Cupric Chloride Dehydrate

Chemical Designations - Synonyms Cupric Chloride Dehydrate Eriochalcite (anhydrous) Chemical Formula CuCljHjO. 

Cupric chloride or copper(II) chloride [7447-39 ], CUCI2, is usually prepared by dehydration of the dihydrate at 120°C. The anhydrous product is a dehquescent, monoclinic yellow crystal that forms the blue-green orthohombic, bipyramidal dihydrate in moist air. Both products are available commercially. The dihydrate can be prepared by reaction of copper carbonate, hydroxide, or oxide and hydrochloric acid followed by crystallization. The commercial preparation uses a tower packed with copper. An aqueous solution of copper(II) chloride is circulated through the tower and chlorine gas is sparged into the bottom of the tower to effect oxidation of the copper metal. Hydrochloric acid or hydrogen chloride is used to prevent hydrolysis of the copper(II) (11,12). Copper(II) chloride is very soluble in water and soluble in methanol, ethanol, and acetone. 

Cupric chloride [7447-39-4] M 134.4, m 498 , 630 (dec). Crystd from hot dilute aq HCl (0.6mL/g) by cooling in a CaCl2-ice bath. Dehydrated by heating on a steam-bath under vacuum. It is deliquescent in moist air but efflorescent in dry air. 

Dehydration of /3-hydroxy ketones [1, 235, before references]. Schmidt and Moos-miiller29 reported that the reaction of carbodiimides with primary and secondary alcohols is catalyzed by cupric chloride. Corey et al,30 in a synthesis of prostaglandins, found that the reaction of (8-hydroxy ketones with DCC catalyzed by cupric chloride is a useful method for dehydration to the a S-unsaturated ketone under mild, nonacidic, nonbasic conditions. Presumably the hydroxyl group reacts to form a carbamidate derivative which undergoes cycloelimination. 

In this section, consideration will be given to the actual processes of acetal- or ketal-formation and not to the more indirect methods by which acetals and ketals of the polyhydric alcohols may be synthesized from compounds (e.g. derivatives of the monosaccharides) containing preformed alkylidene or arylidene groupings. The condensation of a carbonyl compound with a glycol is facilitated by acidic catalysts, and, since the reaction is reversible, by dehydration. The catalysts most frequently employed are concentrated sulfuric, hydrochloric and hydro-bromic acids, gaseous hydrogen chloride, zinc chloride and cupric sulfate others are phosphorus pentoxide, sulfosalicylic acid, and anhydrous sodium sulfate. The formation of benzylidene compounds is promoted less efficiently by phosphorus pentoxide than by either concentrated sulfuric acid or concentrated hydrochloric acid 1" the reaction is assisted by chloro- and nitro-substituents on the aromatic nucleus, but hindered by methyl- and methoxy-groups.18... 

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