Cupric nitrite

Cupric nitrite.—The nitrite is only known in solution, prepared by addition of lead nitrite to cupric-sulphate solution.5 Exposure of its dilute solution to air causes slow formation of nitrate. On evaporation of a concentrated solution over sulphuric acid, there is partial decomposition in accordance with the equation 6... 

The formation of (II) provides a quite selective spot test for palladium. Gold must be removed prior to the test because it will cause the development of a deep ruby red in the spot plate test and a diffused violet spot on the paper, apparently due to the reduction of the gold ions to the colloidal metal. Interference may also arise from 0s04 , Os+, Ru+, and RuCle ions because they have distinct self-colors. Mercurous ion causes partial interference by the reduction of part of the palladium to the elementary state, but a positive response can still be seen. It is possible to detect I part of palladium in the presence of 200 parts of platinum or 100 parts of rhodium. Less favorable ratios should be avoided because of the color of these salts. No interference is caused by mercuric and iridic chloride, but free ammonia, ammonium ions, stannous, cyanide, thiocyanate, fluoride, oxalate, and tetraborate ions do interfere. Lead, silver, ferrous, ferric, stannic, cobaltous, nickel, cupric, nitrite, sulfate, chloride, and bromide ions do not interfere. 

The immediate outcome of the Hantzsch synthesis is the dihydropyridine which requires a subsequent oxidation step to generate the pyridine core. Classically, this has been accomplished with nitric acid. Alternative reagents include oxygen, sodium nitrite, ferric nitrate/cupric nitrate, bromine/sodium acetate, chromium trioxide, sulfur, potassium permanganate, chloranil, DDQ, Pd/C and DBU. More recently, ceric ammonium nitrate (CAN) has been found to be an efficient reagent to carry out this transformation. When 100 was treated with 2 equivalents of CAN in aqueous acetone, the reaction to 101 was complete in 10 minutes at room temperature and in excellent yield. 

Nitric oxide (NO) and nitrite were found to be oxidized by Prussian blue and indium hexacyanoferrate-modified electrodes [75-77], For pharmaceutical application oxidation of isoprenaline [78] and vitamin B-6 [79] at cupric hexacyanoferrate-modified electrodes was shown. 

The primary function of the mammalian red blood cell is to maintain aerobic metabolism while the iron atom of the heme molecule is in the ferrous (Fe+2) oxidation state however, copper is necessary for this process to occur (USEPA 1980). Excess copper within the cell oxidizes the ferrous iron to the ferric (Fe+3) state. This molecule, known as methemoglobin, is unable to bind oxygen or carbon dioxide and is not dissociable (Langlois and Calabrese 1992). Simultaneous exposure of sheep to mixtures of cupric acetate, sodium chlorite, and sodium nitrite produced a dose-dependent increase in methemoglobin formation (Calabrese et al. 1992 Langlois and Calabrese 1992). 

The NO reduction of the Cu(II) complex Cu(dmp)2(H20)2+ (dmp = 2,9-dimethyl-l,10-phenanthroline) to give Cu(dmp)2 plus nitrite ion (Eq. (20)) has been studied in aqueous solution and various mixed solvents (42a). The reduction potential for Cu(dmp)2(H20)2+ (0.58 V vs. NHE in water) (48) is substantially more positive than those for most cupric complexes owing to steric repulsion between the 2,9-methyl substituents that provide a bias toward the tetrahedral coordination of Cu(I). The less crowded bis(l,10-phenanthroline) complex Cu(phen)2(H20)2+ is a weaker oxidant (0.18 V) (48). 

Sodium Nitrotetrazolate Dihydrate (NaNT) Anhydrous aminotetra-zole (8.48 g, 0.10 mol) and copper sulfate pentahydrate (0.2 g, 0.8 mmol) were added to a solution of nitric acid (9 mL, 65 %) in distilled water (60 mL). This was added to a pre-cooled solution of sodium nitrite (20.8 g, 0.30 mol) and cupric sulfate pentahydrate (11 g, 0.044 mol) in distilled water (100 mL). The solution was maintained at 15 to 18 °C during the addition by means of a cool water bath. After addition, the solution was stirred for 30 min at the same temperature... 

In a study of octopus hemocyanin (Salvato et al., 1989), a green half-methemocyanin could be formed in the presence of slight molar excess of sodium nitrite and ascorbate. This form was believed to consist of cuprous and cupric metals, but the amoung of NO directly bound was less than 0.1 mol. NOi was believed to be the oxidizing species its relationship to the endogenous ligand was not addressed. Apparently, hemocyanins are most likely to be found in deoxy, or reduced, forms, and it is difficult to oxidize them. 

Formation of chloroquinazolines by amine diazotization can also been performed, but in the case of 4-amino-2-chloro-5-iodo-6,7-dimethoxyquinazoline 122, chlorination with isobutyl nitrite and cupric chloride to give 123 was accompanied by hydrolysis to the analogous quinazolinone 124 <2005TL983>. 

Cupric sulfate, 5-Aminotetrazole, Sulfuric acid, Sodium nitrite... 

Preparation of sodium-5-nitrotetrazole dihydrate The diazotization of 5-ami-notetrazole monohydrate (AT) in the presence of excess of sodium nitrite and copper sulfate gives a complex cupric salt intermediate [Cu(NT)2 HNT-4H20] which is then converted to the sodium salt [NaNT-2H20]. 

Cupric halides in alcohols absorb nitric oxide giving unstable blue or violet species. Decomposition leads to alkyl nitrites, presumably via RO- attack (equation 22). 

Nitrobenzo[6]thiophene may be prepared by reaction of the 3,4-dinitro compound with alcoholic ammonium sulfide422-538 other workers have claimed that this method yields only traces of the desired product.84 It may also be prepared by deamination of 5-amino-4-nitrobenzo[6]thiophene,162,422 or by decomposition of 4-benzo[6]-thiophene diazonium cobaltinitrite with aqueous sodium nitrite in the presence of cuprous oxide and cupric sulfate.84 7-Nitrobenzo[6]-thiophene may be obtained by the latter method (15% yield) from the corresponding amine.84... 

A. Rosenheim and I. Koppel obtained a green compound, thought to be copper cobaltic nitrite, by the action of sodium cobaltic nitrite on a cupric salt. 

Hadjidemetriou [25] has carried out a comparative study of the determination of nitrates in calciferous soils by the phenoldisulfonic acid and the chromotropic acid spectrophotometric methods. He used 0.02 N cupric sulfate as soil extractant. Silver sulfate was added to remove chlorides. Nitrites, if present, were eliminated by acidifying the extract with N in sulfuric acid. The phenol disulfonic acid method is subject to interference by other ions. Details of the chromotropic acid method are given below. 

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