Copper chloride with hydrazines

A number of pyridazines have been prepared by standard condensations of enediones with hydrazine but a general synthesis of the intermediate enediones is notable. This involved iodine-copper exchange of an iodoenone 3, followed by reaction of the resulting cuprate with acid chlorides. However, only a few of these enediones were actually converted into pyridazines <06OL1941>. 

For example, treatment of esters 819-21 with hydrazine in refluxing ethanol gave the N-unsubstituted bicycles 9 (R1 = H). 1-Methyl derivatives (9 R1 = Me) were also prepared.22 The hydrazine 11, obtained from the acid 10a, was heated at reflux without puriiication in dilute acid to give 12 (R = H). The acid chloride 10b furnished hydrazide intermediates 10c,17,23,24 which were cyclized by fusing the solid,23 refluxing with pyridine in the presence of copper powder,24 or by heating with potassium carbonate in 1-pentanol.17... 

Anion-exchange resin useful for the extraction of copper from esters has been obtained by the amination of methylmethacrylate — DVB copolymer with hydrazine or guanidine Acryloyl chloride undergoes spontaneous polymerization with polyethylenepolyamine at room temperature to give an anion-exchange resin with high capacity and selectivity for bivalent metal ions... 

The reaction of diketone 75 with hydrazine afforded the monohydrazone 76, which was further oxidized with copper(I) chloride, O2 and p5n idine or activated manganese dioxide to give the a-diazo ketone 77. Thermal decomposition of 77 in methanol gave 2-azuloin methyl ether 79,... 

The compatibility with a keto functionality can also be realized by using a magnesium cuprate such as 33. In this case, the resulting copper species 34 com-plexed with MgXj undergoes a facile trapping with an acyl chloride, leading to the diketone 35 in 85% yield. Reaction with hydrazine provides the heterocyde 36 in 91% yield (Scheme 9.10) [22]. 

Azoalkanes have been prepared by oxidation of N,H -(lialkylhydrazines with copper(II) chloride or with yellow mercury (II) oxide.The dialkyl hydrazines are obtained by Jilivylation of N,N -diformylhydrazine and subsequent hydrolysis, by reduction of the corresponding azine with lithium aluminum hydride, or by catalytic hydrogenation of the azine over a platinum catalyst. 

The essential difference between the hydroxylamine reaction and the hydrazine reaction appears to be that silver nuclei are formed in the solution much more readily by hydrazine than by hydroxylamine. At sufficiently low pH and in the absence of copper, hydroxylamine does not readily form nuclei in the solution, and the catalytic reduction of the silver chloride occurs essentially at a solid interface with the silver nuclei. Hydrazine, on the other hand, readily forms nuclei in the solution and an important fraction of the total reaction involves the catalytic reduction of dissolved silver chloride. This would account for the well-known photographic properties of the two agents. Hydroxylamine is a cleanworking developer which, under proper conditions, yields little fog. Hydrazine shows much less selectivity and, although it develops an image, it also yields a relatively high fog density. 

The action of an active intermediate oxidation product would explain another feature of the reaction. The reduction of silver ions by hydrazine is extremely sensitive to the presence of small amounts of copper. For example, a solution containing a mixture of silver nitrate, sodium sulfite and hydrazine which normally showed no sign of reduced silver for several minutes underwent almost immediate reaction when merely stirred with a clean copper rod. In the presence of gum arabic as stabilizer, streamers of colloidal silver passed out from the copper surface. Similarly, the addition of small amounts of cupric sulfate to a hydrazine solution eliminated the induction period of the reaction with silver chloride. 

B., 18, 90, 786.) When a primary aryl hydrazine is boiled with neutral copper sulphate or ferric chloride, or treated with alkaline copper sulphate in file cold, the hydrazine radical is replaced by hydrogen, the corresponding aryl hydrocarbon being formed. 

The reaction of phenylhydrazine with copper(II) chloride in aqueous solution gives [Cu4Cl4(PhNNH)] (13) and the reactions of 1,2-disubsti-tuted hydrazines with copper(II) salts give complexes such as [Cu2-Cl2(MeNNMe)l (46, 142). The reaction of substituted hydrazines (or lithiated, substituted hydrazines) with halido complexes of the transition metals can yield diazene complexes. Complexes of Ni, Pd, Pt (147, 199,213), and Rh (209) have been prepared in this manner [Eq. (25)]. 

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