Copper salts amine complexes

Copper salt-amine complexes can also be used for the reduction of aromatic compounds to the corresponding amine.A more general and convenient method for reducing nitroso compounds to amines involves the use of a nickel/aluminum alloy. The low cost and ready commercial availability of nickel/aluminum alloy are important features of this reduction procedure which may find wide acceptance as a preparative method. 

Trilialophenols can be converted to poly(dihaloph.enylene oxide)s by a reaction that resembles radical-initiated displacement polymerization. In one procedure, either a copper or silver complex of the phenol is heated to produce a branched product (50). In another procedure, a catalytic quantity of an oxidizing agent and the dry sodium salt in dimethyl sulfoxide produces linear poly(2,6-dichloro-l,4-polyphenylene oxide) (51). The polymer can also be prepared by direct oxidation with a copper—amine catalyst, although branching in the ortho positions is indicated by chlorine analyses (52). 

The major problem of these diazotizations is oxidation of the initial aminophenols by nitrous acid to the corresponding quinones. Easily oxidized amines, in particular aminonaphthols, are therefore commonly diazotized in a weakly acidic medium (pH 3, so-called neutral diazotization) or in the presence of zinc or copper salts. This process, which is due to Sandmeyer, is important in the manufacture of diazo components for metal complex dyes, in particular those derived from l-amino-2-naphthol-4-sulfonic acid. Kozlov and Volodarskii (1969) measured the rates of diazotization of l-amino-2-naphthol-4-sulfonic acid in the presence of one equivalent of 13 different sulfates, chlorides, and nitrates of di- and trivalent metal ions (Cu2+, Sn2+, Zn2+, Mg2+, Fe2 +, Fe3+, Al3+, etc.). The rates are first-order with respect to the added salts. The highest rate is that in the presence of Cu2+. The anions also have a catalytic effect (CuCl2 > Cu(N03)2 > CuS04). The mechanistic basis of this metal ion catalysis is not yet clear. 

Another situation is observed when salts or transition metal complexes are added to an alcohol (primary or secondary) or alkylamine subjected to oxidation in this case, a prolonged retardation of the initiated oxidation occurs, owing to repeated chain termination. This was discovered for the first time in the study of cyclohexanol oxidation in the presence of copper salt [49]. Copper and manganese ions also exert an inhibiting effect on the initiated oxidation of 1,2-cyclohexadiene [12], aliphatic amines [19], and 1,2-disubstituted ethenes [13]. This is accounted for, first, by the dual redox nature of the peroxyl radicals H02, >C(0H)02 and >C(NHR)02 , and, second, for the ability of ions and complexes of transition metals to accept and release an electron when they are in an higher- and lower-valence state. 

The major problem of these diazotizations is oxidation of the initial aminophenols by nitrous acid to the corresponding quinones. Easily oxidized amines, in particular aminonaphthols, are therefore commonly diazotized in a weakly acidic medium (pH 3) so-called neutral diazotization or in the presence of zinc or copper salts. This process, which is due to Sandmeyer, is important in the manufacture of diazo components for metal complex dyes, in particular those derived from l-amino-2-naphthol-4-sulfonic acid. 

Nitrotetrazole is readily prepared from the diazotization of 5-aminotetrazole in the presence of excess sodium nitrite and is best isolated as the copper salt complex with ethylenediamine. The salts of 5-nitrotetrazole have attracted interest for their initiating properties. The mercury salt is a detonating primary explosive. The amine salts of 5-nitrotetrazole are reported to form useful eutectics with ammonium nitrate. ... 

The [Cr(en)3]2+ and [Cr(pn)3]2+ salts have reflectance spectra (Table 11) resembling those of the hexaammines, and the six N donor atoms are assumed to complete tetragonally distorted octahedra around the metal. Stability constant measurements (Table 39) have shown that the ions [Cr(en)(aq)]2+ (vmax= 18 300 cm-1, e = 25 dm3 mol-1 cm-1) and [Cr(en)2(aq)]2+ (vma = 17 500 cm-1, e = 17 dm3 mol-1 cm-1) exist in aqueous solution, but that, as in the copper(II) system, the third ethylenediamine molecule is only weakly bound, and care is needed to prevent loss of en from tris(amine) complexes in the preparations. Several bis(amine) complexes, e.g. [CrBr2(en)2], have been isolated, and these are assigned trans structures because of IR spectral resemblances to the corresponding oopper(II) complexes. Since the spectrum of [Cr(S04)(en)2] also shows the presence of bidentate sulfate, this is assigned a trans octahedral structure with bridging anions. 

Polymerization also takes place when 4-halo-2.6-disubstituted phenols are oxidized with copper-amine catalysts and oxygen (5,35). In this case, stoichiometric amounts of copper salt or some other chloride acceptor (inorganic bases or strongly basic amines) are necessary since the amine complexes of copper (II) halides are not catalysts for the polymerization. Blanchard (5) has also described the polymerization of these 4-halo-phenols under conditions similar to those used by Price using certain copper (II) complexes as initiators. 

Phenols such as 2.6-dimethyIphenol are converted rapidly and in high yield to high molecular weight polymers at room temperature with oxygen in the presence of amine complexes of copper salts as catalyst. Much of the work described in the literature has been performed with copper (I) chloride as catalyst and pyridine as ligand and solvent. Other amines, primary, secondary or tertiary can be used as ligands for the catalyst. Autoxidation of copper (I) chloride in pyridine results in the... 

Copper (II) salts have been found to be inactive as catalysts for the reaction with the exception of the copper (II) carboxylates which are considerably less reactive. In addition, the polymerization of 2.6-xylenol in pyridine with copper (II) acetate as catalyst appears to terminate before high molecular weight polymers are formed. However, treatment of an amine complex of a copper (II) salt with an equivalent of a strong gives the active catalyst. Similarly, although copper (II) hydroxide in pyridine is inactive as a catalyst, treatment with an equivalent of hydrogen chloride generates the active catalyst. Hence it can be concluded that the active catalyst is a basic salt (XV). 

When 2,6-dimelhylphenol is oxidized with oxygen in the presence of an amine complex of a copper salt as catalyst a high-molecular weight polyether (PPO) is formed. 

In another related process, aryl ethers have been shown to undergo a facile cleavage reaction upon treatment with copper salts in the presence of an amine (Fig. 8-8). The driving force for the reaction is primarily the stabilisation of the phenoxide by co-ordination to the metal. Simple azo complexes have been shown to undergo these reactions under very mild conditions. The process is somewhat reminiscent of the Arbuzov reactions discussed in Chapter 4. The pyridine probably functions as both a ligand and as a base in this reaction. Reactions of this type are the basis of a useful conversion of a methoxy-substi-tuted dye, 8.6, to the corresponding phenol, 8.7, in the presence of copper(n) salts and ammonia. 

Copper Complexes. The preparation of copper and nickel complexes of tridentate metallizable azo and azomethine dyes is easily carried out in aqueous media with copper and nickel salts at pH 4-7 in the presence of buffering agents such as sodium acetate or amines. Sparingly water soluble precursors can be metallized in alkaline medium at up to pH 10 by using an alkali-soluble copper tetram(m)ine solution as coppering reagent, which is available by treating copper sulfate or chloride with an excess of ammonia or alkanolamines [3],... 

The structure of the parent material in this study—due to its uniqueness with respect to its inequivalent chloride ions both as coordinated and lattice chlorides—represents yet still another example of a solid state copper imidazole material. Others include copper(II) perchlorate salts complexed with amines [10] and copper(I) imidazole complexes based on a cavitand ligand design [11], Copper(I) imidazole complexes have been... 

Thio- and selenoacetals and esters are excellent substrates for mild Friedel-Crafts reactions, because of the affinity of sulfur and selenium for copper (Sch. 23). Anisole was readily acylated with methylselenoesters 94 at room temperature with activation by CuOTf to affordpnra-substituted (> 95 %) derivatives 95 [50,51]. Mercury(II) and copper(II) salts, which were effective for the activation of selenyl esters for reaction with alcohols, amines, and water, were not effective for the Friedel-Crafts reaction. Aromatic heterocycles 96 could be acylated in high yields, and the alkylation product 100 was obtained from dibutylthioacetal 99 and anisole. Vedejs has utilized this methodology in the cyclization of 101 to afford 102 in 77 % yield [52]. This intramolecular variant did not require the use of the more reactive bis copper triflate-benzene complex. 

Terminal alkenes containing hydrogen linked to the triple bond undergo oxidative coupling to diacetylenes by cupric salts [5cuprous salts [59, 66] (equation 139). Copper salts are solubilized by complexing with tertiary amines, most frequently pyridine [59, 357] and tetramethylethylenediamine [66]. The coupling can also be carried out with cuprous salts of acetylenes [5 S]. 

Diethanolamine will react with acids, acid anhydrides, acid chlorides, and esters to form amide derivatives, and with propylene carbonate or other cyclic carbonates to give the corresponding carbonates. As a secondary amine, diethanolamine reacts with aldehydes and ketones to yield aldimines and ketimines. Diethanolamine also reacts with copper to form complex salts. Discoloration and precipitation will take place in the presence of salts of heavy metals. 

Triethanolamine is a tertiary amine that contains hydroxy groups it is capable of undergoing reactions typical of tertiary amines and alcohols. Triethanolamine will react with mineral acids to form crystalline salts and esters. With the higher fatty acids, triethanolamine forms salts that are soluble in water and have characteristics of soaps. Triethanolamine will also react with copper to form complex salts. Discoloration and precipitation can take place in the presence of heavy metal salts. 

Better yields were often also obtained by use of the complex copper salt (17), prepared in situ from KCN and CUSO4 in the presence of NH3 (equation 20). In a thorough investigation Japanese workers recently treated a series of aromatic amines with sodium nitrite in a mixture of polyethylene glycol and CH2CI2 with HCl in a little water at 0 °C. After addition of the crystalline complex salt (17) the corresponding arenenitriles were obtained in high yield. 

The oxidative coupling of terminal alkynes by copper salts, discovered in 1869 by Glaser, has evolved to the modified method reported in 1962 by Hay. In the Hay procedure, oxygen is passed through a solution of the alkyne and a catalytic amount of a copper(I) salt in a complex-forming solvent, such as pyridine and TMEDA. Although the oxidative coupling by Cu salt catalysts in suitable amines has wide scope, it is less successful for less acidic terminal alkynes, such as alkyl- or silyl-alkynes. 

Since the yield in the oxidative coupling is practically quantitative, the oxidative polymerization of a,( )-diethynyl monomers would be expected to yield high molecular weight, linear polymers, as shown in equation (18). Hay has reported that almost any diethynyl monomer, even organometallic monomers, can be polymerized to high molecular weight polymers in Ae presence of a soluble amine complex catalyst of a copper(I) salt (Hay modification). ... 

In addition to reactions initiated with copper metal, reactions have been conducted with copper salts, such as copper oxides, alloys and coordination complexes. Reactions with many bases in several polar solvents have also been explored. Diphenylamine and o-bromonitrobenzene couple with stoichiometric amounts of copper(I) oxide and copper(I) bromide in DMA (equation 59)234. The synthesis of triaryl amines from aryl iodides and arylamines in one-pot proceeds in the presence of Cul and potassium tart-butoxide at 135 °C235. The highest yields were obtained with aryl iodides and electron-rich arylamines. 

Decomposition of aryl diazonium salts. Cuprous oxide (1, 169-170) has been the catalyst of choice for homolytic decomposition of aryl diazonium salts.2 It has the disadvantage of being effective only in an acidic medium. Lewin and Michl3 have examined the effectiveness of various copper(I) perchlorates complexed with heterocyclic amines. Of the various copper(I) salts, tetrakis(pyridine)copper(l) perchlorate is... 

---