Nickel chloride dihydrate

V,4.1.3.5 The entropy and heat capacity of nickel chloride dihydrate... 

The CASS Test. In the copper-accelerated acetic acid salt spray (CASS) test (42), the positioning of the test surface is restricted to 15 2°, and the salt fog corrosivity is increased by increasing temperature and acidity, pH about 3.2, along with the addition of cupric chloride dihydrate. The CASS test is used extensively by the U.S. automobile industry for decorative nickel—chromium deposits, but is not common for other deposits or industries. Exposure cycle requirements are usually 22 hours, rarely more than 44 hours. Another corrosion test, now decreasing in use, for decorative nickel—chromium finishes is the Corrodkote test (43). This test utilizes a specific corrosive paste combined with a warm humidity cabinet test. Test cycles are usually 20 hours. 

Answer (a) Nickel(II) chloride dihydrate (b) aluminum fluoride ... 

Procedures for the preparation of nickel(II) chloride dihydrate and nickel(II) bromide dihydrate follow. From these, the preparation via the orthoformate ester dehydration route of the anhydrous tetrakis(ethanol) and 1,2-dimethoxyethane complexes is described. The preparation of nickel(II) iodide-bis(l,2-dimethoxyethane) from nickel(II) iodide pentahydrate is also given. 

One-inch-thick layers of hydrated nickel chloride are arranged in open Pyrex ovenware dishes which are then stored for 17 hours at 80° in a circulating air oven, continuously purged with dry air. The resultant yellow hygroscopic nickel(II) chloride dihydrate is pulverized in a Waring Blendor and then transferred promptly to securely capped jars. The water content (Karl Fischer titration) varies from 1.88 to 2.2 hydrate. 

E. C. Lingafelter and D. L. Cullen, The Crystal Structure of Bis[2,2 -imino-bis(acetamidoxime)]nickel(II) Chloride Dihydrate, paper presented at the Tenth International Conference on Coordination Chemistry, Nikko, Japan, 1967. 

The system containing nickel(II) chloride dihydrate reduces alkyl chlorides and sulfonates (mesylates, triflates) to hydrocarbons. 

Thermodynamic data have been reported for the nickel chloride hexahydrate, tetrahy-drate and dihydrate, and the existence of a heptahydrate has been reported at low temperatures (below - 30°C) [33BOY]. At 0.1 MPa, in contact with saturated aqueous solutions, the hexahydrate was reported [lODERAnG] to be the stable form to approximately 36.25°C, and dehydration of the tetrahydrate to the dihydrate occurs above 60°C [33BOY], The lower hydrates can also be prepared by equilibration with aqueous HCl solutions at room temperature [23FOO]. 

Derby and Yngve [16DER/YNG] and Uvaliev et al. [93UVA/TIM] both reported water vapour pressure measurements for the dehydration of nickel chloride tetrahydrate to the dihydrate. 

The compositions of solid nickel chloride hydrates were determined at different water vapour pressures. The water vapour pressures were set using an isopiestic arrangement with aqueous H2SO4 solutions. At 25 and 35°C, the transition from the dihydrate to the tetrahydrate was found to occur at 0.998 kPa and 1.70 kPa, respectively. At 25 and 35°C, the transition from the tetrahydrate to the hexahydrate was found to occur at 1.19 kPa and 2.61 kPa, respectively. The imcertainty in the reported transition water vapour pressures is estimated in the present review as 0.05 kPa. 

CBH26Cl2NioNi06, Bis(2,2 -iminobis(acetamidoxime))nickel(II) chloride dihydrate, 35B, 687... 

C20H2 Br2N2Ni, Dibromo(cis-endo-N,N -di(4-methylbenzylidene)-meso-2,3-butanediamine)nickel(II), 37B, 551 C2oH2 ClN404Re, Dioxotetrakis(pyridine)rhenium(V) chloride dihydrate, 44B, 796... 

The reduction of different aliphatic or aromatic aldehydes or ketones 15 was easily achieved using the combination of dihydrated nickel(II) chloride, lithium and a catalytic amount of naphthalene (16%) or DTBB (8%) in THF, yielding the corresponding alcohols without (534) or with (535) deuterium labelling in 57-86% yield. For imines 536, the same process afforded the corresponding amines 537 or deuterio amines 538 in 54- >95% yield . 

Thermogravimetric analysis of nickel(II) chloride hexa-hydrate shows that water evolution occurs from ambient temperatures (25°) to 66.6°. The resulting dihydrate is stable up to 133.3°, beyond which temperature further water loss occurs. Differential thermal analysis shows an endotherm at 53.9° related to the first dehydration step, and a second, strong endotherm at 118.9°, not accompanied by any weight loss, indicates the transformation of an octahedrally coordinated to a close-packed cubic structure. 

Perhaps the most clearly defined example involves the macrocyclic complex of Curtis, Ni(CT)X2. The solid, violet, paramagnetic, anhydrous chloride and bromide must be carefully protected from moisture for they readily revert to yellow, diamagnetic dihydrates. The fact that two molecules of water are taken up to produce a diamagnetic nickel(II) ion is especially interesting for displacement of the halide, and coordination by the water molecules would surely produce a violet, paramagnetic species... 

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