Copper oxide pentahydrate

The use of sofid supports in conjunction with permanganate reactions leads to modification of the reactivity and selectivity of the oxidant. The use of an inert support, such as bentonite (see Clays), copper sulfate pentahydrate, molecular sieves (qv) (151), or sifica, results in an oxidant that does not react with alkenes, but can be used, for example, to convert alcohols to ketones (152). A sofid supported permanganate reagent, composed of copper sulfate pentahydrate and potassium permanganate (153), has been shown to readily convert secondary alcohols into ketones under mild conditions, and in contrast to traditional permanganate reactivity, the reagent does not react with double bonds (154). 

Zinc. Next to sodium, zinc is the most used reductant. It is available in powder, dust, and granular (mossy) forms. Zinc gets coated by a l er of zinc oxide which must be removed to activate it before it can reduce effectively. It can easily be activated by shaking 3 to 4 min. in a 1% to 2% hydrochloric acid solution. This means for every 98 ml of water volume, add 2 ml of coned hydrochloric acid. Then wash this solution with water, ethatiol, acetone, and ether. Ot activation can be accomplished by washing zinc in a solution of anhydrous zinc chloride (a very small amount) in ether, alcohol, or tetrahydrofuran. Another way is to stir 180 g of zinc in a solution of 1 g copper sulfate pentahydrate. Personally, I like the HCl acid method. 

Zinc dust is frequently covered with a thin layer of zinc oxide which deactivates its surface and causes induction periods in reactions with compounds. This disadvantage can be removed by a proper activation of zinc dust immediately prior to use. Such an activation can be achieved by a 3-4-minute contact with very dilute (0.5-2%) hydrochloric acid followed by washing with water, ethanol, acetone and ether [/55]. Similar activation is carried out in situ by a small amount of anhydrous zinc chloride [156 or zinc bromide [157 in alcohol, ether or tetrahydrofuran. Another way of activating zinc dust is by its conversion to a zinc-copper couple by stirring it (180g) with a solution of 1 g of copper sulfate pentahydrate in 35 ml of water [/55]. 

Preparation of Copper(I) Oxide. Dissolve 2.5 g of copper vitriol (copper sulphate pentahydrate) in 15 ml of warm water and add 1.5 g of glucose. Heat the solution and rapidly add 2.5 ml of a 20% sodium hydroxide solution to it. Stir the mixture and let it stand for an hour. Wash the precipitate with distilled water. Write the equations of the reactions. 

Potassium permanganate adsorbed on copper sulfate pentahydrate oxidizes dithiol 112 into 1,2-dithiepane 113 (Equation 35) <1998S1587>. 

The role of the supports in the reactions just described is not clear. Even less clear is the function of copper sulfate pentahydrate, in the presence of which oxidations with solid potassium permanganate result in excellent yields of ketones. Traces of water are essential. Primary alcohols, on the other hand, give poor yields of aldehydes and acids [844 (equation 255). 

COPPER SULFATE PENTAHYDRATE (7758-98-7) Violent reaction with strong bases, hydroxylamine, magnesium. Contact with potassium chlorate is potentially explosive. Incompatible with acetylene. Aqueous solution is an acid incompatible with sulfuric acid, caustics, ammonia, aliphatic amines, alkanolamines, amides, alkylene oxides, epichlorohydrin, organic anhydrides, isocyanates, vinyl acetate. 

Copper oxide (ic) Cupric sulfate anhydrous Cupric sulfate pentahydrate Lithium bromide Nickel... 

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. 

Dissolve 35 g (0.14 mol) of copper(n) sulphate pentahydrate and 9.2 g (0.157 mol) of pure sodium chloride in 125 ml of water warming may be necessary. Add a solution of 8.4 g (0.044 mol) of sodium metabisulphite (1) in 90 ml of water to the hot solution during about 5 minutes with constant shaking. Cool to room temperature (use an ice bath if neccessary) and decant the supernatant liquor from the colourless copper(i) chloride. Wash the precipitate twice by decantation with water containing a little dissolved sulphur dioxide, the latter to prevent oxidation. For most purposes a solution of copper(i) chloride is required the moist copper(i) chloride is dissolved in 60 ml of concentrated hydrochloric acid. The solution should be used within 24 hours of its preparation as it tends to oxidise (and therefore darken) on keeping. If it is not to be used immediately, the solution is kept in a tightly stoppered bottle (2). If the dry solid copper(i)... 

The remainder of Richards s work on copper by chemical methods concerned the composition of cupric oxide and cupric sulphate, and was undertaken principally with the object of investigating the nature and magnitude of the errors of earlier workers. Cupric oxide prepared from the nitrate by ignition was found to contain occluded gases, mainly nitrogen. The impossibility of avoiding partial decomposition in the preparation of cupric sulphate free from water by dehydration of the pentahydrate was also demonstrated. At 260° C. the salt retains more than 0-1 per cent, of water, and at 400° C. 0-042 per cent. These errors vitiated the results of most of the early workers on the atomic weight of copper, and explain the low values found by Hampe. 

The synthesis of 7-methoxyindole was accomplished starting from 1-acetylindoline (34). Regioselec-tive intr uction of iodine was achieved using thallium trifluoroacetate, then potassium iodide. Deacetylation and oxidation to the indole (35), followed by reaction with sodium methoxide in DMF, gave the 7-methoxyindole (36) in 48% overall yield (Scheme 13). More recently, Somei et al have reported that treating the intermediate thallium species with copper(II) sulfate pentahydrate gives directly the l-acetyl-2,3-dihydro-7-hydroxyindole (37) in 42% yield (Scheme 14). It remains to be seen whether this is a general process. 

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