Nitrite potassium

CONTACT WITH COMBUSTIBLE MATERIAL MAY CAUSE FIRE, HARMFUL IF TAKEN INTERNALLY 

White or slightly yellow, deliquescent, crystalline solid mp, 44 LC (decomposition starts 

Avoid contact with clothing and other absorbent fabrics.2 

Soluble in water slightly soluble in alcohol. Decomposed even by weak acids with evolution of brown fumes of nitrogen dioxide.1 

Toxic if swallowed.2 LD50 (oral, rabbit) 108 mg anion/kg.1 

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Addition of excess potassium nitrite acidified with ethanoic acid gives a precipitate of the potassium hexanitro-cobaltate(lll), K3[Co(N02)6] (P. 403). 

Silver nitrite. Warm concentrated solutions of silver nitrate (containing 48 g. of AgNOj) and potassium nitrite (containing 30 g. of KNOj) are mixed, and the mixture is allowed to cool. The silver nitrite which separates is filtered off and washed with water. It may be recrystallised from water at 70°, and is dried either in a vacuum desiccator or in an air oven at about 40° the yield is about 90 per cent. Silver nitrite should be stored in an tightly-stoppered amber bottle. 

A characteristic feature of aromatic fluorodenitration is modest yield due to side reactions promoted by potassium nitrite and/or its decomposition product, potassium oxide, with the aryl fluoride or starting material... 

The use of phthaloyl dichlonde as a scavenger for potassium nitrite and/or potassium oxide [108, 109, III] significantly increases yields of aryl fluorides, m fluoronitrobenzene is obtained in 70% yield with sulfolane as a solvent at 200 °C after 72 h Addition of tetraphenylphosphonium bromide as a phase-transfer catalyst to the phthaloyl dichlonde scavenger system further increases the yield of m-fluoronitrobenzene to 89% under less forcing conditions 150-180 C, 5 h) [if 2] This optimized technique can be applied to give m-fluorobenzonitnle from in-m-trobenzonitnle in 86% yield [/i2]... 

Potassium nitrite by-product can react with nitroaromatic substrate to suppress yields of aryl fluorides Modest yields (40-60%) of fluorophthafic anhydride are obtained from 3- or 4-nitiophthalic anhydride and potassium fluonde due to formation of by-product dipotassium salt of 3- or 4-nitrophtlialic acid [1/3,114, 115] (equation 33) Higher yields (93%) of 3-fluorophfhalic anhydride can be realized by regenera tion of 3-nitrophthalic anhydride from the dipotassium salt with thionyl chloride, followed by addition of fresh potassium fluoride [7/5] (equation 33)... 

The red [SSNO] anion (9.2) (2max 448 nm) is produced by the reaction of an ionic nitrite with elemental sulfur or a polysulfide in acetone, DME or DMSO. ° The formation of 9.2 probably proceeds via an intermediate such as the [S2NO2] anion. This process is thought to occur in the gunpowder reaction, which also entails the reaction of potassium nitrite (produced by reduction of potassium nitrate with charcoal) and sulfur. 

A convenient laboratory route involves the reduction of an aqueous solution of nitrous acid or potassium nitrite with bisulfite under carefully... 

Quite recently, it was reported that heating of tetracyano derivative 268 with potassium nitrite and potassium carbonate in DMF provided 53% of phenoxathiin 270 (Scheme 42) (OOlHl 161). The probable mechanism is, that one activated nitro group in 268 is displaced with a nitrosoxy group by nucleophilic substitution of nitrite ion, followed by hydrolysis to 269, which then undergoes denitrocyclization reaction to the final product. 

Replacement of silver nitrite by inexpensive sodiiunor potassium nitrite enhances the imlity of this process Treatment of alkenes v/ith sodiiun nitrite and iodine in ethyl acetate and water in the presence of ethylene glycol gives conjngatednitroalkenesin49-82% yield The method for generation of nitryl iodide is improved by the treatment of iodme v/ith potassium nitrite complexed v/ith 18-crovm-6 in THF under sonicadon, as shovmin Eq 2 32 ... 

Potassium nitrite - Fused Poor (violent reaction)... 

Measurements were performed on a potassium nitrite melt (KNO3) at 450°C. Fig. 73, curve 1 presents the spectrum obtained for a melt layer 0.05-0.1 mm thick, which was placed on a reflective surface (polished platinum). Fig. 73, curve 2 presents the inverted spectrum (relative to curve 1) of a relatively thin layer placed on an absorptive bottom surface (carbon-glass). 

If a solution of a nitrite is titrated in the ordinary way with potassium permanganate, poor results are obtained, because the nitrite solution has first to be acidified with dilute sulphuric acid. Nitrous acid is liberated, which being volatile and unstable, is partially lost. If, however, a measured volume of standard potassium permanganate solution, acidified with dilute sulphuric acid, is treated with the nitrite solution, added from a burette, until the permanganate is just decolorised, results accurate to 0.5-1 per cent may be obtained. This is due to the fact that nitrous acid does not react instantaneously with the permanganate. This method may be used to determine the purity of commercial potassium nitrite. 

For practice, determine the percentage of N02 in potassium nitrite, or the purity of sodium nitrite, preferably of analytical-grade quality. 

A direct preparation of 1-nitroisoquinolines from the corresponding isoquinolines was accomplished with potassium nitrite and acetic anhydride in DMSO <96JCS(P1)1777>. This method has preparative merit since 1-nitroisoquinolines are not readily accessible by other methods. 

C17-0022. Potassium nitrite is used as a food preservative. Determine the pH and concentrations of all species in an aqueous solution of KNO2 whose concentration is 0.22 M (see values in Table DM)-... 

In the presence of molten sodium nitrite, sodamide forms an explosive substance. It is also the case for potassium nitrite it detonates violently when heated with sodamide. 

When it is mixed with potassium nitrite in the melted state (440°C), ammonium nitrate detonates. The presence of rust decreases the temperature of the explosion to 80-120°C. This behaviour is linked to the chemical incompatibility of the nitrite ion and ammonium ion. 

Potassium pemnanganate Potassium nitrite Potassium nitrate Potassium sulphite Potassium stannate IV Potassium sulphate Poptassium metabisulphite Potassium peroxodisulphate Potassium tellurate (IV) Potassium pyrophosphate... 

Lead(II) oxide Non-metals Lead(IV) oxide Non-metals Nitric acid Non-metals Nitrogen oxide Non-metals Nitrosyl fluoride Metals, etc. Nitryl fluoride Non-metals Oxygen difluoride Non-metals Potassium nitrite Boron Potassium nitrate Non-metals Silver difluoride Boron, etc. Sodium peroxide Non-metals... 

Analytical decomposition of powdered diamond by fusion with potassium hydroxide may become explosive. This can be avoided by fusion with a potassium carbonate-sodium carbonate mixture, followed by addition of small portions of potassium nitrite or nitrate. 

It is unstable at ambient temperature, and is formed on contact of the nitrate with sodium or potassium nitrites. 

Oxidation of 4-methylcyclohexanone by addition of nitric acid at about 75°C caused a detonation to occur. These conditions had been used previously to oxidise the corresponding alcohol, but although the ketone is apparently an intermediate in oxidation of the alcohol, the former requires a much higher temperature to start and maintain the reaction. An OTS report, PB73591, mentions a similar violent reaction with cyclohexanone [1], Presence of nitrous acid is essential for the smooth oxidation of cycloalkanones with nitric acid to a, rw-hcxanedioic acids. Because high-purity nitric acid (free of nitrous acid) is now commonly available, addition of a little sodium or potassium nitrite to the acid is necessary before its use to oxidise cycloalkanones [2],... 

Fusion of urea (2 mol) with sodium nitrite (or potassium nitrite, 1 mol of either) to give high yields of the cyanate must be carried out exactly as described to avoid the risk of explosion. 

The reaction of alkyl halides with metal nitrites is one of the most important methods for the preparation of nitroalkanes. As a metal nitrite, silver nitrite (Victor-Meyer reaction), potassium nitrite, or sodium nitrite (Kornblum reaction) have been frequently used. The products are usually a mixture of nitroalkanes and alkyl nitrites, which are readily separated by distillation (Eq. 2.47). The synthesis of nitro compounds by this process is well documented in the reviews, and some typical cases are listed in Table 2.3.92a Primary and secondary alkyl iodides and bromides as well as sulfonate esters give the corresponding nitro compounds in 50-70% yields on treatment with NaN02 in DMF or DMSO. Some of them are described precisely in vol 4 of Organic Synthesis. For example, 1,4-dinitrobutane is prepared in 41 -46% yield by the reaction of 1,4-diiodobutane with silver nitrite in diethyl ether.92b 1-Nitrooctane is prepared by the reaction with silver nitrite in 75-80% yield. The reaction of silver nitrite with secondary halides gives yields of nitroalkanes of about 15%, whereas with tertiary halides the yields are 0-5%.92c Ethyl a-nitrobutyrate is prepared by the reaction of ethyl a-bromobutyrate in 68-75% yield with sodium nitrite in DMF.92d Sodium nitrite is considerably more soluble in DMSO than in DMF as a consequence, with DMSO, much more concentrated solutions can be employed and this makes shorter reaction times possible.926... 

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