Copper II nitrate

The rate of the uncatalysed reaction in all four solvents is rather slow. (The half-life at [2.5] = 1.00 mM is at least 28 hours). However, upon complexation of Cu ion to 2.4a-g the rate of the Diels-Alder reaction between these compounds and 2.5 increases dramatically. Figure 2.2 shows the apparent rate of the Diels-Alder reaction of 2.4a with 2.5 in water as a lunction of the concentration of copper(II)nitrate. At higher catalyst concentrations the rate of the reaction clearly levels off, most likely due to complete binding of the dienophile to the catalyst. Note that in the kinetic experiments... 

In the previous section efficient catalysis of the Diels-Alder reaction by copper(II)nitrate was encountered. Likewise, other bivalent metal ions that share the same row in the periodic system show catalytic activity. The effects of cobalt(II)nitrate, nickel(II)nitrate, copper(II)nitrate and zinc(ll)nitrate... 

On the basis of the studies described in the preceding chapters, we anticipated that chelation is a requirement for efficient Lewis-acid catalysis. This notion was confirmed by an investigation of the coordination behaviour of dienophiles 4.11 and 4.12 (Scheme 4.4). In contrast to 4.10, these compounds failed to reveal a significant shift in the UV absorption band maxima in the presence of concentrations up to one molar of copper(ir)nitrate in water. Also the rate of the reaction of these dienophiles with cyclopentadiene was not significantly increased upon addition of copper(II)nitrate or y tterbium(III)triflate. 

Reaction of dnnamaldehyde 4.35 with (2-pyridyl)hydrazine (4.36) yielded the desired hydrazone 4.37. As anticipated, this compound coordinates readily to copper(II)nitrate in aqueous solution as... 

Unfortunately, addition of copper(II)nitrate to a solution of 4.42 in water did not result in the formation of a significant amount of complex, judging from the unchanged UV-vis absorption spectrum. Also after addition of Yb(OTf)3 or Eu(N03)3 no indications for coordination were observed. Apparently, formation of a six-membered chelate ring containing an amine and a ketone functionality is not feasible for these metal ions. Note that 4.13 features a similar arrangement and in aqueous solutions, likewise, does not coordinate significantly to all the Lewis acids that have been... 

As anticipated from the complexation experiments, reaction of 4.42 with cyclopentadiene in the presence of copper(II)nitrate or ytterbium triflate was extremely slow and comparable to the rate of the reaction in the absence of Lewis-acid catalyst. Apparently, Lewis-acid catalysis of Diels-Alder reactions of p-amino ketone dienophiles is not practicable. 

After in situ neutralisation, the complexation behaviour of 4.44 was studied using UV-vis spectroscopy. The absorption maximum of this compound shifted from 294 nm in pure water to 310 nm in a 10 mM solution of copper(II)nitrate in water. Apparently, 4.44, in contrast to 4.42, does coordinate to copper(II)nitrate in water. 

Note that for 4.42, in which no intramolecular base catalysis is possible, the elimination side reaction is not observed. This result supports the mechanism suggested in Scheme 4.13. Moreover, at pH 2, where both amine groups of 4.44 are protonated, UV-vis measurements indicate that the elimination reaction is significantly retarded as compared to neutral conditions, where protonation is less extensive. Interestingy, addition of copper(II)nitrate also suppresses the elimination reaction to a significant extent. Unfortunately, elimination is still faster than the Diels-Alder reaction on the internal double bond of 4.44. 

Most importantly, analysis using UV-spectroscopy also demonstrated that, as anticipated, the elimination reaction of 4.51 is less efficient than that of 4.44. Ag in, addition of copper(II)nitrate significantly suppresses this reaction. 

Fortunately, in the presence of excess copper(II)nitrate, the elimination reaction is an order of magnitude slower than the desired Diels-Alder reaction with cyclopentadiene, so that upon addition of an excess of cyclopentadiene and copper(II)nitrate, 4.51 is converted smoothly into copper complex 4.53. Removal of the copper ions by treatment with an aqueous EDTA solution afforded in 71% yield crude Diels-Alder adduct 4.54. Catalysis of the Diels-Alder reaction by nickel(II)nitrate is also... 

Finally, in the last step, the chelating auxiliary had to be removed Ideally, one would like to convert 4.54 into ketone 4.55 via a retro Mannich reaction. Unfortunately, repeated attempts to accomplish this failed. These attempts included refluxing in aqueous ethanol under acidic and basic conditions and refluxing in a 1 1 acetone - water mixture in the presence of excess paraformaldehyde under acidic conditions, in order to trap any liberated diamine. Tliese procedures were repeated under neutral conditions in the presence of copper(II)nitrate, but without success. 

Copper Nitrates. The ttihydrate [10031 3-3] crystallizes as blue rhombic plates. Copper(II) nitrate hexahydrate [13478-38-17,... 

Copper(II) nitrate [1003143-3] Cu(N02)2 3H20 electronics, fuel oil treatment, colorant, pyrotechnics, catalyst... 

The bridged annulene 5,10-epoxy[10]annulene behaves as an aromatic 1 Ore-system rather than an oxepin and reacts with copper(II) nitrate in acetic anhydride to give a 1 1 mixture of 1-and 2-nitro-5,10-epoxy[10]annulene 2 and 3.154... 

Attempts to brominate cyclopent[/>]azepine (10) with bromine failed, as did nitration with copper(II) nitrate in acetic anhydride 2 however, with one equivalent of A -bromosuccinimide in acetic acid a separable mixture of the unstable 8-bromo 11 and 6-bromo 12 derivatives, along with the stable 6,8-dibromo derivative 13, is formed. An excess of brominating agent yields the dibromo compound as the sole product. 

The 1/7-1,2-benzodiazepines 6 react with lead(IV) acetate to give 3-acetoxy-3//-l, 2-benzo-diazepines 5 with mcthanolic copper(II) nitrate, the 3-methoxy-3//-l,2-benzodiazepines 7 arc formed.123... 

With ten 7i-electrons delocalized over seven atoms, trithiadiazepine is electron rich and should undergo electrophilic substitution, which indeed it does. Nitronium tetrafluoroborate at — 10 C or copper(II) nitrate gives the mononitro derivative 5, which can be converted into the dinitro compound 6 by the action of an excess of nitronium tetrafluoroborate at 10 C.388... 

M.7 Copper (II) nitrate reacts with sodium hydroxide to produce a precipitate of light blue copper(II) hydroxide. 

Seif-Test 12.1A Copper reacts with dilute nitric acid to form copper(II) nitrate and the gas nitric oxide, NO. Write the net ionic equation for the reaction. 

Substances Copper(II) nitrate tiihydrate Nitric acid (65%)... 

C03-0068. Write chemical formulas for these compounds (a) potassium chlorate (b) ammonium hydrogen carbonate (c) iron(II) phosphate (d) copper(II) nitrate hexahydrate (e) aluminum chloride (Q cadmium(II) chloride and (g) potassium oxide. 

Metal nitrates and acetic anhydride are particularly dangerous nitrating reagents if mixtures are made according to certain proportions. The danger also depends on the nature of the salt. Thus, with copper (II) nitrate or calcium nitrate, the mixture is always explosive whatever the proportions. 

Use of mixtures of metal nitrates with acetic anhydride as a nitrating agent may be hazardous, depending on the proportions of reactants and on the cation copper nitrate or sodium nitrate usually cause violent reactions [ 1], An improved procedure for the use of the anhydride-copper(II) nitration mixture [2] has been further modified [3] to improve safety aspects. 

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