less of the ammonium sulfate by-product. Developed by DSM Research, The Netherlands, operated by DSM Polymers and Hydrocarbons, and offered for license by Stamicarbon. 

Of the processes based on modification of the conventional route, only Stamicarbon s hydroxylamine phosphate oxime (HPO) process completely avoid all production of ammonium sulfate before the Beckmann rearrangement. The steps in the HPO process are listed below and shown in Figure 21.146, 264 ... 

Ammonium nitrate solution is reduced to hydroxylamine phosphate with hydrogen under pressure on a suspended precious metal catalyst (substrate activated charcoal) in the presence of phosphoric acid (HPO Hydroxylamine Phosphate Oxime) ... 

The HPO (hydroxylamine phosphate oxime) process, developed byDSMand licensed by Siamicarbon, totally eliminates the production of ammonium sulfate, both in the production of hydroxylamine itself and in die oxime production stage. It consists of the catalytic hydrogenation of the nitrate ions resulting from the oxidation of ammonia to hydroxylamine ions in a solution buffered by phosphates. The nitrate reduction reaction is as follows ... 

The Dutch State Mines process uses hydroxylamine phosphate oxime (HPO) to carry out the oximation of cyclohexanone. The process sequence is shown in Figure 14. In this process phosphoric acid/ammonium nitrate... 

Hydroxalamine disulfonic acid, 193 Hydroxylamine phosphate oxime (HPO), 219 Hydroxylamine sulfate, 192-194, 219 Hydroxylammonium phosphate, 219, 220 Hydroxylated polyesters, 160 Hypochlorus acid, 149... 

Keywords hydroxylamine phosphate, acetone, large scale, exhaust gas purification, flow system, gas-solid reaction, acetone oxime... 

Recently Benkovic and Schrayl28b and Clark and Kirby,26c have investigated the hydrolysis of dibenzylphosphoenolpyruvic acid and mono-benzylphospho-enolpyruvic acid which proceed via stepwise loss of benzyl alcohol (90%) and the concomitant formation of minor amounts (10%) of dibenzylphosphate and monobenzylphosphate, respectively. The pH-rate profiles for release of benzyl alcohol reveal that the hydrolytically reactive species must involve a protonated carboxyl group or its kinetic equivalent. In the presence of hydroxylamine the course of the reaction for the dibenzyl ester is diverted to the formation of dibenzyl phosphate (98%) and pyruvic acid oxime hydroxamate but remains unchanged for the monobenzyl ester except for production of pyruvic acid oxime hydroxamate. The latter presumably arises from phosphoenolpyruvate hydroxamate. These facts were rationalized according to scheme (44) for the dibenzyl ester, viz. 

Oxime formation with cyclohexanone takes place with a hydroxylamine salt (either sulfate or phosphate) at 85°C46 ... 

In the case of the DSM/HPO process, the buffer mixture containing the phosphate and oxime reacts with cyclohexanone in the presence of toluene, which extracts the oxime as it is formed. The oxime is recovered from its solution in toluene by distillation, and the buffer mixture is recycled to hydroxylamine production. 

Hydrogen cyanide adds to hydrazones in a similar reaction.248 Moreover, it adds analogously to oximes, for Hurd and Longfellow250 found that propionaldehyde or butyraldehyde react with hydroxylamine hydrochloride, sodium cyanide, and sodium dihydrogen phosphate in aqueous solution to afford... 

Hydroxylamines deprotonated by KOH substitute for chloride in (chloro-arene)Cr(C0)3 in high yields [24]. Reaction of a (fluoroarene)Cr(CO)3 complex with dialkyl phosphite 12 resulted in formation of a phosphate 13 [25]. The ar-ylation of oximes under phase transfer conditions leads to a simple process for benzofuran formation [26]. 

In the first instance, the inhibitor reacts with the serine hydroxyl moiety of the enzyme to produce the alkylphosphate ester [14]. The formation of this ester is reversible and the enzyme activity may be recovered by nucleophilic attack with compounds such as hydroxylamine [15] and oximes [16]. Alternatively, dealkylation of the enzyme-phosphate may then occur [17], a process known as ageing [18], and the covalent link between the enzyme and the phosphate is stabilised, so preventing any recovery of enzyme activity by oximes [19]. 

Cyclohexanone alone is the main starting point for the newer nylon-6 the hydrogenation of phenol can be directed to give this material, but KA oil (or cyclohexanol) must be dehydrogenated. The sulphate or, more recently, phosphate of the oxime, formed by reaction with hydroxylamine (as its salt), undergoes the Beckmann rearrangement in the presence of oleum. (Excess acid is neutralized with ammonia for sale into fertilizers.)... 

Originally they were prepared by reaction of oxime with anhydrous hydrogen cyanide (82,131,132), Subsequently the oxime was added to an aqueous solution of hydroxylamine hydrochloride, sodium cyanide and sodium hydrogen phosphate (131), Lastly hydroxylamine hydrochloride, aldehyde and sodium cyanide may be mixed in a one-pot synthesis (79). 

One of the methods used for the determination of pyridoxal in the presence of pyridoxal-5-phosphate already mentioned on p. 65 is the transformation of both substances into oximes. This occurs quantitatively in the presence of excess hydroxylamine. But even then the separation of waves is poor, and only with the application of a derivative circuit can an analysis be made of a mixture containing comparable concentrations of pyridoxaloxime and pyridoxaloxime-5-phosphate (Fig. 33). 

In the DSM HPO process, nitrate ions are reduced to hydroxylamine using a palladium/carbon catalyst in an aqueous phosphate buffer solution. It was possible to prepare cyclohexanone oxime by a process involving the extraction of cyclohexanone from solution in toluene, into an immiscible aqueous solution of hydroxylamine in a two phase liquid reactor. The spent solution was then recycled with added nitric acid to the reduction step and sulfate production was eliminated ... 

Antidotes. Because the acute toxicity to man of many of the phosphorus insecticides is high, first-aid remedies are kept on hand. The most useful of these is an injection of atropine (which acts primarily on muscarinic sites) followed by an oxime specific for nicotinic sites. These oximes reactivate phosphorylated acetylcholinesterase in patients (Holmes and Robins, 1955) just as with the isolated enzyme (Wilson and Meislich, 1953). This reaction involves a competition, between the hydroxyl-groups of serine and of the hydroxylamine, for the phsphoryl-group. The covalent bond with the serine is broken, and simultaneously a new covalent bond formed with the hydroxylamine (see Scheme 12.1). One of the best reactivators is pralidoxime 12.27) (2-PAM), which is the anti form of pyridine-2-aldoxime methochloride. Widely differing doses of antidote are required, depending on the strength of the phosphate-enzyme bond, which varies with the nature of the insecticide. 

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