Copper with cyanide

The phenanthroline-containing ligands 66a and b (Chart 5.19) have been incorporated into Cu complexes and electropolymerized [74]. The geometry at the Cu" " center in poly-[Cu(66a)2] and poly-[Cu(66b)2] was probed using X-ray absorption. It was shown that the Cu centers in poly-[Cu(66b)2] contribute to the conductivity of the film. Removal of the copper with cyanide causes the structure of the polymer to irreversibly collapse in poly-[Cu(66a)2], whereas the presence of the hexyl chains in poly-[Cu(66b)2] help to maintain an intact polymer structure after the removal of the metal. 

In the first method a secondary acetylenic bromide is warmed in THF with an equivalent amount of copper(I) cyanide. We found that a small amount of anhydrous lithium bromide is necessary to effect solubilization of the copper cyanide. Primary acetylenic bromides, RCECCH Br, under these conditions afford mainly the acetylenic nitriles, RCsCCHjCsN (see Chapter VIII). The aqueous procedure for the allenic nitriles is more attractive, in our opinion, because only a catalytic amount of copper cyanide is required the reaction of the acetylenic bromide with the KClV.CuCN complex is faster than the reaction with KCN. Excellent yields of allenic nitriles can be obtained if the potassium cyanide is added at a moderate rate during the reaction. Excess of KCN has to be avoided, as it causes resinifi-cation of the allenic nitrile. In the case of propargyl bromide 1,1-substitution may also occur, but the propargyl cyanide immediately isomerizes under the influence of the potassium cyanide. 

In the flask were placed a solution of 7 g of anhydrous LiBr in 50 ml of dry THF, 0.40 mol of the allenic bromide (see Chapter VI, Exp. 31) and 0.50 mol of finely powdered copper(I) cyanide. The mixture was swirled by hand and the temperature rose in about 15 min to 60°C. It was kept between 55 and 60°C by occasional cooling in a water-bath. When the exothermic reaction had subsided, the flask was warmed for an additional 30 min at 55-60°C and the brown solution was then poured into a vigorously stirred solution of 30 g of NaCN and 100 g of NH,C1 in 300 ml of water, to which 150 ml of diethyl ether had been added. During this operation the temperature was kept below 20 c. The reaction flask was subsequently rinsed with the NaCN solution. After separation of the layers the aqueous layer was extracted with ether. The extracts were dried over magnesium sulfate and then concentrated... 

Zinc ores are generally floated at the mine (18). In the case of simple zinc sulfide ores, flotation is carried out by treatment with copper sulfate to activate the sphalerite causing it to be wet by the organic collector (eg, xanthate). The now-hydrophobic zinc ore particles attach themselves to the rising bubbles. Oxidized ore particles present must be sulftdized with sodium sulfide to be floated (19). Flotation produces concentrates which are ca 50—60% zinc. In mixed ore, the lead and copper are usually floated after depressing the sphalerite with cyanide or zinc sulfate. The sphalerite is then activated and floated. 

Bromomethyl-5-methylthiophene gives normal displacement products with amines but it is isomerized on attempted reaction with copper(I) cyanide (Scheme 59) 48MI30200. Whereas 2-hydroxymethylthiophene reacts normally with hydrogen halides to give 2-halomethylthiophenes, reaction of 2-hydroxymethylfuran (2-furfuryl alcohol) with hydrochloric acid results in formation of laevulinic acid (151). 2-Furfuryl alcohol derivatives are... 

Iodide ions reduce Cu to Cu , and attempts to prepare copper(ll) iodide therefore result in the formation of Cul. (In a quite analogous way attempts to prepare copper(ll) cyanide yield CuCN instead.) In fact it is the electronegative fluorine which fails to form a salt with copper(l), the other 3 halides being white insoluble compounds precipitated from aqueous solutions by the reduction of the Cu halide. By contrast, silver(l) provides (for the only time in this triad) 4 well-characterized halides. All except Agl have the rock-salt structure (p. 242). Increasing covalency from chloride to iodide is reflected in the deepening colour white yellow, as the... 

For the in situ preparation of the required arenediazonium salt from an aryl amine by application of the diazotization reaction, an acid HX is used, that corresponds to the halo substituent X to be introduced onto the aromatic ring. Otherwise—e.g. when using HCl/CuBr—a mixture of aryl chloride and aryl bromide will be obtained. The copper-(l) salt 2 (chloride or bromide) is usually prepared by dissolving the appropriate sodium halide in an aqueous solution of copper-(ll) sulfate and then adding sodium hydrogensulfite to reduce copper-(ll) to copper-(1). Copper-(l) cyanide CuCN can be obtained by treatment of copper-(l) chloride with sodium cyanide. 

The bromo substituent in 10-bromodibenz[/>,/]oxepin can be replaced by nucleophiles. With copper(I) cyanide in the presence of pyridine, dibenz[fr,/]oxepin-10-carbonitrile (3) is obtained.161 The substitution of bromine by various TV-substituted piperazines to give dibenz[/>,/]oxepins 4 has been accomplished using potassium cm-butoxide.197 This latter reaction probably proceeds via an intermediate with a C-C triple bond.160... 

Trithiadiazepine 4 is readily thalliated by thallium(III) trifluoroacetate the product 19 reacts in situ with potassium iodide, copper(I) cyanide, and methanol/carbon monoxide300 to give 20a-c, respectively.33 ... 

PcH2 was obtained for the first time in 1907 as a byproduct during the preparation of 2-cyanobenzamide.50 However, this discovery initiated no interest at that time. In 1927, PcCu was prepared in 23% yield by heating 1,2-dibromobenzene with copper(I) cyanide in pyridine.51 The term phthalocyanine was first used by Linstead in 1933.52 From 1929 to 1939, Linstead et al. elucidated the structure of phthalocyanines and developed improved synthetic methods for several metal phthalocyanines.52 - 61... 

A second reaction which is very often used for the preparation of phthalonitriles, although the yields are usually not reproducible, is the Rosenmund-von Braun reaction (see Houben-Weyl, Vol. E5, p 1460).106 107 Herein, a benzene derivative with a 1,2-dibromidc or 1,2-dich-loride unit is treated with copper(I) cyanide in dimethylformamidc or pyridine. During this reaction the formation of the respective copper phthalocyanine often occurs. This can be used as an easy procedure for the exclusive synthesis of copper phthalocyanines (see Section 2.1.1.7.),1 os-109 but can also lead to problems if the phthalonitrile is required as the product. For example, if l,2-dibromo-4-trifluoromethyl-benzene is subjected to a Rosenmund-von Braun reaction no 4-trifluoromethylphthalonitrile but only copper tetra(tri-fluoromethyljphthalocyanine is isolated.110... 

A solution of trimethylsilyl lithium (10 mmol) in HMPA (CAUTION— CANCER SUSPECT AGENT) (5 ml) and ether (10 ml, from the MeLi) prepared as above was cooled to 0°C and diluted with THF (20 ml). Copper(i) cyanide (5 mmol) was added in one portion, and the resulting black mixture was stirred at 0°C for 20min. 

To a stirred slurry of copper(i) cyanide (110 mmol) in THF (100 ml), cooled to 0 °C, was added a solution of dimethylphenylsilyl lithium (220 mmol, 1.3 m in THF), and the mixture was stirred at 0°C for a further 30min. After cooling to —78°C, a solution of methyl cinnamate (100mmol) in THF (50 ml) was added, and stirring was continued at —78°Cfor6h. At this time, iodomethane (300 mmol) (CAUTION—CANCER SUSPECT AGENT) was added, and the mixture allowed to warm to ambient temperature with... 

There has been a plethora of recent hterature regarding the synthetic manipulations of the 2(lH)-pyrazinone skeleton. Even though the addition-elimination reactions at the C-3 position to decorate the pyrazinone scaffold are well documented [24], the versatihty of such approaches can be found somewhat limited. Selective attack of nucleophiles on the chloroimine group of the pyrazinone system can generate 3-alkoxy- and 3-amino-pyrazinones (Scheme 9) [27,28]. The 3-CN group was introduced via a Rosemund-von Braun reaction with copper(I)cyanide under harsh conditions (heating in NMP at 150 °C) [27] (Scheme 9). 

The cyanide ion is an ambident nucleophile and isocyanides may be side products. If the preparation of isocyanides is desired, they can be made the main products by the use of silver or copper(I) cyanide (p. 459). Vinylic bromides can be converted to vinylic cyanides with CuCN, with KCN, a crown ether, and a... 

Arylthallium bis(trifluoroacetates) (see 12-21) can be converted to aryl nitriles by treatment with copper(I) cyanide in acetonitrile. Another procedure uses excess aqueous KCN followed by photolysis of the resulting complex ion ArTl(CN)3 in the presence of excess KCN. Alternatively, arylthallium acetates react with Cu(CN)2 or CuCN to give aryl nitriles. Yields from this procedure are variable, ranging from almost nothing to 90 or 100%. 

After preparation from interaction of 3-bromopropyne with copper(I) cyanide and filtration from copper salts, an explosion occurred dining distillation of the evaporated filtrate at 45-60°C/66 mbar. This was attributed to explosion of some dissolved copper acetylide(s). After refiltration the product was again distilled at 45-48°C/53 mbar without incident, and it appeared to be stable, unlike true haloalkynes. However it is undoubtedly an endothemic compound with its two triple bonds. 

When the published method [1] for preparing the 4-isomer is used to prepare 2-nitrobenzonitrile, a moderate explosion often occurs towards the end of the reaction period. (This may be owing to formation of nitrogen trichloride as a byproduct.) Using an alternative procedure, involving heating 2-chloronitrobenzene with copper(I) cyanide in pyridine for 7 h at 160°C, explosions occurred towards the end of the heating period in about 20% of the preparations [2],... 

Compound 145 on lithiation <1999SM(102)987> and subsequent reaction with carbon dioxide afforded compound 146. Sandmeyer reaction of 2-bromodi thieno[3,2-A2, 3 -with copper(l)cyanide in hot iV-methyl pyrrolidine (NMP) gave the corresponding nitrile 148 which was then converted to the tetrazole 149 with a mixture of sodium azide and ammonium chloride in NMP in low overall yield (Scheme 14) <2001JMC1625>. 

The alkenylboronic esters were synthesized according to a literature procedure [56], Hydrozirconation of alkenylboronic esters with zirconocene hydrochloride, Cp2Zr(H)Cl, prepared by Buchwald s procedure [57], took place smoothly in CH2C12, providing in each case the corresponding borazirconocene 1,1-alkane 18 [34], Addition of propargyl bromide and a catalytic amount of copper(I) cyanide was accompanied by the disappearance of the yellow color associated with these compounds and by carbon—carbon bond... 

Several studies of occupational exposures and one study with a human subject were located. In the occupational exposures (summarized in Table 5- 3), neurological symptoms consistent with cyanide intoxication were demonstrated, but the likelihood of concomitant exposure to other chemicals could not be ruled out. For example, cleaners and cutting oils, as well as sodium and copper cyanide, may be present in electroplating operations (ATSDR 1997). The experimental human study involved the exposure of a single subject and a dog to a high concentration for a short exposure period. 

The related zinc cuprates formed from diorganozinc reagents and copper(I) cyanide also undergo smooth SN2 substitution reactions with propargyl oxiranes in the presence of phosphines or phosphites (Scheme 2.12). These transformations can also be performed with catalytic amounts of the copper salt since no direct reaction between the organozinc reagent and the substrate interferes [31, 34], and therefore should also be applicable to functionalized organozinc compounds. 

The use of the zinc-copper couple to effect the reduction of the methanesulfonate 168 with rearrangement furnished 169 (Scheme 20.34) [10]. Treatment of 168 with methylmagnesium bromide in the presence of copper(I) cyanide to induce an SN2 -type reaction produced the methylated adduct 170. The half-life of the Myers-Saito cyclization of 169 is 66 h at 37 °C, whereas that of 170 is 100 min. The faster rate of cyclization for 170 has been attributed to a steric effect favoring the requisite s-cis or twisted s-cis conformation. 

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