Nickel powder-acetic acid

The tributyltin hydride-mediated carbon-carbon bond formation via radical addition and cyclization of alkyl halides with alkenes has often been a choice for construction of various organic molecules [1], However, the requirement for high-temperature initiators or photo initiation and the difficulties associated with purification of the products from tributyltin halides tend to limit the widespread use of these methods, despite the efforts to make the methods easier [Ic, 2], Recently, nickel-mediated radical additions and cyclizations have been introduced as promising alternatives to the tributyltin hydride methods. These are the nickel powder-acetic acid method for cyclization of haloamides to y-lactams, y -lactams and in-dolones, the borohydride exchange resin-nickel boride method for radical addition, nickel-catalyzed electroreductive cyclization and nickel-catalyzed Kharasch addition of polyhalo compounds. 

A variety of y-lactams are prepared by 5-exo or 5-endo cyclization of a-haloamides depending on the substrate [4, 5]. Dimethylbromoacetanilide 4 reacted smoothly with nickel powder-acetic acid in 2-propanol to give the bromolactam 5 in 68% yield together with debrominated lactam 6 (23%). However, when 2-propanol was replaced by cyclohexane, a poorer hydrogen donor, bromide 5 was the sole product (85%). 

Nickel acetate tetrahydrate [6018-89-9] Ni(C2H202) 4H2O, is a green powder which has an acetic acid odor, density 1.74 g/cm. When heated, it loses its water of crystallization and then decomposes to form nickel oxide. Nickel acetate is used as a catalyst intermediate, as an intermediate in the formation of other nickel compounds, as a dye mordant, as a sealer for anodized aluminum, and in nickel electroplating (59). 

Sodium acetate [127-09-3] M 82.0, m 324°, d 1.53. Crystd from acetic acid and pumped under vacuum for lOh at 120°. Alternatively, crystd from aqueous EtOH, as the trihydrate. This material can be converted to the anhydrous salt by heating slowly in a porcelain, nickel or iron dish, so that the salt liquefies. Steam is evolved and the mass again solidifies. Heating is now increased so that the salt melts again. (NB if it is heated too strongly, the salt chars.) After several minutes, the salt is allowed to solidify and cooled to a convenient temperature before being powdered and bottled (water content should now less than 0.02%). 

The tetrahydrate is a green crystalline solid sweet taste odor of acetic acid density 1.744 g/cm loses water on heating to form a yellow-green powder of anhydrous nickel acetate decomposes above 250 C soluble in water, 17g/100mL at 20 C sparingly soluble in alcohol. 

Oxalate of lime is a white powder, formed whenever oxalic acid, or one of its soluble salts, is added to a calcareous solution. It is also found in a crystallized state in animal and vegetal tissues. It is insoluble in water, solution of chloride of ammonia, or acetic acid, hut dissolves readily in dilute nitric or hydrochlorio acid, and is decomposed on prolonged boiling with soluble salts of load, copper, silver, cadmium, zinc, nickel, cobalt, strontia, or baryta. 

Dilute sulphuric acid to which hydrogen peroxide has been added attacks nickel, but a mixture of peroxide with glacial acetic acid is without action.6 Potassium hydroxide, even when fused, has no action on nickel, but when fused with caustic soda the nickel is rapidly oxidised.7 When heated in the form of wire in oxygen it burns like iron, whilst nickel powder prepared by reduction with hydrogen below 270° C. is pyrophoric.8 At red heat nickel slowly decomposes steam. 

During reduction of the nitro derivatives 261 (with stannous chloride in hydrochloric acid, - with hydrogen over Raney nickel in ethanol, with iron powder in 50% acetic acid, - or with triethyl phosphite - at 170-1 SOX), the resulting amino derivatives 262 sometimes underwent spontaneous cyclization and gave the linearly annelated tricyclic compounds 263. Cyclization of the amino derivatives 262 was effected ther-mally or by the action of phosphoryl chloride. - ... 

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