Dehydration copper sulfate

Colvin and Hume [56] showed that, on dehydration, copper sulfate pentahydrate yielded amorphous trihydrate which, in vacuum, reacted further to form the monohydrate, but in water vapour the crystalline trihydrate could be formed (see also Guenot et al. [57]). Cooper et al. [58] attributed an observed decrease in rate during dehydration of the trihydrate to impedance of the escape of water by the residual solid. 

Copper(II) sulfate monohydrate [10257-54-2] CuS04-H2 0, which is almost white in color, is hygroscopic and packaging must contain moisture barriers. This product is produced by dehydration of the pentahydrate at 120—150°C. Trituration of stoichiometric quantities of copper(II) oxide and sulfuric acid can be used to prepare a material of limited purity. The advantages of the monohydrate as opposed to the pentahydrate are lowered freight cost and quickness of solubilization. However, these advantages are offset by the dustiness of the product and probably less than one percent of copper sulfate is used in the monohydrate form. 

The reaction is cataly2ed by all but the weakest acids. In the dehydration of ethanol over heterogeneous catalysts, such as alumina (342—346), ether is the main product below 260°C at higher temperatures both ether and ethylene are produced. Other catalysts used include siUca—alumina (347,348), copper sulfate, tin chloride, manganous chloride, aluminum chloride, chrome alum, and chromium sulfate (349,350). 

Butyl Ether. -Butyl ether is prepared by dehydration of -butyl alcohol by sulfuric acid or by catalytic dehydration over ferric chloride, copper sulfate, siUca, or alumina at high temperatures. It is an important solvent for Grignard reagents and other reactions that require an anhydrous, inert medium. -Butyl ether is also an excellent extracting agent for use with aqueous systems owing to its very low water-solubiUty. 

DEHYDRATION Copper(II) sulfate. Triphenylphosphine-Diethyl diazodi-carboxylate. 

The dehydration of ds-chroman-3,4-diols with copper sulfate or p-toluenesulfonic acid gives the chroman-3-one (68BSF4203), whilst pyrolysis of the chlorohydrin (615) yields the naphthopyran-3-one (Scheme 235) (67JCS(C)1472). 

Methylpropene can be removed from the reaction mixture by distillation and easily is made the principal product by appropriate adjustment of the reaction conditions. If the 2-methylpropene is not removed as it is formed, polymer and oxidation products become important. Sulfuric acid often is an unduly strenuous reagent for dehydration of tertiary alcohols. Potassium hydrogen sulfate, copper sulfate, iodine, phosphoric acid, or phosphorus pentoxide may give better results by causing less polymerization and less oxidative degradation which, with sulfuric acid, results in the formation of sulfur dioxide. 

The dehydration of alcohols under mild conditions is affected by copper(II) Lewis acids. Copper sulfate has long been utilized as a dehydrating agent. An example of its effectiveness for alcohol dehydration is demonstrated in the conversion of the sensitive propargylic alcohol 1 to enyne 2 (Sch. 1) [4]. A carbocation mechanism is suggested by the formation of bis ethers in these reactions [5]. The addition of pyridine... 

Widjaja E, Chong HH, Tjahjono M (2010) Use of thermo-Raman spectroscopy and chemometric analysis to identify dehydration steps of hydrated inorganic samples -application to copper sulfate pentahydrate. J Raman Spectrosc 41 181-186... 

Calcium chloride, CaCl CaCl. H O CaCl. -6H2O, used as cheap drying agent Calcium oxide, CaO, used in water treatment Copper sulfate, CuSO, used as a dehydrating agent... 

The DSC, TG curves of solvates and hydrates are related to the phase diagrams between substance and solvent (or water). Eutectic are observed. Fusion or decomposition of the solvate may occur during heating. Therefore, one may observe the melting of the solvate followed by recrystallization into the anhydrous form or the endothermic desolvatation in the solid state. In certain cases both phenomena may over-lapp. Details about experimental factors and examples can be found in Ref. If the anhydrous form is metastable, further phase transitions follow the desolvatation. If several solvates or hydrates exist, the transitions observed depend on the pressure, as demonstrated by Soustelle in the case of copper sulfate pentahydrate. Depending on the pressure, the direct dehydration into the anhydrous or the dehydration via the monohydrate, or the three dehydration steps trihydrate, monohydrate and anhydrous forms may be obtained. Hydrates have been the subject of... 

In contrast to the group II hydroxides, compounds containing so-called water of crystallization can be readily dehydrated. Eq. (3) represents the reactions reported for copper sulfate penta-hydrate heated at atmospheric pressure (7). 

The first step in any kinetic study is to identify all the products and intermediates of the reaction. Dehydration often involves several distinct steps which may be very dependent upon reaction conditions, e,g, copper sulfate pentahydrate may yield trihydrate and/or monohydrate [29,30], Metastable intermediates may be formed, e,g, amorphous magnesium carbonate produced on dehydration undergoes [18] exothermic recrystallization at higher temperatures,... 

Modification of the ketal substituents involved deketalization of RE 39571 with aqueous trifluoroacetic acid followed by reaction with the appropriately substituted ketone or aldehyde and anhydrous copper sulfate as the dehydrating agent (Scheme 3). If the glycoside-ether is the desired product, this can readily be obtained by glycosidation with methanol in the presence of hydrogen chloride followed by alkylation of the 2-hydroxyl group with the appropriate halide. 

The dehydration of inorganic salt hydrates is usually stepwise but not always predictable. For copper sulfate pentahydrate, three DSC peaks are apparent corresponding to the loss of 2, 2, and 1 waters of hydration. Further, there is an increase in dehydration enthalpy of this salt with increasing numbers of hydration waters removed. This type of study is of importance in the estimation of the purity of the sample since the dehydration enthalpy is directly proportional to the water content of the sample. Similarly, DSC can be used to determine the moisture content of materials generally, since the measured endothermic dehydration DSC peaks are directly proportional to the water content of the material. 

The scope of temperature- and time-resolved SCTGA has been revealed by Parkes, Barnes and Charsley, via studies of the decomposition of inorganic salts. Temperature-resolved SCTA is particularly useful for resolving the dehydration characteristics of copper sulfate pentahydrate. A typical linear heating (LH) TGA profile for this salt is shown in Fig. 10, and is compared with a proportional heating (PH) SCTGA profile over the same temperature range. 

Fig. 10.3 Schematic energy diagram of dehydration of blue copper sulfate [11]...

Dehydration. Chromanol-4 (1) is converted into A3-chromene (3) in 76% yield when heated with anhydrous copper sulfate at 160° at 20 mm. It is suggested that the unshared pair of electrons of the oxygen are bonded to the incomplete 3d orbital of copper (2). Attempted dehydration with p-toluenesulfonic acid gave resinous products.2... 

To avoid the difficulties of preparation, several dry preparations have been put on the market, from which a spray can be simply prepared with water. A stable product of high activity that is less phytotoxic and is resistant to weather is formed by dehydrating the 10% aqueous suspension of copper sulfate and calcium hydroxide with a stream of hot air at 80-175°C (Hess et al., 1968). 

The average partial vapor pressure of water in the atmosphere is about 10 mm. It will be less on a dry winter s day and more on a humid summer s day. From the curve DR, the dissociation pressure of CuS04-H20 is 10 mm at 105°. We must therefore dry the salt at 105°, and preferably higher, to be on the safe side. The higher the temperature, the faster the dehydration but if we heat above 550°, the copper sulfate will lose 80 and pass into the basic salt, CuO-CuS04,... 

At 25°, the partial pressure of water vapor in the system CaCl2 6H20 + CaCU + water vapor is 0.36 mm. From curve D, the dissociation pressure of CuS04 H20 is 0.04 mm at 25°. We do not, therefore, get anhydrous copper sulfate by drying over calcium chloride at 25°. On the contrary, we could use anhydrous copper sulfate to dehydrate CaCl2 6H20. 

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