Copper salts reactions with

In these reactions, diazonium salts are cleaved to aryl radicals, in most cases with the assistance of copper salts. Reactions 14-17 and 14-18 may also be regarded as belonging to this category with respect to the attacking compound. For nucleophilic substitutions of diazonium salts, see 13-17-13-20. 

Many of the early workers who studied the thermal decomposition reactions of diazocarbonyl compounds found that the addition of copper metal or copper salts allowed the reaction to be achieved at a lower temperature,<63AG(E)565, 64CB2628, 73JOU431> although no detailed study of this catalytic effect was undertaken. Alonso and Jano studied the copper-salt reaction of ethyl diazopyruvate 26 with acetonitrile and benzonitrile. The... 

The reaction of aminoguanidine with sodium nitrite under neutral conditions yields tetra-zolylguanyltetrazene hydrate (85), a primary explosive commonly known as tetrazene. Tetrazene (85) is only formed in the absence of free mineral acid and so a common method for its preparation treats the bicarbonate salt of aminoguanidine (84) with one equivalent of acetic acid followed by addition of aqueous sodium nitrite. " Tetrazene (85) is decomposed by aqueous alkali to form triazonitrosoaminoguanidine (86) which is isolated as the cuprate salt (87) on addition of copper acetate to the reaction mixture. Acidification of the copper salt (87) with mineral acid leads to the formation of 5-azidotetrazole (88) (CHN7 = 88 % N).55 56... 

The regioselectivity of Grignard addition to (V-alkoxycarbon y I pyridinium salts can often be controlled by changing the conditions. For example, C(4) addition can be enhanced by the presence of catalytic amounts of copper salts reaction of salt 288 (R = Me) with lithium dimethylcuprate gives also almost exclusively the 1,4-dihydro product 290 (R = Me, R Me). 

Another methodology applied to the monosubstitution of diols is the use of copper complexation of dianions. The dianion is first formed by reaction of a diol with two equivalents of NaH. The copper complex is then formed by addition of a copper salt. Reaction of the copper complex with various electrophiles (alkyl halides, acyl chlorides) then gives the selectively protected products. As with the phase-transfer technique, very little disubstitution is observed. However, as illustrated in Scheme 3.16, the regioselectivity is reversed (i.e., 4,6-diols give mainly 4-substitution and 2,3-diols give mainly 3-substitution). Using this technique, both alkylations (benzylation, allylation) and acylations (acetylation, benzoylation, pivaloylation) have been carried out. As usual, the degree of selectivity depends on reaction conditions and structural factors [44]. 

DMSO solvent, requires the presence of a weak acid such as acetic or trifluorobenzoic and involves a significant kinetic isotope effect indicating that C-H bond cleavage is, at least partially, rate determining. " The trifiuoromethylation of iodoheteroaromatics, such as 4-iodopyridine, by copper-catalysed reaction with trifluoromethyldiphenylsul-fonium salts is likely to involve the intermediacy of trifiuoromethylcopper. " Copper catalysis has also been used in the synthesis of Ai-arylpurines, (59), by reaction of purines with diaryliodonium salts. 

This reaction also proceeded well even in the presence of a substoichiomet-ric amount of copper salt, albeit with a slightly decreased regioselectivity. The... 

Both yields and enantioselectivities obtained with this methodology are comparable to the copper-catalysed reaction with (/ )-QumoxP L32 [108]. However, when the enone is provided with p-substituents that contain multiple bonds, the reaction is more efficient with L36 in the absence of a copper salt, probably because competitive reactions of the Cu-B(pm) complex with the alk5fne or alkene moieties are avoided this way. 

Aminofluorination is a valuable approach to the simultaneous incorporation of multiple functional groups. Using this approach, a variety of styrene derivatives were functionahzed (Scheme 3.35) [33], While a number of copper compounds promoted the reaction, the combination of a simple copper salt along with a bathocuproine ligand was the most effective. The reaction was highly regioselective and added to the fluorine to the a-position. 

The use of copper catalysts to promote the hydrophosphination of alkynylphosphines was reported (Scheme 4.302) [469]. The authors screened a range of catalysts for these reactions and found Cul to be effective for the addition reactions. The catalyst system was comprised of a low loading of this copper salt along with a mineral base. The reaction... 

Copper(II) ions in aqueous solution are readily obtained from any copper-containing material. The reactions with (a) alkali (p. 430), (b) concentrated ammonia (p 413) and (c) hydrogen sulphide (p. 413) provide satisfactory tests for aqueous copper(II) ions. A further test is to add a hexacyanoferrate(II) (usually as the potassium salt) when a chocolate-brown precipitate of copper(II) hexacyanoferrate(II) is obtained ... 

The conversion of an aromatic diazonium compound into the corresponding arsonic acid by treatment with sodium arsenite in the presence of a catalyst, such as copper or a copper salt, is called the Bart reaction. A modification of the reaction employs the more stable diazonium fluoborate in place of the diazonium chlorid.i. This is illustrated by the preparation of />-nitrophenylarsonic acid ... 

Tertiary acetylenic halides give unsatisfactory results owing to further isomerization of the allenic halide into a conjugated diene system under the influence of the copper salt. Bromo- and iodoallenes with the structures R R2C=C=CH-X can also be synthesized by an aqueous procedure, consisting of reaction between... 

Charge-Transfer Salts. Most charge-transfer salts can be prepared by direct mixing of donors and acceptors in solution. Semiconducting salts of TCNQ have been prepared with a variety of both organic and inorganic counterions. Simple salts of the type TCNQ can be obtained by direct reaction of a metal such as copper or silver with TCNQ in solution. Solutions of metal iodides can be used in place of the metals, and precipitation of the TCNQ salt occur direcdy (24). 

Reactions of the Hydroxyl Group. The hydroxyl proton of hydroxybenzaldehydes is acidic and reacts with alkahes to form salts. The lithium, sodium, potassium, and copper salts of sahcylaldehyde exist as chelates. The cobalt salt is the most simple oxygen-carrying synthetic chelate compound (33). The stabiUty constants of numerous sahcylaldehyde—metal ion coordination compounds have been measured (34). Both sahcylaldehyde and 4-hydroxybenzaldehyde are readily converted to the corresponding anisaldehyde by reaction with a methyl hahde, methyl sulfate (35—37), or methyl carbonate (38). The reaction shown produces -anisaldehyde [123-11-5] in 93.3% yield. Other ethers can also be made by the use of the appropriate reagent. 

Specific diarylamiaes aot easily obtaiaed by the above methods can be prepared by the Ullmann (29) and Chapman (30) reactions. For example, y -chloroaniliae reacts with (9-chloroben2oic acid ia the preseace of potassium carboaate and a catalytic amount of a copper salt to give 2-[(3-chlorophenyl)amiao]ben2oic acid [13278-36-9] which is then decarboxylated on heating to 3-chlorodiphenylamine [101 -17-7]. 

Ammonia forms a great variety of addition or coordination compounds (qv), also called ammoniates, ia analogy with hydrates. Thus CaCl2 bNH and CuSO TNH are comparable to CaCl2 6H20 and CuSO 4H20, respectively, and, when regarded as coordination compounds, are called ammines and written as complexes, eg, [Cu(NH2)4]S04. The solubiHty ia water of such compounds is often quite different from the solubiHty of the parent salts. For example, silver chloride, AgQ., is almost iasoluble ia water, whereas [Ag(NH2)2]Cl is readily soluble. Thus silver chloride dissolves ia aqueous ammonia. Similar reactions take place with other water iasoluble silver and copper salts. Many ammines can be obtained ia a crystalline form, particularly those of cobalt, chromium, and platinum. 

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